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High quality pork is consumed as fresh meat, whereas other carcasses are used in the processing industry. Meat quality is determined measuring technical muscle variables. The objective of this research was to investigate the molecular regulatory mechanisms underlying meat quality differences of pork originating from genetically different Pietrain boars. Pietrain boars were approved for high meat quality using a DNA marker panel. Other Pietrain boars were indicated as average. Both groups produced litters in similar Pietrain sows. The LM were sampled from 9 carcasses produced by approved boars and 8 carcasses of average boars. Total RNA was isolated, and an equal portion of each sample was pooled to make a reference sample representing the mean of all samples. Each sample was hybridized on microarrays against the reference in duplicate using a dye swaps design. After normalization and subtraction of 2 times the background, only genes expressed in at least 5 carcasses were analyzed. For all analyses the mean of the M-values relative to the reference (i.e., fold change), were used. Sixteen genes showed significant linear or quadratic associations between gene expression and meat color (Minolta [a.sup.*] value, Minolta [L.sup.*] value, reflection, pH 24 h) after Bonferroni correction. All these genes had expression levels similar to the reference in all carcasses. Studying association between gene expression levels and meat quality using only genes with expression statistically differing from the reference in at least 5 carcasses revealed 29 more genes associating with the technological meat quality variables, again with meat color as a main trait. These associations were not significant after Bonferroni correction and explained less of the phenotypic variation in the traits. Bioinformatics analyses with The Database for Annotation, Visualization and Integrated Discovery (DAVID) using the list of genes with more than 2-fold changed expression level revealed that these genes were mainly found in muscle-specific processes, protein complexes, and oxygen transport, and located to muscle-specific cellular localizations. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed pathways related to protein metabolism, cellular proliferation, signaling, and adipose development differing between the 2 groups of carcasses. Approved meat carcasses showed less variation in gene expression. The results highlight biological molecular mechanisms underlying the differences between the high meat quality approved and average boars. Key words: association study, bioinformatics analysis, high fresh meat quality tested boar, longissimus, microarray, Sus scrofa Pietrain doi: 10.2527/jas.2010-2952

The value of incorporating spray-dried plasma (SDP) into the diet of weanling pigs to improve feed intake and growth performance has been well documented. However, limited work has been done to confirm that the spray-drying process eliminates all viral contaminates including porcine circovirus type 2 (PCV2). To determine the effect of spray-drying on PCV2 infectivity, colostrum-fed, crossbred, specific-pathogen-free (SPF) pigs were inoculated with PCV2-contaminated SDP intraperitoneally (SDP-IP) or by oral gavage (SDP-OG), inoculated intraperitoneally with PCV2-positive plasma (POS), or left uninoculated (NEG). The plasma used for the experimentally produced SDP was collected from a SPF pig experimentally infected with a PCV2b isolate. Pigs in the NEG group remained seronegative, and PCV2 viremia was not detected. All pigs in the POS group became PCV2 viremic by 14 d postinoculation (DPI) and seroconverted by 28 DPI. In the SDP-IP group, all pigs became viremic by 35 DPI and seroconverted by 49 DPI. In the SDP-OG group, all animals became viremic by 35 DPI and 2/3 pigs seroconverted by 35 DPI. There were no significant (P > 0.05) differences between anti-PCV2-IgG antibody sample-to-positive ratios among pigs in the POS, SDP-OG, or SDP-IP groups. This work provides direct evidence that the experimental spray-drying process used in this study was not effective in inactivating PCV2b in the plasma of a PCV2-infected pig based on a swine bioassay using PCV2-naive pigs. This work suggests that SDP sourced from pigs could represent a biosecurity risk for the industry. Key words: porcine circovirus type 2, seroconversion, spray-dried plasma, viremia doi: 10.2527/jas.2009-2696

Increasing dietary electrolyte balance (dEB) has previously been shown to reduce the incidence of nonambulatory and noninjured swine, improve meat quality, and reduce the incidence of gastric ulcers. The objective of this study was to evaluate the effect of dEB under commercial conditions. Due to the variability in feed withdrawal, transport, and lairage conditions in the swine industry, it was necessary to determine first the persistence of blood changes during the marketing process after alteration of dEB. Sixteen pens of 8 crossbred barrows were assigned to a low (121 mEq/kg) or high (375 mEq/kg) dEB diet, calculated as [Na.sup.+] + [K.sup.+] - [Cl.sup.-], to determine the persistence of blood changes associated with the alteration of dEB. Diets were formulated to meet or exceed NRC (1998) requirements for energy, protein, vitamins, and minerals. Dietary treatments were provided for ad libitum intake for 3 d before slaughter. Before transport, animals were fasted in the barn for approximately 10 h. After fasting, animals were shipped to the packing plant, rested for 8 h, and subsequently slaughtered. Initial and final BW of the animals were obtained. Blood was sampled at baseline (2 d before administration of diets), before feed withdrawal (0 h), after feed withdrawal (10 h), and at exsanguination (20 h). Consumption of the high dEB diet for 3 d resulted in an increase in blood TC[O.sub.2] (P = 0.001), HC[O.sub.3.sup.-] (P = 0.001), and base excess (P = 0.0003) and a decrease in [Cl.sup.-] (P = 0.0002) and anion gap (P = 0.01). These differences, however, were not maintained for any of the blood components after the 10-h feed withdrawal (P > 0.22). Increasing dEB had no adverse effects (P > 0.18) on growth performance, meat quality, or carcass yield and did not decrease pars esophageal ulcer scores. This study demonstrated that the effect of dEB on blood components was not maintained after a 10-h feed withdrawal. Therefore, it is likely that the ability of the animal to withstand any increased metabolic acid load associated with the stress of transport was lost after feed withdrawal. Further research is needed to determine the effects of dEB alteration in animals that have not been fasted before shipment and using diets with a larger difference in dEB. Key words: acidosis, cation-anion balance, dietary electrolyte balance, swine doi: 10.2527/jas.2009-2139

Although there is increasing evidence regarding the negative welfare and meat quality implications of electric prod use for slaughter-weight pigs, this handling tool continues to be used. Therefore, the behavioral and physiological response and carcass and meat quality of 360 pigs being loaded onto a truck for transportation to slaughter according to 3 handling procedures were studied. The 3 handling procedures were 1) moving with an electric prod and board from the finishing pen to the truck (EP); 2) moving with a board and a paddle from the finishing pen to the truck (PAD); 3) moving with a board and a paddle from the finishing pen and using a compressed air prod in the ramp before going into the truck (CAP). A subpopulation of 144 pigs (48 pigs/treatment) was equipped with heart rate monitors. Blood samples were collected from the same animals at exsanguination for the analysis of creatine phosphokinase and lactate. Data were analyzed using an ANOVA for factorial design, with the animal as the experimental unit. Behavior was analyzed with MIXED model procedure with treatment as a fixed effect. During loading, EP pigs slipped and fell (P < 0.001) and overlapped (P = 0.03) more often, but stopped (P < 0.001) and attempted turns (P = 0.01) less often than CAP or PAD. With CAP, pigs made more 180[degrees] turns (P = 0.01) than with PAD or EP. Loading with EP led to more and longer vocalizations (P = 0.02 and P = 0.001, respectively) than loading with CAP or PAD. Loading took longest with CAP and was quickest with EP (P = 0.01). Pigs handled with EP had a greater heart rate than those moved with PAD and CAP at loading (P < 0.001), wait at loading (P < 0.001), at unloading (P = 0.05), and in lairage (P = 0.02). Pigs loaded with EP had greater (P = 0.05) lactate concentrations in blood at exsanguination compared with pigs handled with CAP, with pigs loaded with PAD being intermediate. Furthermore, ultimate pH values in the semimembranosus and adductor muscles of EP pigs were greater (P = 0.002 and P = 0.004, respectively) compared with those from PAD and CAP pigs. Greater (P = 0.04) incidence of blood-splashed hams was found in EP pigs compared with PAD and CAP pigs. Therefore, considering animal welfare, carcass bruising, and blood splashes standpoints, EP should be replaced with PAD or CAP. However, additional research is necessary to identify methods that improve the loading efficiencies of PAD and CAP without adversely affecting animal welfare parameters. Key words: behavior, blood metabolite, handling, heart rate, meat quality, pig doi: 10.2527/jas.2010-2833

After slaughter of pigs, the pH of the meat decreases due to lactate accumulation within the tissue. In addition to calcium homeostasis, energy metabolism plays a key role during the muscle-to-meat transition, and it is interesting to know how specific enzymes of the glycolytic and oxidative pathways change during this process, especially in relation to the antemortem situation, and if there is an impact of these alterations on the meat quality characteristics. Therefore, in the present study samples of the LM from the pig genetic groups Pietrain (Pi), Duroc (Du), and a Du x Pi crossbreed population (DuPi) were collected 24 h before as well as 1 min, 40 min, and 12 h after slaughter, and the activities of the glycogen phosphorylase (GP), phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), NADH-ubiquinone oxidoreductase (complex I), and cytochrome oxidase were analyzed. Additional investigations include carcass and meat quality characteristics as well as the microstructure of the LM. The Pi breed had greater (P < 0.05) carcass yield and lean meat values, but no differences (P > 0.05) of the meat quality traits could be determined between the investigated pig breeds. The Pi pigs exhibited a greater (P < 0.05) percentage of fast-twitch glycolytic and had smaller amounts (P < 0.05) of slow-twitch-oxidative fibers in comparison with the Du pigs. The enzyme activities of the GP, PFK, and complex I increased (P < 0.05) immediately after slaughter (1 min postmortem) of the pigs and the activity of the LDH within 40 rain postmortem. After 12 h, the GP, PFK, LDH, and complex I activities decreased to the amount of the preslaughter sample. No differences could be found with regard to the enzyme activities of the CS and cytochrome oxidase at all determination times. Considering the enzyme activities within the different breeds, the Pi pigs exhibited greater (P < 0.05) GP and PFK and the Du animals exhibited greater (P < 0.05) CS and complex I activities. The study indicates that the glycolytic enzymes GP, PFK, and LDH as well as the complex I influence the muscle-to-meat transition process after slaughter of the animals without an impact on the muscle quality. The activities of the GP, PFK, CS, and complex I reflect the differences of the muscle fiber composition between the Pi and Du pigs. Key words: carcass characteristic, glycolytic and oxidative enzyme, meat quality, muscle structure, pig doi: 10.2527/jas.2010-3136

The application of phytase in conventional dry swine diets has been shown to improve P availability and utilization. The effectiveness of phytase may be further improved by steeping feedstuffs with phytase before feeding. A study was conducted to determine the value of steeping high-moisture corn (HMC) with phytase in P-deficient liquid diets for starter pigs. A total of 384 pigs were weaned at 19 to 23 d of age and 6.7 [+ or -] 0.1 kg of BW. Pigs were randomly assigned to pens, with 8 barrows and 8 gilts per pen and 5 pens per dietary treatment (only 4 pens for the control treatment). The 5 dietary treatments (all HMC-based 3-phase feeding programs) were 1) negative control with no added phytase, 2 and 3) negative control with phytase added to the HMC to achieve 62.5 or 125 phytase units (FTU)/kg of HMC (DM basis) of phytase added to the HMC and allowed to steep for 24 h before feeding, and 4 and 5) negative control with the same amount of phytase added to the base mix without steeping before feeding. Total P content (88% DM basis) averaged 0.49% in phase I and 0.37% in phase II and III diets. Individual pig BW and per pen ADFI were measured on a weekly basis. Apparent total tract digestibility of DM, OM, CP, P, and Ca were measured using titanium dioxide as an indigestible marker in phase III diets. At the end of the study (7 wk postweaning), 4 pigs from each pen were killed for assessment of body composition, breaking strength and mineral content of metacarpals, total and soluble P content in duodenal digesta, and urinary P content. There was no effect of added phytase on ADG, ADFI, or G:F. The soluble P:total P ratio in duodenal digesta was increased with the addition of phytase (P < 0.05). Steeping HMC with phytase resulted in greater digestibility of DM and CP (P < 0.01). A trend toward increased digestibility of Ca with added phytase was observed (P = 0.07), but there was no effect of dietary treatment on P digestibility. Urinary P content was considerably greater in pigs fed diets with exogenous phytase (P < 0.05). Additional phytase resulted in increased P and Ca content in the empty body (P < 0.05). Metacarpal content of P (P < 0.05) and Ca (P = 0.07) and breaking strength (P < 0.05) were improved with added phytase. Despite a lack of effect on P digestibility, added phytase improved retention of Ca and P in starter pigs fed P-deficient HMC-based liquid diets. There was little benefit from steeping HMC with phytase before feeding. Key words: high-moisture corn, liquid feed, performance, phosphorus, phytase, starter pig doi: 10.2527/jas.2010-3011

The present project aimed to estimate bioavailability of dietary vitamin B12, for which little information is available in growing pigs. Two approaches, each using 2 quantities of dietary cyanocobalamin, were compared; the first was based on whole body retention for 8 d and the second was based on nycthemeral portal net flux of vitamin [B.sub.12]. In the first trial, 15 blocks of 3 pigs (31.7 [+ or -] 0.5 kg of BW) were formed according to their vitamin [B.sub.12] status. Within each block, 1 pig (CONT) was killed and tissues were sampled for vitamin [B.sub.12] determination. The remaining 2 piglets were fed 25 ([B.sub.12]-25) or 250 ([B.sub.12]-250) [micro]g daily of cyanocobalamin for 8 d. Urine was sampled twice daily, and the pigs were killed and sampled as CONT pigs. The total content of vitamin [B.sub.12] in the carcass, urine, and intestinal tract was affected by the dietary treatments (P < 0.01) but not in the liver (P > 0.019). The whole body retention of vitamin B12 was greater (P = 0.02) in [B.sub.12]-250 than [B.sub.12]-25 pigs, but the corresponding bioavailability was estimated to be 5.3 and 38.2%, respectively. In trial 2, 11 pigs (35.1 [+ or -] 4.0 kg of BW and 75.4 [+ or -] 5.9 d of age) fed a diet unsupplemented with vitamin [B.sub.12] from weaning at 28 d of age were surgically equipped with catheters in the portal vein and carotid artery and an ultrasonic flow probe around the portal vein. Each pig received 3 boluses of 0 ([B.sub.12]-0), 25, and 250 [micro]g of dietary vitamin [B.sub.12] according to a crossover design. Postprandial nycthemeral arterial plasma concentrations of vitamin [B.sub.12] reached minimum values (P < 0.01) between 15 and 18 h postmeal that were 29.6, 15.6, and 10.0% less than the premeal values for [B.sub.12]-0, [B.sub.12]-25, and [B.sub.12]-250 pigs, respectively (linear, P < 0.01). The cumulative net flux of vitamin [B.sub.12] for 24 h corresponded to 2.4 and 5.1 [micro]g for [B.sub.12]-25 and [B.sub.12]-250 treatments, respectively, and the corresponding bioavailability was estimated to be 9.7 and 2.0%, respectively. Although bioavailability estimates varied according to approaches, both showed the inverse relationship between dietary vitamin [B.sub.12] and bioavailability of the vitamin. The dietary supplement of 25 [micro]g was sufficient to maximize hepatic vitamin [B.sub.12] retention and to attenuate the nycthemeral decrease of arterial plasma concentration of the vitamin. Key words: cyanocobalamin, intestinal absorption, pig, retention, vitamin [B.sub.12] doi: 10.2527/jas.2010-2979

Sirtuin 1 (Sirt1) plays an important role in fat metabolism. In the current study, we examined the breed differences in Sirt1 between Jinhua pigs (a fatty breed of China) and Landrace pigs (a leaner breed). In addition, the effect of insulin on the gene expression of Sirt1 and the major lipase, adipose triglyceride lipase (ATGL), and hormone-sensitive lipase (HSL) in fat metabolism was also studied in vitro. Compared with the Landrace pigs, the BW of Jinhua pigs was less (P < 0.01), whereas the body fat content were greater (P < 0.01). The protein content and the mRNA abundance of Sirt1 in Jinhua pigs were less (P < 0.01) in subcutaneous adipose tissues compared with the Landrace pigs. Likewise, the mRNA abundance of ATGL and HSL were also less (P < 0.01) in Jinhua pigs. In vitro, treatment with a different dose of insulin (10, 50 and 100 nM) decreased (P < 0.01) glycerol release and the mRNA abundance of Sirt1, ATGL, and HSL in porcine adipocytes. Likewise, treatment with 50 nM insulin for 24 and 48 h also decreased (P < 0.05) glycerol release and the expression of Sirt1, ATGL, and HSL in porcine adipocytes. Furthermore, insulin and Sirt1-specific small interfering RNA treatment decreased (P < 0.01) the expression of Sirt1, ATGL, and HSL compared with the control or insulin treatment. These results indicate that insulin may regulate transcription of Sirt1, ATGL, and HSL in porcine adipocytes and provide information for manipulating these gene expressions in regulating fat metabolism in pigs. Key words: adipose triglyceride lipase, hormone sensitive lipase, insulin, pig, Sirtuin 1 doi: 10.2527/jas.2010-2880

In Exp. 1, 50 sows and their litters were used to determine the effects of adding a feed flavor to the creep diet on the proportion of pigs consuming creep feed ('eaters') and preweaning performance. Sows were blocked according to parity and date of farrowing and allotted to 2 experimental treatments: 1) litters fed a creep diet with no flavor (negative control) or 2) negative control diet with the feed flavor (Luctarom) included at 1,500 mg/kg. Both creep diets contained 1.0% chromic oxide and were offered ad libitum from d 18 until weaning at d 21. Adding flavor to the creep diet did not (P > 0.41) affect weaning weights, total BW gain, ADG, total creep feed intake, daily creep feed intake, or the proportion of creep feed eaters in whole litters. In Exp. 2, 480 weanling pigs (6.58 [+ or -] 0.41 kg; 20 [+ or -] 2 d) from Exp. 1 were randomly selected by preweaning treatment group, blocked by initial BW, and allotted to 1 of 8 treatments in a randomized complete block design to determine the interactive effects of preweaning exposure to flavor (exposed vs. unexposed), nursery diet complexity (complex vs. simple), and flavor addition to nursery diets (with vs. without flavor). Each treatment had 10 replications (pens) with 6 pigs per pen. Diets with flavor were supplemented with the flavor at 1,500 mg/kg in phase 1 diets and 1,000 mg/kg in phase 2 diets. A tendency for a 3-way interaction for ADG from d 5 to 10 (P = 0.10), 10 to 28 (P = 0.09), and 0 to 28 (P = 0.06) was observed. Postweaning ADG of pigs exposed to flavor in creep feed and fed flavored complex diets in the nursery was greater than pigs in any other treatment combination. Increasing diet complexity improved (P < 0.01) ADG and ADFI during both postweaning phases. Adding flavor to creep feed had no effect on G:F (P > 0.34) and pig BW (P > 0.45) in both postweaning periods. Adding flavor to starter diets tended to improve ADFI (P = 0.06) during d 0 to 5. In conclusion, adding flavor to the creep feed did not affect litter creep feed intake, the proportion of piglets consuming creep feed, or preweaning performance when creep was provided for 3 d before weaning. Preweaning exposure to feed flavor improved postweaning ADG in pigs fed complex diets supplemented with the same flavor but did not influence performance of pigs fed simple diets. Key words: creep feeding, diet complexity, feed flavor, pig doi: 10.2527/jas.2009-2724

We developed and implemented change-point recursive models and compared them with a linear recursive model and a standard mixed model (SMM), in the scope of the relationship between litter size (LS) and number of stillborns (NSB) in pigs. The proposed approach allows us to estimate the point of change in multiple-segment modeling of a nonlinear relationship between phenotypes. We applied the procedure to a data set provided by a commercial Large White selection nucleus. The data file consisted of LS and NSB records of 4,462 parities. The results of the analysis clearly identified the location of the change points between different structural regression coefficients. The magnitude of these coefficients increased with LS, indicating an increasing incidence of LS on the NSB ratio. However, posterior distributions of correlations were similar across subpopulations (defined by the change points on LS), except for those between residuals. The heritability estimates of NSB did not present differences between recursive models. Nevertheless, these heritabilities were greater than those obtained for SMM (0.05) with a posterior probability of 85%. These results suggest a nonlinear relationship between LS and NSB, which supports the adequacy of a change-point recursive model for its analysis. Furthermore, the results from model comparisons support the use of recursive models. However, the adequacy of the different recursive models depended on the criteria used: the linear recursive model was preferred on account of its smallest deviance value, whereas nonlinear recursive models provided a better fit and predictive ability based on the cross-validation approach. Key words: Bayesian analysis, change point, litter size, piglet mortality, recursive model doi: 10.2527/jas.2009-2557

This study estimated the long-term exposure of fumonisin B1 (FB1) in nursery swine diets and associated toxicological adverse effects on negative productivity potential using quantitative exposure assessment. Fumonisin [B.sub.1] is a mycotoxin produced by Fusarium verticillioides and Fusarium proliferatum and is a common biological contaminant of corn (Zea mays L.) and other grains. Acute effects from [FB.sub.1] exposures are well recognized and managed in the swine industry, but practices to limit prolonged low-dose exposures to [FB.sub.1] have been less fully considered and may negatively affect production efficiency. Deterministic (single-point estimates) and stochastic (probabilistic) modeling were performed for comparative analyses of [FB.sub.1] exposures originating from genetically engineered Bacillus thuringiensis (Bt)-corn, conventional non-Bt corn, and distillers dried grains with solubles (DDGS). Six feeding scenarios differing in the source of corn in diets were modeled to assess variation in FB1 exposure representing a mixture of 1) Bt and non-Bt grain and DDGS (blended); 2) Bt grain and Bt DDGS; 3) non Bt grain and non-Bt DDGS; 4) Bt and non-Bt grain; 5) Bt grain; and 6) non-Bt grain. Long-term exposure estimates (49-d duration) were compared with chronic levels of concern (LOC). The first LOC (LOC1; 1 mg of [FB.sub.1]/kg of diet, least observed adverse effects concentration) represents a decrease in ADG. Concentrations of 5 mg of [FB.sub.1]/kg of diet represent the second LOC (LOC2), which showed pulmonary pathological alterations and a significant dose-dependent increase in pulmonary weight. Estimates indicated LOC1 was frequently exceeded regardless of feeding scenario, but LOC2 was not attained. Diets where the corn fraction was entirely from Bt-corn showed the least [FB.sub.1] exposure (exceeding LOC1 in 35% of occasions), whereas a blended diet or diets using non-Bt grain and DDGS sources more commonly exceeded this threshold (95% of occasions). Based on these estimates, under blended corn source feeding conditions, swine populations in nursery facilities may frequently exhibit incipient effects (i.e., LOC1) of [FB.sub.1] toxicity; however, impacts on production efficiency remain uncertain. Key words: Bacillus thuringiensis corn, diet, distillers dried grains with solubles, fumonisin, risk assessment, swine doi: 10.2527/jas.2009-2422

We evaluated the preferences of nursery pigs for diets containing increasing distillers dried grains with solubles (DDGS), varying in color, or high-protein distillers dried grains (HP-DDG) and the effects of flavor supplementation on pig preference and growth performance. In Exp. 1 through 5, diet preference was determined in weanling pigs adjusted to a commercial diet for at least 10 d, and then housed individually for a 2-d double-choice preference test. In Exp. 1, a total of 60 pigs (11.6 [+ or -] 0.3 kg of BW) were given a choice between a reference diet (0% DDGS) and test diets containing 0, 10, 20, or 30% DDGS. In Exp. 2, a total of 80 pigs (10.8 [+ or -] 0.1 kg of BW) were given a choice between a reference diet (0% HP-DDG) and diets containing 0, 10, 20, or 30% HP-DDG. In Exp. 3, a total of 80 pigs (10.3 [+ or -] 0.2 kg of BW) were given a choice between a reference diet (0% DDGS) and a diet containing 0%, 30% light, or 30% dark DDGS. In Exp. 4, a total of 80 pigs (11.2 [+ or -] 0.2 kg of BW) were given a choice between a reference diet without DDGS and a diet containing either 0% DDGS, 10 or 20% light DDGS, or 10 or 20% dark DDGS. In Exp. 5, a total of 108 pigs (9.0 [+ or -] 0.2 kg of BW) were given a choice between a reference diet (0% DDGS and no flavor) and a diet without or with flavor and containing 0, 10, or 20% DDGS. In Exp. 1 and 2, DDGS and HP-DDG, respectively, linearly decreased (P < 0.01) pig preference. In Exp. 3, dark DDGS were preferred (P < 0.05) compared with light DDGS. In Exp. 4, preferences were linearly reduced (P < 0.01) with DDGS inclusion, and dark DDGS tended (P = 0.06) to be preferred compared with light DDGS. In Exp. 5, DDGS reduced preference (P < 0.01) and flavor reduced preference (P < 0.01) regardless of DDGS level. In Exp. 6, a total of 192 pigs (6.7 [+ or -] 0.1 kg of BW) were fed starter 1 diets without or with flavor for 1 wk. Subsequently, pigs were fed starter 2 and 3 diets (2 wk each) containing 0, 10, or 20% DDGS while continuing to receive their respective flavor treatment. Flavor addition during the starter 1 phase increased ADFI (P = 0.02), and DDGS inclusion tended to decrease ADG (P = 0.06) and decreased ADFI (P = 0.03) during the starter 2 phase. Volatile components in DDGS and HPDDG varied greatly depending on the source. Nursery pigs preferred a diet without DDGS or HP-DDG, and this appeared to be unrelated to color differences between sources. Knowledge of volatile compounds that enhance or suppress the palatability of feed may lead to further development of feed additives for masking relatively unpalatable, albeit cost-effective, ingredients. Key words: distillers grains, flavor, palatability, performance, pig, preference doi: 10.2527/jas.2009-2640

Ninety-six Large White growing barrows were used to determine the effect of temperature on thermoregulatory responses during acclimation to increased ambient temperature. Pigs were exposed to 24[degrees]C for 10 d and thereafter to a constant temperature of 24, 28, 32, or 36[degrees]C for 20 d. The study was conducted in a climate-controlled room at the INRA experimental facilities in Guadeloupe, French West Indies. Relative humidity was kept constant at 80% throughout the experimental period. Rectal temperature, cutaneous temperature, and respiratory rate were measured [breaths per minute (bpm)] 3 times daily (0700, 1200, and 1800 h) every 2 or 3 d during the experiment. The thermal circulation index (TCI) was determined from rectal, cutaneous, and ambient temperature measurements. Changes in rectal temperature, respiratory rate, TCI, and ADFI over the duration of exposure to hot temperatures were modeled using nonlinear responses curves. Within 1 h of exposure to increased temperature, rectal temperature and respiratory rate increased by 0.46[degrees]C/d and +29.3 bpm/d, respectively, and ADFI and TCI decreased linearly by 44.7 g x [d.sup.-2] x [kg.sup.-0.60] and 1.32[degrees]C/d, respectively until a first breakpoint time ([td.sub.1]). This point marked the end of the short-term heat acclimation phase and the beginning of the long-term heat acclimation period. The td1 value for ADFI was greater at 28[degrees]C than at 32 and 36[degrees]C (2.33 vs. 0.31 and 0.26 d, respectively, P < 0.05), whereas [td.sub.1] for the TCI increase was greater at 36[degrees]C than at 28 and 32[degrees]C (1.02 vs. 0.78 and 0.67 d, respectively; P < 0.05). For rectal temperature and respiratory rate responses, [td.sub.1] was not influenced by temperature (P > 0.05) and averaged 1.1 and 0.89 d, respectively. For respiratory rate and rectal temperature, the long-term heat acclimation period was divided in 2 phases, with a rapid decline for both variables followed by a slight decrease (P < 0.05). These 2 phases were separated by a second threshold day ([td.sub.2]). For rectal temperature, [td.sub.2] increased significantly with temperature (1.60 vs. 5.16 d from 28 to 36[degrees]C; P < 0.05). After [td.sub.2], the decline in rectal temperature during the exposure to thermal challenge was not influenced by temperature, suggesting that the magnitude of heat stress would affect thermoregulatory responses only at the beginning of the long-term heat acclimation period. The inclusion of random effects in the nonlinear model showed that whatever the temperature considered, interindividual variability of thermoregulatory responses would exist. Key words: acclimation, heat stress, nonlinear mixed model, swine, temperature doi: 10.2527/jas.2009-2169

Nursery pigs are vulnerable to environmental risks associated with the microclimate and aerial contaminants. This study was carried out to assess the effect of microclimate (i.e., temperature, relative humidity, and air speed) on the quantity of particulate matter (PM), airborne bacteria, and odorants in nursery houses. Data were collected from 15 farms in different locations throughout South Korea during 4 seasons; daily sampling times were from 1000 to 1100 h in the morning. A nonparametric correlation analysis revealed correlations between microclimate variables and airborne contaminants in different seasons. Over the entire year, negative correlations were observed between temperature, air speed, and some odorous compounds (P < 0.05). Furthermore, negative correlations were observed between temperature, air speed, and relatively large airborne particulates, such as PM10 (PM mean aerodynamic diameter [less than or equal to] 10 [micro]m), [PM.sub.7] (PM mean aerodynamic diameter [less than or equal to] 7 [micro]m), and total suspended particles (P < 0.05). A possible reason for these negative correlations is that increased ventilation at an increased room temperature could transfer most airborne particulates that are carried with odorous compounds out of the nursery houses. On the other hand, because of the sensitivity of coliform bacteria to temperature, positive correlations were observed between temperature and total coliform and Escherichia coli counts (P < 0.01). Because it is a challenging task to control the quantity of aerial contaminants in nursery houses, the relationships between the microclimate and airborne contaminants established in this study could be used to reduce those contaminants by controlling microclimate variables. The correlations established in the current study could also be helpful in establishing guidelines for good management practices in nursery houses. Key words: airborne bacteria, microclimate, odorous compound, particulate matter doi: 10.2527/jas.2009-2399

A total of 1,112 pigs (initial BW of 49.8 kg) were used in a 78-d study to evaluate the effects of 0, 5, 10, 15, or 20% dried distillers grains with solubles (DDGS) and sex on carcass fat quality of finishing pigs. All diets contained 6% choice white grease and were fed in 4 finishing phases (50 to 59, 59 to 82, 82 to 105, and 105 to 123 kg, respectively). The experiment was conducted in a commercial research finishing barn in southwestern Minnesota. There were 9 replicates of each dietary treatment, with 25 to 28 pigs per pen, and barrows and gilts were distributed equally in each pen. On d 57, the 3 heaviest barrows from each pen were visually selected, removed, and marketed, and a total of 6 pigs per treatment were selected randomly for fatty acid analysis. On d 78, the remaining pigs from each pen were individually tattooed and shipped to a pork processing plant. Jowl fat, backfat, and belly fat samples were collected from 1 barrow and 1 gilt chosen randomly from each pen and analyzed for fatty acid composition. Iodine value (IV) was calculated for diets and fat samples. Fat quality data were analyzed as a split plot with DDGS treatment as the whole plot and sex as the subplot. Concentrations of C18:2n-6, PUFA, and IV increased (linear, P = 0.02) with increasing DDGS in backfat, jowl fat, and belly fat in pigs marketed on d 57 and 78. In contrast, C18:1 cis9 and MUFA concentrations decreased linearly (P = 0.05) in all 3 fat depots with increasing DDGS. For every 10% DDGS included in the diet, IV of backfat, jowl fat, and belly fat increased by 2.3, 1.6, and 2.2 g/100 g, respectively. In pigs slaughtered on d 78, there were no (P [greater than or equal to] 0.10) sex x dietary DDGS interactions observed. Compared with barrows, gilts had greater (P < 0.05) C18:2n-6, PUFA, and PUFA:SFA ratio and lesser (P < 0.03) C14:0 concentrations in backfat and belly fat but not jowl fat. Gilts had greater (P = 0.03) belly fat IV than barrows, but there were no (P > 0.25) differences between gilts and barrows in backfat and jowl fat IV. In summary, feeding increasing amounts of DDGS linearly increased the IV of backfat, jowl fat, and belly fat in pigs. Although jowl fat was less responsive to increased DDGS than backfat and belly fat, pigs fed diets with 20% DDGS and 6% choice white grease exceeded the maximum jowl IV of 73 g/100 g set by some packing plants. Key words: dried distillers grains with solubles, fat quality, iodine value, pig doi: 10.2527/jas.2010-2937

In 2 experiments, a total of 184 pigs (PIC, initial BW of 10.3 and 9.7 kg for Exp. 1 and 2, respectively) were used to develop an available P (aP) release curve for commercially available Escherichia coli-derived phytases. In both experiments, pigs were fed a corn-soybean meal basal diet (0.06% aP) and 2 diets with added inorganic P (iP) from monocalcium phosphate (Exp. 1:0.075 and 0.15% aP; Exp. 2:0.07 and 0.14% aP) to develop a standard curve. In Exp. 1, 100, 175, 250, or 500 phytase units (FTU)/kg of OptiPhos 2000 or 200, 350, 500, or 1,000 FTU/kg of Phyzyme XP were added to the basal diet. In Exp. 2, 250, 500, 750, or 1,000 FTU/kg of OptiPhos 2000; 500, 1,000, or 1,500 FTU/kg of Phyzyme XP; or 1,850 or 3,700 FTU/ kg of Ronozyme P were added to the basal diet. One FTU was defined as the amount of enzyme required to release 1 [micro]mol of iP per minute from sodium phytate at 37[degrees]C. For all phytase products, the manufacturer-guaranteed phytase activities were used in diet formulation. All diets were analyzed for phytase activity using both the Phytex and AOAC methods. Pigs were blocked by sex and BW and allotted to individual pens with 8 pens per treatment. Pigs were killed on d 21, and fibulas were collected and analyzed for bone ash. In both experiments, increasing iP improved (linear, P < 0.01) G:F and percentage bone ash. Pigs fed increasing OptiPhos had improved (Exp. 1: linear, P < 0.001; Exp. 2: quadratic, P < 0.001) percentage bone ash, as did pigs fed increasing Phyzyme XP (linear, P < 0.001). In Exp. 2, increasing Ronozyme P improved (quadratic, P < 0.01) percentage bone ash. Using analyzed values from the AOAC method and percentage bone ash as the response variable, an aP release curve was developed for up to 1,000 FTU/kg of E. coli-derived phytases (OptiPhos 2000 and Phyzyme XP) in P-deficient diets. The prediction equation was Y = 0.000000125[X.sup.2] + 0.000236X + 0.016, where Y = aP release (%) and X = analyzed phytase (FTU/kg) in the diet. Key words: growth, nursery pig, phosphorus, phytase doi: 10.2527/jas.2010-2936

A study was conducted to determine the AA digestibility and energy concentration of a specialized high-protein corn distillers dried grains (HPCDDG) product and a high-protein sorghum dried distillers grains with solubles (HPS-DDGS) product. Six growing barrows (BW = 22.7 kg) were surgically fitted with T-cannulas at the terminal ileum and allotted randomly to 3 treatments in a crossover design with 3 periods. The treatment diets were 1) 67% HPC-DDG and 2) 50% HPS-DDGS as the sole protein sources, and 3) an N-free diet for determining basal endogenous AA loss. All diets contained 0.25% chromic oxide as an inert marker. Digesta and fecal samples were collected and analyzed for AA and energy concentrations. After chemical analysis, standardized and apparent ileal digestible (SID and AID, respectively) AA and GE were determined for each coproduct. The DE, ME, and NE values for HPC-DDG and HPS-DDGS also were calculated. The chemical composition of HPC-DDG and HPS-DDGS on a DM basis was 40.8% CP, 5.4% fat, 22.9% ADF, 36.6% NDF, 0.04% Ca, and 0.42% P and 48.2% CP, 3.1% fat, 17.5% ADF, 20.4% NDF, 0.13% Ca, and 0.82% P, respectively. The DM content of HPC-DDG and HPS-DDGS was 89.50 and 91.88%, respectively. Analyzed AA content of HPC-DDG was greater than that of traditional corn DDGS. The Lys content of HPC-DDG was 1.36% (DM basis), resulting in a Lys-to-CP ratio of 3.2%. In HPS-DDGS, most AA were present in greater proportions than in HPC-DDG or conventional sorghum DDGS. The HPS-DDGS Lys content was 1.7% (DM basis), equivalent to a Lys-to-CP ratio of 3.5%. In HPC-DDG, the AID for Lys, Met, Thr, and Trp were 65.9 [+ or -] 1.7, 87.0 [+ or -] 1.9, 72.8 [+ or -] 3.4, and 76.2% [+ or -] 3.5, respectively, and SID values were 67.8 [+ or -] 1.7, 87.5 4: 1.9, 75.0 [+ or -] 3.5, and 78.6 [+ or -] 3.7%, respectively. For HPS-DDGS, the AID for Lys, Met, Thr, and Trp were 51.9 [+ or -] 5.3, 73.0 [+ or -] 3.1, 60.6 [+ or -] 5.3, and 71.7 [+ or -] 3.4%, respectively, and SID values were 53.7 [+ or -] 4.9, 73.8 [+ or -] 3.0, 63.0 [+ or -] 4.9, and 73.8 [+ or -] 3.0%, respectively. The GE, DE, and calculated ME and NE values were 5,293, 3,703 [+ or -] 121, 3,426 [+ or -] 121, and 2,131 [+ or -] 88 kcal/ kg of DM, respectively, for HPC-DDG and 5,108, 3,878, 3,549, and 2,256 kcal/kg of DM, respectively, for HPS-DDGS. Results indicate that both coproducts are well suited for use in swine diets and that actual AA digestibility values and calculated energy concentrations can now be used in swine diet formulation. Key words: amino acid digestibility, dried distillers grain, energy, pig doi: 10.2527/jas.2010-3098

Castrated male Iberian (n = 12) and Landrace x Large White (n = 12) pigs were used to study histological structure and enzymatic activity in the small intestine at 3 points of the productive cycle (BW = 15, 50, and 115 kg). Both strains were fed the same cereal-based diets (DE = 2,799 kcal x [kg.sup.-1] and CP = 15%) throughout the entire experimental period. Differences (P < 0.05) in histometrical variables (villus height, width and surface, crypt depth, villus height/ crypt depth relationship, mucosal thickness, muscular layer thickness, and number of goblet cells) were found among samples of small intestinal sections (duodenum, jejunum, and ileum) at the 3 productive stages studied. Also, differences (P < 0.05) in histometrical variables of small intestinal samples were found between Iberian and lean pigs at all productive stages, although these differences tended to disappear with age. Differences (P < 0.05) in enzymatic activities (lactase, sucrase, maltase, isomaltase, aminopeptidase, and alkaline phosphatase) of small intestinal samples were found between the different intestinal sections at all productive stages studied. Although differences (P < 0.05) in enzymatic activities of small intestinal samples were found between Iberian and lean pigs at all productive stages, values tended to equalize with pig age. We concluded that differences previously found in dietary nutritional utilization between Iberian and lean strains are likely not due to differences in intestinal absorption or hydrolytic capacity. Key words: enzymatic activity, histological structure, Iberian pig, lean pig strain, small intestine doi: 10.2527/jas.2010-3040

We investigated effects of loose housing of the sow during lactation and enrichment of the pen pre- and postweaning on performance of newly weaned piglets. Before weaning, piglets (n = 320) were housed in an enriched (straw, wood shavings, peat, and branches) or barren pen with a confined or loose-housed sow (n = 32). Loose-housed sows and their piglets could eat together from a family feeder, whereas confined sows and piglets had separate feeding troughs. Piglets (n = 256) were mixed postweaning, and 4 piglets from each litter were relocated to a barren pen (n = 32 pens) and 4 other piglets were housed in an enriched pen (n = 32 pens). Growth from d 15 until weaning was greater for piglets from enriched pens (4.38 [+ or ] 0.29 vs. 4.71 [+ or ] 0.21 kg/pig, P < 0.05) and tended to be greater for piglets with a loose-housed sow compared with piglets with a confined sow (4.41 [+ or ] 0.26 vs. 4.67 [+ or ] 0.24 kg/pig, P = 0.10). Preweaning feed intake was not affected by preweaning conditions (P > 0.25). Piglets from enriched preweaning pens ate more in the first 2 d postweaning than piglets from barren pens (first 48 h, barren 0.45 [+ or ] 0.05 kg/pig, enriched 0.53 [+ or ] 0.04 kg/ pig, P < 0.05). Piglets relocated to an enriched pen after weaning showed a greater growth in the 2 wk after weaning (barren 5.5 [+ or ] 0.2 kg/pig, enriched 6.2 [+ or ] 0.2 kg/pig, P < 0.0001), had a profoundly reduced diarrhea prevalence than piglets housed in barren pens after weaning (barren 2.4 [+ or ] 0.4 d, enriched 1.0 [+ or ] 0.3 d, P < 0.0001), and had a greater feed efficiency (barren 0.81 [+ or ] 0.03, enriched 0.85 [+ or ] 0.02, P < 0.05). Enrichment of the preweaning environment likely stimulates development of feeding behaviors and consequently increases feed intake immediately after weaning. Providing piglets with an enriched environment after weaning positively affected postweaning growth, feed efficiency, and incidence of diarrhea, which may be caused by decreased stress or increased gut health. Enrichment of the pre- and postweaning environment seems important in improving performance and health of newly weaned pigs. Key words: environmental enrichment, learning, piglet, sow housing, weaning doi: 10.2527/jas.2010-2940

Using suppression subtractive hybridization technique, we found that 2 novel genes (AEUG1 and AEUG3) were highly expressed in the adipocytes compared with preadipocytes. We then identified that these 2 genes were both angiotensin-converting enzyme 2 (ACE2). We applied 3'RACE (rapid amplification of cDNA end), 5'RACE, and PCR to obtain the full-length porcine ACE2 cDNA sequence. Because eicosanoids derived from PUFA are involved in regulating blood pressure, we hypothesized that PUFA can regulate the expression of the vasodilator ACE2. Preadipocytes from Landrace pigs were induced to differentiate for 4 d, then treated with 50 [micro]M of different PUFA, CLA, arachidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or stearic acid (18:0). Addition of EPA or 18:0 for 48 h did not change the ACE2 mRNA abundance, whereas the treatments of arachidonic acid, CLA, and DHA significantly decreased ACE2 mRNA abundance after 48 h (P [less than or equal to] 0.05). Treatment with PUFA did not change (P > 0.05) type I and type II angiotensin receptor mRNA abundance. To further understand how PUFA metabolites affect ACE2 mRNA expression, we inhibited individual enzymes that are involved in eicosanoid production. We found that 3 individual eicosanoid pathway enzyme inhibitors recovered the PUFA effect on the expression of ACE2, indicating these pathways are involved in mediating the PUFA function. In conclusion, we obtained the full-length porcine ACE2 cDNA sequence and found PUFA could downregulate the expression of ACE2 through its metabolites without changing the expression of their receptor in porcine adipocytes. Key words: amplification of complementary deoxyribonucleic acid end, angiotensin-converting enzyme, polyunsaturated fatty acid doi: 10.2527/jas.2010-2905

The aim of this study was to quantify the partial correlation coefficients ([r.sub.p]) between fat depot traits (FDT) and the fatty acid composition of abdominal subcutaneous adipose tissue and LM intramuscular fat in 639 [F.sub.2] pigs derived from a White Duroc x Chinese Erhualian cross. Fat depot traits are classified into 2 groups: 1 is adipose tissues (abdominal subcutaneous adipose tissue weight, mesenteric adipose tissue weight, perirenal adipose tissue weight, and backfat thickness at 4 locations); the other is LM [intramuscular fat content (IMF) and marbling score]. Correlations of FDT within classification groups were markedly greater (P < 0.001) than those observed between the 2 groups ([r.sub.p] = 0.62 vs. 0.26), indicating variability in fat content of muscle is relatively independent of amount of carcass fat. In general, fatter pigs had greater (P < 0.05) proportions of SFA and MUFA, and less PUFA, than leaner pigs. However, the relationships of individual fatty acids with FDT varied. We found that the amounts of some fatty acids regarded as neutral (e.g., stearic acid) or beneficial (e.g., palmitoleic acid and linolenic acid) for human health were associated with smaller amount of adipose tissues, or merely with greater IMF (P < 0.05). Therefore, we conclude that increasing the proportions of these neutral or healthy fatty acids can be achieved without reducing the IMF of LM, which is positively related to eating quality. Key words: abdominal subcutaneous adipose tissue, correlation, fat depot trait, fatty acid composition, longissimus muscle, pig doi: 10.2527/jas.2009-2602

The purpose of this study was to determine the association of production factors with stayability to parity 4 (STAY4) under controlled experimental conditions. Data were from 2,293 female pigs, sampled from 6 genetic lines that were entered into the National Pork Producers Council Maternal Line National Genetic Evaluation Program. Genetic lines evaluated included Newsham (NH), National Swine Registry (NSR), American Diamond Swine Genetics (ADSG), Danbred (DAN), and 2 Dekalb-Monsanto lines (DK44 and GPK347). Stepwise logistic regression was utilized in the analysis of STAY4. All effects were nested within genetic line. Categorical effects in the model were arrival date to the wean-to-finish unit (entry date) and breed-gestation-farrowing facility (farm). Continuous effects in the model were gilt backfat, LM depth, ADG, age at puberty, age at first farrowing, and traits recorded before the last litter of the sow (prefarrow backfat, number born alive, number weaned, litter weaning weight, lactation feed intake, lactation backfat loss, and lactation length). Factors significant for STAY4 included farm, entry date, age at first farrowing, ADG, gilt backfat, and lactation before removal effects, as well as feed intake, number born alive, and lactation length. Age at first farrowing and lactation feed intake affected all genetic lines. Regression coefficients for STAY4 on age at first farrowing were -0.014, -0.022, -0.017, -0.016, -0.011, and -0.021 (all P < 0.05), respectively, for NH, NSR, ADSG, DK44, GPK347, and DAN genetic lines. Regression coefficients for STAY4 on lactation feed intake were 0.043, 0049, 0.051, 0.061, 0.120, and 0.097 (all P < 0.05), respectively, for NH, NSR, ADSG, DK44, GPK347, and DAN females. Age at puberty, age at first farrowing, and lactation feed intake had the greatest effect on STAY4. Key words: genetic, longevity, sow, stayability doi: 10.2527/jas.2009-2319

The impact of colonic fermentation on postileal absorption of Ca, Mg, P, Cu, Fe, Mn, and Zn was investigated in 8 ileally cannulated grower pigs (initial BW = 29.1 [+ or -] 1.6 kg) according to a double 4 x 4 Latin square. A semi-purified diet was supplemented with 5.20% low viscous, low fermentable cellulose (CEL), 6.25% high viscous, low fermentable carboxymethyl-cellulose (CMC), 8.95% low viscous, high fermentable oat [beta]-glucan (LG), or 9.25% high viscous, high fermentable oat [beta]-glucan (HG), resulting in 5% actual added nonstarch polysaccharides (NSP) in the diets. Because of the intrinsic mineral content in LG and HG, pigs receiving the LG and HG diets had a greater (P < 0.05) daily intake of Mg, P, Cu, Fe, Mn, and Zn, and also Ca for the HG diet compared with the CEL and CMC diets. Different amounts of minerals reached the large intestine for the 4 diets as indicated by the 60 to 86% less (P < 0.05) ileal flow of Ca, Mg, P, and Fe for CMC compared with CEL and HG. Apparent mineral retention was generally less (P < 0.05) for CEL compared with CMC. Regression analyses indicated that postileal flux of Ca, Cu, and Zn were related ([R.sup.2] = 0.24 to 0.99; P < 0.05) to short-chain fatty acid (SCFA) concentrations in feces. Postileal Ca absorption was negatively related ([R.sup.2] = 0.24; P < 0.05) to fecal total SCFA concentrations when SCFA concentrations were greater than 95.6 mmol/kg of DM. Furthermore, postileal Zn ([R.sup.2] = 0.99; P < 0.001) and Cu secretion ([R.sup.2] = 0.94; P < 0.001) decreased with increasing total SCFA concentrations in feces. Additionally, postileal secretion of Fe increased ([R.sup.2] = 0.20; P < 0.05) with increasing 16S rRNA gene copies of Enterobacteriaceae in feces, whereas the secretion of Cu decreased ([R.sup.2] = 0.25; P < 0.01) with increasing gene copies of Enterobacteriaceae. Overall, the apparent retention of Ca, Mg, and P was 27 to 85% less (P < 0.05) for CEL and HG than for CMC, whereas the apparent retention of Fe, Mn, and Zn was less (P < 0.05) for CEL than for CMC, LG, and HG. In conclusion, these data indicate that the stimulation of fermentation by dietary NSP affects net mineral flux in the large intestine that, in turn, can influence mineral excretion in feces. Additionally, negative effects of CEL on apparent retention may increase the daily requirement for minerals of grower pigs. Key words: bacteria, fermentation, mineral, nonstarch polysaccharide, pig doi: 10.2527/jas.2010-2906

Swine dysentery is a contagious mucohemorrhagic diarrheal disease caused by the intestinal spirochete Brachyspira hyodysenteriae that colonizes and induces inflammation of the cecum and colon. It has been reported that a diet containing chicory root and sweet lupin can prevent swine dysentery. This experiment was conducted to test the hypothesis that inulin in the chicory root rather than galactans in lupins was responsible for protective effects. An experiment with a 2 x 2 factorial arrangement of treatments was undertaken using pigs fed barley- and triticale-based diets, with the main effects being protein source [185 g/kg of canola meal (decreased galactans) or 220 g/kg of lupins (greater galactans)] and inulin supplementation (0 or 80 g/kg). Forty Large White x Landrace pigs weighing 21 [+ or -] 3 kg, with 10 pigs per diet, were allowed to adapt to the diets for 2 wk, and then each pig was challenged orally 4 times with a broth culture containing B. hyodysenteriae on consecutive days. Pigs were killed when they showed clinical signs of dysentery or 6 wk postchallenge. Pigs fed diets without inulin had 8.3 times greater risk (P = 0.017) of developing swine dysentery and were 16 times more likely (P = 0.004) to have colon contents that were culture-positive for B. hyodysenteriae, compared with the pigs fed a diet with 80 g/kg of inulin. Diets containing lupins did not prevent pigs from developing clinical swine dysentery; however, inclusion of lupins or inulin or both in the diets delayed the onset of disease compared with the diet based mainly on canola meal (P < 0.05). Diet did not influence the total concentration of organic acids in the ileum, cecum, or upper and lower colon; however, the molar proportions of the organic acids were influenced (P < 0.05). Consequently the pH values in the cecum, and upper and lower colon were not influenced (P > 0.05) by diet. However the pH values of the ileal digesta were decreased in pigs fed the diet with both lupins and inulin compared with the diet containing only lupins (P < 0.05). In conclusion, this study shows that diets supplemented with highly fermentable carbohydrates from inulin protected pigs against developing swine dysentery. Key words: Brachyspira hyodysenteriae, fermentable carbohydrate, inulin, lupin, pig, swine dysentery doi: 10.2527/jas.2009-2719

The study was conducted to determine the effects of probiotics (Bacillus subtilis endospore and Clostridium butyricum endospore complex) supplementation and different energy and nutrient densities on growth performance, nutrient digestibility, and meat quality in growing-finishing pigs. A total of 96 pigs with initial BW of 47.50 [+ or -] 1.14 kg were used in a 10-wk experiment. Pigs were randomly allotted to 1 of 4 treatments in a 2 x 2 factorial arrangement of treatments with 2 levels of energy and nutrient density (low and high energy, CP, and Lys) and 0.2% probiotics according to their sex and BW (6 pens, with 2 gilts and 2 barrows/pen). From 0 to 5 wk, ADG and G:F, as well as the apparent total tract digestibility (ATTD) of N and energy, were improved (P < 0.05) in the probiotic groups and in the high-energy and high-nutrient-density groups. From 6 to 10 wk, ADG and G:F, as well as the ATTD of DM, N, and energy, were increased (P < 0.01) when pigs were fed the high-energy and high-nutrient-density diets. Pigs fed the probiotic supplement or the high-energy and high-nutrient-density diets had increased (P < 0.01) ADG and G:F overall. Moreover, pigs fed the high-energy and high-nutrient-density diets had increased (P < 0.05) meat color scores, marbling scores, drip loss values, pH, and LM area (P < 0.05) compared with those fed the low-energy and low-nutrient-density diets, whereas the probiotic treatment groups had increased (P < 0.01) meat color scores, marbling scores, and redness values. The lightness and yellowness values in the low-energy and low-nutrient-density dietary treatments were greater (P < 0.05) than those in the high-energy and high-nutrient-density dietary treatments. Interactive effects of dietary energy and nutrient density and probiotics were also observed (P < 0.05) on the digestibility of N at wk 10 and energy at wk 5, as well as on meat firmness at the end of the experiment. In conclusion, dietary supplementation of probiotics increased growth performance throughout the experiment and exerted beneficial effects on ATTD. Meat quality was improved when pigs were fed high-energy and high-nutrient-density diets. Key words: energy and nutrient density, growing-finishing pig, growth performance, meat quality, probiotic doi: 10.2527/jas.2009-2308

During mammalian oogenesis, intercellular communication between oocytes and the surrounding follicle cells through gap junction channels is crucial for oocyte development and maturation. The channel properties of gap junctions may be affected by the composition or combination of connexins, the expression of which is regulated by gonadotropins and other factors. Thus, identification and expression analysis of connexin genes in oocytes and follicle cells will help us to better understand how oogenesis and folliculogenesis are regulated in a species-specific manner in mammals. We previously reported the spatiotemporal expression of multiple connexin genes in porcine follicle cells. Here, we searched for connexin genes specifically expressed in porcine oocytes that may be involved in the formation of gap junctions between oocytes and follicle cells. To achieve this, we constructed an oocyte-specific cDNA library to identify which connexin genes are expressed in these cells and found that gap junction protein, alpha 10, which encodes connexin-60, and a porcine ortholog of mouse gap junction protein, gamma 1 encoding connexin-45, are the major connexins expressed in porcine oocytes during folliculogenesis. Immunostaining and in situ hybridization of sectioned porcine ovaries confirmed oocyte expression of these genes at 3 different stages of ovary development. Furthermore, their gap junction channel activity was assessed using a heterologous cell system. However, gap junction protein, alpha 4, which encodes connexin-37 and is expressed in the oocytes of several other mammals, was undetectable. We demonstrate that there is diversity in the connexin genes expressed in mammalian oocytes, and hence in the gap junctions connecting oocytes and cumulus cells. Key words: connexin-37, connexin-45, connexin-60, oocyte complementary deoxyribonucleic acid library, ovarian follicle, porcine oocyte doi: 10.2527/jas.2009-2781

High prolificacy of sows and increased fetal survival lead to greater incidence of intrauterine crowding (IUC), which may then affect pre- and post-natal development of the progeny. The aim of the study was to assess the impact of IUC, using unilaterally hysterectomized-ovariectomized gilts (UHO), on organ and muscle development of their progeny at birth. In the study, 7 UHO and 7 intact control (Con) Swiss Large White gilts were used. At farrowing, if available, 3 male and 3 female progeny with a low (>0.8 and 1.2 and 1.6 kg) birth weight (BtW) were killed. Internal organs and brain were weighed, and semitendinosus (STN), psoas major (PM), and rhomboideus (RH) muscles were collected. Histological analyses were performed in PM, RH, and STN (dark and light portion) using myofibrillar ATPase staining after preincubation at pH 10.3. Myosin heavy chain (MyHC) polymorphism was determined in the PM using SDS-PAGE gel electrophoresis. Despite that only one-half of the uterine space was available, litter size was smaller (P < 0.01) only by 35% in UHO compared with Con gilts. However, UHO progeny tended (P = 0.06) to be lighter than Con progeny. The average BtW of the selected piglets did not differ (P = 0.17) between the 2 sow groups, whereas PM and kidneys tended to be lighter (P < 0.07) in UHO than in Con progeny. Compared with Con progeny, the PM and the [STN.sub.dark] of UHO progeny had fewer (P [less than or equal to] 0.05) secondary and total myofibers as well as fewer (P = 0.10) primary myofibers in the PM. In the RH, the secondary-to-primary myofiber ratio was smaller (P < 0.01) in UHO than in Con progeny, whereas the total number of myofibers did not (P = 0.96) differ. The relative abundance of fetal MyHC was less (P = 0.02) and that of type I MyHC tended (P = 0.09) to be greater in UHO than in Con offspring. With increasing BtW, organ and brain weights increased (P < 0.01). Muscle cross-sectional area and total number of myofibers in the light portion of the STN were greater (P < 0.05) in high and medium than in low piglets. In conclusion, IUC reduced hyperplasia of secondary and total myofibers in the [STN.sub.dark] and PM. These effects were independent of the BtW and sex. Key words: birth weight, intrauterine crowding, myogenesis, pig doi: 10.2527/jas.2010-2867

Variance components and genetic correlations were estimated among estrus, puberty, growth, and composition traits in Landrace-Large White gilts (n = 1,225; Genetic Improvement Services, Newton Grove, NC) from 59 sires and 330 dams. Four groups of gilts entered the North Carolina Swine Evaluation Station in Clayton at an average age of 162 d and were checked daily for estrus. Once 70% of gilts had reached puberty, recording of estrus symptoms occurred every 12 h for 30 d, using fence-line boar contact. Subjective estrus traits were maximum strength of standing reflex with or without a boar present, total strength of standing reflex with or without a boar present, and strength of vulva reddening and swelling. Objective estrus traits consisted of vulva redness, vulva width, length of estrus in consecutive days based on 12-h observations, and age at puberty (AGEPUB). Growth and composition traits included puberty weight, days to 114 kg (DYS), 10th-rib backfat, and 10th-rib LM area at 114 kg (BF, LMA) and puberty. Variance components were estimated using AIREMLF90 with an animal model. All models included gilt development diet class and breed composition as fixed effects, entry age as a covariate (except DYS, BF, and LMA), a random common litter effect, and a random animal genetic effect. Heritability estimates for length of estrus, maximum strength of the standing reflex with a boar, total strength of the standing reflex with a boar, maximum strength of the standing reflex without a boar, total strength of the standing reflex without a boar, vulva redness, strength of vulva reddening and swelling, and vulva width were 0.21, 0.13, 0.26, 0.42, 0.42, 0.26, 0.45, and 0.58, respectively. Heritability estimates for AGEPUB, puberty weight, 10th-rib backfat at puberty, 10th-rib LM area at puberty, DYS, BF, and LMA were 0.29, 0.39, 0.41, 0.38, 0.24, 0.47, and 0.39, respectfully. Common litter effect estimates ranged from 0.01 to 0.09. The estimated genetic correlation between length of estrus and maximum strength of standing reflex with a boar was 0.99. Genetic correlations between AGEPUB and length of estrus, maximum strength of standing reflex with a boar, and vulva redness were -0.23, -0.32, and 0.20, respectively. Length of estrus had positive genetic associations with DYS and BF (0.30 and 0.29, respectively). It was concluded that past selection for lean BW gain may have weakened the strength of the standing reflex and that sufficient genetic variation exists to make selection for improved swine estrus traits effective. Key words: estrus, genetic, pig, puberty doi: 10.2527/jas.2009-2639

The aim of this study was to investigate whether there is heritable social variation in ADG from birth until weaning in piglets. Nursing and the establishment of teat order are sources of social interaction among suckling piglets nursed by the same sow. If a heritable social effect is present, but ignored, the selected animals might be the most competitive ones with negative effects on growth of their group mates, resulting in less response to selection than expected. The social interaction model was extended with a maternal component to estimate genetic maternal and social effects. Four different animal models were compared: a basic model with a direct heritable effect only; a social model accounting for direct and social heritable effects; a maternal model with a heritable maternal effect in addition to the basic model; and a social-maternal model accounting for direct, social, and maternal heritable effects. Estimates of direct, maternal, and social heritability were 0.07, 0.06, and around 0.0007 (not significantly different from zero, SE = 0.0005), respectively. Total heritable variance, including direct, social, and maternal heritable variance and their covariances ranged from 0.07 to 0.15 of the phenotypic variation. Both maternal models were significantly better than equivalent nonmaternal models (P [greater than or equal to] 0.005). The social model was not significantly better than the basic model (P = 0.102), and the social-maternal model was also not significantly better than the maternal model (P = 0.486). There was no evidence for heritable social effects among piglets in a group. The generally used maternal model fit the data as well as the social-maternal model. Sufficient cross-fostering is needed to partition social and maternal variation. Key words: average daily gain, competition, genetic parameter, maternal effect, piglet, social interaction doi: 10.2527/jas.2009-2494

Experiments were conducted to assess the effect of dried whey (DW; 70% lactose) or milk chocolate product (MCP; 20% lactose and 60% sugars) on wk-1 feed intake and growth performance of pigs. Diets contained 1.60, 1.40, 1.40, and 1.20% total Lys for phase 1 (d 0 to 7), 2 (d 7 to 14), 3 (d 14 to 21), and 4 (d 21 to 35), respectively. Pigs were blocked by initial BW; sex and littermates were balanced across treatment; treatments were replicated with a minimum of 5 pens of 4 pigs each. Pigs were weaned at 24, 19, and 24 d of age with an initial BW of 6.5, 6.0, or 6.3 kg for Exp. 1 to 3, respectively. In Exp. 1 and 2, the treatments were 1) negative control (NC), no lactose added, 2) positive control (PC) with DW, 3) 25% replacement of the level of DW of the PC diet with MCP (25MCP), and 4) 50% replacement of the level of DW of the PC diet with MCP (50MCP). The level of DW or combinations of DW and MCP were 20, 10, and 5% for phases 1, 2, and 3 respectively. A common diet with no lactose was fed during phase 4. In Exp. 3, the treatments were 1) NC, 2) PC, and 3) 100% replacement of the level of DW of the PC diet with MCP (100MCP). In the combined data of Exp. 1 and 2, daily collected feed intake during wk 1 was increased (P < 0.10) from d 3 to 7 for the PC pigs; on d 2, 3, 4, and 7 for the 25MCP pigs; and from d 2 to 7 for the 50MCP pigs compared with the NC pigs. There was no difference (P > 0.10) on any day of wk 1 among pigs fed the PC and MCP diets. During phase 1, ADG and ADFI were increased (P < 0.10) for the PC, 25MCP, and 50MCP pigs compared with the NC pigs, but G:F was not affected (P > 0.10). During phases 2, 3, 4, and overall, there were no differences (P > 0.10) in growth performance among pigs fed the PC and MCP diets. In Exp. 3, collected daily feed intake during wk 1 was increased (P < 0.10) from d 2 to 5 for PC pigs and on d 1 and 2 for the 100MCP pigs compared with the NC pigs. However, there was no difference (P > 0.10) on any day of wk 1 between the PC and 100MCP pigs. Growth performance was not affected (P > 0.10) during any phase of the experiment. Combined data from Exp. 1, 2, and 3 using the NC and PC diets indicated that dietary DW increased (P < 0.10) final BW and increased ADG and ADFI during phases 1, 2, 3, and overall. These results indicate that partial or total replacement of DW with MCP had no effect on wk-1 feed intake or growth performance of weanling pigs and that MCP could be considered as a formulation alternative to DW. Key words: chocolate, lactose, nursery, pig doi: 10.2527/jas.2009-2726

Pigs (n = 240) were allotted in a 5 x 2 factorial arrangement with 5 levels of distillers dried grains with solubles (DDGS): 0, 15, 30, 45, and 60%, and 2 ractopamine (RAC) levels: 0 and 5 mg/kg. Four pigs per pen (2 barrows, 2 gilts) closest to pen mean BW were used for meat quality evaluation. Loins (n = 119) were evaluated for objective color; moisture and fat; subjective color, marbling, and firmness; and drip loss. Bellies (n = 119) were evaluated for weight, length, width, thickness, objective fat color, and firmness. Cured bellies were evaluated for pump yield, cook loss, and sliced bacon cook loss. Loin thiobarbituric acid reactive substances (TBARS) were evaluated on enhanced (salt and phosphate) boneless chops held in modified atmosphere (80% [O.sub.2]/20% C[O.sub.2]) packages for 0, 7, 14, and 21 d. Bacon TBARS were evaluated on sliced bacon held in vacuum packages for 0, 28, 56, and 84 d. Fat samples were collected from each jowl and belly and evaluated for fatty acid profile and iodine value (IV). Increasing DDGS decreased subjective marbling (P = 0.0134) and firmness (P = 0.0235), and increased drip loss (P = 0.0046). Distillers dried grains with solubles did not affect loin pH, subjective or objective color, percent moisture, or percent fat (P > 0.05). The RAC decreased subjective color (P = 0.0239), marbling (P = 0.0445), and [a.sup.*] (P = 0.0355). Increasing DDGS decreased belly weight (P = 0.0155), length (P = 0.0008), thickness (P = 0.0019), and firmness (P = 0.0054); decreased belly fat [L.sup.*] (P = 0.0818); and increased belly cook loss (P = 0.0890). Ractopamine did not affect any belly measurements, and there were no DDGS x RAC interactions (P > 0.05). Distillers dried grains with solubles did not affect loin TBARS at 0, 7, or 14 d. At 21 d, loin TBARS from 30, 45, and 60% DDGS groups were increased compared with 0 and 15% groups (P < 0.05). Ractopamine did not affect (P > 0.05) loin TBARS, and there were no (P > 0.05) DDGS x RAC interactions. Distillers dried grains with solubles and RAC did not affect bacon TBARS (P > 0.05). Increasing DDGS increased belly (P = 0.0207) and jowl (P < 0.0001) IV, and decreased MUFA:PUFA in belly (P < 0.0001) and jowl (P < 0.0001) fat. Ratio of SFA:unsaturated fatty acids decreased in jowl (P = 0.0002) and belly fat (P = 0.2815). Ractopamine did not affect fatty acid profiles or IV, and there were no DDGS x RAC interactions (P > 0.05). Results indicate that increased DDGS have minimal effects on loin quality, but decrease belly quality, bacon processing characteristics, and fat stability. Ractopamine does not negatively affect these characteristics and does not interact with DDGS. Key words: belly quality, distillers dried grains with solubles, fatty acid, pig, shelf life doi: 10.2527/jas.2009-2472

The objective of this study was to investigate the relationships among birth weight, birth order, or litter size on growth performance, carcass quality, and eating quality of the ultimate pork product. Data were collected from 98 pig litters and, with the addition of recording birth weight and birth order, farrowing and piglet management were according to normal barn practices. In the nursery and during growout, the pigs received the normal feeding program for the barn and, with the addition of individual tattooing, were marketed as per standard procedure. From 24 litters, selected because they had at least 12 pigs born alive and represented a range of birth weights, 4 piglets were chosen (for a total of 96 piglets) and sent to Agriculture and Agri-Food Canada--Lacombe Research Centre (Lacombe, Alberta, Canada) when they reached 120 kg for extensive meat quality and sensory analysis. Individual BW was measured at birth, on the day of weaning, 5 wk after weaning, at nursery exit, at first pull, and at the time of marketing. Litter sizes were divided into 3 categories: small (3 to 10 piglets), medium (11 to 13 piglets), and large (14 to 19 piglets). There were 4 birth-weight quartiles: 0.80 to 1.20, 1.25 to 1.45, 1.50 to 1.70, and 1.75 to 2.50 kg. Increased litter size resulted in reduced mean birth weight (P < 0.05), but had no effect on within litter variability or carcass quality (P > 0.05) when slaughtered at the same endpoint. Lighter birth-weight pigs had reduced BW at weaning, 5 and 7 wk postweaning, and at first pull and had increased days to market (P < 0.05). Birth weight had limited effects on carcass quality, weight of primal cuts, objective quality, and overall palatability of the meat at the same slaughter weight (P > 0.05). In conclusion, increased litter size resulted in decreased mean birth weight but no change in days to market. Lighter birth-weight pigs took longer to reach market. Despite some differences in histological properties, birth weight had limited effects on carcass composition or final eating quality of the pork when slaughtered at the same BW and large litter size resulted in more pigs weaned and marketed compared with the smaller litters. We concluded that based on the conditions of this study, other than increased days to market, there is no reason based on pig performance or pork quality to slow down the goal of the pork industry to increase sow productivity as a means to increase efficiency. Key words: birth weight, carcass quality, litter size, pig performance, pork quality doi: 10.2527/jas.2009-2222

An experiment was conducted to determine the apparent (AID) and standardized (SID) ileal digestibility of CP and AA in weanling pigs of 4 soybean products, fish meal, and casein. The 4 soybean products were conventional dehulled soybean meal (SBM), soy protein isolate (SPI), fermented soybean meal (FSBM), and enzyme-treated soybean meal (ESBM). Seven weanling barrows (initial BW: 10.9 [+ or -] 2.3 kg) were individually fitted with a T-cannula in the distal ileum. The barrows were allotted to a 7 x 7 Latin square design with 7 diets and seven 7-d periods. Six cornstarch-based diets were prepared using each of the protein sources as the sole source of CP and AA. An N-free diet was used to measure basal endogenous losses of CP and AA. Results showed that except for Lys, the AID and SID of AA in FSBM was not different from SBM, and with a few exceptions, the AID and SID of most AA in SBM, FSBM, and ESBM were not different from each other and from the AID and SID of AA in fish meal. Likewise, the AID and SID of AA in ESBM and SPI were not different, but the AID and SID of most AA in SPI were greater (P < 0.05) than in SBM and FSBM. The AID and SID of most AA in SPI were not different from the AID and SID of AA in casein. In conclusion, FSBM and ESBM had similar SID of most AA as SBM, but SPI has the greatest SID of AA among the 4 soybean products. Casein had the greatest SID of AA among the protein sources studied. Key words: amino acid, digestibility, enzyme-treated soybean meal, fermented soybean meal, pig, soy protein isolate doi: 10.2527/jas.2009-2677

Forty crossbred neonatal pigs with an average initial age of 4 d and BW of 2.16 kg were used in a 28-d experiment to evaluate the nutritional effects of autoclaving a commercial sugar-free, spray-dried egg albumen (EA) compared with casein. Basal diet protein sources were lactic acid casein and EA. Two more dietary treatments were made by replacing the EA with dry-autoclaved EA (DAEA) or wet-autoclaved EA (WAEA, EA and water mixed in a 1.0:1.2 ratio before autoclaving). The DAEA and WAEA were autoclaved at 121[degrees]C and 1.75 kg/[cm.sup.2] pressure for 30 min, and WAEA was oven-dried after autoclaving. Analyzed trypsin inhibitor units/mg of EA, DAEA, and WAEA were 535.0, 9.0, and 6.5, respectively. Pigs were fed the diets in gruel form to appetite in individual metabolism cages every 2 h during the experiment. Blood samples were taken on d 7, 14, and 21, and total urine and fecal grab-samples were collected from d 14 to 21 of the experiment. Response criteria were N and energy balance, plasma urea N (PUN) and glucose concentrations, and growth performance. The WAEA was a higher quality protein source for neonatal pigs than DAEA. Pigs fed the diet containing WAEA absorbed and retained more (P < 0.05) grams of N/d, had higher (P < 0.05) percentages of N and energy that were absorbed and retained/intake, had lower (P < 0.05) concentrations of PUN overall, and had higher (P < 0.05) ADG and G:F than pigs fed the diet containing DAEA. Most response criteria of pigs fed the diets containing DAEA or EA were not different, although pigs fed the diet containing DAEA had lower (P < 0.05) overall PUN concentrations, and pigs fed the diet containing EA had higher (P < 0.05) percentages of energy absorbed and retained/intake, and higher ADG and G:F than pigs fed the diet containing DAEA. Growth performance was not different for pigs fed the diets containing WAEA or casein. However, pigs fed the diet containing casein excreted less (P < 0.05) fecal N, retained more (P < 0/05) grams of N/d, had higher percentages of N absorbed and retained/intake, and had lower (P < 0.05) PUN concentrations overall than pigs fed the diet containing WAEA. In conclusion, WAEA was a higher quality protein source for neonatal pigs than DAEA or EA, whereas lactic casein was a higher quality protein source for neonatal pigs than EA, DAEA, or WAEA. Key words: casein, energy and nitrogen balance, growth performance, neonatal swine, plasma urea nitrogen, spray-dried egg albumen doi: 10.2527/jas.2010-2811

The underconsumption of feed frequently observed in young sows during lactation can result from an adaptation problem of the sow to the new feeding management in terms of diet composition and feeding amount. Our study aimed to investigate how the sow manages her own feed transition when given the choice between the gestation diet and the lactation diet from moving into the farrowing crate (12 d before farrowing) until the second week postpartum. The effect of adding dietary fiber to the gestation diet on this transition was also evaluated. During gestation, 16 primiparous sows (Large White x Landrace) were fed 2.4 kg/d of a control (CON) diet (3.5% of crude fiber), or 2.9 kg/d of a high-fiber (HF) diet (12.8% of crude fiber). The daily allowance of NE was 24 MJ in both treatments. Twelve days before the expected parturition day (d -12), sows were moved into farrowing crates that were equipped with a computerized feeding device allowing the gestation and lactation diets to be supplied via 2 rewarded push buttons placed above the trough, until d 14 postpartum. The feeding transition was evaluated through the daily ratio of ingestion of the lactation diet. Feeding behavior was measured through daily feed and energy intakes, number of daily meals, meal size, and the nycthemeral distribution of feeding activity. Sows were weighed and backfat thickness was measured at the beginning and end of gestation and lactation. Piglets were weighed every week from birth until weaning. The transition to the lactation diet occurred earlier in HF sows (P < 0.05); the 50% threshold of lactation diet ingestion was reached on d -8 and 12 in HF and CON sows, respectively. Dietary treatment did not affect the feeding pattern, and all sows presented a diurnal feeding activity. During lactation, there was an interaction (P < 0.05) between the hour of the day and the dietary treatment for the distribution of pushes on the rewarded buttons, with pushes being more spread out throughout the day in CON sows compared with HF sows. Variations in sow backfat thickness were not affected by dietary treatment, but HF sows lost more BW during lactation (P < 0.05). Growth of piglets was not affected by dietary treatment. In conclusion, sows chose the lactation diet spontaneously on the week preceding parturition when they were fed a fibrous diet during gestation. This highlights the possible impact of such a gestation diet to promote early intake of the lactation diet. Key words: feeding behavior, fiber, free choice, primiparous, sow doi: 10.2527/jas.2009-2307

Air-classified pulse (non-oilseed legume) protein and starch may replace specialty protein and starch feedstuffs in diets for weaned pigs. In Exp. 1, three specialty protein sources (5% soy protein concentrate, 5% corn gluten meal, and 5% menhaden meal in the control diet) were replaced with 16% zerotannin hulled or dehulled faba bean, or 17.5% field pea protein concentrate. In total, 192 group-housed pigs (2 gilts and 2 barrows per pen; BW = 7.5 [+ or -] 1.4 kg) were fed wheat-based diets (3.60 Mcal/kg of DE and 3.3 g of standardized ileal digestible Lys/Mcal DE) over 28 d for 12 pen observations per each of 4 diets. Overall, protein source did not affect ADFI, ADG, or G:F. Apparent total tract digestibility (ATTD) of DM, GE, and P was greater (P < 0.05) for dehulled faba bean and field pea protein concentrate diets than the diet with 3 specialty protein sources. In Exp. 2, faba bean and field pea starch concentrates were compared with corn, wheat, tapioca, and potato starch as dietary energy sources. In total, 36 individually housed barrows (BW = 8.0 [+ or -] 1.5 kg) were fed 1 of 6 diets for 15 d. Feces and urine were collected from d 8 to 14, and jugular blood was sampled after overnight fast and refeeding on d 15. Starch source did not affect N retention as a percentage of N intake. For d 0 to 14, ADFI of pigs fed field pea starch was greater (P < 0.05) than pigs fed corn, wheat, potato, and faba bean starch. Pigs fed tapioca, field pea, wheat, or corn starch grew faster (P < 0.05) than those fed faba bean or potato starch. For d 0 to 14, pigs fed corn or wheat starch had a 0.1 greater (P < 0.05) G:F than pigs fed faba bean, field pea, or potato starch. The ATTD of DM, GE, CP, and starch and the DE value of potato starch were much less (P < 0.05) than those of other starch diets. Postprandial plasma glucose was 4.9, 6.3, and 9 mmol/L greater (P < 0.05) for pigs fed tapioca than for pigs fed faba bean, wheat, and potato starch, respectively. However, postprandial plasma insulin tended to be 844 and 577 pmol/L greater (P < 0.10) for pigs fed faba bean and corn starch, respectively, than for pigs fed potato starch. The high insulin response of pigs fed faba starch could not be explained. In conclusion, air-classified pulse protein concentrates can replace specialty protein feedstuffs in diets for weaned pigs. Feeding air-classified pulse starch concentrates to starter pigs achieved a similar N retention as a percentage of N intake. The factors responsible for the reduced ADFI associated with feeding faba bean starch remain unclear. Key words: air-classification, faba bean, field pea, pig, protein, starch doi: 10.2527/jas.2009-2291

Selection for litter size may result in an increase in uterine crowding due to a faster increase in ovulation rate than in litter size. Increased ovulation rate does not result in a proportionally increased number of piglets born alive. In this study, the effect of ovulation rate on vitality characteristics of fetal-placental units at d 40 of pregnancy was investigated. For this, 43 Large White gilts were treated with hormones to induce superovulation. Average ovulation rate was 45.16 [+ or -] 13.22; average number of vital fetuses at d 40 of pregnancy was 17.09 [+ or -] 3.61 that weighed 11.26 [+ or -] 1.99 g; their placenta weighed 31.88 [+ or -] 14.79 g; and they occupied 11.69 [+ or -] 4.90 cm of the uterus. Loss in oocytes (i.e., that did not result in a vital fetus at d 40) increased with increasing ovulation rate and occurred before (early mortality; P = 0.0003) and after implantation (late mortality, i.e., traces visible at d 40; P < 0.0001). With respect to the vital fetuses, increased ovulation rate resulted in decreased fetal (P = 0.0008) and placental weight (P = 0.0008) and decreased length of the area in the uterus that was occupied by the placenta (P = 0.0011). Strong correlations existed between placental and fetal weight [0.68; 95% confidence interval (CI) = 0.64 to 0.72], and placental weight and length (0.78; 95% CI = 0.74 to 0.82). Fetal-placental characteristics were weakly correlated to distance to the implantation sites of neighboring fetuses, a measure of crowdedness [-0.002 (95% CI = -0.042 to 0.038) with fetal weight to 0.16 (95% CI = 0.12 to 0.20) with placental length]. Increased ovulation rates, but more specifically increased late mortality rates, have negative effects on the remaining vital fetuses with respect to the fetal (P = 0.0085) and placental weight (P < 0.0001) and length of the implantation site (P = 0.0016). The most extreme effect was on placental weight, in which a uterus with 18 cases of late mortality (P < 0.0001). Furthermore, increased ovulation rates resulted in decreased within litter variation for fetal (P = 0.0018) and placental weight (P = 0.0084). At increased ovulation rates, the number of live fetuses remained similar, but placental development is impaired and the growth of the fetus is retarded compared with reduced ovulation rate, with effects likely lasting into adult life. Key words: fetal development, intrauterine crowding, mortality, ovulation rate, pig, superovulation doi: 10.2527/jas.2009-2561

The physiological role of cumulus cells (CC) surrounding oocytes is particularly important for normal cytoplasmic maturation of oocytes. However, removal of CC from oocytes is inevitable for some embryo manipulation techniques, such as germinal vesicle (GV) transfer, somatic cell haploidization, and oocyte cryopreservation. The present study was designed to determine an optimal method to culture porcine denuded oocytes (DO). The results indicated CC from cumulus-oocyte complexes at the GV stage (GVCC) or at the metaphase II stage, and mural granulosa cells could not improve the maturation of DO. However, GVCC could enhance the development of matured porcine DO after fertilization; the percentage of blastocysts was increased from 1.1 to 17.2% (P < 0.05), and the relative value of the x-axis and y-axis of spindles was also increased (P < 0.05). Coculture with GVCC had no effect on the distribution of mitochondria and cortical granules. The results contribute to our understanding of the mechanisms by which CC promote oocyte maturation and contribute to optimization of protocols for in vitro maturation of DO. Key words: coculture cell monolayer, cortical granule, maturation, mitochondria, oocyte, spindle doi: 10.2527/jas.2009-2714

A previous genome-wide search with a moderate-density 10,000-SNP set identified many marker associations with twinning rate on BTA14 through either single-marker analysis or combined linkage-linkage disequilibrium (LLD; haplotype) analysis. The objective of the current study was to fine-map putative QTL using a more densely populated marker map and both a larger and an independent set of phenotypic data. Holstein bulls (n = 921) from 100 paternal half-sib families were genotyped for 129 SNP markers that included both original and additionally selected markers for increasing marker density in the targeted 34 megabase region. Twinning rate predicted transmitting abilities were calculated using calving records from 1994 to 1998 (data I) and 1999 to 2006 (data II), and the underlying liability scores from threshold model analysis were used as the trait in marker association analyses. The previous analysis used 201 bulls with daughter records in data I. In the current analysis, this was increased to 434, providing a revised estimate of effect and significance. Bulls with daughter records in data II totaled 851, and analysis of these data provided an opportunity for an independent analysis separate from data I. Single-marker association and LLD analyses were performed. Fifteen significant single-marker associations were found (minimally exceeding P < 8.74 x [10.sup.-3]) to concur between data sets. Three and 12 regions in data I and data II, respectively, showed positive results for the presence of QTL from LLD analysis (P < 0.001) within the respective data sets. After combining results from single-marker association, LLD analysis, and model-building strategies, 3 QTL were identified on BTA14. Based on single-marker results from data II, BTA14 harbors QTL responsible for approximately 24% of the variation in twinning rate predicted transmitting ability. Key words: Holstein, linkage disequilibrium, single nucleotide polymorphism, twin, twinning rate doi: 10.2527/jas.2010-2808

Selection for increased litter size has been one of the main objectives in Danish pig breeding since 1992. This selection has led to an average increase of 0.30 piglets/litter per year for Landrace and Yorkshire sows, resulting in an average litter size of 15.3 piglets born alive in 2007, with an SD of 3.5 piglets. The objective of this study was to investigate differences in identity by state relationships and allele effects associated with litter size across 17 selected microsatellite marker positions on chromosomes 11, 13, and 15. For this purpose, 357 Danish Landrace sows with high and low EBV for litter size were genotyped. An assignment test showed that 91 and 90% of the sows could be assigned correctly to the group of sows representing high and low EBV, respectively, based on genotype information. Allele effects were estimated separately for each marker by using deregressed EBV and a linear model that include both a polygenic and an allele effect. The investigated region on chromosome 13 was found to have a greater average identity by state relationship compared with the other regions, indicating that selection has taken place in this region. This is supported by an increased average allele effect of microsatellite alleles in the region. In spite of the apparent increased historical selection pressure on chromosome 13, fairly large variation in allele effects was observed, indicating that the markers within the region may be used for marker-assisted selection. However, substantial variation in allele effects was observed for several markers on all 3 investigated chromosomes, indicating that selection should preferably be based on several markers. Key words: estimated allele effect, identity by state relationship, litter size, pig, quantitative trait locus doi: 10.2527/jas.2009-2274

Assimilating accurate behavioral events over a long period can be labor-intensive and relatively expensive. If an automatic device could accurately record the duration and frequency for a given behavioral event, it would be a valuable alternative to the traditional use of human observers for behavioral studies. Therefore, the objective of this study was to determine the accuracy in the time spent at the waterer and the number of visits to the waterer by individually housed nursery pigs between human observers scoring video files using Observer software (OBS) and an automatic water meter Hobo (WM, control) affixed onto the waterline. Eleven PIC USA genotype gilts (22 [+ or -] 2 d of age; 6.5 [+ or -] 1.4 kg of BW) were housed individually in pens with ad libitum access to a corn-based starter ration and one nipple waterer. Behavior was collected on d 0 (day of weaning), 7, and 14 of the trial using 1 color camera positioned over 4 attached pens and a RECO-204 DVR at 1 frame per second. For the OBS method, 2 experienced observers recorded drinking behavior from the video files, which was defined as when the gilt placed her mouth over the nipple waterer. Data were analyzed using nonparametric methods and the general linear model and regression procedures in SAS. The experimental unit was the individual pen housing 1 gilt. The GLM model included the method of observation (WM vs. OBS) and time (24 h) as variables, and the gilt nested within method was used as the error term. Gilts consumed more water (P = 0.04) on d 14 than on d 0. The time of day affected (P < 0.001) the number of visits and the time spent at the waterer regardless of the method. However, the OBS method underestimated (P < 0.001) the number of visits to the waterer (3.48 [+ or -] 0.33 visits/h for OBS vs. 4.94 [+ or -] 0.33 for WM) and overestimated (P < 0.001) the time spent at the waterer (22.6 [+ or -] 1.46 s/h for OBS vs. 13.9 [+ or -] 1.43 for WM) compared with WM. The relationship between the 2 methods for prediction of time spent at the waterer and number of visits made by the gilts was weak ([R.sup.2] = 0.56 and 0.69, respectively). Collectively, these data indicate that the use of the traditional OBS method for quantifying drinking behavior in pigs can be misleading. Quantifying drinking behavior and perhaps other behavioral events via the OBS method must be more accurately validated. Key words: automatic, behavior, drinking, Hobo, pig, validation doi: 10.2527/jas.2008-1737

The objectives of this study were to determine the effects of dietary glycyl-glutamine (Gly-Gln) on postweaning growth, small intestinal morphology, and immune response of stressed or nonstressed piglets. Pigs (n = 144; initially 4.49 kg and 14 d of age) were randomly allocated to 24 pens (6 pigs/pen) in an environmentally controlled nursery and assigned to Escherichia coli lipopolysaccharide (LPS) challenge (PBS vs. LPS) and Gly-Gln supplementation (0 vs. 0.15%) in a 2 x 2 factorial arrangement of treatments with 6 pens/treatment. The LPS was the stress-inducing agent, and it was injected on d 7 and 14 of the 21-d experiment. Inflammatory challenge with LPS reduced ADG (P < 0.05) and tended to reduce ADFI (P = 0.06) of piglets from d 7 to 21 of the experiment. Supplementation of Gly-Gln increased ADG and G:F from d 0 to 21 (P < 0.05). On d 21 (1 wk after the second LPS injection), there was an LPS challenge x diet GlyGln interaction for ADFI (P < 0.05), but it was difficult to ascertain whether Gly-Gln increased ADFI. A trend for an LPS challenge x diet Gly-Gln interaction was observed for ADG (P = 0.07). There were no differences in lymphocyte proliferation among treatments. The LPS challenge increased crypt depth (CD) of the duodenum and decreased the ratio of villus height (VH) to CD of the ileum (P < 0.05) on d 14 (1 wk after the first LPS injection), whereas dietary supplementation of Gly-Gln increased VH of the ileum and VH:CD of the duodenum (P < 0.05). The concentration of peripheral blood IL-1[beta] was increased by injection of LPS (P < 0.05) and was decreased by dietary Gly-Gln supplementation during the experimental period (P < 0.05); however, there was no interaction of LPS challenge x Gly-Gln addition for IL-1[beta] concentration. Concentrations of peripheral blood IL-2 tended to increase at d 14 (P = 0.09) and soluble IL-2 receptor tended to decrease at d 7 (P = 0.06) in piglets supplemented with Gly-Gln; therefore, the peripheral blood IL-2/soluble IL-2 receptor system tended to favor the secretion of IL-2 during the first 2 wk of the experiment. In conclusion, considerable suppression of growth and immune function occurred in early weaning piglets challenged with LPS, and such depression could be alleviated by dietary Gly-Gln supplementation independent of the LPS challenge. Key words: glycyl-glutamine, growth, immunity, lipopolysaccharide, weaning piglet doi: 10.2527/jas.2008-1120

The primary goal of this study was to detect and confirm QTL on SSC6 for growth and fatness traits in 2 experimental [F.sub.2] intercrosses: Iberian x Landrace (IB x LR) and Iberian x Meishan (IB x MS), which were used in this study for the first time in a QTL analysis related to productive traits. For this purpose, single--and joint-population analyses with single and bivariate trait models of both populations were performed. The presence of the SSC6 QTL for backfat thickness previously identified in the IB x LR cross was detected in this population with additional molecular information, but also was confirmed in the IB x MS cross. In addition, a QTL affecting BW was detected in both crosses in a similar position to the QTL detected for backfat thickness. This is the first study in which a QTL affecting BW is detected on SSC6 in the IB x LR cross, as well as in the IB x MS resource population. Furthermore, we analyzed a previously described nonsynonymous leptin receptor (LEPR) SNP located in exon 14 (c.2002C > T) for causality with respect to this QTL within both [F.sub.2] populations. Our results supported the previously reported association between LEPR alleles and backfat thickness in the IB x LR cross, and this association was also confirmed within the IB x MS cross. An association not reported before between LEPR alleles and BW was identified in both populations. Key words: backfat thickness, body weight, joint analysis, leptin receptor, pig, polymorphism

The objectives of this study were to measure death intervals and survival, to determine mortality rate and mortality risks, and to investigate the association of herd factors with mortality risk in individual female pigs. This study was conducted by obtaining female data with lifetime records of 65,621 females born between 1999 and 2002, and herd data with mean measurements of 5 yr from 2000 to 2004 in 105 herds. Annualized mortality rate was calculated as the number of dead females divided by the sum of life days in all gilts and sows, multiplied by 365 d. Mortality risk was calculated as the number of dead females divided by the number of surviving females at farrowing in each parity. Death interval in gilts was defined as the number of days from birth to death, and that in sows was the number of days from the last farrowing to death. A Cox proportional hazards model was used to obtain the survival probability by parity. Logistic regression analyses were used to investigate the association of herd factors with mortality risk in individual females in each parity. Of the 65,621 females, the mortality risk was 9.9%, and the annualized mortality rate was 3.9%. Of the 6,501 dead females, death intervals in gilts and sows were 294.7 and 55.0 d, respectively. In gilts, survival probability rapidly decreased at 33 and 50 wk of age, around the first mating and the first parturition. In contrast, survival probability in sows decreased at wk 1 after farrowing, and rapidly decreased at wk 20 and 21 after farrowing in all parity groups that were around a subsequent peripartum period. The percentages of death on wk 0, 1, and 2 after the last farrowing in all the dead sows were 6.5, 23.5, and 10.1%, respectively. Approximately 10% of deaths also occurred from wk 20 to 21 after the last farrowing. Death interval in parity [greater than or equal to] 5 was the shortest among all parity groups (49.2 d; P < 0.05). Mortality risks in parities 0 and 1 were 1.44 and 1.83%, respectively. As parity increased from 2 to [greater than or equal to] 5, mortality risk increased from 1.63 to 5.90%. Herd factors (greater herd mortality, less herd productivity, and smaller herd size) were associated with greater mortality risk in individual females in parity 0 to [greater than or equal to] 5, parity 4 and [greater than or equal to] 5, and parity 1 to 4, respectively (P < 0.05). In conclusion, females in peripartum periods, gilts, and high-parity sows are at a greater risk of dying. Increased care should be implemented for prefarrowing females and early-lactating SOWS. Key words: death, management, mortality, sow, survival, well-being

Lines of pigs selected for increased uterine capacity have improved conceptus survival, whereas pigs selected for increased ovulation rate have decreased conceptus survival relative to an unselected control line. The objective of this study was to evaluate conceptus development during blastocyst elongation as a potential contributing factor to differences in conceptus survival rate among these pig lines. Conceptuses were recovered from pregnant control, uterine capacity, and ovulation rate line gilts at d 10 and 12 of gestation. At d 10 of gestation, conceptus morphologic diversity was assessed by comparing within-litter average conceptus diameter and the standard deviation of conceptus diameters. At d 12 of gestation, conceptus morphologic diversity was assessed by comparing blastocyst populations obtained from individual gilts. Real-time PCR analyses for transcripts involved in steroidogenesis, cellular differentiation, and immune responsiveness were performed on spherical, ovoid, and filamentous conceptuses recovered from these selection lines. Uterine flushings were also assayed for total protein and estradiol-17[beta] at d 10 and 12 of gestation. Morphological data were analyzed using ANOVA with the fixed effects of line, farrowing season, and their interactions. Conceptus mortality, uterine flushing, and real-time PCR data were analyzed using ANOVA with the fixed effects of line, day or blastocyst morphology, farrowing season, and their interactions. Conceptus mortality, measured as the ratio of conceptus recovery to ovulation rate, was not different between the lines on d 10 and 12 of gestation. There were no significant line effects for conceptus morphologic diversity at d 10 and 12 of gestation. Expression of transcripts associated with steroidogenesis (steroidogenic acute regulatory protein, cytochrome P450 side chain cleavage, and aromatase), cellular differentiation (cytokeratin-18 and vimentin), and immune responsiveness (interleukin-1[beta]) in spherical, ovoid, and filamentous conceptuses was not different between the lines. Furthermore, protein and estradiol-17[beta] in uterine flushings at d 10 and 12 of gestation were not different between the selection lines. These findings indicate limited, if any, deviations between these lines of pigs in conceptus development during blastocyst elongation and suggest that mechanisms involved in generating line differences in survival rate likely are manifested later in gestation. Key words: blastocyst elongation, estradiol, gene expression, pig, ovulation rate, uterine capacity

The objective of this study was to quantify the effect of heat stress during the life of a pig on its final weight, as a first step toward a genetic evaluation for heat tolerance. Data included carcass weights of 23,556 crossbred pigs [Duroc x (Landrace x Large White)] raised on 2 farms in North Carolina and slaughtered from May 2005 through December 2006. Weather data were available from a nearby weather station. Lifetime of a pig was assumed to be partitioned into 2 periods. During an initial period, the effect of heat stress was assumed to be negligible or compensated for later. During the second period ending in slaughtering, the ADG was assumed to be affected linearly by heat load. Weekly heat load was calculated as degrees of average temperature-humidity index in excess of a threshold (18[degrees]C). The total heat load (H) was the sum of weekly heat loads during the second period. During the months of January to May H was 0; H reached a peak in September. The final BW during the peak of heat stress decreased about 6 kg compared with BW during months of non-heat stress. Weekly and monthly averages of carcass weight generally moved similarly to H. However, there were large fluctuations unrelated to H; the fluctuations were different on the 2 farms. The model included the effects of farm-year of slaughter, sex, age at slaughter, and H, where age at slaughter and H were linear regressions. In analyses, the threshold was varied from 16 to 20[degrees]C, and the second period was varied from 8 to 16 wk. The greatest [R.sup.2] (10.4%) was at the threshold of temperature-humidity index = 18[degrees]C for a period of 10 wk. Varying the threshold and the length of time reduced [R.sup.2] less than 1%. Least squares means of year-month and year-week of carcass weight were calculated using a model with the fixed effects farm-year-month or farm-year-week of slaughter, sex, and age at slaughter (linear covariate), and the random effect of birth litter. Changes in BW of finisher pigs due to heat stress can be quantified by H during the last 10 wk of the life of the pig. Key words: carcass weight, heat stress, pig

The objective of the study was to test the hypothesis that birth weight (BtW) influences growth, carcass characteristics, meat quality, and postmortem (pm) proteolysis differently when pigs originate from small (S) or large (L) litters. Swiss Large White barrows (60) used in this study originated from 20 litters with either less than 10 (S) or more than 14 (L) piglets born per litter. Within each of the S and L litters, 3 barrows were selected at birth: the lightest (L-BtW), the heaviest (H-BtW), and the one with a BtW nearest to the average BtW of the litter (M-BtW). The BW and total feed intake of the individually penned pigs were determined weekly. At slaughter, carcass characteristics were assessed. Meat quality traits were determined in the LM and dark portion of semitendinosus muscle. Titin, nebulin, desmin, and integrin proteolysis were evaluated by SDS-PAGE and Western blot technique, and p- and m-calpain activities were monitored using casein zymography. Litter size affected BtW of L-BtW and M-BtW but not of H-BtW barrows (BtW x litter size interaction; P = 0.07). From weaning to slaughter, L-BtW barrows grew slower (P < 0.01), ingested less feed (P < 0.01), and were less efficient (P < 0.01) than H-BtW and M-BtW barrows. The carcass yields were greater (P < 0.01), and livers and kidneys were lighter (P < 0.01) in L-BtW compared with H-BtW barrows. Regardless of BtW, barrows from S litters had greater percentages of shoulder (P = 0.02) and lower percentages of omental fat (P = 0.06) than barrows from L litters. Compared with the LM of H-BtW barrows, the LM of L-BtW barrows was redder (P < 0.01). The semitendinosus muscle of M-BtW barrows was more (P < 0.01) tender than that of L-BtW and H-BtW barrows. The extent of titin and nebulin proteolysis at 24 and 72 h pm was greater (P [less than or equal to] 0.07) in the LM of H-BtW than in L-BtW barrows. At 72 h pm, integrin of the LM had been less (P = 0.08) degraded in barrows originating from S than from L litters. These results confirm the known effect of BtW on growth performance, whereas its effect on carcass characteristic and meat quality traits could only be partially demonstrated. Although litter size affected average BtW of the L-BtW and M-BtW barrows, its effect on growth performance, carcass characteristics, and meat quality was minor. The almost complete absence of significant BtW x litter size interaction indicates that litter size affects swine growth and carcass and meat quality through its inverse relationship with BtW. Key words: birth weight, litter size, meat quality, pig, proteolysis

The objective of this study was to describe genetic variability of pig carcass weight as a function of heat stress. Data included carcass weights of 23,556 crossbred pigs [Duroc x (Landrace x Large White)] raised on 2 farms in North Carolina and harvested from May 2005 through December 2006. Weather data were obtained from a weather station located about 20 km from the furthest farm. Weekly heat load was calculated as degrees of average temperature-humidity index (THI) in excess of 18[degrees]C. The total heat load (H) was the sum of heat loads for 10 wk before harvest. Variance components were estimated with 3 models: univariate (UNI)--not accounting for heat stress, 2-trait (MT2), and random regression (RR). In all of the models, effects included contemporary group, sex, age at harvest, sire, and litter. In MT2, observations in months in which heat stress was observed ('hot') and not observed ('cold') were treated as separate traits. Heat stress was observed in the months of August to November 2005, as well as July to October 2006. No heat stress was observed in the months of May to July 2005, January to June 2006, and November to December 2006. The RR model added a random regression on heat load for the sire effect. Heat load was adjusted to a scale ranging from 0 (no heat stress) to 5 (greatest heat stress). The heritability estimate [+ or -] SE of carcass weight in UNI was 0.17 [+ or -] 0.01. In MT2, the estimates were 0.14 [+ or -] 0.01 for 'cold' and 0.28 [+ or -] 0.01 for 'hot'; the genetic correlation between carcass weight in 'hot' and 'cold' months was 0.42 [+ or -] 0.13. The heritability estimates obtained with RR were 0.20 [+ or -] 0.11, 0.19 [+ or -] 0.15, and 0.51 [+ or -] 0.17 for H = 0, 2.5, and 5, respectively. The genetic correlation between the performance in 'cold' months (H = 0), and performance under maximum heat load (H = 5) was 0.02, between H = 0 and intermediate heat load (H = 2.5) was 0.52, and between H = 2.5 and H = 5 was 0.86. Rank correlations between EPD derived from the different models ranged from 0.82 to 0.94 between carcass weights under similar H, 0.18 to 0.54 between carcass weights under high and low H, and 0.66 to 0.91 between carcass weights of intermediate and high/low H. Heritability for growth was greater under heat stress. Selection for crossbred performance would be optimal when data for periods both in the absence and presence of heat stress were considered. Key words: carcass weight, genetic parameter, heat stress, pig, random regression

Dietary trace mineral sources and levels were fed to developing gilts to evaluate their performance responses during the growth phase, but treatments were continued into the reproductive phase in which subsequent reproductive responses were evaluated. In Exp. 1, three groups of gilts (n = 216) were used in a 2 x 2 factorial in a randomized complete block design (6 replicates) with treatment diets initially fed at 30 kg of BW. The first factor was trace mineral source (organic or inorganic), whereas the second factor evaluated dietary levels. The NRC requirement was the first level evaluated, whereas the second level was formulated to average industry standards (IND). Organic trace minerals were mineral proteinates, whereas the inorganic minerals were provided in salt form. The results of Exp. 1 indicated that trace mineral source or level did not affect gilt growth or feed performance responses to 110 kg of BW. Experiment 2 continued with the same females but was a 2 x 3 factorial in a split-plot design using 3 groups of females over a 6-parity period and had a total of 375 farrowings. Factors in Exp. 2 were the same as in Exp. 1, except that 2 additional pens of gilts during their development had been fed the IND level trace mineral levels of both trace mineral sources. At breeding, the gilts from these 2 additional pens were continued on the same trace mineral source and level but fed greater dietary Ca and P levels (IND + Ca:P). Litters were standardized by 3 d postpartum within each farrowing. Sows fed organic trace minerals farrowed more (P < 0.05) total (12.2 vs. 11.3) and live pigs (11.3 vs. 10.6) compared with sows fed inorganic trace minerals. Sows fed the IND + Ca:P level tended to have fewer (P < 0.10) total pigs born for both trace mineral sources. Litter birth weights were heavier (P < 0.05) when sows were fed organic trace minerals, but individual piglet weights were similar. Nursing pig ADG tended to be greater (P < 0.10) when sows were fed organic trace minerals. Other sow reproductive traits (BW, feed intake, and rebreeding interval) were not affected by trace mineral source or level. Daily mineral intake increased by parity but declined when trace mineral intakes were expressed on an amount per kilogram of BW and declined during later lactations. These results suggest that feeding sows organic trace minerals may improve sow reproductive performance, but there were minimal effects on other reproductive measurements. Key words: mineral, pig, reproduction, sow

The objective of this study was to determine the effects of diets containing crude glycerol on pellet mill production efficiency and nursery pig growth performance. In a pilot study, increasing crude glycerol (0, 3, 6, 9, 12, and 15%) in a corn-soybean meal diet was evaluated for pellet mill production efficiency. All diets were steam conditioned to 65.5[degrees]C and pelleted through a pellet mill equipped with a die that had an effective thickness of 31.8 mm and holes 3.96 mm in diameter. Each diet was replicated by manufacturing a new batch of feed 3 times. Increasing crude glycerol increased both the standard (linear and quadratic, P < 0.01) and modified (linear, P < 0.01; quadratic, P [less than or equal to] 0.02) pellet durability indexes up to 9% with no further benefit thereafter. The addition of crude glycerol decreased (linear; P < 0.01) production rate (t/h) and production efficiency (kWh/t). In a 26-d growth assay, 182 pigs (initial BW, 11.0 [+ or -] 1.3 kg; 5 or 6 pigs/pen) were fed 1 of 7 corn-soybean meal-based diets with no added soy oil or crude glycerol (control), the control diet with 3 or 6% added soy oil, 3 or 6% added crude glycerol, and 6 or 12% addition of a 50:50 (wt/wt) soy oil/crude glycerol blend with 5 pens/diet. The addition of crude glycerol lowered (P < 0.01) delta temperature, amperage, motor load, and production efficiency. The addition of crude glycerol improved (P < 0.01) pellet durability compared with soy oil and the soy oil/crude glycerol blend treatments. Pigs fed increasing crude glycerol had increased (linear, P = 0.03) ADG. Average daily gain tended to increase with increasing soy oil (quadratic; P = 0.07) or the soy oil/crude glycerol blend (linear, P = 0.06). Adding crude glycerol to the diet did not affect G:F compared with the control. Gain:feed tended to increase with increasing soy oil (linear, P < 0.01; quadratic, P = 0.06) or the soy oil/crude glycerol blend (linear, P < 0.01; quadratic, P = 0.09). Nitrogen digestibility tended (P = 0.07) to decrease in pigs fed crude glycerol compared with pigs fed the soy oil treatments. Apparent digestibility of GE tended (P = 0.08) to be greater in the pigs fed soy oil compared with pigs fed the soy oil/crude glycerol blends. In conclusion, adding crude glycerol to the diet before pelleting increased pellet durability and improved feed mill production efficiency. The addition of 3 or 6% crude glycerol, soy oil, or a blend of soy oil and glycerol in diets for 11- to 27-kg pigs tended to increase ADG. For pigs fed crude glycerol, this was a result of increased ADFI, whereas, for pigs fed soy oil or the soy oil/crude glycerol, the response was a result of increased G:F. Key words: feed manufacturing, glycerol, pelleting, pig