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Our objectives were to determine the effect of starter crude protein (CP) content on body composition of male Holstein calves from birth to 10 wk of age in an enhanced early nutrition program, and to compare the enhanced program to a conventional milk replacer program. Calves (n = 45) were purchased on the day of birth and assigned to a randomized block design. Eight calves were harvested at baseline and remaining calves were divided among the following 3 dietary treatments: (1) low rate of milk replacer [LMR; 20.6% CP, 21.7% fat; 1.25% of body weight (BW) as dry matter (DM)] plus conventional starter (CCS; 21.5% CP, DM basis); n = 11 calves; (2) high rate of milk replacer (HMR; 29.1% CP, 17.3% fat; 1.5% of BW as DM for wk 1, 2% of BW as DM wk 2-5, 1% of BW as DM wk 6) plus conventional starter; n = 12 calves; and (3) enhanced milk replacer (HMR) plus high-CP starter (HCS; 26% CP, DM basis); n = 14 calves. A subset of calves (n = 8) was harvested on d 2 to provide baseline data. Calves began treatments on d 2 or 3 of age. Calves were weaned at d 42. Starter was available ad libitum. Calves from each treatment were harvested at 5 (n = 18) and 10 (n = 19) wk of age and divided into 4 fractions: carcass; viscera; blood; and head, hide, feet, and tail. Fractions were analyzed for energy, CP, lipid, and ash. Average weekly starter intake did not differ between enhanced treatments. Gain of BW was greater for calves fed HMR than for LMR, but was unaffected by starter CP. Carcass weights at 5 wk were greater for HMR but did not differ between starter CP content. At 10 wk, carcass weights were heavier for HMR and had a greater percentage of empty BW for HMR + CCS than for HMR + HCS. At 10 wk, the weights of reticulorumen and liver were greater for calves fed HMR + HCS than for those fed HMR + CCS. At 5 wk, empty BW gain for HMR contained more water and less fat and ash than in calves fed LMR. At 10 wk, empty BW gain for calves fed HMR + HCS contained a greater percentage of water and less fat than for calves fed HMR + CCS. Plasma β-hydroxybutyrate was greater after weaning for calves fed HMR + HCS than for those fed HMR + CCS. After weaning, calves fed HMR had greater plasma total protein concentration than those fed LMR, and total protein was greater for calves fed HMR + HCS than those fed HMR + CCS. Plasma urea N was greater for calves fed HMR treatments, and postweaning was greater for calves fed HMR + HCS. A high-CP starter had minimal effect on empty BW gain before weaning, but after weaning it tended to increase mass of reticulorumen and liver.

Ninety carcasses were used to evaluate the effects of feeding ractopamine (RAC) to gilts, physically castrated (PC) barrows, and immunologically castrated (IC) barrows. Finishing diets (0, 5, and 7.5 mg/kg RAC) were fed for the last 26 d before slaughter starting 7 d after the second dose of Improvest. Carcasses from IC barrows had less ( P P = 0.02) than PC carcasses but had more ( P ≤ 0.04) fat than gilt carcasses. Feeding RAC increased ( P = 0.03) bone-in carcass yields by 1.4 percentage units. Gilt and IC carcasses had 2.0 percentage units greater ( P P = 0.01) bone-in lean yields, and 1.5 percentage units greater ( P = 0.04) bone-in carcass yields than PC carcasses. Loin firmness, pH, and marbling were unaffected by sex and RAC feeding ( P ≥ 0.22). Bellies from IC carcasses were 0.3 cm thinner ( P ≤ 0.05) than PC but 0.3 cm thicker ( P ≤ 0.05) than gilts. Flop distances of IC bellies were similar to gilt bellies but reduced ( P ≤ 0.05) 13 cm compared with PC bellies. Iodine values of IC bellies were similar to PC bellies but reduced ( P ≤ 0.05) 3 units compared with gilts. Feeding RAC did not affect ( P ≥ 0.23) fresh belly characteristics. Overall, immunological castration and feeding RAC were additive in terms of improving carcass cutability but had only minimal effects on fresh pork loin or belly quality.

Effects of sex class (physically castrated, PC or immunologically castrated, IC) and diet (0 or 5mg/kg ractopamine hydrochloride, RAC) on characteristics of ham and bellies were determined from pigs slaughtered in three groups with similar ending live weights. One carcass per pen per marketing group (n=8) was selected to evaluate further processing characteristics. Data were analyzed as a 2×2 factorial design with a split plot in time and fixed effects of sex, diet, marketing group, and their interactions. IC fresh bellies were thinner (P0.01) and softer (P0.01) than PC bellies. IC hams and bellies were leaner (P0.05) than those from PC pigs. RAC feeding did not affect (P0.05) fresh ham or belly characteristics but decreased (P0.01) fat in cured PC bellies. Marketing group affected (P0.05) fresh quality, processing characteristics, and composition of hams and bellies. Immunological castration and RAC produced leaner finished products but did not alter processing yield of hams or bacon.

The study was performed to evaluate the effect of feeding ractopamine (RAC) to physically castrated barrows (PC), immunologically castrated barrows (IC), and gilts (gilts) using a randomized complete block design with a 3 × 3 factorial arrangement of treatments: 1) sex (PC, IC, and gilts) and 2) RAC inclusion level (0, 5, and 7.5 mg/kg). The IC received 2 doses of gonadotropin releasing factor analog-diphtheria toxoid conjugate (Improvest; Zoetis, Kalamazoo, MI) at the start of the study (wk 16 of age; 69.6 ± 2.96 kg BW) and 4 wk later. The study used 180 pigs housed in groups of 4 (5 groups/sex × RAC subclass) and was performed over a fixed time of 61 d with RAC being fed for the final 26 d of study. Diets were formulated to meet requirements of intact males for the first 35 d and of intact males fed 7.5 mg/kg RAC for the remainder of the study. Pigs had ad libitum access to feed and water throughout the study period. At the end of the study, pigs were harvested at a commercial facility and HCW and last rib backfat thickness were measured. There were no treatment interactions (P > 0.05) for any variables. For the overall study period, IC had greater (P ≤ 0.05) overall ADG compared to PC, which grew faster (P ≤ 0.05) than gilts (1,246, 1,083, and 1,025 g/d for IC, PC, and gilts, respectively; SEM = 20.3); ADFI was lower (P ≤ 0.05) for gilts than IC and PC, which had similar ADFI (3.36, 3.37, and 2.87 kg/d, respectively; SEM = 0.051); and G:F was greater (P ≤ 0.05) for IC than gilts and greater for gilts than PC (0.371, 0.322, and 0.358 kg/kg, respectively; SEM = 0.0039). For the period from the second dose to the end of study, IC had greater (P ≤ 0.05) ADG (28.6%), ADFI (12.3%), and G:F (14.3%) than PC. Carcass yield was lower (P ≤ 0.05) for IC compared to PC and gilts (72.8, 75.0, and 74.6%, respectively; SEM = 0.25). Feeding RAC increased (P ≤ 0.05) ADG (15.7 and 14.5% for 5 and 7.5 mg/kg, respectively), G:F (17.1 and 16.4%, respectively), carcass weight (3.7 and 3.2 kg, respectively), and carcass yield (1.0 and 1.0 percentage unit, respectively) compared to the control. These results highlight sex differences in and effects of RAC on growth and carcass characteristics and suggest that the relative response to RAC is similar in IC and PC.

The objective of this study was to determine the effect of feeding ractopamine hydrochloride (RAC) in an equal weight marketing scenario. Barrows and gilts (n = 427) were assigned to 3 different RAC feeding programs before slaughter: control (0 mg/kg), 5 mg/kg for up to 35 d, or 5 mg/kg for 21 d followed by a step-up to 7.4 mg/kg for up to 14 d. Treatments including RAC were pooled and compared against control pigs using single df estimate statements. Coefficient of variation in beginning BW of RAC (7.16%) and control pigs (6.95%) did not (P = 0.68) differ; however, RAC-fed pigs had a lower (P < 0.01) market BW CV (3.91%) than controls (5.27%). Pigs fed RAC reached market weight 2.5 d earlier (P = 0.01) than control pigs (26.8 vs. 29.3 d). Ractopamine-fed pigs had a 21% greater (P < 0.01) ADG than control pigs, even though ADFI did not (P = 0.19) differ between RAC and control pigs. Pigs fed RAC produced 3% heavier HCW (P < 0.01), 3% greater loin depths (P = 0.05), and a 1 percentage unit greater dressing percent (P < 0.01) than control pigs. Sort loss per kilogram was less (P < 0.01) for RAC-fed than control-fed pigs, with 8 control pigs having HCW less than the sort loss threshold compared with only 2 RAC pigs. Ractopamine can be an important tool in reducing the variation in market weight and sort loss of finishing pigs.

The objective was to investigate the effect of various doses and durations of ractopamine hydrochloride (RAC) on pig HCW, cutting yields, and meat quality. Late-finishing pigs (approximately 93 kg) were allotted to 12 treatments 35 d before slaughter. Treatments consisted of negative control (NEG; 13.1% CP, 0.64 TID Lys), positive control (POS; 17.8% CP, 0.94 TID Lys), and 2 RAC doses (5 and 7.4 mg/kg) with 5 different feeding durations for each dose (7, 14, 21, 28, or 35 d). Pigs on ractopamine-duration diets were fed NEG until incorporation of RAC, and then the diet was switched to POS to comply with label requirements. A subset of 240 pigs was utilized to determine the effects of RAC on carcass cutting yields. This subset was selected by taking the 5 pigs closest to the average pen weight from 4 complete replicates. Differences in response to RAC between 5 and 7.4 mg/kg were not significant. Therefore, RAC dosages were pooled, resulting in an average dose of 6.2 mg/kg, which was then compared with NEG and POS diets. Ractopamine increased (P < 0.05) HCW by 2.5 and 2.3 kg compared with the NEG and POS diets, respectively. Hot carcass weight also increased linearly (P=0.003) as RAC duration increased. Indicators of carcass leanness increased with RAC compared with NEG. Estimated carcass lean percentage increased (P=0.010) 1 percentage unit from 54.79 to 55.79%, carcass cut yield increased (P

The objective of this experiment was to determine if increasing lysine in the diets of immu- nologically castrated (IC) male pigs would increase per- centage fat free lean and carcass cutting yields when compared with physical castrates. The anti-gonado- tropin-releasing factor (GnRF) immunological product (Improvest, Pfizer Animal Health) is used worldwide to immunologically castrate entire male pigs to control boar taint and take advantage of the inherent ability of the entire male to deposit more muscle, less fat, and grow more efficiently than physically castrated males. The immunization process essentially allows the pig to grow as an entire male pig for most of its life and then removes any boar odor (boar taint) before slaughter. Reported lean meat advantages may also provide eco- nomic benefits to the domestic meat industry. Approxi- mately 1,200 male pigs (physical castrates, IC males, and entire males) were each assigned to 1 of 4 diet programs which differed in lysine content. In each case, lysine was fed in a conventional step-down program that culminated with the following concentrations in the late finishing diet: physical castrates fed low lysine (0.7%), IC fed low lysine (0.7%), IC fed low/medium lysine (0.8%), IC fed medium/high lysine (0.9%), IC fed high lysine (1.0%), and entire males fed high lysine (1.0%). At 25 wk of age (5 wk post-second injection), pigs were individually weighed and the 2 pigs (n = 96) in each pen closest to the median pig BW were selected and slaughtered. The right side of each carcass was dissected into soft tissue, skin, and bone. Proxi- mate composition was determined on the soft tissue to determine percentage fat-free lean. The left side of each carcass was weighed and initially fabricated into ham, loin, belly, and whole shoulder. Each primal piece was weighed again and further fabricated into respec- tive subprimal cuts. Immunological castration did not change (P > 0.05) shear force values or ultimate pH when compared with either physical castrates or entire males. Marbling appeared to decrease as dietary lysine was increased among IC males. As expected, IC males had a greater (P < 0.05) percentage fat-free lean than physical castrates but less (P < 0.05) than entire males. Immunologically castrated males fed diets with medi- um/high and high lysine had greater (P < 0.05) lean cutting yields and carcass cutting yields than physical castrates. Lean cutting yield and carcass cutting yields appeared to increase as dietary lysine was increased among IC males. Overall, immunological castration im- proved carcass cutability, increased percentage fat free lean, and had no effect on pork quality when compared with physical castrates.

The effects of dietary energy source and feed withdrawal on muscle glycolytic potential (GP) and blood acid-base responses to handling were investigated in slaughter-weight pigs (initial BW 94.7 ± 1.01 kg). Crossbred pigs (n = 96; 48 barrows, 48 gilts) were used in a randomized complete block design with a 4 × 2 × 2 factorial arrangement of treatments: l) diet (control, high fat (10% supplemental fat), low- digestible carbohydrate (20% total starch), and high- fat/low-digestible carbohydrate (10% supplemental fat and 20% total starch)); 2) feed withdrawal (0 and 36 h); and 3) sex (barrow and gilt). Diets were fed for 28 d before the feed withdrawal treatment was applied, at the end of which all pigs were individually moved through a 12.20-m-long × 0.91-m-wide passageway for 16 laps (195 m total distance), with the assistance of an electric goad (2 times per lap). Longissimus muscle biopsies were collected at the beginning of the feeding and feed withdrawal periods and immediately after and 4 h after the handling procedure. Venous blood was collected 2 h before and immediately after the handling procedure to measure acid-base responses. At the end of the feeding period, pigs fed the control and high-fat diets were heavier (P 0.05) blood acid-base responses to handling. Muscle GP at the end of the feeding period and 4 h posthandling was least (P 0.05) for fasted and fed pigs receiving the 2 low-digestible carbohydrate diets. In conclusion, neither dietary energy source nor fasting affected blood acid-base responses to handling; however, fasting-induced changes in LM GP were diet dependent.

Two studies were conducted with refined glycerin (97.7 and 97.5% glycerin for studies I and II, respectively) to determine ME content and effects on growth performance and carcass and pork quality measures of finishing pigs. An energy balance study using 24 barrows (21.5 ± 0.6 kg initial BW) determined the apparent ME content of glycerin using a generalized randomized block design with 2 dietary treatments: 1) control (99.85% corn + vitamins and minerals) and 2) glycerin (30% of corn in the control diet replaced with glycerin). A 7-d adaptation was followed by a 5-d collection period for feces and urine. The energy content of diets, feces, and urine was determined by bomb calorimetry. The DE of the glycerin diet was greater (P0.01) than that of the control diet (4,298 vs. 3,902 kcal/kg of DM); however, the ME content of the 2 diets was similar (3,820 vs. 3,723 kcal/kg of DM). The ME of refined glycerin (estimated by difference) was 3,584 kcal/kg of DM. A growth study was conducted with 128 gilts housed in groups of 4 and reared from 92.5 ± 0.24 kg of BW for a 28-d period, using a split-plot design with a 4 × 2 factorial arrangement of treatments: 1) dietary glycerin level (0, 5, 10, and 15%) and 2) preslaughter handling (gentle vs. intense). The handling treatment was included to simulate the range in handling intensities that are likely to be experienced in practice. At the end of the 28-d period, one-half of the pens on study were slaughtered and used for carcass and pork quality evaluation with 2 pigs from each pen being subjected to each of the preslaughter handling treatments. There were no interactions (P0.05) between dietary glycerin and preslaughter handling treatment. Dietary glycerin had no effect (P0.05) on growth performance, carcass measures, or meat quality. There were no differences (P0.05) between the gentle and intense handling treatments for carcass or pork quality measures. In conclusion, feeding glycerin to finishing pigs at up to 15% of the diet had no negative effect on growth performance or carcass and pork quality characteristics.

Analyses were conducted to evaluate the ability of the USDA yield grade equation to detect differences in subprimal yield of beef-type steers and calf-fed Holstein steers that had been fed zilpaterol hydrochloride (ZH; Intervet Inc., Millsboro, DE) as well as those that had not been fed ZH. Beef-type steer (n = 801) and calf-fed Holstein steer (n = 235) carcasses were fabricated into subprimal cuts and trim. Simple correlations between calculated yield grades and total red meat yields ranged from -0.56 to -0.62 for beef-type steers. Reliable correlations from calf-fed Holstein steers were unobtainable; the probability of a type I error met or exceeded 0.39. Linear models were developed for the beef-type steers to predict total red meat yield based on calculated USDA yield grade within each ZH duration. At an average calculated USDA yield grade of 2.9, beef-type steer carcasses that had not been fed ZH had an estimated 69.4% red meat yield, whereas those fed ZH had an estimated 70.7% red meat yield. These results indicate that feeding ZH increased red meat yield by 1.3% at a constant calculated yield grade. However, these data also suggest that the calculated USDA yield grade score is a poor and variable estimator (adjusted R(2) of 0.31 to 0.38) of total red meat yield of beef-type steer carcasses, regardless of ZH feeding. Moreover, no relationship existed (adjusted R(2) of 0.00 to 0.01) for calf-fed Holstein steer carcasses, suggesting the USDA yield grade is not a valid estimate of calf-fed Holstein red meat yield.

The objective of these studies was to evaluate the effects of zilpaterol hydrochloride (ZH), fed for 0, 20, or 30 d, on meat quality attributes of calf-fed Holstein steers. Steers were slaughtered at a commercial facility, and carcasses were selected by HCW to represent the pen mean. Further carcass selection was based on quality grade (Choice and Select) and yield grade. Proximate composition, measures of water holding capacity, and tenderness using Warner-Bratzler shear force after 7, 14, or 21 d postmortem were evaluated on the shoulder clod (triceps brachii), top butt (gluteus medius), and strip loin (longissimus lumborum). Percentage of purge for the 3 subprimals was not different (P0.05) among ZH treatments. Steers fed ZH for 20 d or 30 d had decreased (P0.05) percentages of fat in the triceps brachii, compared with 0-d ZH. Percentage of fat was less (P0.05) in the gluteus medius and longissimus lumborum when steers were fed ZH for 30 d compared with those steers fed ZH for 0 d. Percentage of fat was greater in Choice triceps brachii (P0.05) and longissimus lumborum (P0.10) compared with Select. Thaw loss was not different (P0.05) for any muscle due to ZH treatment. Only longissimus had a greater (P0.05) cooking loss with ZH treatment. Cooking loss was not different (P0.05) for the gluteus medius or longissimus lumborum due to quality grade or aging day. At each aging day, the 20- and 30-d ZH longissimus lumborum had greater (P0.05) shear force values than 0 d; however, 20- and 30-d ZH had a greater absolute change in shear force from 7 to 21 d than that of 0 d ZH. Triceps brachii steaks were less tender (P0.05) after ZH treatment, but gluteus medius steaks were not different (P0.05). There was no difference (P0.05) in shear force due to quality grade. Results illustrate the use of ZH in calf-fed Holstein steers will have minimal effects on purge, thaw, or cooking loss. Percentage of intramuscular fat will decrease, especially when fed for longer durations. Steaks from ZH treated steers were tougher than steaks from control animals at all aging times, but ZH steaks became more tender with postmortem aging.

The objective of this study was to determine whether culled beef cows fed a high-concentrate diet (FED) would have improved live performance, carcass traits and muscle characteristics compared with forage fed (CON) cows. In addition, ractopamine (RAC) supplementation was evaluated for added benefits over high concentrate alone. Live weight, average daily gain, hot carcass weight, ribeye area, marbling, quality grade and carcass fat measurements increased (P ≤ 0.05) by realimentation. As a percent of hot carcass weight, muscle yields did not differ (P > 0.05). Lipid content increased (P ≤ 0.05) in 5 out of the 10 muscles from FED cows. Cows fed ractopamine showed some numeric improvements over feeding alone, but few statistical differences (P > 0.05). This may result from variability associated with cull cows, and warrants investigation into the best dose/duration for ractopamine. However, realimentation by itself was able to improve cull cow quality. PRACTICAL APPLICATION The U.S. beef industry continues to explore new avenues to enhance undervalued sectors of the production system. Through realimentation, cull cow quality can be improved. The data presented herein demonstrate that feeding a high-concentrate diet to cull cows increases both live and carcass weights. In addition, high concentrate-fed cull cows display more marbling and whiter fat cover than those fed at maintenance level. Qualification for premium programs, heavier weights and overall higher quality may lead to increased value for this underutilized sector of the beef industry.

From an experiment in which 60 beef cull cows were assigned to one of three feeding treatments, forage fed, high concentrate or high concentrate plus ractopamine, 10 muscles were removed from both sides of the carcass. Muscles from one side of the carcass were enhanced with a solution to target 0.3% salt and 0.3% phosphate in the final product. Minimal to no differences were observed in color, pH, sensory characteristics or shear force as a result of dietary treatment. Enhancement resulted in muscles with higher (P ≤ 0.05) pH and darker color. Sensory scores for juiciness and tenderness were improved (P ≤ 0.05) with enhancement. The Adductor was the only muscle not exhibiting lower shear values due to enhancement (P > 0.05). To add further value to meat from cull cows, enhancement could be utilized, independent of feeding regimen prior to slaughter. PRACTICAL APPLICATIONS The use of enhancement in the beef industry has become common practice, particularly in beef from lower grading cattle. However, research examining the improvement in palatability with enhancement has focused mainly on younger cattle. Our research demonstrates that enhancement is able to improve the sensory characteristics of meat from cull cows. Thus, in meat from older animals, which is usually characterized as being less palatable, enhancement could be used to improve the organoleptic traits. This practice may assist the beef industry in capturing further value from cull cows.

Sixty-four market-weight (130.0 +/- 0.65 kg) barrows (n = 16) and gilts (n = 48) were used in a split-plot design with a 2 x 2 x 2 factorial arrangement of treatments: 1) handling intensity (gentle vs. aggressive), 2) transport floor space (0.39 vs. 0.49 m(2)/pig), and 3) distance moved during handling (25 vs. 125 m) to determine the effects of multiple concurrent stressors on metabolic responses. For the handling intensity treatment, pigs were moved individually approximately 50 m through a handling course with either 0 (gentle) or 8 (aggressive) shocks from an electric goad. Pigs were loaded onto a trailer and transported for approximately 1 h at floor spaces of either 0.39 or 0.49 m(2)/pig. After transport, pigs were unloaded, and the distance moved treatment was applied; pigs were moved 25 or 125 m through a handling course using livestock paddles. Rectal temperature was measured, and blood samples (to measure blood acid-base status) were collected 2 h before the handling intensity treatment was applied and immediately after the distance moved treatment was applied. A LM sample to measure glycolytic potential was collected after the distance moved treatments on a subset of 32 pigs. There were handling intensity x distance moved interactions (P < 0.05) for several blood acid-base measurements. In general, there was no effect of distance moved on these traits when pigs were previously handled gently. However, when pigs were previously handled aggressively, pigs moved 125 compared with 25 m had greater (P < 0.05) blood lactate and less (P < 0.05) blood pH, bicarbonate, and base-excess. Pigs transported at 0.39 compared with 0.49 m(2)/pig had a greater (P < 0.01) increase in creatine kinase values; however, transport floor space did not affect any other measurements. Data were analyzed by the number of stressors (the aggressive handling, restricted transport floor space, and 125-m distance moved treatments) experienced by each pig (0, 1, 2, or 3). As the number of stressors experienced by the pig increased, rectal temperature, blood lactate, and LM lactate increased linearly (P

Beef complexus (chuck), serratus ventralis (chuck), vastus lateralis (round), vatsus medialis (round), and longissimus dorsi (loin) muscles were enhanced (0.3% salt, 0.4% phosphate), vacuum packaged, and aged for 7 or 14 d. Enhancement increased positive sensory attributes (tenderness, juiciness, beef flavor, saltiness) and decreased negative attributes (off-flavors) of all muscles but had greater effects on some than on others. It increased the oily mouthfeel (10%) and saltiness (40%) and decreased the L* value and chroma of the complexus (chuck). It increased tenderness, juiciness, and beef flavor and decreased off-flavors, visual red and brown colors, shear value, and cook loss of the serratus ventrali (chuck), vastus lateralis (round), vastus medialis (round), and longissiumus dorsi (loin). Aging slightly decreased rancid and liver off-flavor scores, visual brown color, and shear value and increased the hue angle and L* and b* values.

Ractopamine HCl (RAC) is a phenethanolamine β-adrenergic agonist used as a feed supplement that repartitions nutrients from fat deposition to increased protein synthesis and muscle protein accretion without deleteriously affecting pork quality. This literature review, as well as meta-analyses of the available results, was undertaken to evaluate the live performance, carcass, and pork quality responses to the various dietary inclusion levels (0, 5, 10, and 20 mg/kg) of RAC. Consensus of literature and meta-analysis indicated that pigs fed RAC, regardless of dietary inclusion level, gained faster (P

The objective of this study was to determine the effects of loin muscle location on glycolytic potential (GP) and fresh pork quality traits. Seven sections (5-cm thick) from approximately between the eighth rib and fourth lumbar vertebra were evaluated. Numerous quality measurements were taken within each section. Ultimate pH was similar (P > 0.05) at all locations. Drip loss decreased (P

One hundred eighty barrows were evaluated to determine the effects of ractopamine hydrochloride (RAC) on lean carcass yields and pork quality. The pens were blocked by weight (six pens per block) with starting block weights of 69.0, 70.7, 73.8, 76.6, 78.4, and 84.3 kg. Pens within a block were assigned randomly to one of three RAC treatments so each treatment in a block was replicated twice. Treatments (as-fed basis) included control diet, 10 ppm of RAC added (R10), and 20 ppm of RAC added (R20) and ranged from 25 to 41 d depending on block. Pigs were slaughtered by blocks when block average live weights were 109 kg. Gain and feed efficiency were improved (P 0.05). Dressing percentage was higher (P 0.05) among treatments. Carcass weights were heavier (P 0.05) among dietary treatments. Trained sensory evaluation panel results for tenderness decreased in a low-dose plateau response fashion for nonenhanced chops (P = 0.004). Tenderness of enhanced chops decreased linearly (P = 0.04) with increasing RAC concentrations. No differences (P > 0.05) were found in juiciness or flavor of enhanced or nonenhanced chops. Feeding RAC to late-finishing swine resulted in faster growing, more efficient animals with increased boneless subprimal yields, and it had little effect on pork juiciness and flavor.

Pigs from four commercial packing facilities were utilized to characterize the impact of downer pigs on meat quality and the impact of respiratory health on downer pigs. Lungs of downer pigs were evaluated for pneumonia and the pH of the longissimus was measured at approximately 45 min postmortem on 246 carcasses. At approximately 24 h postmortem, subjective color, marbling, firmness of the loin, carcass conformation, gender, objective loin color and ultimate pH of the longissimus were determined on 229 carcasses. Muscle score, 45 min pH and lung score averaged 2.14, 6.32 and 1.67, respectively. Subjective color, marbling, firmness, Minolta L-value, pH and drip loss averaged 3.75, 2.72, 3.16, 45.72, 6.00 and 1.91%, respectively. Downer pigs tended to produce pork that was dark in color with a relatively high ultimate pH and low drip loss. Virtually no relationship was observed between downer pigs and lung score.

This study was carried out to evaluate the effect of feed withdrawal and handling intensity on blood acid-base responses and muscle glycolytic potential in slaughter-weight pigs. Sixty crossbred pigs (BW = 107.7 +/- 0.56 kg; 44 barrows and 16 gilts) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: 1) feed withdrawal (0 vs. 24 h), and 2) handling intensity (low vs. high). The high-intensity handling treatment consisted of moving the pigs through a passage (12.2 m long x 0.91 m wide) for eight laps using an electric goad two times per lap. Pigs in the low-intensity handling treatment were moved at their own pace through the passage for eight laps using a livestock panel and paddle. Biopsy samples were collected from the LM at the beginning of feed withdrawal, at the end of the handling procedure, and 4 h after handling. Blood samples were collected 2 h before and immediately after the handling procedure. There were no interactions between feed withdrawal and handling intensity for any of the variables measured. Feed withdrawal decreased (P < 0.05) baseline and posthandling body temperature (38.85 vs. 38.65 degrees C; SEM = 0.060 and 39.70 vs. 39.37 degrees C; SEM = 0.04, respectively) and blood glucose, lowered (P < 0.05) baseline partial pressure of oxygen and partial pressure of carbon dioxide, and increased (P < 0.01) baseline and posthandling plasma free fatty acid concentrations. High-intensity handling produced higher (P < 0.01) posthandling lactate and glucose, and lower (P < 0.01) posthandling blood pH (7.33 vs. 7.18 +/- 0.02, respectively), bicarbonate, base excess, and total carbon dioxide than low-intensity handling. Longissimus muscle glycolytic potential of fasted pigs was lower (P < 0.01) than in fed pigs at the end of the handling procedure (177.2 vs. 137.0 micromol/g of wet tissue; SEM = 10.08, respectively). There was no effect of handling intensity on longissimus muscle glycolytic potential. Feed withdrawal did not attenuate the blood acid-base changes caused by handling; however, the combination of feed withdrawal and handling decreased muscle glycolytic potential.

Results from univariate outbred F2 interval mapping and sib-pair analyses of 12 growth and 28 carcass traits to identify QTL on SSC 2, 6, 13, and 18 were compared. Phenotypic and genetic data were recorded on a three-generation resource population including 832 F2 pigs from a cross between three Berkshire sires and 18 Duroc dams. Thirty markers with an average spacing of approximately 16 cM were genotyped across the four chromosomes. The outbred F2 mixed model included the effects of sex, birth month, and year, one-QTL additive, dominance and imprinting coefficients calculated every 1 cM using interval mapping, and a random family effect. The general sib-pair model used to describe the phenotypic differences between sib-pairs included the same systematic and random effects and a one-QTL additive coefficient calculated every 1 cM. The outbred F2 analysis found significant evidence of QTL on SSC 2 associated with 105-d weight, backfat thicknesses, LM area, fat percent, shear force, juiciness, marbling, and tenderness. In addition, QTL were identified on SSC 6 relating to 42-d weight and LM area, and on SSC 18 for fat and moisture percents. In most instances, the outbred F2 approach offered greater power to detect QTL; however, the sib-pair analysis offered greater power in several instances. The trait-specific superiority could be due to the relative advantage of each model within a trait data set. The two approaches provided complementary evidence for QTL segregating between the Berkshire and Duroc breeds used in the study that may be used to aid marker-assisted introgression and selection and candidate gene studies to improve swine growth and meat quality characteristics.

Forty-eight barrows and forty-eight gilts (PIC 337 sires x PIC C22 dams) were evaluated to determine the effects of feeding ractopamine hydrochloride (RAC) and different cereal grains on the carcass and fat quality in late finishing pigs. The study was carried out using four replicates with 24 animals in each replicate (four pigs per pen, six pens per replicate, two replicates per slaughter date, 12 pens per slaughter date). Treatments for the experiment included corn, wheat, and barley (early finisher period); and corn, corn + RAC, wheat, wheat + RAC, barley, and barley + RAC for the late finisher period. Ractopamine was fed at the level of 10 mg/kg (as-fed basis) of feed. Pigs were allotted to early finisher period treatments at approximately 45 kg BW. Pigs were then given late finisher period treatments at approximately 80 kg BW and fed for 28 d. The dietary digestible lysine level for all diets was maintained at 2.7 g/Mcal of ME. Pigs fed the wheat and corn diets during the late finisher period had a greater (P

Yearling (12 Angus, 12 Wagyu≥Angus) and 2-year old heifers (12 Angus, 12 Wagyu≥Angus) were fed elevated levels of Vitamin D3and/or Vitamin E to evaluate beef quality. Warner-Bratzler shear force (WBS) and sensory characteristics were determined on steaks from the Longissimus lumborum (LL) aged 21 days and on steaks from the Gluteus medius (GM) and Psoas major (PM) aged 7 days. Steaks were cut from all muscles, displayed for 5 days then L*value and hue angle were determined. Vitamin E supplemented heifers received the highest sensory tenderness and juiciness scores, while no differences were observed among other treatments. D3+E supplemented Angus LL had higher WBS values than other treatments and breeds. Display time affected both color measures for all muscles, but especially hue angles of GM and PM. Vitamin treatment affected LL and GM color measures in yearlings to a greater extent than in 2-year olds.

A study was conducted to characterize the relationship between Longissimus thoracis ultimate pH (LTpH) and pork quality. Animals (n =47) were selected based on LTpH measured at 24 h postmortem. Data were analyzed using regression procedures with ultimate pH as the independent variable, and relationships were determined to be linear (L), quadratic (Ql or cubic (C). Ultimate pH explained 79% (C) of the variation in subjective color, which increased as pH increased. Drip loss, purge loss and L* value decreased as LTpH increased (R2 = 0.57C, 0.77 Q and 0.68 Q, respectively). Shear force decreased and sensory juiciness increased as LTpH increased (R' = 0.26 Q and 0.46C, respectively). However, offlavor intensity increased as LTpHfell below pH 5.2 or exceeded 6.1(R2= 0.52C). Increasing LTpH, up to a point, will improve fiesh pork quality and processed meat properties, whereas, above approximately 6.1, of-jlavor may increase.

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.

Intact sides were subjected to accelerated chill (AC: -3OC for 2.5 h, 4C for 20-22 h) or conventional chill (CC: 4C for 22-24 h). Color, drip loss, and pH were evaluated 24 h postmonem at three sites (inner, mid, and outer) in the Semimembranosus (SM) and Biceps femoris (BF) with the inner site closest to the femur. Zle Longissimus thoracis (LT) and the Longissimus lumborum (LL) were also evaluated. Accelerated chill improved color and drip loss of the Longissimus muscle. Accelerated chill had no fleet on the quality measurements of the ham, although site differences occurred. The fleets of genotype on color, drip loss, andpH in the loin and ham muscles were not consistent in the muscle groups studied. Compared to CC, AC has beneficial fleets on fresh pork quality of the Longissimus muscle, but not the ham muscles.

The objective of this study was to compare the carcass and meat quality of pigs of two sire lines (A vs B) reared in either a spacious or crowded environment. A total of 128 pigs (barrows and gilts) were used in the study. Animals were slaughtered at 120 kg live weight. Dressing percentage was greater for line A in the spacious but not the crowded environment and line A had a greater loin eye area than line B. Compared to line B, the longissimus from line A had lower pH, higher L* and b* values, and was judged to be paler and softer with a lower marbling fat content. Longissimus L* values were lower for pigs reared in the crowded compared to the spacious environment. Longissimus drip loss was greater for line A compared to line B in the spacious but not the crowded environment. This study highlights genetic differences in pork quality and suggests rearing environment effects that warrant further study.

ABTRACT Boneless, paired pork loins (n=120) were selected based on pH at 14 h postmortem. Ultimate pH, drip loss, instrumental color (L*, a*, and b* values), and proximate analysis were determined prior to pumping. Paired loins were cut into four sections and pumped to 100%, 106%, 112% or 118% of original weight to result in a product containing 0.4% sodium tripolyphosphate (STP) for Experiment 1 (Exp. 1) and 0.4% STP plus 0.4% salt for Experiment 2 (Exp. 2). In Exp. I, additional pump level increased (P

Halothane negative Durocs (n=36) were slaughtered, and subjected to: accelerated chill (AC: -30C for 2 h, with air circulation, followed by equilibration at 4C for 20-22 h), conventional chill (CC: 4C for 22-24 h with water sprayed every 2 h until 12 h postmortem), and slow chill (SC: 10-12C for 12 h followed by equilibration at 4C for 10-12 h). Color, pH, and drip loss were determined for the Semimernbranosus (SM) Biceps femoris (BF), Longissirnus thoracis (LlJ, and Longissirnus lumborum (LL). In the ham muscles, AC decreased b * values and drip loss. Decreased drip loss was restricted to the outer sites. Ham muscles were darkest in the mid location and lightest in the inner locations. In the Longissirnus, AC decreased pH but did not afect color or drip loss. Compared to SC, ACproved beneficial, however, AC had no advantages over CC in pigs with minimal predisposition to quality problems.

The objective of this study was to compare the effects of longissimus glycolytic potential (GP) and of time of feeding of supplemental magnesium sulfate heptahydrate on carcass and pork quality traits. The study was carried out in a 2 x 2 x 4 factorial arrangement; the treatments were sex (castrate vs gilt), GP (Low [normal] vs High), and time of feeding of magnesium sulfate-fortified diets (0 [control] vs 2 vs 3 vs 5 d prior to slaughter). Glycolytic potential was determined on a biopsy sample of longissimus from the live animal prior to the start of the study. A total of 144 pigs were allotted to the feeding-time treatments on the basis of sex (castrate and gilt), weight, and GP. Pigs were placed in individual pens and had free access to water. Prior to the start of the study, pigs were given ad libitum access to a standard finisher diet. During the study, animals were fed at a fixed level of 2.75 kg of a standard finisher diet/day; the fortified diet contained 3.2 g/d of additional magnesium. At the end of the feeding period, animals were transported to a commercial packing facility and slaughtered within 15 min of arrival. Fresh meat quality was measured on the longissimus. There were no treatment interactions. Carcass traits were similar across time of feeding treatments. Backfat thickness at the last lumbar vertebra and 10th rib were lower (P < 0 .05) for High than for Low GP pigs. High GP pigs had lower ultimate pH (P < 0.001) and higher drip (P < 0.05) and purge loss (P < 0.01) than Low GP pigs. Drip loss was reduced (P < 0.05) for pigs fed the magnesium-fortified diet for 5 and 2 but not for 3 d compared to controls (8.98, 7.29, 7.89, and 7.41 for the 0-, 2-, 3-, and 5-d treatments, respectively, SEM 0.447). Purge loss was similar for all of the time of feeding treatments. Longissimus L* values were lower (P < 0.05) for the 2-d treatment than for the controls. Results from this study suggest an inconsistent effect of short-term feeding of magnesium sulfate on muscle color and drip loss in pigs with both Low (normal) and High GP.

The objective of this research was to examine the impact of supplementation with creatine monohydrate (CMH) on the quality of various muscles from normal and heterozygous halothane carrier pigs. Twenty-nine crossbred pigs, 16 normal (NN) and 13 halothane carrier (Nn) genotypes, were supplemented with 0 or 25 g x pig(-1) x d(-1) of CMH for 5 d before slaughter. Supplemented pigs gained 2.26 kg more weight (P 0.05) drip loss or muscle composition. Supplementation with CMH also resulted in lower L* values in two ham muscles, semitendinosus (5.15 units) (P < 0.05) and semimembranosus (1.95 units) (P < 0.10) for Nn carcasses. Genotype had significant effects on most quality indicators, with Nn carcasses producing lower-quality lean as evidenced by less desirable subjective and objective color and higher drip losses. Genotype also affected the composition of several muscles, with the NN carcasses having more fat and less moisture.

Effects of feeding ractopamine (RAC; 5 mg/kg) to physically castrated (PC) and immunologically castrated (IC) pigs on carcass characteristics, cutting yields, and loin quality were evaluated using 285 carcasses. Male pigs were randomly assigned to sex treatments (PC and IC) at birth and fed the same nursery diets before allotment into 32 pens with 22 pigs per pen in a grow-finish barn. Pigs in the PC group were physically castrated at approximately 5 d of age, and pigs in the IC group were administered Improvest at 11 and 18 wk of age. Diet treatments (control or RAC) were initiated on study d 87. Pigs were marketed at 12 d (4.5 wk post-second Improvest dose), 19 d (5.5 wk post-second Improvest dose), and 33 d (7.5 wk post-second Improvest dose) following the start of final diet treatments. Three carcasses per pen were selected for evaluation of cutting yields and loin quality. Data were analyzed using PROC MIXED in SAS with fixed effects of sex, diet, market group, and their interaction; carcass (N = 285) was the experimental unit. Carcasses from RAC-fed pigs were heavier (P0.01) and had deeper (P = 0.02) loins than control-fed carcasses. Carcasses from IC pigs were similar (P = 0.22) in weight but had less (P0.01) fat and shallower (P = 0.02) loins when compared to PC carcasses. There were differences (P0.05) among market groups for carcass weights, fat depths, loin depths, and estimated carcass leanness. For cutting yields, RAC-fed carcasses had greater (P ≤ 0.03) bone-in lean and total carcass cutting yields than control-fed carcasses while there were no differences (P0.05) between RAC-fed and control-fed carcasses when evaluating LM color, marbling, firmness, pH, drip loss, and tenderness. Carcasses from IC pigs had greater (P0.05) boneless lean yields, bone-in lean yields, and total carcass cutting yields than PC carcasses. There were minimal differences (P0.05) in LM marbling, firmness, composition, and tenderness between PC and IC pigs. There was an interaction (P = 0.03) between sex and diet for LM composition. Control-fed PC loins had more (P0.01) lipid than all other treatment combinations. Market group had effects (P0.05) on carcass cutting yields, LM color, marbling and firmness scores, pH, purge loss, composition, and tenderness. The results from this study indicated RAC and immunological castration were additive in terms of improving carcass cutting yields while having minimal effects on pork quality.

Growth performance and carcass characteristics of physically castrated (PC) and immunologically castrated (IC) pigs fed ractopamine hydrochloride (RAC; 5 mg/kg) were evaluated in 64 pens of 22 pigs each. Male pigs were randomly assigned to castration method at birth. Pigs in the PC group were physically castrated at 5 d of age while IC pigs were administered Improvest at 11 and 18 wk of age. Pigs entered the grow-finish barn at approximately 9 wk of age (d 0). Dietary treatments (control or RAC) were initiated on d 87. Final treatment arrangement was a 2 × 2 factorial of castration method and diet. Data were analyzed using a mixed model with fixed effects of castration method, diet, market group, and all 2- and 3-way interactions. Pen was the experimental unit. From d 0 to 65, IC pigs had 11.2% greater (P < 0.01) G:F and 11.6% less (P < 0.01) ADFI than PC pigs, but ADG was increased 1.0% in PC pigs compared with IC pigs (P < 0.01). From d 65 to 87, IC pigs had 7.9% greater (P < 0.01) ADG and 12.1% greater (P < 0.01) G:F than PC pigs while having similar (P = 0.16) ADFI. At the initiation of diet (RAC) treatments, BW of all treatments were similar (P ≥ 0.32). From d 87 to 120 (RAC feeding period), IC pigs had 10.0% greater (P < 0.01) ADG and 10.5% greater (P < 0.01) ADFI than PC pigs while having similar (P = 0.64) G:F. Feeding RAC increased (P < 0.01) ADG by 16.9% and G:F by 17.9% while having no effect (P = 0.42) on ADFI from d 87 to 120. There were no significant interactions between castration method and diet on growth performance from d 87 to 120. For the entire study (d 0-120), IC pigs had 2.6% greater (P < 0.01) ADG, 4.6% less (P < 0.01) ADFI, and 7.3% greater (P < 0.01) G:F than PC pigs. Averaged over market groups, IC pigs were 2.5 kg heavier (P < 0.01) and had similar (P = 0.10) carcass weights and 1.8 percentage units less (P < 0.01) dressing yields than PC pigs. Additionally, IC pigs had 1.3 mm less (P < 0.01) fat and 1.7 mm less (P < 0.01) loin depth than PC pigs. Pigs fed RAC were 2.9 kg heavier (P < 0.01) and had 2.3 kg heavier (P < 0.01) carcasses and 2.2 mm deeper (P < 0.01) loins but similar (P = 0.21) dressing yields and tended (P < 0.10) to have 0.4 mm less fat than control-fed pigs when averaged over market groups. Group 3 pigs were the heaviest (P < 0.01) at slaughter and had the heaviest (P < 0.01) carcasses, greatest (P < 0.01) dressing yields, and the most (P < 0.01) carcass fat of all market groups. Overall, immunological castration and RAC were additive in terms of improving growth performance and carcass characteristics.

High pressure water (110 kPa) was compared to the Whizard knife (WK) with respect to quantity and composition of tissue recovered from thoracic, lumbar, and cervical vertebrae of swine and beef carcasses. High pressure water (HPW) recovered tissue contained less collagen than that recovered using the WK. A higher percentage of tissue was recovered from beef bones by WK than by HPW, but HPW tissue was higher in noncollagen protein. Recovery differed due to vertebral location; thoracic and lumbar vertebrae yielded a higher percentage of tissue than did cervical vertebrae. Centrifugation at 4000 x g was required to reduce the moisture content of HPW-recovered tissue to that of WK-recovered tissue, Fat content of HPW-recovered beef tissue was lower than that of WK-recovered tissue, however the reverse was true for tissue recovered from pork vertebrae. Recovery method had no effect on total protein or ash content.

Animals (n = 72) with longissimus glycolytic potential (GP) values ranging from 113.8 to 301.1 μmol/g of tissue, were classified as having low (n = 24), moderate (n = 24), and high (n = 24) GP levels. Meat quality measurements such as longissimus ultimate pH and subjective color score decreased, while Hunter L* values, percentage drip loss and purge loss increased for animals classified as having either high or moderate GP levels compared to those with low GP values. Animals with higher GP had decreased longissimus protein content and improved taste panel tenderness scores and lower shear force indicating superior eating quality. Increasing aging time from 2 to 21 days decreased shear force and improved taste panel tenderness scores. These data indicate that both glycolytic potential level within the muscle and aging time can have significant effects on pork quality characteristics.

Progeny of three commercial sire lines mated to the same halothane negative crossbreed dam line were compared for growth, carcass and meat quality characteristics. Sire line A (halothane reactor) produced halothane carrier progeny; line C was halothane negative and produced negative progeny; line B (a cross between lines A and C) was a halothane carrier line that produced both carrier (BNn) and negative (BNN) progeny within the same litter. Line A pigs grew more slowly (P ≤ 0.05) and consumed less feed (P ≤ 0.05) than the progeny of the other lines (885, 1049, 1057 and 1082 g d−1 and 2.37, 2.82, 2.72 and 2.79 kg d−1 for lines a, BNN, BNn and C respectively). However, gain:feed was similar for all lines. Dressing percentage was similar for lines A, BNn and BNN (77.42, 77.62 and 77.00% respectively) but lower for line C (75.31%: P ≤ 0.05). Line differences for linear carcass measurements, lean cut yield and fat-free lean content were relatively small. Line A had higher shear force than the others (4.32, 3.21, 3.57, and 3.30 kg for A, BNN, BNn and C, respectively; P ≤ 0.05) and lines A and BNn had reduced taste panel tenderness and juiciness (P ≤ 0.05) compared with lines BNN and C. This study highlights commercially important differences between sire lines for pork quality traits. the variation in pork quality within this study resulted from the halothane gene and, potentially, other single genes that affect meat quality parameters. Key words: halothane gene, meat quality, sire line, pigs, carcass quality

Eight hybrid gilts of Hampshire descent were selected at 110 kg live weight, grouped together in one pen and given a one-week adaption period prior to sampling. Longissimus samples (approximately 0.5 g) were taken using spring-loaded biopsy equipment with animals either unrestrained and free to move in the pen or, 3 h later, restrained with a nose snare for two minutes prior to sampling. There was no difference among the two handling approaches for glycolytic potential (P > 0.05). Animals were slaughtered and four longissimus samples (0.5 g) were taken from each carcass immediately following exsangination to evaluate four sample storage methods. Two viable storage methods, freezing in liquid nitrogen followed by freeze drying or immediate homogenization in perchloric acid, yielded relatively high and similar values for muscle glycolytic potential.

Three trials were conducted to determine the effects of the changed USDA quality grade guidelines and finishing environment on the performance and carcass merit of Angus-sired and Wagyu-sired single-calving heifers. In trial 1, nine Angus and 15 Wagyu single-calving heifers were finished to a compositional subcutaneous fat cover of 1.0 cm on a corn/corn silage-based diet. Feedlot performance was not affected by sire breed. Wagyu (59.4 ± 0.49%) heifers had a higher ( P P P P P >0.10) lower as a result. Carcass merit was not significantly affected by finishing environment. The single-calving heifer system was a viable option for beef production despite the changes in USDA quality grade guidelines.

The objective of the study was to investigate the influence of amino acid-deficient diets and high dietary leucine levels offered for intervals of either 21 or 35 days pre-slaughter on the intramuscular fat content of pig muscle. Twenty-four hybrid gilts were offered individually ad libitum one of four diets that comprised combinations of amino acid levels (supplemented or deficient: 5·6 v. 4·0 g lysine per kg) and low or high leucine levels (10·3 v. 30·3 g leucine per kg). Live weights at the start of the study were 74·5 and 87·0 kg for pigs on the 35- and 21-day feeding regimens, respectively. There were no significant effects of dietary amino acid level, leucine level, or feeding interval on food intake, daily live-weight gain or food efficiency. Pigs given the amino acid-deficient diets had lower killing-out proportions (736 v. 747 (s.e. 3·4) g/kg; P < 0·05) and longissimus dorsi muscle areas (32·6 v. 35·7 (s.e. 0·71) cm2, P < 0·01) than those given amino acid-supplemented diets. Subjective score for longissimus dorsi colour indicated that pigs on the high leucine diet had darker muscle than those on the low leucine diet. Intramuscular fat contents of the longissimus dors i muscle at the Wth/llth rib and the 3rd/4th lumbar vertebra and of the semimembranosu s muscle were increased by 19, 18 and 18 g/kg, respectively (P < 0·05), for pigs given amino acid-deficient compared with those given amino acid-supplemented diets. Dietary leucine level had no significant effect on intramuscular fat level. Pigs given the diets for 35, compared with 21, days had higher fat levels in the semimembranosu s muscle (52 v. 30 (s.e. 5·2) g/kg; P < 0·01) but not in the other two muscle locations studied. This study suggests that relatively short-term feeding of amino acid-deficient diets can produce substantial increases in intramuscular fat levels.

Five barrows and five gilts of each of two breeds (Meishan [Ms] and Yorkshire [Y]) were slaughtered at birth and at 41, 71, 123, and 171 d of age and five gilts of each breed were slaughtered at 260 d of age. Major organ and visceral weights were obtained immediately postmortem (PM), whereas carcass characteristics, carcass composition, femur measurements, and two individual muscle weights were obtained 24 h PM. Linear and quadratic regression coefficients on age differed between the two breeds, in favor of Y barrows and gilts, for live weight, carcass weight, longissimus muscle area (LMA), liver, heart, spleen, and kidney weights, and femur cross-sectional, medullary, and cortical areas (P

Special fed veal calves (N = 75) were slaughtered in study 1 and assigned to the following treatments; control (C), electrical stimulation (ES) immediately postmortem for 20 s (ES20–IP) or 40 s (ES40–IP), and ES 10 min postmortem for 20 s (ES20–10) or 40 s (ES40–10) using a Jarvis BV 80 electrical stimulator. Temperature, pH and 24 h carcass traits were evaluated. ES durations of 40 s produced more desirable carcass traits. In study 2, 40 calves were slaughtered and assigned to C or ES40–IP treatments. Temperature, pH, carcass characteristics, purge loss, percent free water, color stability, Warner-Bratzler shear force and palatability of biceps femoris slices were evaluated. ES reduced (P < 0.05) pH (at 45 min, 3 h and 24 h) and decreased (P < 0.05) percentage free water, but did not affect color stability, palatability or shear force values of veal from study 2. Low voltage ES enhanced postmortem pH decline in both studies (especially in study 1) and improved the 24 h (postmortem) longissimus characteristics of veal in study 1.

Effects of porcine somatotropin (pST) on growth and carcass characteristics of Meishan (Ms) and Yorkshire (Y) barrows given 3 mg of pST or saline daily were determined for two end points. First, 26 Ms and 26 Y barrows were treated from 119 d of age until the Y barrows reached 108 kg. Second, another 18 Ms barrows were treated to 108 kg BW. Age- and weight-matched treatments were analyzed. Results for both groups indicated pST effects (P < .05) for feed conversion (+) and intake (-), dressing percentage (-), percentage of carcass fat (-) and protein and water (+), leaf fat (-), backfat (BF) thickness (-), longissimus muscle area (LMA; +), skin thickness (+), muscle firmness and marbling scores (-), organ weights (+), belly (-), clear plate (-), ham (+), and total boneless cuts (BC; +). Somatotropin effects were also present for loin (-) and boneless Boston butt (BBB; +) in the age-matched group and for ADG (+), carcass weight (-), loin (-), jowl (-), and tenderloin (+) in the weight-matched group. Breed effects (P < .05), in favor of Y barrows, in both treatments existed for ADG (+) and feed intake (+), carcass weight (+), dressing percentage (+), LMA (+), skin thickness (-), muscle color and firmness scores (-), muscling score (+), all wholesale cuts (WC; +) except clear plate (age-matched), all trimmed cuts (TC; +) except picnic shoulder (weight-matched), and all BC (+). Breed effects, in favor of Y barrows, were also determined for carcass length (+), percentage of carcass ash (-), leaf fat (+), average BF thickness (+), and heart (-) and liver (-) weights in age-matched animals and percentage of carcass fat (-), protein (+), water (+), leaf fat (-), 10th rib, average, and P2 BF thicknesses (-), marbling score (-), femur length (-), and liver weights (+) in weight-matched animals. A higher response to pST (P < .05) was determined in Ms barrows than in Y barrows for percentage of carcass protein (+), liver (+), and heart (+) in the age-matched treatment and 10th rib BF thickness (-) and heart weight (+) in the weight-matched treatment. Yorkshire barrows treated with pST had more improved values for color score (+; age-matched) and BBB (+; weight-matched).

Samples from subcutaneous, intermuscular and internal fat depots of 30 crossbred pig carcasses with tenth rib fat thickness ranging from 1.5 to 4.3 cm were used to evaluate the relationships of backfat thickness and fat depot composition (moisture, lipid and cholesterol contents). Moisture and cholesterol were highest and lipid content was lowest in intermuscular fat while cholesterol was lowest (P < 0.05) in subcutaneous fat when compared to the other fat depots. Significant (P < 0.01) linear effects of tenth rib fat depth on moisture and lipid contents of all fat depots were observed. Linear effects (P < 0.05) of tenth rib fat thickness on cholesterol content of subcutaneous and internal fat depots were observed on both a wet and dry bases. However, the linear effect (P < 0.05) of tenth rib fat depth on cholesterol content in the intermuscular fat depot was observed only on a dry basis. When the three fat depots were combined, increased tenth rib fat depth resulted in decreased moisture and cholesterol contents on a dry basis while percentage lipid increased (P < 0.05).

Fifty growing pigs were used in two experiments to evaluate the effects of cannulation and hyperalimentation on performance and body composi- tion responses. Surgical implantation of a cannula into the greater curvature of the stomach and subsequent management associated with maintenance of the cannula did not result in a reduction (P > ,051 of voluntary feed intake. Cannulation did not negatively affect gain (P > .05). Over the entire trial, feed efficiency was not changed by cannulation (P > .05). Cannulation itself did not affect protein or fat deposition (P > .05) in the carcass. Hyperalimentation to approximately 120% of control intake resulted in increased daily gain (P .05) compared with that of control animals, Hyperalimentation decreased protein deposi- tion (P < .05) and tended to increase fat deposition.

Knowledge of the genetic control of pork quality traits and relationships among pork quality, growth, and carcass characteristics is required for American swine populations. Data from a 2 x 2 diallel mating system involving Landrace and Duroc pigs were used to estimate heritabilities and genetic correlations among growth (ADG), real-time ultrasonic (US) measures of backfat thickness (BF) and longissimus muscle area (LMA), carcass characteristics, and various pork quality traits. Data were collected from 5,649 pigs, 960 carcasses, and 792 loin chops representing 65, 49, and 49 sires, respectively. Genetic parameters were estimated by REML assuming animal models. Heritability estimates were moderate to high for ADG, USBF, USLMA, carcass BF, and LMA, percentage of LM lipid (IMF), pork tenderness, and overall acceptability. Estimates were low to moderate for percentage of cooking loss, pH, shear force, percentage of LM water, water-holding capacity (WHC), pork flavor, and juiciness. Genetic correlations between US and carcass measures of BF and LMA indicate that selection based on US data will result in effective improvement in carcass characteristics. Selection for increased LMA and(or) decreased BF using US is, however, expected to result in decreased IMF and WHC, increased percentage of LM water and shear value, and in decreased juiciness, tenderness, and pork flavor. Average daily gain was favorably correlated with IMF and unfavorably correlated with shear force. Selection for increased ADG is expected to improve WHC but to decrease the percentage of LM water, with an associated decrease in juiciness. The results of this study suggest the feasibility of including meat quality in selection objectives to improve product quality. Favorable genetic correlations between IMF and eating quality traits suggest the possible merit of including IMF in the selection objective to improve, or restrict change in, pork eating quality.

Zilpaterol hydrochloride (ZH) is designed to increase carcass leanness, chilled side weight (CSW), and percent saleable yield. The objective of this study was to evaluate the effect of a single dose of ZH on cutability and subprimal yield of calf-fed Holstein steers when fed for increasing durations. Two hundred forty steers were fed 8.3 mg/kg of ZH on a DM basis for 0, 20, 30, or 40 d, with a 3-d withdrawal before slaughter. After slaughter, steers were fabricated into 4 pieces (round, loin/flank, rib/plate, and chuck), packaged in combos, shipped to 2 locations, and further fabricated into subprimal pieces and trim. Trim was collected from each primal and separated into groups based on composition of 90, 80, and 50% lean. Zilpaterol hydrochloride increased (P = 0.01) CSW by 6.22 kg and saleable yield by 6.4 kg when included in the diet for 20 d. Furthermore, saleable yield as a percentage of CSW was increased (P = 0.03) 1.18 percentage units when included in the diet for 20 d. Steers fed ZH for 20 d had heavier strip loins (4.47 vs. 4.12 kg, P = 0.02), tenderloins (2.75 vs. 2.49 kg, P = 0.02), and ribeye rolls (5.74 vs. 5.30 kg, P = 0.01) than steers not fed ZH. These advantages are further demonstrated as a percentage of CSW. Strip loins (P = 0.06), tenderloins (P = 0.04), and ribeye rolls (P = 0.04) of ZH-fed steers had a greater percentage of CSW than controls. Zilpaterol hydrochloride also increased the percentage of CSW of the 3 primary components of the round when fed for 20 d. The knuckle was 0.10 percentage units heavier (P = 0.11), the top round was 0.24 percentage units heavier (P = 0.04), and the bottom round was 0.22 percentage units heavier (P = 0.03) in ZH-fed steers when compared with steers not fed ZH. Based on these data, it can be concluded that ZH significantly increased subprimal cutting weights, yields, and percentage saleable yield of calf-fed Holstein steers when fed for at least 20 d before slaughter. Zilpaterol hydrochloride increased percentage of CSW of subprimal cuts from Holstein steers in the round and to a lesser degree in the loin.

Carcass characteristics, meat quality traits, and sensory attributes were evaluated in late-finishing barrows and gilts, weighing between 100 to 130 kg of BW, fed 0, 5, or 7.4 mg/kg of ractopamine hydrochloride (RAC) for the final 21 to 28 d before slaughter. Carcass data were collected from carcasses from barrows and gilts (n = 168), and all primal cuts from the right sides of these carcasses were fabricated to calculate primal yields as a percentage of the HCW. Subjective (National Pork Producers Council and Japanese) color, firmness, and marbling scores were determined on the LM of each loin and the semimembranosus muscle (SM) of the ham, whereas the moisture, extractable lipid, Warner-Bratzler shear force (WBSF), and trained sensory evaluations (juiciness, tenderness, and pork flavor) were measured on the LM samples only. Gilts produced heavier (P < 0.05) HCW than barrows, whereas feeding RAC increased (P < 0.05) HCW over pigs fed diets devoid of RAC. Carcasses from gilts also had greater (P < 0.02) primal cut and lean cut (P < 0.01) yields than barrows, and dietary inclusion of 5 mg/kg of RAC increased (P < 0.05) total boneless cut and lean cut yields when compared with carcass from pigs fed 0 or 7.4 mg/kg of RAC. Warner-Bratzler shear forces values were greater (P < 0.05) in the LM of gilts than barrows, but only juiciness scores were greater (P < 0.03) in LM chops from barrows than gilts. The LM from barrows had greater intramuscular lipid (P < 0.001) than the LM from gilts, and even though the LM from pigs fed 5 mg/kg of RAC had greater (P < 0.04) WBSF values than the LM from pigs fed 0 or 7.4 mg/kg of RAC, including RAC in the late-finishing diets for 21 or 28 d did not affect sensory panel rating or percentages of moisture and intramuscular lipid. In summary, addition of RAC in the late-finishing diet improved carcass and primal cut yields when it was fed at 5 and 7.4 mg/kg without altering pork quality traits regardless of whether RAC was fed for 21 or 28 d.

The objective was to determine belly and bacon quality traits in pigs fed ractopamine (RAC) for various durations during finishing. A 2×3×2 factorial arrangement was used with barrows and gilts, fed RAC levels of 0.0, 5.0, or 7.4ppm, for 21 or 28d prior to harvest. Bellies were fabricated and measured for length, thickness, firmness, and processing yields. Once processed, 1.27cm slices were removed at 25%, 50%, and 75% the distance from the blade end, packaged and digitally imaged using a Chem1 Genius(2) Bio Imaging System. Total slice area (TA), total slice length (TL), secondary lean length (SL), secondary lean area (SA), and percent lean area (TA - all lean components=LA) were determined by tracing images in Adobe Photoshop Elements. A composite sample from the three slices was used for proximate analysis to determine moisture and fat composition for each belly. Feeding RAC increased belly yield, TA, TL, SA, and LA (P0.05), but did not alter moisture or fat composition (P0.05). Gilts had decreased firmness and higher pump uptakes compared to barrows (P0.05). Additionally gilts had increased TL, SL, and LA with lower fat and higher moisture content (P0.05). RAC feeding duration had no significant effect on belly or bacon quality traits (P0.05), furthermore, no interactions were found to be significant (P0.05). RAC administration during finishing resulted in improved belly and bacon yields with no negative effects on the quality traits evaluated.

The Illinois Spring Barrow Show, a large annual carcass show of performance-tested pigs, may provide an indication of phenotypic trends in the pork industry over time. Objectives of this study were 1) to investigate time trends in live and carcass weights (LWT, CWT), dressing percentage (DP), length (LEN), loin muscle area (LEA), backfat (BF), muscle color, firmness and marbling (C,F,M) scores, estimated fat-standardized lean yield (FSL), FSL/d of age (LDOA) and FSL/d on test (LDOT) and 2) to assess use of carcass characteristics to predict DP. Data on 5,983 barrows exhibited between 1968 and 1989 were analyzed. Linear regressions expressed as change/yr (1977 to 1989, all P < .001) were .56 kg (LWT), .53 kg (CWT), .11 % (DP), .50 mm (10th rib BF), −49 g (wt-adj. FSL), 2.0 g (wt-adj. LDOA, 1977 to 1983) and −2.2 g (wt-adj. LDOT, 1984 to 1989). There were only small changes in LEN, C, F and M. Between 1968 and 1976, LEA increased .42 cm2/yr, then decreased .23 cm2/yr until 1984, increased .34 cm2/yr to 1988 and fell 1.2 cm2 in 1989 (all P < .001). Models including year, breed and their interaction (YB), ± linear and quadratic regressions on LWT, CWT, 10th rib BF, LEA and LEN, were used to assess the amount of variability in DP that could be accounted for by these carcass measures. R2 values (model effects in parentheses) were .16 (YB ± LWT), .28 (YB + CWT ± BF ± LEA) and .31 (YB + CWT + LEN ± [BF + LEA]). In conclusion, performance tested carcass show barrows have become heavier and fatter over time. Lean growth rate has decreased over the past 5 yr. Tenth rib fat and loin muscle area had no value as predictors of dressing percentage. Dressing percentage was not useful as a predictor of lean growth rate or lean yield.

The longissimus from caribou (n = 6), reindeer (n = 6) and beef (n = 6) were evaluated to determine differences in composition, color and sensory properties. Caribou contained the least fat followed by reindeer, and then beef (P 0.05) were found in ultimate pH or juiciness (sensory panel) among any of the products. Results from this study indicate that reindeer and caribou are a low-fat source of protein with desirable sensory characteristics.