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A total of 606 sows (PIC 1050) and their progeny (PIC 1050 × 280) were used to determine if feeding gestating and lactating sows a proprietary strain of Pichia guilliermondii as a whole-cell inactivated yeast product (WCY ; CitriStim, ADM Animal Nutrition, Quincy, IL) improves sow and litter performance in a commercial production system. Once confirmed pregnant at d 35 post-breeding pregnancy check, sows were fed a basal gestation control (CON) diet (0.55% SID lysine) or the control diet fortified with 0.15% of the WCY replacing corn in the CON diet. Dietary treatments were also fed in lactation (1.05% SID lysine) once sows were moved into farrowing crates on approximately d 112 of gestation until weaning. Sows supplemented with WCY in gestation and lactation had increased total born piglets by 0.45 pigs (P < 0.04), piglets born alive (14.27 vs. 13.85; P < 0.04), and, therefore, heavier born alive litter weights (P < 0.001) compared to CON fed sows. A greater post cross-foster litter size (P < 0.001) meant that litter size at weaning was increased by 0.54 pigs when sows were fed WCY compared to CON (P < 0.001). However, litter weaning weights and 21-d adjusted litter weaning weights were similar (P > 0.158), although numerically greater, for WCY fed sows. Pigs from CON fed sows were 0.35 kg heavier at weaning compared to pigs from WCY fed sows (P < 0.001). This increase in weaning weight of pigs from CON fed sows is partially explained by their 0.93 d longer lactation (P < 0.001) and may also be due to the smaller litter size throughout lactation. The percent of litters treated for scours decreased from 38.3 to 14.2% when sows were fed WCY (P < 0.001). The distribution of birth and weaning weights was not impacted (P > 0.2461) by treatment. In conclusion, feeding gestating and lactating sows a proprietary strain of Pichia guilliermondii as a whole-cell inactivated yeast product increased the number of pigs born and weaned, and decreased the prevalence of scours during lactation. [ABSTRACT FROM AUTHOR]

Background: There is an increasing need to account for genotype-by-environment (G × E) interactions in livestock breeding programs to improve productivity and animal welfare across environmental and management conditions. This is even more relevant for pigs because selection occurs in high-health nucleus farms, while commercial pigs are raised in more challenging environments. In this study, we used single-step homoscedastic and heteroscedastic genomic reaction norm models (RNM) to evaluate G × E interactions in Large White pigs, including 8686 genotyped animals, for reproduction (total number of piglets born, TNB; total number of piglets born alive, NBA; total number of piglets weaned, NW), growth (weaning weight, WW; off-test weight, OW), and body composition (ultrasound muscle depth, MD; ultrasound backfat thickness, BF) traits. Genetic parameter estimation and single-step genome-wide association studies (ssGWAS) were performed for each trait. Results: The average performance of contemporary groups (CG) was estimated and used as environmental gradient in the reaction norm analyses. We found that the need to consider heterogeneous residual variance in RNM models was trait dependent. Based on estimates of variance components of the RNM slope and of genetic correlations across environmental gradients, G × E interactions clearly existed for TNB and NBA, existed for WW but were of smaller magnitude, and were not detected for NW, OW, MD, and BF. Based on estimates of the genetic variance explained by the markers in sliding genomic windows in ssGWAS, several genomic regions were associated with the RNM slope for TNB, NBA, and WW, indicating specific biological mechanisms underlying environmental sensitivity, and dozens of novel candidate genes were identified. Our results also provided strong evidence that the X chromosome contributed to the intercept and slope of RNM for litter size traits in pigs. Conclusions: We provide a comprehensive description of G × E interactions in Large White pigs for economically-relevant traits and identified important genomic regions and candidate genes associated with GxE interactions on several autosomes and the X chromosome. Implementation of these findings will contribute to more accurate genomic estimates of breeding values by considering G × E interactions, in order to genetically improve the environmental robustness of maternal-line pigs. [ABSTRACT FROM AUTHOR]

Pre-weaned piglets prefer higher temperatures than lactating sows. To address this, swine producers use heating lamps or pads in combination with maintaining farrowing room macroenvironment temperatures at the upper end of the thermoneutral zone (24-25℃) of the lactating sow. This may inadvertently cause thermal stress for lactating sows resulting in decreased feed consumption, and ultimately, reduced milk production and litter growth. Therefore, the objective was to determine the sow level macroenvironment temperature that would improve both sow and litter productivity. In two repetitions, 37 lactating sows (parity = 3.1 ± 1.7) and their litters (d 1 litter size = 12.0 ± 1.0) were housed within 1 of 3 farrowing rooms set to different macroenvironment temperatures: LOW (n = 12 sows and litters; 15.0 ± 0.4℃), MID (n = 13 sows and litters; 19.3 ± 0.2℃), and HIGH (n = 12 sows and litters; 24.6 ± 0.8℃). Lactating sows and their litters were on trial from the onset of farrowing until weaning (19.8 ± 0.9 d of age). Individual farrowing crate temperatures were recorded throughout the trial in 0.14 s intervals using thermocouples mounted at sow head height. Piglets were provided a 0.34 x 1.52 m heating pad with a verified steady state of 35.0℃. Sow body weight (BW) was recorded at 24 h post-farrowing and at weaning, and piglet weights were measured on d 1, 7, 14 and at weaning to determine average daily BW gain (ADG). Liveborn piglet mortality was recorded throughout the trial. Sow feed intake (FI) was recorded daily from d 1 post-farrowing until weaning. The sow was considered the experimental unit for sow level measures and the litter was considered the experimental unit for piglet measures. Data were analyzed using PROC GLIMMIX in SAS 9.4 and using GLM in JMP 15. Regression models were used to determine the optimal macroenvironment temperature to improve sow FI and piglet ADG. Sow FI was greater (P < 0.01) for LOW (7.91 ± 0.38 kg) and MID (7.32 ± 0.37 kg) versus HIGH (6.37 ± 0.39 kg) sows, but similar for LOW and MID sows. Piglet ADG was greater from d 1 to weaning (P < 0.01) for LOW (0.25 ± 0.01 kg) and MID (0.26 ± 0.01 kg) versus HIGH (0.21 ± 0.01 kg) piglets, but similar for LOW and MID piglets. Pre-weaning mortality was similar (P = 0.32; 15.6%) among all treatments. A quadratic effect was observed (P < 0.01) where sow FI was maximized at a macroenvironment temperature of 17.2℃. A cubic effect was observed (P < 0.01) where piglet ADG was greatest at 17.0℃. In summary, these data have implications towards housing lactating sows and their litters at lower macroenvironment temperatures to improve growth performance. [ABSTRACT FROM AUTHOR]

Larger litter sizes in swine production systems and potential milk limitations for piglets have given new opportunities to incorporating creep feeding as a management strategy. Sows (n = 51) and their litters were used to test the effects of creep feed and nursery diets on piglet lactation and nursery growth performance. Ten days before weaning, litters were assigned to one of three creep feeding treatments: 1) Control diet: 2) Control+Flavoring (50 ppm Allium XL, Pancosma): 3) No creep feed. Creep feed was delivered twice/day via one bowl creep feeder/litter. Sows and litters (17/treatment) were allotted to equalize parity (average = 2.8), genetics, number of piglets (average = 10.9), and weaning age (average = 19.1). Litter weights and creep feed intake were recorded on d 0, 4, and 10 (weaning). Post-weaning pigs were allotted to Control or Flavoring (50 ppm Allium XL) diets in a 3x2 factorial arrangement. During nursery there were 10 pens/treatment with 7 or 8 pigs/pen, blocked by initial BW within creep treatment. Nursery treatments were fed in phase 1 (1.13 kg/pig) and 2 (2.27 kg/pig) diets followed by common phase 3 (6.8 kg/pig) and 4 (ad lib to d 35) diets. Weekly pig BW and feed intake were used to calculate nursery pen ADG, ADFI, and G:F. Data were analyzed using GLM procedure of SAS 9.4. Creep feeding treatment during lactation did not affect litter or piglet BW gain pre-weaning. Flavoring did not affect total creep feed intake (control = 114 g/pig vs. flavoring = 110 g/pig). Providing creep feed during lactation increased ADFI on days 2, 3, and 4 post-weaning (P < 0.013). Pigs fed either creep feed increased week 1 nursery ADFI (8.8%; P< 0.02), numerically increased ADG (5.2%), and greater d ay7 BW (P = 0.055). Week 3 ADG (P < 0.05) and ADFI (P < 0.05) were greater for the no creep pigs than pigs fed the control creep feed, flavored creep feed pigs were intermediate. For week 4, ADG, and week 4 and 5 ADFI, pigs previously fed control creep had greater growth performance than pigs previously fed flavored creep with pigs fed no creep being intermediate (P< 0.05). Overall (days 0-35), pigs fed control creep had greater ADG (P< 0.05) and ADFI (P < 0.05) than flavored creep fed pigs with no creep pigs being intermediate in ADG and greater ADFI than flavored creep fed pigs. Final BW (P < 0.05) was greater for control creep fed pigs than flavored creep fed pigs with no creep pigs being intermediate (23.5 kg, 23.0 kg, 23.3 kg, respectively). Nursery dietary flavoring treatment did not affect post-weaning ADG, ADFI, or G:F at any point during the study (P > 0.12). Lactation creep feeding significantly increases ADFI and ADG during the first week post-weaning, which could improve post-weaning performance and reduce the rate of pigs failing to thrive post-weaning. [ABSTRACT FROM AUTHOR]

Changes in weaning age and diet complexity can impact pig growth post-weaning. Weanling gilts and barrows [n = 432 Topigs Duroc X (US York X Landrace)] from the same farrowing group were utilized for a 30 or 35 day growth trial to compare early (EW) versus late weaning (LW) and high or low levels of specialty proteins in nursery diets. Pigs (n = 216) were EW (18 or 19 d, average Age = 18.4 days, average BW = 5.96 kg) and 216 pigs were LW 5 days later (24, 25 or 26 d, average Age = 24.6 d, average BW = 7.50 kg). At weaning pigs were blocked by weaning age, BW, sex and litter, and randomly allotted to 48 pens with 9 pigs/pen. Pigs at each weaning age were fed a High Complexity (HC) or a Low Complexity (LC) diet. The trial was conducted as a 2X2 factorial design: 1) EW+HC; 2) EW+LC; 3) LW+HC; 4) LW+LC. Pigs and feeders were weighed on d 0, 7, 14, 21, 28, and 35 for EW, and on d 0, 7, 14, 21, 28, and 30 for LW. The LW pigs had improved ADG and ADFI from days 0-7, 7-14, 14-21, and the final week of the nursery (P < 0.05). There were no differences in ADG and ADFI from days 21-28 (P > 0.05) between weaning ages. G:F decreased for LW pigs from days 21-28 (P < 0.01) compared with EW pigs; however, for the overall nursery trial LW pigs had increased G:F (P = 0.01). The LW pigs had increased overall nursery ADG vs EW pigs (452.5 g/d vs 400 g/d; P < 0.01). End of nursery BW was greater for LW vs EW pigs (21.70 kg vs 20.74 kg; P = 0.001). When comparing pigs of similar BW at weaning, LW pigs were lighter at end of nursery (20.13 kg vs. 21.66 kg; P < 0.01) but were more feed efficient (P < 0.01) than EW pigs. There was a BW block by weaning age interaction, EW heavy pigs had less ADG compared with LW heavy pigs; however, when comparing light weight pigs, the EW light pigs had improved ADG compared with LW light weight pigs (P = 0.017). The EW pigs were lighter at market (approximately day 146 of age) compared with LW pigs (120.78 vs 124.16 kg; P = 0.014). An interaction between weaning age, nursery diet, and sex (P < 0.07) was observed for market weight, EW barrows fed LC diets were lighter at market (120.77 kg) than EW barrows fed HC diets (126.54 kg). Whereas for LW barrows fed LC had greater market weights (130.04 kg) than LW barrows fed HC diets (127.59 kg). A similar, but nonsignificant pattern was observed for gilts. Weaning age and feeding pigs the correct diet for their age in the nursery can have a lifelong effect on the pig. [ABSTRACT FROM AUTHOR]

Selection of replacements for the sow herd is one of the most important facets in swine production. Although our current methods of selection are effective, there is still a large amount of variation in sow reproductive performance traits such as pigs per sow per year (PSY). Therefore, the objective of this study was to determine if on-farm phenotypic traits at 21 d postnatal (PN) or perinatal environmental factors could predict sow reproductive performance. Data were prospectively collected from 2,146 gilts born on a commercial sow production facility and included birth and weaning weights, vulva length and width at 21 d PN, birth and nursing litter size, days nursed, average daily gain from birth to weaning, and age at first estrus. Of the initial animals, 400 (17%) were selected for the sow herd, 353 remained after removal of animals culled for non-reproductive reasons. Animals were assigned to 1 of 5 reproductive performance categories based on observation of estrus or pigs per sow per year (PSY) across two farrowings: High Fertility (HF; 23%; n = 82; ≥26 PSY), Middle Fertility (MF2; 12%; n = 43; 20–25 PSY), Low Fertility (MF3; 15%; n = 54; <20 PSY), Infertile-Estrus (IFe; 10%; n = 36; estrus, no pregnancy), and Infertile-No Estrus (IFno; 39%; n = 138; no estrus, no pregnancy). Generalized linear model analysis indicated vulva width (P = 0.03) was related to PSY, however, it only explained 1.5% of the total variation in PSY. To determine if preweaning variables were predictive of gilt fertility outcome, animals were grouped as those that became pregnant (n = 179) or not (n = 174). Vulva width tended to be greater in fertile animals versus infertile (P = 0.07). Binomial regression analysis revealed a positive relationship between vulva width and gilt fertility, however, this relationship is not strong enough to make sow herd selection decisions. [ABSTRACT FROM AUTHOR]

Heat stress (HS) is a major welfare and economic issue in the swine industry. However, it is not a trivial task to appropriately quantify the environmental HS. Therefore, this study aimed to 1) define the critical periods and environmental descriptors (based on public weather station information) to evaluate heat tolerance (HT); and 2) estimate genetic parameters for HT in Large White pigs. The traits included in this study were: weaning weight (WW; kg), off-test weight (OTW; kg), total number of piglets born (TNB), number of piglets born alive (NBA), and number of piglets weaned (WN). The number of phenotypic records ranged from 6,059 (WN) to 172,984 (TNB), and genotypes were available for 8,686 animals. Seven climatic variables (maximum, minimum and average temperatures, average relative humidity, dew point, discomfort index and temperature-humidity index) based on public weather station records were compared based on three criteria [GxE estimate as measured by the slope term; theoretical accuracy of the genomic estimated breeding values (GEBV); deviation of GEBV per environmental value]. Relative humidity (for WN and WW) and maximum temperature (for OTW, TNB, and NBA) are the recommended environmental gradients for the studied traits. The acute HS (average of 30 days before measurement date) was the critical period recommended for OTW. For WN and WW, a period of 34 days prior to farrowing up to weaning is recommended. For TNB and NBA, the critical period of 20 days prior breeding to 30 days into gestation is recommended. In general, WN and WW were largely affected by the environment, while the remaining traits showed moderate correlations (OTW, TNB, and NBA). Heritabilities estimated for HT ranged from 0.08 (WW) to 0.25 (OTW). In summary, these results suggest that there is genotype-by-environment interaction for all traits analyzed, and genetic progress can be achieved through genetic selection. [ABSTRACT FROM AUTHOR]

Genetic selection for health and welfare-related traits is paramount in livestock breeding. Piglet allergic responses to soybean protein negatively impact animal growth and welfare. The objectives of this study were to estimate the heritability of soybean allergic responses and genetic correlations between soybean and peanut allergies (r1,2) in divergently-selected pig lines. The base population consisted of nine sire lines (primarily Yorkshire and Landrace) and two dam sources (Yorkshire × Chester White-F1 and Landrace × Yorkshire-F1). Soybean and peanut-allergic responses were measured through a skin test (0-6 scale; 0-no allergic responses; 6-severe allergic responses; characterized by wheal and flair) on pigs fed a diet containing soybean meal for 21 d post-weaning. A total of 5,505 animals from nine generations of two contrasting lines (i.e., high and low skin test reaction) were included in the analyses. The statistical model included contemporary group, breeding lines, replication, sex, and weaning weight (linear covariate) as fixed effects (P-value < 0.05), and additive genetic, maternal genetic, and maternal permanent environment as random effects. Threshold and linear Bayesian models were used to estimate genetic parameters, using a pedigreebased relationship matrix containing 9,201 animals. The heritability estimates for the general soybean allergic response were 0.199 ± 0.045 and 0.119 ± 0.025 for the threshold (liability scale) and linear models, respectively, suggesting that soybean allergic responses are heritable and can be improved through selective breeding. A weak negative genetic correlation between allergic responses and birth weight was observed (r1,2 = -0.253 ± 0.192), which shows that the genetic variance of soybean allergy is less dependent on birth weight. However, a high positive genetic correlation was estimated between soybean and peanut-allergic responses (r1,2 = 0.89 ± 0.048), which indicates a potential cross-reactivity of soybean and peanut allergies. Our findings suggest that it is possible to reduce food allergy responses in pigs through selective breeding. [ABSTRACT FROM AUTHOR]

Genetically selecting for improved animal resilience has become of great interest in modern livestock breeding. In this context, piglets experience a transitory allergic response to soybean proteins that has a negative impact on their growth and welfare. The main objective of this study was to determine whether soybean allergy response is a heritable trait, using divergently selected pig lines. The base generation pigs were generated from nine sire lines (primarily Yorkshire and Landrace) and two dam sources (Yorkshire × Chester White F1 and Landrace × Yorkshire F1). Soybean allergic response was measured, following a skin test protocol, on pigs that received a diet containing 28% soybean meal for 21 consecutive days post-weaning. The skin test was performed with an intradermal injection of soybean protein. Wheel and flare scores (ranging from 0 to 3) were assigned approximately 60 minutes postinjection. Based on the skin test total scores (i.e., the sum of the wheal and flair scores, ranging from 0 to 6), animals were selected to create two (a high and a low) soybean protein reacting lines, and bred within lines for nine generations. Phenotypes used in this study were measured on a total of 5,505 animals born from generations one to nine, in both high and low reacting lines. Significant systematic effects (P < 0.05) included in the statistical model were birth year, birth season, sex, and weaning weight (as a covariate). Genetic parameters for the skin test were estimated using a pedigree-based relationship matrix containing 9,201 animals, and a threshold animal mixed model. The genetic variance estimated for soybean allergy was 0.091, indicating that there is genetic variability in this trait. The heritability estimated for soybean allergy response was 0.139, which indicates that food allergy response is a heritable trait and can be improved through selective breeding. [ABSTRACT FROM AUTHOR]

Induction can be a useful herd management tool. However, inducing too early can negatively impact critical biological processes for the sow and her piglets. Although inducing at 115 d of gestation is widely accepted for commercial sows, the natural gestation length of purebred lines can exceed 115 days. Therefore, the objective of this study was to estimate the effect of induction at 115 vs. 117 d of gestation on the performance of purebred sows and their piglets. Purebred Landrace females from a commercial multiplier were used for this study. Sows were mated to one of the following genetic lines: A, B, or C. Of the 601 sows placed on test, 264 and 135 sows farrowed as a result of induction at 115 or 117 days of gestation, respectively. From these 399 sows, piglets sired by line C (n=1,715) were used for subsequent analyses. Traits of the sow analyzed included: percent stillborn, sow mortality (from 0 to 24 days post-farrowing), and removal rate (between farrowing and weaning). Traits of the piglet analyzed included: weaning weight, lactation ADG, and pre-weaning mortality. All traits were analyzed using a generalized linear model, except for mortality and removal rate, which were analyzed using a LOGIT model. Piglets from the 117 group had significantly greater weaning weight (P=0.02), significantly greater ADG (P=0.0009), and numerically lower pre-weaning mortality (P=0.16) than piglets from the 115 group. Sows induced at 117 days of gestation had numerically lower percent stillborn, lower mortality, and lower removal rate than sows induced at 115 days of gestation, although not significant (P=0.13, P=0.48, and P=0.50, respectively). In conclusion, there was a numerically or significantly favorable effect of inducing sows at 117 vs. 115 d of gestation on both sow performance and earlylife piglet performance. [ABSTRACT FROM AUTHOR]

A total of 606 sows (PIC 1050) and their progeny (PIC 1050×280) were used to determine if feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product (WCY; CitriStim, ADM Animal Nutrition, Quincy, IL) improves sow and litter performance in a commercial production system. Once confirmed pregnant at d 35 post-breeding pregnancy check, sows were fed either a basal gestation control (CON) diet (0.55% SID Lysine) or the control diet fortified with 0.15% (1.36 kg/ton) of the WCY replacing corn in the CON diet. Dietary treatments were also fed in lactation (1.05% SID Lysine) once sows were moved into farrowing crates on approximately d 112 of gestation until weaning. Sows supplemented with WCY in gestation and lactation had a greater number of total born piglets by 0.45 pigs (P=0.040), born alive (P< 0.04), heavier born alive litter weight (P< 0.001), and greater post cross-foster litter size (P< 0.001) compared to CON fed sows. Litter size at weaning was increased by 0.54 pigs when sows were fed WCY compared to CON (P< 0.001). However, the average piglet weaning weights from CON fed sows were heavier by 0.35 kg compared to WCY (P< 0.001). This increase in body weight of piglets from CON fed sows is partially explained by their 0.93 days longer lactation (P< 0.001), and may also be due to the smaller litter size nursed throughout lactation. The percent of litters treated for scours decreased from 38.3% to 14.2% when sows were fed WCY (P< 0.001). The distribution of birth weights by body weight range was not different (P=0.2461) between treatments. In conclusion, feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product increased the number of piglets born and number weaned as well as decreased the prevalence of scours during lactation. [ABSTRACT FROM AUTHOR]

Inflammatory mediators, such as cytokines, can reduce feed intake and drastically modify the partitioning of nutrients. Thus, it may increase the animal's maintenance requirements, reduce milk production and piglet growth, impact reproductive performance, and reduce sow lifetime productivity. The objective of this experiment was to evaluate a non-invasive method, not tested before in swine, to assess cytokine profiles from post-partum uterine lavage. The uteri of second and third parity sows (n=14) were flushed with sterile saline solution (0.9%) on days 2, 4, and 14 postparturition. An artificial insemination (AI) catheter, in its plastic covering, to avoid vaginal contents, was inserted through the vagina into the cervix. A flexible inner catheter was passed through the outer AI catheter and into the uterine horn. Sterile saline (30-40 mL) was flushed through the inner catheter into one uterine horn. After inner catheter removal, a tube was attached to the end of the outer AI catheter to allow collection of the natural back-flow of uterine lavage fluid (avg 24.7% recovery). Uterine fluid collected was immediately centrifuged and the supernatant stored at -20°C. Samples were freeze-dried, re-suspended in sterile saline (2 mL), and stored at -80°C. Cytokine profiles of the uterine fluid were evaluated using a multiplex ELISA panel including interleukin (IL)-1β, IL-6, IL-8, IL-4, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ). Cytokine concentrations were calculated relative to protein content (pg/mg of protein). IFN-γ and TNF-α were lower than the limit of detection in most samples (5/38 and 1/38, respectively). IL-4 and IL-10 concentrations did not differ among days of collection (P >0.14). IL-8 was greater on day 4 than on days 2 or 14 (P< 0.05). IL-1β and IL-6 were greater on days 2 and 4 than on day 14 (P< 0.05). Uterine flushing is a novel non-invasive method to access uterine inflammatory cytokines in sows. [ABSTRACT FROM AUTHOR]

Pregnant sows, especially during late-gestation, may be susceptible to heat stress due to increased metabolic heat production and body mass. Therefore, the study objective was to determine the thermoregulatory and physiological responses of sows exposed to increasing ambient temperature (TA) at 3 reproductive stages. In 3 repetitions, 27 multiparous sows (parity 3.22±0.89) were individually housed and had jugular catheters placed 5.0±1.0 d prior to the experiment. To differentiate between reproductive stages, sows were categorized as open (not pregnant, n=9), mid-gestation (59.7±9.6 days pregnant, n=9), or late-gestation (99.0±4.8 days pregnant, n=9). During the experiment, sows were exposed to 6 consecutive 1 h periods of increasing TA (period 1, 14.39±2.14°C; period 2, 16.20±1.39°C; period 3, 22.09±1.87°C; period 4, 26.34±1.39°C; period 5, 30.56±0.81°C; period 6, 35.07±0.96°C), with 1 h transition phases in between each period. Respiration rate (RR), heart rate (HR), skin temperature, and vaginal temperature (TV) were measured every 20 min and the mean was calculated for each period. At the end of each period, blood gases, leukocytes, and red blood cell counts were measured. Overall, RR and HR were greater (P=0.04; 45.6% and 12.9%, respectively) in late-gestation versus mid-gestation sows. Compared to mid-gestation and open sows, TV tended to be greater (P=0.06) during period 4 (0.18°C and 0.29°C, respectively) and period 5 (0.14°C and 0.18°C, respectively) in late-gestation sows. Blood O2 increased (P< 0.01; 18.1%) for all sows with advancing period, regardless of reproductive stage. Late-gestation sows had reduced (P=0.02; 16.1%) blood CO2 compared to mid-gestation sows, regardless of period. In summary, late-gestation sows appear to be more sensitive to increasing TA as indicated by increased RR, HR, TV, and blood O2, and reduced blood CO2 when compared to mid-gestation or open sows. This change in O2 and CO2, due to increasing RR and heat stress sensitivity of late-gestation sows, may suggest an alteration to the acid-base balance, leading to respiratory alkalosis. [ABSTRACT FROM AUTHOR]

Simple Summary: There is a growing interest in worldwide swine breeding programs to genetically select for pork quality and primal cuts in addition to the traditional growth and carcass leanness traits. Accurate population genetic parameters are needed to estimate correlated responses to selection and incorporate novel traits in the selection objective. Therefore, we estimated heritabilities and genetic correlations for 39 pork quality, growth and carcass traits in Duroc pigs. In general, moderate and favorable genetic correlations were observed between pork quality (e.g., loin color and marbling scores) and carcass traits. Additionally, moderate to low correlations were found among pork quality, growth and carcass traits. Our findings suggest that pig breeders can successfully incorporate pork quality and novel carcass traits in the selection objectives without undesirable impacts upon growth rate and carcass leanness. More recently, swine breeding programs have aimed to include pork quality and novel carcass (e.g., specific primal cuts such as the Boston butt or belly that are not commonly used in selection indexes) and belly traits together with growth, feed efficiency and carcass leanness in the selection indexes of terminal-sire lines, in order to efficiently produce pork with improved quality at a low cost to consumers. In this context, the success of genetic selection for such traits relies on accurate estimates of heritabilities and genetic correlations between traits. The objective of this study was to estimate genetic parameters for 39 traits in Duroc pigs (three growth, eight conventional carcass (commonly measured production traits; e.g., backfat depth), 10 pork quality and 18 novel carcass traits). Phenotypic measurements were collected on 2583 purebred Duroc gilts, and the variance components were estimated using both univariate and bivariate models and REML procedures. Moderate to high heritability estimates were found for most traits, while genetic correlations tended to be low to moderate overall. Moderate to high genetic correlations were found between growth, primal-cuts and novel carcass traits, while low to moderate correlations were found between pork quality and growth and carcass traits. Some genetic antagonisms were observed, but they are of low to moderate magnitude. This indicates that genetic progress can be achieved for all traits when using an adequate selection index. [ABSTRACT FROM AUTHOR]

To evaluate the relationship between skin lesion scores and aggressive behavior categories (unilateral active attack, standoff, and being bullied) of individual pigs when placed into pens after weaning, duration and frequency of three aggressive behavior categories were observed from video. Behavior of 500 weaned pigs was recorded and observed during the first 48 h after mixing. The skin lesion scores at 24 h before mixing and at 2, 24, and 48 h after mixing was assessed. Canonical correlations and generalized linear mixed models analyses between three aggressive behavior categories and skin lesion scores were performed. The score of skin lesion on the front body was significantly greater (P < 0.05) than those on the middle and rear body at 2, 24, and 48 h after mixing. These behavior categories and skin lesion scores of weaned pigs reached the maximum at 2 h after mixing and then decreased gradually. Skin lesion score on the front of the body at 2 and 24 h were associated with CSS (comprehensive standoff score), and CBS (comprehensive being bullied score). The skin lesion score on front body at 2 h after mixing were positively associated with CBS and CSS during the first (P < 0.01) and the second (P < 0.01) hour after mixing. After mixing the skin lesion score on the front body at 2 h was positively associated with CAS (comprehensive unilateral active attack score) at the first hour (P < 0.01), but not at the second hour after mixing. The skin lesion score on the front body at 24 h were positively associated with CBS at the first 12 h and at the second 12 h (from 13 to 24 h) after mixing (P < 0.01). CAS was negatively associated with the skin lesion score on front body at the first 12 h after mixing, and negatively associated at the second 12 h after mixing (P < 0.05). In conclusion, skin lesion score of weaned pigs was the greatest on the front body at 2 h after mixing. The skin lesion score on front body at 24 h after mixing was positively associated with behavior of standoff and being bullied, but not unilateral active attack. These results suggest that the severity of skin lesions is not primarily caused by unilateral active aggressive behavior of weaned pigs after mixing at the individual pig level. [Display omitted] [ABSTRACT FROM AUTHOR]