The objective of this study was to extract novel phenotypes related to disease resilience using daily feed intake data from growing pigs under a multifactorial natural disease challenge that was designed to mimic a commercial environment with high disease pressure to maximize expression of resilience. Data used were the first 1,341 crossbred wean-to-finish pigs from a research facility in Québec, Canada. The natural challenge was established under careful veterinary oversight by seeding the facility with diseased pigs from local health-challenged farms, targeting various viral and bacterial diseases, and maintaining disease pressure by entering batches of 60–75 pigs in a continuous flow system. Feed intake (FI) is sensitive to disease, as pigs tend to eat less when they become ill. Four phenotypes were extracted from the individual daily FI data during finishing as novel measures of resilience. The first two were daily variability in FI or FI duration, quantified by the root mean square error (RMSE) from the within individual regressions of FI or duration at the feeder (DUR) on age (RMSEFI and RMSEDUR). The other two were the proportion of off-feed days, classified based on negative residuals from a 5% quantile regression (QR) of daily feed intake or duration data on age across all pigs (QRFI and QRDUR). Mortality and treatment rate had a heritability of 0.13 (±0.05) and 0.29 (±0.07), respectively. Heritability estimates for RMSEFI, RMSEDUR, QRFI, and QRDUR were 0.21 (±0.07) 0.26 (±0.07), 0.15 (±0.06), and 0.23 (±0.07), respectively. Genetic correlations of RMSE and QR measures with mortality and treatment rate ranged from 0.37 to 0.85, with QR measures having stronger correlations with both. Estimates of genetic correlations of RMSE measures with production traits were typically low, but often favorable (e.g., −0.31 between RMSEFI and finishing ADG). Although disease resilience was our target, fluctuations in FI and duration can be caused by many factors other than disease and should be viewed as overall indicators of general resilience to a variety of stressors. In conclusion, daily variation in FI or duration at the feeder can be used as heritable measures of resilience.

This study explored the possibility of sex-specific effects on embryonic survival in primiparous sows subjected to restricted feed intake during the last week of lactation and bred after weaning (Restrict; n = 16), compared with control sows fed close to ad libitum feed intakes (Control; n = 17). Restrict sows were in a substantial negative net energy balance at weaning, and lost 13% of estimated protein and 17% of fat mass during lactation, yet the weaning-to-oestrous interval and ovulation rate were not different between treatments. However, embryonic survival at Day 30 of gestation was lower (P < 0.05) in Restrict than Control sows, and selectively reduced the proportion of female embryos surviving (P < 0.01). A decrease in weight and crown-rump length of surviving female (P < 0.05) and male (P < 0.05) embryos was seen in Restrict litters. The mechanisms mediating this sex-specific effect on embryonic loss in feed-restricted sows are unclear. The data presented here indicate that feed-restriction during the last week of lactation in primiparous sows causes a selective decrease in survival of female embryos and limits the growth of all surviving embryos.

The objective was to estimate genetic parameters of performance and resilience of growing pigs under disease. Data were from 3,139 Yorkshire x Landrace wean-to-finish pigs that were exposed to a natural polymicrobial disease challenge that was established by entering naturally infected animals into a nursery barn, targeting various viral and bacterial diseases. The challenge was maintained by entering batches of 60 to 75 healthy nursery pigs every 3 weeks in a continuous flow system. Traits analyzed included average daily gain (ADG), feed intake (ADFI), and duration (ADFD), feed conversion ratio (FCR), residual feed intake (RFI), mortality (MOR), number of health treatments (TRT), health scores (Hscore), carcass weight (CWT), back fat (CBF) and loin depth (CLD), dressing percentage (DRS), lean yield (LYLD), day-to-day variation in feed intake and duration (VARFI and VARDUR), and the proportion of off-feed days (OFFFI and OFFDUR). Analyses were by mixed linear models with genomic relationships. The resilience traits TRT, MOR, and Hscore were lowly heritable (up to 0.15) but had high genetic correlations with each other. Performance traits ADG, ADFI, ADFD, FCR, RFI, and carcass traits were moderate to highly heritable (0.17 to 0.49). Heritabilities of resilience indicator traits OFF and VAR had low to moderate heritabilities (0.08 to 0.23) but were higher when based on duration versus amount. ADFI had a low genetic correlation with ADFD (0.13). ADG in the challenge nursery had stronger negative genetic correlations with both TRT and MOR than ADG in the finisher (-0.37 to -0.74 versus -0.15 to -0.56). ADFI and FCR had moderate negative (-0.21 to -0.39) and positive (0.34 to 0.49), respectively, genetic correlations with TRT and MOR. ADFD and RFI had very low genetic correlations with TRT and MOR. CWT and DRS were moderately negatively correlated with TRT and MOR (-0.33 to -0.59). Resilience indicator traits based on feed intake or duration had moderate to high positive genetic correlations with TRT (0.18 to 0.81) and MOR (0.33 to 0.87). In conclusion, performance and resilience traits under a polymicrobial disease challenge are heritable and can be changed by selection. Phenotypes extracted from feed intake patterns can be used as genetic indicator traits for disease resilience. Most promising is day-to-day variation in intake duration, which had a sizeable heritability (0.23) and favorable genetic correlations with mortality (0.79) and treatment rate (0.20).

This study aimed to describe the abundance and localization of BMP2, BMP6, BMP15, GDF9, BMPR1A, BMPR1B, BMPR2 and TGFBR1 mRNA during pig preovulatory follicular development and to evaluate their implication in improving follicular maturity in the preovulatory period preceding the second versus first post-weaning oestrus. Oocytes, granulosa (GC) and theca cells (TC) were recovered from antral follicles of primiparous sows at day 1, 2 and 4 after weaning and at day 14, 16 and 20 of their subsequent oestrous cycle. Realtime PCR analysis revealed that with the exception of BMP6 mRNA, which was absent in GC, all genes were expressed in every cell type. Although BMP6, BMP15 and GDF9 mRNA were most abundant in the oocyte, their expression remained relatively constant during follicular development. By contrast, receptor BMPR1B and TGFBR1 expressions in the GC and TC were temporally regulated. BMPR1B mRNA abundance was positively correlated with plasma oestradiol (E 2 ) suggesting that its regulation by oestrogen may be implicated in normal folliculogenesis. Interestingly, the increase in BMPR1B mRNA and protein abundance during the periovulatory period in GC and TC suggests a role for bone morphogenetic protein (BMP) 15 in the ovulatory process. Finally, expression of these ligands and receptors was not associated with potential differences in follicle maturity observed during the second versus first post-weaning preovulatory follicular wave. In conclusion, our results clearly demonstrate the presence of a complex signalling system within the pig follicle involving the transforming growth factor-b superfamily and their receptors, and provide evidence to support a role for BMP15 and BMPR1B during ovulation.

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This study investigated whether specific proteins from distinct seminal plasma fractions of boars could be related to in vivo fertility. Nine boars with acceptable sperm motility and morphology for use in artificial insemination demonstrated major differences in total number born and pregnancy rate when low sperm doses (1.5 billion sperm) were used to breed a minimum of 50 gilts per boar. The 2 lowest-fertility and 2 highest-fertility boars were chosen for evaluation of specific seminal plasma proteins. On 4 occasions, semen was collected and separated into 3 fractions based on sperm concentration (Sperm-Peak, Sperm-Rich, and Sperm-Free), and the fractions were analyzed for total protein concentration and abundance of major seminal plasma glycoprotein (PSP-I), AWN-1, and osteopontin protein using Western blotting techniques. The concentrations of these seminal plasma proteins were lower in the Sperm-Peak fractions compared with the SpermFree fractions (P , .05). Seminal plasma from the pooled SpermRich fraction used for artificial insemination was also subjected to two-dimensional gel electrophoresis to investigate novel protein markers related to in vivo fertility. Total piglets born (r 5 20.76, P 5 .01) and sperm motility at day 7 (r 5 20.74, P 5 .037) were again negatively correlated with a 22-kDa protein identified by mass spectrometry as PSP-I. However, fertility index and farrowing rate tended to be positively correlated (P , .10) with a 25-kDa protein, identified as glutathione peroxidase (GPX5), an antioxidant enzyme that may protect sperm membranes from oxidative damage. These candidate proteins merit further investigation as markers of fertility in boars.

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