Yorkshire Gilts Research Articles

Friend or foe: effects of social experience and genetic line on responses of young gilts in a social challenge paired interaction test

The increased focus on group housing of sows in commercial pig production emphasises the importance of saving appropriate gilts which later become sows that are well-adapted to group housing systems. This study aimed to assess the short-term effects of social mixing experience and genetic line on social and exploration responses of young gilts in standardised 3-min social challenge paired interaction tests. The study included 96 gilts, from 26 litters, of two different genetic lines (Swedish Yorkshire and Dutch Yorkshire). These lines were chosen because the dam lines have been selected in group-housed and individual stall systems, respectively, a background which was hypothesised to have modified their social behaviour over time. The gilts were subjected to different early (opportunity to co-mingle with piglets in the neighbouring farrowing pen vs. no opportunity to co-mingle) and late (mixed with unfamiliar piglets at weaning vs. kept with familiar littermates after weaning) social mixing treatments, to test whether the enhanced social experience was beneficial in a socially challenging situation. Paired interaction tests were conducted at 5 and 20 weeks of age, and social and exploration behaviour of the gilts was recorded and analysed. The results showed that Swedish Yorkshire gilts explored the pen fittings more than Dutch Yorkshire gilts during the 5-week test, whereas Dutch Yorkshire gilts explored the pen fittings more than Swedish Yorkshire gilts during the 20-week test. No differences in play behaviour were found during the 5-week test, but in the 20-week test, gilts with early social mixing experience in their farrowing pen showed more locomotor play behaviour than gilts without this experience. Overall, these results suggest that genetic line and early social mixing experience can influence the social and exploration behaviours of young gilts in paired interaction tests. There was no support for the hypothesis that genetic selection in different housing systems has altered social behaviour, but it may have affected the level of exploration behaviour. There was little support for our prediction that early social experience has beneficial effects in a socially challenging situation.

Effects of porcine somatotropin administration on the responses to dietary lysine and a near-ideal blend of amino acids on the amino acid composition of whole-body protein and amino acid accretion rate in growing pigs.

An experiment was conducted to assess the effects of porcine somatotropin (pST) on the responses to a near-ideal blend of AA on the AA composition of empty, whole-empty body (WEB) protein and WEB essential AA accretion rate in pigs from 22 to 60kg BW. Forty Hampshire × Yorkshire gilts were individually penned and assigned to a 4 × 2 factorial arrangement of treatments consisting of four diets with and without pST injection. A fortified corn-soybean meal basal diet was formulated to contain 1.50% total Lys with Thr, Met, and Trp added to obtain a near-ideal blend of these AA relative to Lys. In three additional diets, Lys was reduced to 1.25%, 1.00%, and 0.75% by diluting the basal diet with cornstarch, cellulose, and sand such that the diets also contained the same ratios of AA. Pigs that received pST were administered a daily i.m. injection of 2mg of pST. At 60kg BW, the WEB (carcass, head, viscera, blood, nails, and hair) was ground and analyzed for proximate and AA composition. Administration of pST increased (P < 0.001) accretion rates of WEB protein and essential AA. Increasing dietary essential AA increased (quadratic, P < 0.03) accretion rate of WEB protein, His, Leu, Trp, and Val in pST-treated pigs, but not in untreated pigs. Lysine composition in the accreted WEB protein was not affected (P > 0.05) by dietary Lys. The efficiency of Lys utilization for WEB Lys accretion was linearly affected (P < 0.01) by dietary Lys. These results indicated that the dietary Lys needed to achieve maximum WEB Lys accretion is markedly increased by pST administration.

212 Growth and behavior of Yorkshire gilts exhibiting physiological resilience to weaning stress

Abstract Weaning is an acute early-life stressor and therefore, an excellent model for examining lasting impacts of stress resilience. Our objective was to identify gilts exhibiting physiological resilience or vulnerability to weaning stress and characterize long-term impact on growth and behavior. Purebred Yorkshire litters born to multiparous sows from a single farrowing group were used. At weaning (26 ± 1 d of age), blood samples were collected from all gilt piglets of 13 litters (n = 101) at -1 d, 0 d, and +4 d pre- and post-weaning. Serum cortisol concentrations were quantified by the Michigan State University Veterinary Diagnostic Laboratory. For each litter, serum cortisol was used to identify the gilt most capable of returning to baseline concentrations by +4 d as stress resilient (SR, n = 13) and the gilt least capable as stress vulnerable (SV, n = 13). Skin lesions were recorded at -1 d, +1 d, and +4 d at weaning and when gilts were mixed into grow-finish cohorts. Body weights were recorded at birth, 4 wk, 8 wk, and 12 wk and used to calculate average daily gain (ADG) for the farrowing, nursery, and early grow-finish stages. To assess behavior, focal gilts underwent a social dyad test in a novel arena at 7 wk, a handling test at 8 wk, and novel object test at 12 wk. We observed no differences in skin lesions at weaning, but at 8 wk SR gilts had significantly more rear lesions -1 d pre-mixing (P = 0.031) and middle lesions 4 d post-mixing (P = 0.049). No differences in body weight or ADG were observed at any stage. We did not observe differences between SR and SV pigs during the social dyad or handling tests. During the novel object test, SR gilts exhibited a tendency towards increased activity as demonstrated by a greater number of total zone crosses, 1 m line crosses, and 0.5 m line crosses (P = 0.062, 0.091, and 0.103, respectively). In conclusion, we found gilts resilient to weaning stress were involved in more agonistic behavior at mixing and exhibited increased activity levels in a novel situation. The absence of growth differences supports the potential to select for resilience without negatively impacting growth performance, and the observed behavioral differences could suggest implications for ease of handling and adaptability if females are retained for breeding.

Comparative Analysis of the Ovary Transcriptome among Wanyue Black and Yorkshire Gilts Using RNA-Seq.

Pubertal genetic variations between the indigenous Chinese Wanyue Black pig breed and the imported Yorkshire breed significantly impact their reproductive capacity. In order to identify the differentially expressed genes, gene networks, and metabolic pathways in ovary transcriptome of gilts, the serum hormone levels were analyzed by ELISA, and RNA-seq was performed to analyze ovarian genes. Our results reveal higher estradiol (E2) levels in Wanyue black gilts compared to Yorkshire gilts, while Yorkshire gilts exhibit elevated progesterone (P4) and GnRH levels. We identified a total of 154 differentially expressed genes (DEGs), with 87 up-regulated and 67 down-regulated genes in the Wanyue black gilts ovaries compared to the Yorkshire gilts. GO enrichment analysis unveiled the participation of DEGs in processes such as "Reproduction", "Reproductive system development", and "Ovarian follicle development". Moreover, KEGG enrichment analysis revealed the involvement of DEGs in multiple signaling pathways associated with hormone biosynthesis and puberty, encompassing "Steroid hormone biosynthesis", "Estrogen signaling pathway", and "Prolactin signaling pathway". The subsequent bioinformatics analysis identified nine functional genes that potentially contribute to the disparity in ovaries between Wanyue black gilts and Yorkshire gilts. This study offers significant insights into the endocrine and genetic aspects of pubertal development in gilts.

9 Relationship Between Progesterone and Reproductive Tract Microbiota in Pregnant Gilts

Abstract Female reproductive performance is essential for economic profitability of swine operations, and sex steroid hormones, such as progesterone (P4), are necessary for proper reproductive function. Recent research targeting the reproductive microbiome in beef cattle found that as P4 concentrations fluctuate during the estrous cycle, bacterial communities in reproductive tissues also change. However, characterizing the relationship between P4 concentrations and bacterial communities within the reproductive tract has yet to be fully determined in swine. Therefore, the objective of this project was to correlate the abundance of reproductive tract bacterial communities with plasma P4 concentrations from pregnant gilts. Duroc X Landrace X Yorkshire gilts (n = 25), free of any physical or health related issues, were euthanized and hysterectomized on days (d) 11 (n = 7), 15 (n = 6), 60 (n = 6) or 90 (n = 6) of gestation. For microbiome evaluation, sterile swabs were individually rotated 8 times on each tissue and immediately placed in sterile microcentrifuge tubes for storage (-80°C) until sequencing. Allantoic and amniotic fluid collected on d 60 and d 90 of gestation was placed immediately in a sterile 10 mL conical tube and stored (-80°C) for subsequent analyses. Blood was collected concurrently, centrifuged at 2,500 x g for 25 min at 4°C, and the resulting plasma stored (-20°C). Concentrations of P4 in plasma were quantified using a double-antibody RIA kit. Bacterial sequencing of the V4 hypervariable region of 16S rRNA gene was completed by FERA Diagnostics and Biologicals Corp. The data were analyzed statistically using PROC CORR in SAS 9.4. In the cervix, the relative abundance of the phylum Firmicutes was positively correlated with P4 concentrations (r = 0.45, P = 0.03), and within this phylum, genus Lactobacillus was positively correlated with P4 concentrations (r = 0.54, P = 0.01). Phylum Bacteroidetes was negatively correlated with P4 concentrations (r = 0.45, P = 0.03), and within this phylum, genera Prevotella and Bacteroides were also negatively correlated with P4 concentrations (r = -0.49, P = 0.01; r = -0.05, P = 0.01, respectively). In the uterus, plasma P4 tended to be negatively correlated with phylum Proteobacteria (r = -0.37; P = 0.07) yet positively correlated with Phylum Firmicutes (r = 0.40; P = 0.05). Within Firmicutes, genus Streptococcus in the uterus was positively correlated with P4 concentrations (r = 0.50, P = 0.01), and the relative abundances of genus Lactobacillus in both the uterus and allantoic fluid were positively correlated with concentrations of P4 in plasma (r = 0.43, P = 0.04; r = 0.70, P = 0.02, respectively). There were no significant correlations between concentrations of P4 in plasma and abundances of bacteria within the vagina or amniotic fluid. These results indicate that shifts plasma P4 influence microbiomes in reproductive tissues of gilts during gestation. Further investigation is necessary to understand the interplay between P4 and microbiome fluctuations within reproductive tissues in swine.

20 The Microbiome of Reproductive Tissues, and Amniotic and Allantoic Fluid of Pregnant Gilts During Mid- and Late Gestation

Abstract The differences between the microbial communities in reproductive tissues, and amniotic and allantoic fluids of cattle have previously been investigated. Our objective was to provide insight into microbial differences across reproductive tissues in gilts during mid- and late-gestation. Specifically, we characterized the microbiomes of the vagina, cervix, endometrium, chorion, and allantoic and amniotic fluids. Duroc x Landrace x Yorkshire gilts (n = 12) free of physical, health or reproductive-related issues were euthanized and hysterectomized at either mid-gestation (d 60, n = 6) or late-gestation (d 90, n = 6). A sterile swab was rotated 8 times to collect samples from the mucosal surface of individual tissues and immediately placed in microcentrifuge tubes for storage (-80°C) until sequencing. To sample the endometrium and cervix, a 1 cm incision was made to expose the endometrium and interdigitating prominences, whereas for vaginal sampling, sterile swabs were inserted 6 inches past the vulva and then rotated. For collection of samples of chorion, an incision was made in the endometrium, exposing the chorioallantois to allow sampling of both the chorion-endometrial and chorion-allantois sides. For allantoic and amniotic fluids, 5 mL samples were collected and placed immediately in a sterile 10 mL conical tube and stored (-80°C) for subsequent analyses. Bacterial DNA was extracted and genome sequencing targeting the V4 hypervariable region of the 16S rRNA gene was conducted by FERA Diagnostics and Biologicals Corp. Data were analyzed statistically using the GLM procedure in SAS. Across all samples, abundances of the phylum Firmicutes was affected by stage of pregnancy with greater relative abundance at d 90 compared with d 60 (52.23 ± 2.85% vs 42.60 ± 3.14%, respectively; P = 0.03). Within this phylum and across all samples, the relative abundance of the genus Lactobacillus differed due to stage of pregnancy with a greater relative abundance at d 90 compared with d 60 (19.33 ± 2.37% vs 12.14 ± 2.61%, respectively; P = 0.05). Lactobacillus was most abundant in allantoic fluid when compared with all other samples (P &amp;lt; 0.01). The relative abundance of the genus Streptococcus, within the phylum Firmicutes, was less in amniotic and allantoic fluid compared with the cervix and vagina (P &amp;lt; 0.01). The phylum Bacteroidetes tended to differ by sample type (P = 0.06) with amniotic fluid having the lowest relative abundance. Within this phylum, the relative abundance of the genus Prevotella was also least in amniotic fluid (P &amp;lt; 0.01). These results suggest that microbial communities of reproductive tissues and fluids differ between mid- and late-gestation in pregnant gilts. Additional research on reproductive microbiomes in swine, and other livestock species, is required to develop methods to modulate bacteria and improve reproductive performance and successful outcomes of pregnancy.

Effects of Chronic Exposure to Diets Containing Moldy Corn or Moldy Wheat Bran on Growth Performance, Ovarian Follicular Pool, and Oxidative Status of Gilts.

Background: We investigated the effect of replacing normal corn (NC) or normal wheat bran (NW) with moldy corn (MC) or moldy wheat bran (MW) on growth, ovarian follicular reserves, and oxidative status. Methods: Sixty-three Landrace × Yorkshire gilts were assigned to seven diets formulated by using MC to replace 0% (control), 25% (25% MC), 50% (50% MC), 75% (75% MC), and 100% NC (100% MC), MW to replace 100% NW (100% MW), and MC and MW to replace 100% NC and 100% NW (100% MC + MW), from postnatal day 110 to day 19 of the second estrous cycle. Results: Feeding the gilts with MC or MW induced a lower average daily gain at days 29–56 of the experiment. Age at puberty remained unchanged, but MC inclusion resulted in a linear decrease in antral follicles with diameter >3.0 mm, and control gilts had a 12.7 more large antral follicles than gilts in the 100% MC + MW treatment. MC inclusion linearly decreased the numbers of primordial follicles, growing follicles, and corpora lutea, associated with a lower anti-Müllerian hormone level in serum and 17β-estradiol level in follicular fluid. MC inclusion decreased the serum concentrations of insulin-like growth factor 1 and its mRNA levels in the liver, combined with higher malondialdehyde concentration and lower total superoxide dismutase activities in serum and liver. Conclusion: Chronic exposure to MC-containing diets caused the loss of follicles, even if levels of deoxynivalenol, zearalenone, and aflatoxin B1 were below the levels allowed by China and Europe standards.

Signaling pathways of Periplaneta americana peptide resist H2O2-induced apoptosis in pig-ovary granulosa cells through FoxO1

Granulosa cell apoptosis induced by oxidative stress is an important cause of follicular atresia. Our previous studies found that Periplaneta americana peptide (PAP) decreased H2O2-induced apoptosis of pig-ovary granulosa cells (PGCs) through FoxO1. The aim of this study is to investigate the signaling pathways involved in PAP resistance against H2O2-induced apoptosis of PGCs. PGCs obtained from the follicles of non-estrous Duroc × Landrace × Yorkshire gilts (5 months old, 50–55 kg) were treated with H2O2 and PAP, or together with inhibitors against PI3K and JNK, and then collected for ROS levels and SOD activities detection, TUNEL staining, qRT-PCR, western blotting, immunofluorescence or coimmunoprecipitation. Results showed that the increased ROS levels and decreased activities of SOD caused by H2O2 stimulation were reversed by PAP. Additionally, PAP downregulated the differential abundance of mRNA of Bax and FasL, thus inhibiting H2O2-induced apoptosis of PGCs. PAP significantly reduces p-JNK expression and increases the p-FoxO1/FoxO1 expression ratio, thereby decreasing caspase-3 expression and cell apoptosis in H2O2-induced PGCs. PAP promotes the combination of FoxO1 with the 14-3-3 protein, increases FoxO1 translocation to the cytoplasm, and decreases FoxO1 acetylation. Therefore, PAP regulates FoxO1 expression through the JNK/FoxO1 signaling pathway and effects the translocation of FoxO1 to the cytoplasm by the FoxO1 interaction with 14-3-3, enabling reversal of the H2O2-induced apoptosis of PGCs. Acetylation of FoxO1 is also involved in the antiapoptotic effect of PAP.

Phytogenic Compounds Supplemented to Gestating Hyperprolific Sows Affects the Gut Health-Related Gene Expression and Histological Responses in Neonate Piglets.

This research aims to determine whether a specific blend of phytogenic compounds (BPC) supplemented in gestating hyperprolific sow diets can promote prenatal maternal effects in terms of piglet gut function and morphology. Twenty-eight (Landrace × Yorkshire) gilts and sows (parity 0 to 7) were randomly distributed by parity number and body weight into two dietary treatments: unsupplemented Control (CON) (n = 14) or CON diet supplemented with 1 g/kg feed of BPC during gestation (n = 14). The BPC supplementation during gestation of sows downregulated the neonate piglets' jejunal genes involved in oxidation (SOD2) and nutrient transport (SLC16A1/MCT1, SLC11A2/DMT1, and SLC39A/ZIP4), while IFNG and CLDN4 related to immune response and barrier function, respectively, were upregulated (q < 0.10). In addition, the jejunal villus height and the ratio of the villus height to crypt depth tended to increase (p < 0.10), while goblet cell volume density was higher (p < 0.05) in BPC compared to CON. In conclusion, dietary supplementation of BPC in gestating diets for hyperprolific sows influences neonatal histomorphology and expression of genes related to the intestinal function and health.

Gut microbiota contributes to the development of endometrial glands in gilts during the ovary-dependent period

BackgroundThe hyper-prolificacy Meishan gilts achieved a superior endometrial gland development (EGD) than white crossbred gilts during the ovary-independent period (before 60 d of age). Then, the EGD continues under the management of ovary-derived steroid hormones that regulated by gut microbiota (after 60 d of age). However, whether Meishan gilts’ superiority in EGD lasting to the ovary-dependent period (after 60 d of age) and the role of gut microbiota in this period both remain unclear.MethodsMeishan gilts and Landrace x Yorkshire (LxY) gilts were raised under the same housing and feeding conditions until sexual maturity and then we compared their EGD and gut microbiota. Meanwhile, we transplanted fecal microbiota from Meishan gilts to L×Y gilts to explore the role of gut microbiota in EGD. We sampled plasma every 3 weeks and collected the uterus, ovary, liver, and rectal feces after the sacrifice. We then determined the hormone concentrations and expressions of the EGD-related genes. We also profiled the gut microbiota using 16S rDNA sequencing and metabolites of plasma and liver tissue using untargeted metabolomics. Finally, the correlation analysis and significant test was conducted between FMT-shifted gut microbes and EGD-related indices.ResultsMeishan gilts have larger endometrial gland area (P < 0.001), longer uterine horn length (P < 0.01) but lighter uterine horn weight (P < 0.05), a distinctive gut microbiota compared with L×Y gilts. Fecal microbiota transplantation (FMT) increased endometrial gland area (P < 0.01). FMT markedly shifted the metabolite profiles of both liver and plasma, and these differential metabolites enriched in steroid hormone biosynthesis pathway. FMT increased estradiol and insulin-like growth factor 1 but decreased progesterone dynamically. FMT also increased the expression of the EGD-related genes estrogen receptor 1 gene, epithelial cadherin, and forkhead box protein A2. There is a significant correlation between FMT-shifted gut microbes and EGD-related indices.ConclusionSexually matured Meishan gilts achieved a superior EGD than LxY gilts. Meanwhile, gut microbiota contribute to the EGD potentially via regulating of steroid hormones during the ovary-dependent period.

Phenotypic and genomic relationships between vulva score categories and reproductive performance in first-parity sows

BackgroundOne of the biggest challenges in the swine industry is to increase female reproductive efficiency. Recently, vulva score categories (VSC), assessed prior to puberty, has been proposed as an indicator trait of efficient reproductive performance in sows. The objective of this study was to validate the use of VSC as an indicator trait for reproductive performance, and to perform genetic and genomic analyses for VSC.MethodsThe phenotypic relationship of VSC, using a three-point scale: small (VSC-S), medium (VSC-M), and large (VSC-L), on reproductive performance was evaluated on three farms. VSC was measured at 15 weeks of age, for farms 1 and 2, and at 14 weeks of age for farm 3 on 3981 Yorkshire gilts, in which 1083 had genotypes (~ 50 K SNPs). Genetic parameters for VSC with reproductive traits were estimated using ssGBLUP. A Genome-wide association study (GWAS) for VSC was performed using BayesB.ResultsFor the phenotypic analysis of VSC across datasets, differences in performance were identified there was a significant effect (P ≤ 0.05) for the interaction between Farm and VSC for total number dead (TND), and a trend (P < 0.10) for total number born (TNB). There were significant (P ≤ 0.05) pre-defined contrasts of VSC-S versus VSC-M + L on TNB, number born alive (NBA), TND, number of stillborn (NSB), and number of mummies (MUM). Heritability estimates for VSC as a categorical trait (VSCc) and a quantitative trait (VSCq) were 0.40 ± 0.02 and 0.83 ± 0.02, respectively, for across farm, 0.13 ± 0.07 and 0.20 ± 0.10, respectively, for Farm1, 0.07 ± 0.07 and 0.09 ± 0.09, respectively, for Farm2, and 0.20 ± 0.03 and 0.34 ± 0.05, respectively, for Farm3. For across farms, favorable genetic correlations estimates were found for TNB (0.28 ± 0.19) and NBA (0.26 ± 0.17). Within farms, moderate genetic correlations between VSC with reproductive traits were found for TNB (0.61 ± 0.47) and MUM (0.69 ± 0.47) for farm 1, for number of services until first farrow (NS; 0.69 ± 0.38) and unique service with successful first farrow (SFS; − 0.71 ± 0.38) for farm 3. Multiple genomic regions associated with VSCc were identified. Of these, a QTL located on chromosome 3 at 33–34 Mb accounted for about 7.1% of the genetic variance for VSCc and VSCq. This region harbors the gene PRM1 that has been associated with early embryonic development in pigs.ConclusionsThe results support potential of VSC for improved reproductive efficiency on first-parity performance, but the results might depend on the interaction between environmental factors and VSC, as well as potentially additive genetics.

Maternal cholecalciferol supplementation during gestation improves antioxidant capacities in gilts and piglets

Various studies have evaluated the relationship between cholecalciferol (vitamin D3) and reproductive performance. This study aimed at investigating the effects of maternal D3 supplementation during gestation on reproductive performance and antioxidant capacities of gilts and their offsprings. Twenty-three Landrace × Yorkshire gilts were randomly allocated into two groups and fed on one of the following two diets during gestation: control diet or D3 supplemented diet. It was found that D3 supplementation had a tendency to increase the number of total born and born alive piglets. Moreover, it elevated serum 25-hydroxycholecalciferol concentrations in gilts and newborn piglets. Besides, D3 supplementation improved the activities of antioxidant enzymes (GSH-Px, T-AOC and T-SOD) in the blood of gilts, umbilical cord and newborn piglets and piglets’ liver, while serum malondialdehyde concentrations of gilts and umbilical cord were reduced in the D3 group. In addition, D3 supplementation upregulated the expression of antioxidant related genes in the placenta and piglets’ liver. In conclusion, D3 supplementation during gestation might improve antioxidant capacities in gilts, placenta and in newborn piglets. Therefore, D3 supplementation has the potential to enhance the reproductive performance of gilts. HIGHLIGHTS D3 supplementation has a significant role in the nutrition of gilts. Maternal D3 supplementation during gestation increased the number of born and born alive piglets. Maternal D3 supplementation during gestation improved the antioxidant capacities of gilts, placenta and newborn piglets.

45 A permutation test for validation of genomic estimated breeding values

Abstract Previous studies have shown that the accuracy of Genomic Estimated Breeding Value (GEBV) as a predictor of future performance is higher than the traditional Estimated Breeding Value (EBV). The purpose of this study was to estimate the potential advantage of selection on GEBV for litter size (LS) compared to selection on EBV in the Canadian swine dam line breeds. The study included 236 Landrace and 210 Yorkshire gilts born in 2017 which had their first farrowing after 2017. GEBV and EBV for LS were calculated with data that was available at the end of 2017 (GEBV2017 and EBV2017, respectively). De-regressed EBV for LS in July 2019 (dEBV2019) was used as an adjusted phenotype. The average dEBV2019 for the top 40% of sows based on GEBV2017 was compared to the average dEBV2019 for the top 40% of sows based on EBV2017. The standard error of the estimated difference for each breed was estimated by comparing the average dEBV2019 for repeated random samples of two sets of 40% of the gilts. In comparison to the top 40% ranked based on EBV2017, ranking based on GEBV2017 resulted in an extra 0.45 (±0.29) and 0.37 (±0.25) piglets born per litter in Landrace and Yorkshire replacement gilts, respectively. The estimated Type I errors of the GEBV2017 gain over EBV2017 were 6% and 7% in Landrace and Yorkshire, respectively. Considering selection of both replacement boars and replacement gilts using GEBV instead of EBV can translate into increased annual genetic gain of 0.3 extra piglets per litter, which would more than double the rate of gain observed from typical EBV based selection. The permutation test for validation used in this study appears effective with relatively small data sets and could be applied to other traits, other species and other prediction methods.

Genetic and genomic characterization of vulva size traits in Yorkshire and Landrace gilts

BackgroundReproductive performance is critical for efficient swine production. Recent results indicated that vulva size (VS) may be predictive of reproductive performance in sows. Study objectives were to estimate genetic parameters, identify genomic regions associated, and estimate genomic prediction accuracies (GPA) for VS traits.ResultsHeritability estimates of VS traits, vulva area (VA), height (VH), and width (VW) measurements, were moderately to highly heritable in Yorkshire, with 0.46 ± 0.10, 0.55 ± 0.10, 0.31 ± 0.09, respectively, whereas these estimates were low to moderate in Landrace, with 0.16 ± 0.09, 0.24 ± 0.11, and 0.08 ± 0.06, respectively. Genetic correlations within VS traits were very high for both breeds, with the lowest of 0.67 ± 0.29 for VH and VW for Landrace. Genome-wide association studies (GWAS) for Landrace, reveled genomic region associated with VS traits on Sus scrofa chromosome (SSC) 2 (154–157 Mb), 7 (107–110 Mb), 8 (4–6 Mb), and 10 (8–19 Mb). For Yorkshire, genomic regions on SSC 1 (87–91 and 282–287 Mb) and 5 (67 Mb) were identified. All regions explained at least 3.4% of the genetic variance. Accuracies of genomic prediction were moderate in Landrace, ranging from 0.30 (VH) to 0.61 (VA), and lower for Yorkshire, with 0.07 (VW) to 0.11 (VH). Between-breed and multi-breed genomic prediction accuracies were low.ConclusionsOur findings suggest that VS traits are heritable in Landrace and Yorkshire gilts. Genomic analyses show that major QTL control these traits, and they differ between breed. Genomic information can be used to increase genetic gains for these traits in gilts. Additional research must be done to validate the GWAS and genomic prediction results reported in our study.

Optimal age of breeding gilts and its impact on lifetime performance

Age at first breeding and lifetime reproductive performance was analyzed on 17,558 F1 Landrace x Yorkshire gilts from 9 piglet producing herds of Midwest, United States entered in herds between 1st Jan 2014 and 31st July 2016. At the time of data collection Dec 2018, 15% of the sows were still active in the herds hence excluded from the analysis. Individual gilt data included date of birth, age in days at first mating, piglet total born by parity, lifetime piglet total born and reason for culling. Quality data checks were done before analysis to eliminate all outlier values together with sows that had no entry information for any listed category. The total database of the sows was classified into 6 classes according to age at the first mating in days 170-190(n=754), 191-211(n=4683), 212-232(n=7123), 233-253(n=3385), 254-274(n=1002) and 275-369 (n=611). Piglet total born obtained from each sow during the lifetime production was significantly (P &lt; 0.05) greater for gilts bred between 233-253 days of age at first mating. Gilts that were bred at &lt;233 days appeared to have a higher risk of removal by farrowing productivity as compared to the other groups. However, the results show that the risk of being culled due to health problems and conformation issues increases as the age at first mating is delayed. Overall reproductive failure appears to be the most economical culling reason across all age groups. There is a need to evaluate the best management decisions for gilt initiation in a herd to maximize her lifetime performance. The results indicate that gilts mated for the first time at the right age, 233–253 days, are more productive, both in lifetime total born and have a minimal risk of culling due to farrowing productivity.

Sow removal patterns in commercial breed-wean herds of Midwest, USA

An observational retrospective study was done to provide up-to-date information on recent sow removal patterns from 9 breed-wean herds of Midwest USA. The study comprised of sow’s removal reasons and removal types of F1 Landrace x Yorkshire gilts entered in the herds between 1st Jan 2014 and 31st July 2016. Data was extracted from existing database on Dec 2018 and 15% of the sows were still active in the herds hence not included in the study. Descriptive statistics showed that out of the 20,009 removed sows, planned removals comprised of farrowing productivity (FP) 3,523 (17.6%) and old age (OA) 1,785 (8.9%) while unplanned removals consisted of reproductive failure (RF) 7,786 (38.9%), health problems (HP) 2,629 (13.1%), locomotion problems (LP) 1,473 (7.4%) and conformation issues (CI) 1,350 (6.8%).‘Did not conceive’ and “No heat” were observed as the main contributing factors accounting for 37.6% and 32.9% respectively for gilts &amp; sows removed by RF.13.5% of the gilts (Parity 0) were removed from the herds before attaining their first litter of which 64.1% of their removals was due to RF. Removal type consisted of slaughter (S) 85.0%, found dead on the farm (DoF) 10.8% and euthanized (E) 4.2%. The research findings depict an upward trend of sow RF removals in the US swine herds posing a serious concern for US swine producers. Characterization and quantification of sow removals gives a revelation on the deeper intrigues about the vulnerability of the various parity in respect to common causes of RF. This helps swine producers to decisively improve on gilt replacement selection, reproductive efficiency, health and nutrition management all aimed at increasing overall swine productivity and efficiency in management. Swine farmers in the US can now focus their efforts towards curbing unnecessary RF removal within parity specifics.

68 Genomic prediction accuracies of vulva size traits in Landrace and Yorkshire gilts

Abstract Recent results indicated that vulva size measured prior to puberty may be predictive of reproductive performance in sows. Therefore, the objective of this study was to estimate genomic prediction accuracies for vulva size traits in purebred gilts. A total of 1,185 Landrace (n = 477) and Yorkshire (n = 708) gilts originated from two different lines were used in this study. All animals had vulva size measurements taken at an average 21.5 weeks of age (SD = 5.8). Measurements included vulva width (VW), vulva height (VH), and vulva area (VA). Genotype data (Geneseek GGP-HD) was available for all animals, for ~40K SNPs. Marker allele substitution effects were estimated using Bayes-B (pi = 0.99) in a model including the fixed effects of contemporary group, line, breed (for multi-breed analysis only) and body weight (covariate), and the random effect of SNPs. Genomic prediction accuracies were estimated using three training and validation strategies: between-breed, within-breed (4 and 6 cross-validation folds for Landrace and Yorkshire, respectively), and multi-breed (10-fold cross-validation, using one-fold per breed for validation at a time). Between-breed accuracies were low and consistently negative, with -0.02, -0.10, and -0.05 in Landrace and -0.05, -0.04 and -0.03 in Yorkshire, for VW, VH, and VA, respectively. Within Landrace, these were moderate, with 0.35 (VW), 0.42 (VH), and 0.56 (VA), whereas lower accuracies were obtained for Yorkshire, with 0.07 (VW), 0.20 (VH), and 0.14 (VA). Multi-breed accuracies were low with 0.14 (VW), 0.14 (VH), and 0.24 (VA) for Landrace, and 0.03 (VW), 0.16 (VH), and 0.09 (VA) for Yorkshire. These results indicate that genomic selection for vulva size traits is possible in Landrace, but limited in Yorkshire gilts. The low between- and multi-breed results suggest that QTL for these traits are in opposite phases between breeds and/or do not segregate in both breeds. Financial support from the Iowa Pork Industry Center is appreciated.

191 Early weaning in pigs induces long-term alterations in intestinal nutrient transporter function and expression partially via beta adrenergic enteric neural receptors

Abstract Early weaning (EW) has negative impacts on performance and health that persist from wean-to-finish. The mechanisms linking EW and lifetime performance reductions are poorly understood. The objective of this study was to investigate whether EW influences the long-term development of intestinal epithelial nutrient transporter function and expression and the potential mechanisms. Yorkshire gilts were split-weaned from their sows at 15 d (EW) or 28 d of age (Late Weaning; LW) and transferred to an on-site nursery room. All pigs received the same diets in a standard phase feeding program and were euthanized at 75 d of age. Mid-jejunum and distal ileum were mounted on Ussing chambers to evaluate Na+-dependent glucose and amino acid (AA) transporter function, measured as nutrient-induced changes in short circuit current (Isc). EW gilts exhibited reduced capacity for electrogenic transport of glucose (by ~30%; P &lt; 0.05) and glutamate, glutamine, and alanine by (~ 30–35%; P &lt; 0.05), compared with LW pigs. In contrast, jejunal and ileal lysine transporter function was upregulated (by 110% and 25%, respectively; P &lt; 0.05) in EW pigs. Epithelial expression for glucose transporter (SGLT1) was reduced (P &lt; 0.05) while glucose/fructose transporter (GLUT2), fructose transporter (GLUT5) and lysine transporters (B0AT1, CAT1, and ATB0, +) were enhanced in the EW jejunum. No differences observed in villus morphology between EW and LW pigs. Pretreatment of ileal mucosa on Ussing chambers with the Na+ channel blocker (Tetrodotoxin) or the β-adrenergic receptor blocker (Propranolol) augmented glucose, lysine and alanine transporter function in EW but not LW pigs. Together, these data show that EW in gilts induces lasting and divergent alterations in intestinal nutrient transporter function and expression which is mediated in part by the enteric nervous system and β-adrenergic receptor pathways. These new findings may explain why EW pigs exhibit lasting deleterious impacts on performance. Further mechanism-based investigations could reveal new targets for optimizing performance in EW pigs throughout the production lifespan.

296 Genetic and genomic analysis of vulva size in Landrace and Yorkshire gilts.

296 Genetic and genomic analysis of vulva size in Landrace and Yorkshire gilts.

Test for high-dimensional regression coefficients using refitted cross-validation variance estimation

Testing a hypothesis for high-dimensional regression coefficients is of fundamental importance in the statistical theory and applications. In this paper, we develop a new test for the overall significance of coefficients in high-dimensional linear regression models based on an estimated U-statistics of order two. With the aid of the martingale central limit theorem, we prove that the asymptotic distributions of the proposed test are normal under two different distribution assumptions. Refitted cross-validation (RCV) variance estimation is utilized to avoid the overestimation of the variance and enhance the empirical power. We examine the finite-sample performances of the proposed test via Monte Carlo simulations, which show that the new test based on the RCV estimator achieves higher powers, especially for the sparse cases. We also demonstrate an application by an empirical analysis of a microarray data set on Yorkshire gilts.