A marker indicative of fertility potential of replacement gilts early in development would decrease culling rates in the sow herd, improve sow herd reproductive efficiency, and reduce production costs. The objective of this study was to determine if vaginal lipid profiles at 21 d postnatal (PN) could predict sow reproductive performance. Vaginal swabs of the anterior vagina were taken at 21 ± 4 d PN from gilts born on a commercial sow production facility for lipidomic analysis. Animals were followed prospectively for two years and assigned to reproductive performance categories based on observation of estrus or piglets weaned per sow per year (PSY) across two farrowings. Lipids were extracted from cellular material collected with swabs taken from high fertility (HF; n=28; ≥26 PSY) and infertile (IF; n=34; no estrus, no pregnancy) animals and multiple reaction monitoring (MRM)-profiling was used for lipidome analysis. Relative abundance of arachidonic acid (ARA, C20:4) and docosahexaenoic acid (DHA, C22:6) were lower (P<0.05) in IF gilts than HF gilts, whereas abundance of the free fatty acids cerotic (C26:0), ximenic (C26:1), and nonadecanoic (C19:0) acids were greater (P<0.05) in IF gilts. Additionally, eicosapentaenoic acid (C20:5) a precursor of prostaglandins was higher (P<0.05) in IF gilts. The perspective of having a panel of lipids captured with vaginal swabs at weaning that can predict reproductive efficiency of gilts shows promise and warrants future research in this area.

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.