The potential of identifying replacement gilts by screening for lipid biomarkers in reproductive tract swabs taken at weaning

Sow longevity affects economic returns to pork producers. The cost of gilt replacements is substantial and sows with greater than three litters have lower costs per pig produced. An early marker of reproductive potential would facilitate early identification of superior females, and likely increase sow longevity. Gilts raised in small litters have greater reproductive competence, but mechanisms associated with increased reproductive responses are not fully understood. Here, early postnatal development of the gilt's reproductive tract is described, and a brief review of literature is presented to support that factors in colostrum regulate the developmental trajectory of the gilt's uterine tissues. We propose that, similar to the uterus, nutritional environment likely affects the postnatal developmental programme of the vagina. A metabolomics approach, multiple reaction monitoring -profiling, for biomarker discovery is described, along with evidence that lipids present in vaginal samples are differentially expressed in gilts exposed to colostrum versus milk replacer fed. These exploratory studies indicate that the vaginal cell lipidome may reflect the postnatal nutritional environment, which defines to a large extent the gilt's reproductive potential. Together findings support further investigations to identify biomarkers predictive of fertility outcomes in the metabolome of gilt reproductive tracts.