Off to a Flying Start: Effects of Colostrum Oligosaccharides on Litter Performance and Microbial Dynamics in an In Vitro Gut Model

The pig production industry is under pressure to increase sustainability and efficiency. Hyper-prolific sows now birth over 16 piglets per litter. Unfortunately, increased litter size is positively associated with pre-wean mortality due to increased numbers of low-birth-weight (LBW) piglets, and lack of functional teats, often resulting in use of commercial milk replacer to supplement nutrition provided by the sow. Colostrum, critical to neonate survival, is rich in bioactive components, such as milk oligosaccharides, which have prebiotic and immunomodulatory effects. This thesis aimed to explore concentrations of porcine milk oligosaccharides (PMO) in hyper-prolific sows and their associations with litter performance, before developing an in vitro model to screen various PMO combinations and identify the best for supplemental use. The most abundant PMO in sow colostrum was 3’-sialyllactose (3’SL) and litter size was a significant but modest predictor of lacto-N-neotetraose (LNnT) concentration (R2 = -0.198; P = 0.0143), with concentration decreasing as litter size increased. This suggests some degree of maternal regulation and that larger litters may benefit from supplementation. Higher concentrations of 2’-fucosyllactose (2’FL) were associated with lower pre-weaning mortality, although this relationship was attenuated following post-hoc adjustment (p = 0.0466; post-hoc p = 0.435), indicating that the potential contribution of individual PMOs to piglet survival requires further investigation. Further, methodology was developed to optimise a protocol for in vitro fermentation in which PMO combinations could be assessed for….. The results demonstrated that fermentation conditions influenced microbial and metabolite responses, highlighting the importance of model design when evaluating candidate prebiotics. Colostrum fermentation produced a distinct microbial profile, and no PMO treatment was able to influence the community composition beyond that which was produced through fermentation of milk replacer (Bray-Curtis; F = 0.914; R2 = 0.301; p = 0.637). The addition of 3’SL to milk replacer, however, was associated with lower Streptococcus and increased Bacteroides, demonstrating a more ‘colostrum-like’ genus profile than other PMO tested. These findings suggest key PMO, namely 3’SL, LNnT and 2’FL, should be explored further and considered as additive prebiotics for piglet supplemental milk to support LBW piglets.