Vanessa Wai-Yin Ng
Hyperprolific sows experience substantial physiological challenges during the gestation and lactation phase due to increased demands for fetal growth, farrowing, colostrum and milk production, and maintenance of maternal body condition. Functional feed additives may help support sow productivity and modulate the gut microbiome during these demanding reproductive stages. This thesis evaluated the impact of supplementing sow diets with a combination of essential oils and prebiotic fibers (DD) on reproductive performance and the gut microbiota during gestation and lactation.Sows were assigned to either a control diet (CON) or a DD-supplemented diet beginning at entry into gestation pens and continuing through weaning. A subset of 25 sows per treatment was used to evaluate reproductive performance and fecal microbiota at approximately 10 days before farrowing, 2 days post-farrowing, and 1 day before weaning. Reproductive performance outcomes, including litter traits, piglet body weight, stillbirths, and litter weight gain, were analyzed using generalized linear mixed models with treatment and parity class as fixed effects and sow as a random effect. The fecal microbiota was evaluated using alpha diversity indices, beta diversity metrics, and differential abundance analyses. Based on the subset of sows evaluated in this study, DD supplementation did not significantly affect reproductive performance outcomes, including litter size, piglet birth weight, piglet weaning weight, stillbirths, or litter weight gain. However, numerical improvements were observed in some reproductive performance measures in the DD group. Alpha diversity did not differ between treatments at any timepoint, suggesting that overall microbial richness, evenness, and phylogenetic diversity remained stable. In contrast, beta diversity differed between treatments across the study, with the strongest treatment-associated separation observed at 2 days post-farrowing. This suggests that the early postpartum period may be a key window when the sow gut microbiome is more responsive to dietary supplementation. At 10 days before farrowing, DD supplementation was associated with greater relative abundance of Ruminococcus, Eubacterium, Cellulosilyticum, and Bacteroides, whereas Lactobacillus and Oscillospira were enriched in CON sows. At 2 days post-farrowing, Limosilactobacillus was enriched in DD sows, while Turicibacter and Terrisporobacter were enriched in CON sows. By weaning, fewer treatment-associated taxa were detected.In addition, a subset of sows from each treatment group (CON, n = 10; DD, n = 9) with parities 5–7 was transported to Purdue University after weaning for necropsy and digestive content collection. Reproductive performance did not differ significantly between treatments. Intestinal segment was the primary determinant of microbial diversity, with the hindgut exhibiting greater diversity than the small intestine. DD supplementation exerted broader effects on microbial diversity in the cecum and more selective changes in the colon. Differential abundance analysis identified more treatment-associated ASVs in DD-fed sows than in CON-fed sows, particularly in the cecum and colon.Overall, DD supplementation was associated with shifts in sow gut microbial community composition, particularly around farrowing. Further studies with larger sample sizes, maternal metabolic measurements, and longitudinal piglet microbiome data are needed to determine whether maternal dietary modulation can influence offspring microbial colonization, growth, and health.