Provision of porcine milk oligosaccharides to support the weaning transition in nursery pigs fed diets including bovine milk co-products.

Milk oligosaccharides (MO) support intestinal, microbial, and immune development in young pigs. However, modern production practices wean pigs at an early age, removing them from their source of MO prior to intestinal and immune maturation. The purpose of this study was to investigate the effects of dietary supplementation of galacto-oligosaccharides (GOS) and 2'-fucosyllactose (FL) on the jejunal mucosa-associated microbiota, intestinal immune signaling, morphology, and growth performance of nursery pigs. Forty-eight pigs (6.8 ± 0.2 kg body weight) weaned at 3-weeks-of-age were allotted into six dietary treatments, using a randomized complete block design, with sex and initial body weight as blocks. Dietary treatments were (1) basal diet; (2) basal diet, with supplemental GOS at 1.5% of the diet; (3) basal diet, with supplemental FL at 0.2% of the diet; (4) basal diet, with GOS and FL at 1.5 and 0.2% of the diet, respectively; (5) basal diet, with GOS at 2.3% of the diet; and (6) basal diet, with FL at 0.3% of the diet. These MO were provided alone or in combination at levels mimicking intake at the end of the suckling period, and at 1.5-fold higher, to observe potential dose-dependent responses. Pigs were fed for 21 days in two phases. On d 21, pigs were euthanized for sampling of jejunal mucosa and jejunal tissue. Data were analyzed using the PROC MIXED of SAS 9.4 and contrasts were used to determine the effects of GOS, FL, and their combination (interaction), in addition to the linear effects of increasing dietary GOS or FL. Increasing levels of GOS and FL linearly decreased (P < 0.05) Shannon and Simpson alpha diversity of the jejunal mucosa-associated microbiota. Supplementation with FL increased (P < 0.05) the absolute abundance of Helicobacter in the jejunal mucosa-associated microbiota, although no dose response was observed. Increasing levels of GOS and FL tended to linearly decrease (P = 0.051 and 0.076, respectively) the gene expression of TLR4. Increasing levels of GOS tended to increase (P = 0.054) and increasing supplementation of FL increased (P < 0.05) the number of Ki-67 proliferative cells in the crypt of the jejunum. Increasing levels of GOS increased (P < 0.05) body weight and average daily gain in the early post-weaning period and tended to increase (P = 0.093) body weight by the end of the experimental period. Notably, increasing levels of GOS, and GOS in combination with FL, improved growth performance, whereas FL alone did not.