Effects of maternal supplementation of fish oil during late gestation and lactation on growth performance, fecal microbiota structure and post-weaning diarrhea of offspring piglets.

Homeostasis of the gut microbiota is a critical contributor to the growth and health of weaning piglets. Fish oil is widely reported to benefit well-being of mammals including preventing intestinal dysfunction, yet its protective effect during suckling-to-weaning transition in piglets remains undetermined. Here, low (30 g/d) and high (60 g/d) doses of n -3-rich fish oil were individually supplemented in sows' diet from day 90 of gestation to day 21 of lactation, with 15 replicates per treatment. Piglets were weaned on day of 21, and 8 piglets with average body weight of its litter were randomly selected, and body weights, serum indicators, gut microbiota and post-weaning diarrhea were measured to evaluate the effects of maternal fish oil on growth performance, systemic immunity, and diarrhea severity. Docosahexenoic acid (DHA) and eicosapentaenoic acid (EPA) concentrations in the colostrum and serum of piglets were significantly and linearly increased by maternal intake of fish oil (all P < 0.05). Growth factors, IGF1 and T3 in nursery (21d old) and weaned (28d old) piglets were significantly induced by maternal administration of fish oil (both P < 0.05), and the increase of IGF1 was dependent on the dosage of maternal fish oil. Meanwhile, colostrum IgG, plasma IgG, IgM in suckling piglets, IgG, IgM and IgA in weaned piglets were significantly lifted up as maternal replenishment of fish oil increased (all P < 0.05). In addition, circulating zonulin, diamine oxidase (DAO), and D-lactate were significantly decreased in suckling and weaned piglets ( P < 0.05), and plasma LPS in weaned piglets was also decreased by maternal fish oil ( P < 0.05), all in a dosage-dependent way. Moreover, stress hormone, cortisol, was not greatly altered in suckling piglets but significantly reduced in weaned pigs by maternal fish oil ( P < 0.05), regardless of dosage. Accordingly, diarrhea incidence were significantly lower in weaned piglets by dietary replenishment of fish oil. Furthermore, 16S rRNA sequencing revealed that maternal exposure to fish oil significantly increased the α-diversity of fecal microbiota in nursery piglets, and fecal Lactobacillus genus, positively correlated with post-weaning IgA, was significantly increased by high dosage of fish oil. Collectively, complementary fish oil in the sow diet during late pregnancy and lactation significantly promoted growth, enhanced immunity, and reduced post-weaning diarrhea, therefore facilitated the suckling-to-weaning transition in piglets, which may be partially due to the altered gut microbial community.