Flaxseed oil supplementation improves intestinal function and immunity, associating with altered intestinal microbiome and fatty acids profile in pigs with intrauterine growth retardation
Flaxseed oil (FO), enriched in n-3 polyunsaturated fatty acids (PUFAs), is an important oil source for intestinal development and health. We aimed to study the different effects of FO versus soybean oil (SO) on growth, intestinal health and immune function of neonates with intrauterine growth retardation (IUGR) using a weaned piglet model. Forty pairs of male IUGR and normal birth weight piglets, weaned at 21 ± 1 d, were fed diets containing either 4% FO or SO for 3 weeks consecutively. Growth performance, nutrient digestibility and intestinal function parameters, immunology and microbiota composition were determined. IUGR led to poor growth rate, nutrient digestibility and abnormal immunology variables, whereas feeding FO diet improved systemic and gut immunity, as indicated by increased plasma concentration of immunoglobulin G and decreased CD3+CD8+ T lymphocytes, as well as down-regulated intestinal expression of genes (MyD88, NF-ĸB, TNF-, IL-10). Although IUGR tended to decrease villous height, moreover, feeding FO diet tended to increase villi-crypt ratio and up-regulated expressions of tight junction genes (Claudin-1 and ZO-1), together with increased mucosa contents of n3 PUFAs and lower Σn6/Σn3 ratio. Besides, FO diet decreased the abundance of pathogenic bacteria Spirochaetes, increased phylum Actinobacteria, genera Blautia and Bifidobacterium in colonic digesta. Our findings indicate that IUGR impairs growth rate, nutrient digestibility, and partly immunology variables, whereas feeding FO-supplemented diet could improve intestinal function and immunity of both IUGR and NBW pigs, associating with the altered gut microbiome and mucosal fatty acids profile.