Effect of barley and oat cultivars with different carbohydrate compositions on the intestinal bacterial communities in weaned piglets

This experiment was aimed at comparing the intestinal microbial community composition in pigs fed hulled common barley supplemented with isolated barley mixed‐linked β‐glucan, four hulless barley varieties and breeding lines with mixed‐linked β‐glucan contents ranging from 41 to 84 g kg −1 and different amylose/amylopectin ratios as well as two oat varieties. Seventy‐two weaned piglets were allocated to one of nine diets composed of 81.5% cereal, 6% whey, 9% soy protein isolate and 3.5% minerals. After 15 days, pigs were sacrificed and ileum and colon contents were collected for quantitative real‐time PCR (qPCR) and denaturing gradient gel electrophoresis to evaluate microbial communities. Shifts in intestinal microbial communities were observed with the hulless barley cultivars with a normal to high β‐glucan content and from normal starch toward either high‐amylopectin or high‐amylose starch. These hulless barleys had the lowest ( P <0.05) microbial diversity, whereas oats had intermediate diversity compared with low‐β‐glucan hulless cultivars and hulled varieties. Furthermore, hulless varieties favoured xylan‐ and β‐glucan‐degrading bacteria whereas mixed‐linked β‐glucan‐supplemented hulled barley favoured lactobacilli. Numbers of lactobacilli decreased in the ileum of pigs fed hulless/high mixed‐linked β‐glucan barley‐based diets. Thus, cultivar differences in both the form and the quantity of carbohydrates affect gut microbiota in pigs, which provides information for future feeding strategies.