Changes in intestinal microbial ecophysiology as related to the carbohydrate composition of barleys and oats cultivars in an in vitro model of the pig gastrointestinal tract

The influence of variation in carbohydrate (CHO) composition within the same type of cereal on intestinal fermentation patterns and microbial community composition in the pig is unknown. Ten hulless barleys (HLB), 6 hulled barleys (HB), 6 oats (O) and 6 oat groats (OG) differing in CHO composition were studied in vitro. They were hydrolyzed enzymatically, inoculated with pig feces and fermented for 72h. Multivariate analysis revealed that microbial profiles analyzed using TRFLP, short-chain fatty acid (SCFA) and fermentation parameters were affected by CHO composition but differently according to the grain type (HLB, HB, O or OG). Members of Clostridium cluster XIVa were associated to higher amylose contents and butyrate production in HB cultivars and in HLB cultivars. Several clostridia phylotypes increased with β-glucan content in HLB and HB. Cellulolytic Ruminococcus-like bacteria tended to increase acetate concentration and were increased with cellulose content in HB, HLB and OG. Bacteroides-like bacteria were increased by amylopectin and starch content of barley cultivars. Cereal cultivars differing in CHO composition can alter the pig intestinal microbial ecophysiology to possibly improve gut health.