AbstractsBiology & Animal Science

An investigation was conducted to determine the contribution of the gastrointestinal microbiota to variation in bioefficacy of methionine sources and the interrelationship between intestinal microbiota and cereal grain type with respect to gastrointestinal physiology. Apparent gastrointestinal absorption of DL-methionine (MET) and 2-hydroxy-4-methylthiobutanoic acid (MHA-FA), post-weaning intestinal morphology, digestive physiology, mucin dynamics and digesta flow were studied in a series of experiments using conventional and gnotobiotic pigs. At 14 d of age, sow - reared conventional (CON) pigs and isolator - reared monoassociated gnotobiotic pigs (EF) were weaned to corn or wheat/barley based diets supplemented with MET or MHA-FA. At 24 d of age, after an overnight fast, pigs were fed experimental diet supplemented with 107 Bq of either 3H-L-MET or 3H-L-MHA-FA per kg of feed and chromic oxide (0.5% wt/wt). Pigs were killed 3 h after consuming the meal to collect digesta and tissue samples from the stomach and along the small intestinal (SI) length. Conventional pigs fed a wheat/barley-based diet had increased (P < 0.05) total aerobes, whereas supplementation with MHA-FA increased (P < 0.05) total aerobes and lactobacilli populations in proximal SI. Among the gnotobiotic pigs, 8 pigs (2 isolators) were monoassociated with a bacteria closely related to Providencia spp. and 16 pigs (4 isolators) were monoassociated with Enterococcus faecium (EF). Species of bacterial contaminant and diet composition did not affect residual MET or MHA-FA in digesta. Decreased (P < 0.05) apparent residual MET in digesta compared with MHA-FA in CON but not monoasscoiated pigs, along with significantly higher (P