Nutritional strategies to improve intestinal digestibility and health of beef cattle fed a high-grain diet

Several mechanisms whereby probiotics (yeast or bacteria) may improve gut health, intestinal microbial balance and production efficiency have been proposed, but few of these have been directly examined in experiments with cattle. With ruminants, the challenge is to deliver probiotics with high activity post-ruminally due to the highly proteolytic environment of the rumen. Two experiments were conducted to determine the effect of adding rumen protected and non-protected yeast products on intestinal digestibility and immune response in finishing beef cattle. Cattle were fed ad libitum diet containing 10% silage and 90% barley concentrate (dry matter [DM] basis). In Exp. 1, 5 rumen cannulated beef heifers (body weight, 650 kg) were used in a 5 × 5 Latin square with 5 treatments: (1) control; (2) monensin (Mon); (3) live yeast (LY); (4) encapsulated LY (EY); and (5) mixed of LY and EY (MY). Intake of DM (average 11.7 kg/d) was not affected by treatments. However, greater (P < 0.03) digestibility (% of intake) of organic matter and fiber in the intestine was observed with either EY or MY versus control diet. Heifers fed protected LY had less (P < 0.05) fecal Escherichia coli counts than control and Mon diets. The reduced fecal E. coli counts suggest an antipathogens activity of LY in the lower gut. In Exp. 2, 5 beef heifers (body weight, 561 kg) with ruminal and duodenal cannulas were used in a 5 × 5 Latin square with 5 treatments: (1) control diet; (2) monensin (Mon); (3) ruminal delivery of yeast culture (rYC); (4) duodenal delivery (dYC); and (5) combination of 3 and 4 (rdYC). Fecal IgA concentration was higher (P < 0.05) with dYC and rdYC than control and rYC. The duodenal delivery of YC resulted in trend of greater (P < 0.08) fecal IgA concentration (76 vs. 59 µg/g). These results indicate the potential postruminal activity of LY, and benefits to feeding protected yeast on improving intestinal digestibility. The study suggests that feeding rumen protected yeast products to feedlot cattle may exert potential beneficial health and food safety effects that reduce possibly pathogen excretion and increase of immune response.

Key Words: beef cattle, intestinal health, yeast products.

Presented at the 9th Symposium on Gut Health in Production of Food Animals, St. Louis, USA, 2021. For information on the next edition, click here.