Influence of dietary supplementation with Streptococcus faecium M-74 on broiler body weight, feed conversion, carcass characteristics, and intestinal microbial colonization

In 2 experiments using mixed sex or male only chickens, the influence of dietary supplementation with Streptococcus faecium was studied. In a randomized block design with 4 replicates S. faecium was given alone for 21, 36 or 44 days, with S. faecium given in water for 44 days, S. faecium given for 44 days but feed restricted from day 8 to 13, or S. faecium given in combination with antibacterial products (AP) for 44 days. Results were compared with an unsupplemented basal diet and a basal diet supplemented only with AP. In experiment 1, feed efficiency was significantly better with the basal and diets supplemented with S. faecium than with those diets supplemented with AP or AP and S. faecium. In experiment 2, body weights of broilers at 44 days old were significantly heavier for broilers receiving S. faecium in the feed and also S. faecium in the water for the first 14 days than for broilers receiving AP or AP and S. faecium. There were no significant differences in carcass yield or composition characteristics. In experiment 1, the scores representing S. faecium colonies found in the intestinal tract were not influenced by diet. The caeca had the highest S. faecium score of any of the intestinal tract locations. In experiment 2, broilers receiving diets containing S. faecium or the basal diet had significantly more S. faecium colonies in the caeca than the broilers receiving the diets containing AP or AP and S. faecium. S. faecium colony counts in the duodenum, jejunum and ileum were significantly lower on days 14 and 21 than on day 7. S. faecium counts from the caeca were significantly lower on day 21 only. Numbers of S. faecium colonies in the duodenum, jejunum, ileum and caeca were increased on day 29. The caeca also consistently yielded the highest S. faecium counts.