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

Two experiments were conducted to determine the influence of Streptococcus faecium M-74 supplementation of broiler diets. Mixed-sex or male only chicks were used in the experiments. Both experiments consisted of six dietary treatments and four replicates per treatment in a randomized block design. The S. faecium was fed alone for 21, 36, or 44 days or for 44 days with S. faecium supplemented in the water for the first 14 days. In another treatment, S. faecium was fed for 44 days, but the feed was restricted for Days 8 through 13. The S. faecium was also fed in combination with antibacterial products (AP) for 44 days. An additional diet was an unsupplemented basal, and another was 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, BW of broilers at 44 days of age were significantly heavier for broilers receiving S. faecium in the feed and also S. faecium in the water for the first 14 days as compared with broilers receiving AP or AP and S. faecium supplementation. 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 dietary treatment. The ceca had the highest S. faecium score of any of the intestinal tract locations.(ABSTRACT TRUNCATED AT 250 WORDS)