Effects of sorbic acid feed fungistat on the intestinal microflora of floor-reared broiler chickens.

The intestinal microflora of a group of broilers fed a diet containing .04% sorbic acid from Days 1 through 49 of their lives was compared with broilers given a diet without the fungistat. Four broilers from each group were killed at 7, 21, 35, and 49 days, and intestinal sections of the duodenum, the lower small intestine, and both ceca were removed aseptically. Samples of the contents of the intestinal sections were analyzed microbiologically. Groups of microorganisms analyzed included total aerobes, total anaerobes, coliforms, streptococci, lactobacilli, clostridia, Bacteroides, Bifidobacterium, yeasts, and molds. Generally, there was a large variation in viable counts of microorganisms for birds of the same treatment. Of the nine groups of microorganisms analyzed the highest counts obtained (greater than 10(6)/g) were for total aerobes, total anaerobes, lactobacilli, and Bifidobacterium. Coliforms, streptococci, and clostridia showed intermediate counts (greater than 10(3)/g), while yeasts and molds and Bacteroides showed the lowest counts (greater than 10(2)/g). Total microbial numbers, in most cases and irrespective of sorbic acid treatment, were highest in the ceca, lower in the small intestine, and still lower in the duodenum. There were no major trends of microbial population changes observed in a given treatment, intestinal location, or group of organisms with age and time on feed. Inclusion of sorbic acid in the feed did not influence total aerobes, total anaerobes, lactobacilli, streptococci, Bifidobacterium, and clostridia. However, broilers on sorbic acid-containing feed had, at 49 days of age, lower coliform counts in the duodenum, lower yeast and mold counts in the ceca, and higher Bacteroides counts in the ceca.