The Intestinal Microflora of Hens as Influenced by Various Carbohydrates in a Biotin-deficient Ration.

The chicken is an animal of great economic importance and is widely used in the assay of certain vitamins, but little is known about its intestinal flora. The first study of the microbial flora of the chicken's intestinal tract was conducted by Kern (1897). His investigations embraced not only the chicken and other gallinaceous birds, but many of the common wild birds. Other work on the microflora of chickens has been reported by Rahner (1901), King (1905), Gage (1911), Menes and Rochlin (1929), and Emmel (1930). All of these workers agreed that Escherichia coli and Aerobacter aerogenes made up the greatest proportion of the intestinal flora. Other types of microorganisms commonly found in the chicken's intestines by these workers were lactobacilli, micrococci, pseudomonads, bacilli, sarcinae, clostridia (in two instances), and yeasts. Unfortunately, none of these studies was quantitative, and some were not too exact from a qualitative standpoint. The type of dietary carbohydrate has a marked effect on the intestinal flora of animals. Early studies on the subject are well reviewed by Rettger and Cheplin (1921), who presented further evidence concerning the influence of carbohydrate upon the intestinal microflora. Later studies have confirmed and enlarged upon these earlier reports (Evenson, 1947). From the standpoint of vitamin synthesis, the type of carbohydrate in the diet is an important factor. Elvehjem and Krehl (1947) have reviewed this subject, hence an account of specific reports on the role of carbohydrates upon intestinal biosynthesis of vitamins will be unnecessary. Elvehjem and Krehl state, "One might place the carbohydrates in the following decreasing order in their favorable effect on vitamin requirement: dextrin, starch, lactose, glucose, sucrose, although this varies with different vitamins." The work presented in this paper was carried out over a period of six months in connection with a nutritional investigation (Couch et al., 1948) that was performed to determine the effects of different carbohydrates upon the intestinal synthesis of biotin by chickens. The microbiological work had as its objective the determination of the influence of various carbohydrates upon the numbers and kinds of microorganisms in the intestinal tract.