Manipulation of the crop and intestinal flora of the newly hatched chick

The ceca of newly hatched chicks obtained either from commercial hatcheries or from a carefully controlled experimental hatchery have been shown to contain high numbers of a variety of microorganisms. Fecal streptococci, clostridia, enterobacteria, pediococci, and occasion- ally Pseudomonas aeruginosa have all been isolated, but never lactobacilli. After the chick has been on feed for 1 day, the numbers of lactobacilli in the crops and ceca are quite variable; by the 3rd day, however, large numbers are present throughout the alimentary tract. Lactobacilli could be established after I day by incorporating them in the feed or by treating the chicks with 0.5 ml of a broth culture. Spraying the eggs before hatching did not lead to their early establishment. Lactobacilli given alone to the newly hatched chick failed to prevent the establishment of Salmonella. However, when the chicks were given a complex mixture of facultative anaerobes and anaerobes which had been isolated from an adult bird, cecal colonization with Salmonella was prevented. The possible importance of the facultative anaerobes, particularly Streptococcusfaecalis, in lowering the redox potential to encourage the growth of the anaerobes is discussed. Am. J. Clin. Nutr. 33: 2426-2433. For many years it has been believed that chickens may be less susceptible to infection or have improved growth yields according to the type of diet and the early establishment in the gut of certain types of microorganisms. It was reported (1) that feeding sour milk to newly hatched chicks appeared to be a good means of preventing, or at least controlling, chick epidemics of bacillary white diarrhea due to Salmonella pullorum. However, sub- sequent work (2) while showing that sour milk feeding had a beneficial influence on the growth of chicks, could not confirm its importance in the control of bacillary white diarrhea. Later work could not establish a particular role for Lactobacillus acidophilus, which occurs in sour milk. More recently, the importance of the early establishment of lactobacilli in the crop of the bird has been discussed (3). Food may be held for up to 6 h in the crop, where a lactobacillus fermentation occurs. The lacto- bacilli have been shown to adhere to the lining of the crop, and it was found that administration of an adhering strain im- proved the growth of the chicks. When the organisms administered were isolated from sources other than birds, they failed to be- come established (3, 4). Lactobacilli are also the most numerous organisms in the small intestine, and have been shown to adhere to the columnar epithelial cells. Salmonella potentially pathogenic for man are often carried asymptomatically in the in- testines of birds. Chicks are most susceptible to Salmonella colonization within the first few days after hatching; the salmonellas are carried in the cecum where they multiply to high levels (5).