Bacterial Cultures in the Nutrition of Poultry I. Effect of Dietary Bacterial Cultures on the Growth and Cecal Flora of Chicks

Abstract

Supplementing a diet for chicks with certain microorganisms isolated from the ceca of chicks fed penicillin resulted in improved weight. The feeding of a culture of one atypical strain of E. coli caused a significant weight response in the absence of dietary penicillin. The feeding of typical E. coli and two atypical strains of E. coli in the presence of dietary penicillin resulted in weights considerably greater than those achieved with the microorganisms or penicillin alone. Part of the activity of a mixed coliform culture was found to be present in the filtrate and part in the viable organisms themselves. A culture of micrococci depressed growth in the absence of penicillin but this inhibition was completely relieved in the presence of dietary penicillin. The feeding of a culture of anaerobes did not improve weight but increased feed efficiency. There appeared to be a synergistic interaction between penicillin and certain of the bacterial cultures fed. In most cases dietary penicillin caused a reduction in numbers of aerobes, anaerobes, coliforms, lactobacilli and enterococci in the ceca. The feeding of coliform cultures tended to reduce the counts of these organisms in the absence of penicillin but increased the counts of aerobes, anaerobes, coliforms and lactobacilli, and reduced the counts of enterococci in the presence of penicillin.