The Intestinal Microflora of Young Swine Obtained by Hysterectomy

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Abstract
Data from young swine fed basal diets either with or without chlortetracycline supplementation show that fluctuations in intestinal flora occur frequently and that a variation in numbers of organisms may not necessarily represent a response to the experimental conditions imposed. Moderate changes from one experiment to another in diet and housing conditions did not result in greater variation in counts of microflora between experiments than occurred within experiments. These findings suggest that in order to attach significance to fluctuations in intestinal microflora of animals fed diets supplemented with antibiotics, many examinations are necessary to establish a consistent pattern. Four experiments were carried out using Chester White swine obtained by hysterectomy, raised in individual units without access to colostrum or contact with other pigs in early life. For each experiment, one group was fed a basal diet without supplementation, the other group was fed a diet supplemented with chlortetracycline. Cultures of fecal samples pooled from respective groups yielded counts for total aerobes, anaerobes, E. coli, enterococci, lactobacilli, clostridia, yeast, and proteus. Fluctuations were encountered whether animals were fed basal diets or diets supplemented with chlortetracycline. At the termination of each experiment contents of the various segments of the intestinal tract were collected. Material from each segment was examined for microflora, chlortetracycline, and respiration activity. The suppression of clostridia and reduction of oxygen uptake activity in the ileum chlortetracycline-supplemented swine was the only marked change which was encountered. This occurrence in the upper portion of the intestinal tract was not detectable by examination of fecal material.