The iron milk most probable number method for enumeration of Clostridium perfringens in the diet and the intestine of the chick.

Seven experiments were conducted to evaluate the iron milk most probable number method for enumeration of Clostridium perfringens in the diet and the intestine of broiler chicks. Levels of 50 ppm of neomycin and 20 ppm of polymixin improved the iron milk tube method when compared to the TSN (tryptone-sulfite-neomycin) agar plate method. Low numbers of the organism, approximately 5 per gram, were detected in the practical diet fed to the chicks. Vegetative cell numbers of C. perfringens increased from 1.7 log10 in the duodenum of chicks to greater than 9.2 log10 in the ceca. Spores of the organism were detected in the ileum and ceca. Results of two experiments demonstrated that C. perfringens became established in the ileum of chicks early in life, before initiation of feeding at 2 days of age.

Effects of diet and antimicrobials on growth, feed efficiency, intestinal Clostridium perfringens, and ileal weight of broiler chicks.

Five experiments were conducted to evaluate the effects of diet and antimicrobials on weight gain, feed efficiency, ileal weight, and Clostridium perfringens in the ileum of broiler chicks. In the first experiment, glucose, sucrose, and fructose were added to a semipurified diet and the results were compared with those from a practical corn and soybean meal diet. All of the diets were fed with and without bacitracin at a level of 55 ppm. Fructose resulted in the greatest depression in weight gain, followed by sucrose. Bacitracin significantly improved weight gain and feed efficiency of chicks fed the fructose, sucrose, and practical diets. Highly significant inverse correlations were obtained between ileal weight and weight gain and the number of C. perfringens in the ileum and weight gain. In other experiments bacitracin, penicillin, chlortetracycline, oxytetracycline, erythromycin, tylosin, virginiamycin, lincomycin, bambermycins, and carbadox, all at a level of 55 ppm, improved weight gain and feed efficiency and significantly reduced the weight of the ileum and the number of C. perfringens in the ileum of chicks fed the practical diet. The antibacterial agents 3-nitro-4-hydroxy-phenylarsonic acid, arsanilic acid, furazolidone, and sulfathiazole had little to no effect on the 4 parameters evaluated. Virginiamycin and lincomycin at 16.5 and 4.4 ppm, respectively, were shown to be effective. In vitro activities of the antimicrobials against C. perfringens did not directly relate to in vivo activities and the effects on growth and feed efficiency. The results of these experiments support the concept of antimicrobials as growth permittants and provide further evidence for C. perfringens as a causative bacteria for growth depression.

Effects of diet, bacitracin, and body weight restrictions on the intestine of broiler chicks.

Six experiments were conducted to evaluate the effects of diet, bacitracin, and body weight restrictions on the intestine of the broiler chick. Bacitracin, at levels of 11 and 55 ppm, significantly increased body weight, significantly reduced small intestine weight, but had no significant effect on liver weight of chicks fed a soybean protein and sucrose-based diet. The greatest effects were observed in the ileum where weight, moisture, length per unit of body weight, and dry matter per unit of length were all significantly reduced. The least effects were observed in the duodenum where weight and length per unit of body weight were significantly reduced and dry matter per unit of length was significantly increased. Intestinal weight, as a percent of body weight, was not significantly affected when body weight was suppressed with a high level of nicarbazin added to a practical diet, but it was significantly reduced when bacitracin was added to the semipurified diet and chicks were restricted in food intake to 70% of controls. A level of 55 ppm of bacitracin added to the practical diet had no significant effect on body weight, intestinal weight, or liver weight. As discussed, the observed changes in the intestine, due to bacitracin, are probably indirect and most likely reflect the action of the antibiotic on the intestinal microflora.

In vitro and in vivo evaluations of the antibiotic efrotomycin.

Experiments were conducted to determine the potential of the antibiotic efrotomycin as a growth permittant for poultry and to further elucidate the mode of action of antimicrobial agents for that purpose. Efrotomycin as the semipurified antibiotic and as fermentation solids demonstrated excellent activity against Clostridium perfringens at .1 to .2 ppm based on suppression of gas production in an anaerobic tube test. Supplementing a soybean protein and sucrose-based diet with levels of 2.2, 11, and 55 ppm of the antibiotic, from the two sources each with two different purities, improved weight gain of chicks an average of 23% and improved feed efficiency an average of 13% at the higher levels (all P less than .01). Computed indexes for each antibiotic treatment, which represent the combined effects of both weight gain and feed efficiency, showed that a maximum response was generally obtained at the 11 ppm level and that the antibiotic as fermentation solids was slightly more active than the semipurified material. Supplementing the soybean protein and sucrose-based diet with levels of 1.1, 5.5, 16.5, and 55 ppm of efrotomycin reduced the numbers of C. perfringens organisms in ileal contents of chicks (all P less than .01). The effects were dose-related. Control chicks in this experiment averaged greater than 7.7 log10 of C. perfringens counts per gram of contents. The results of these experiments show that efrotomycin has excellent growth-permittant activity and the activity correlates with the antibacterial activity against C. perfringens.

Effects of diet and bacitracin on growth, feed efficiency, and populations of Clostridium perfringens in the intestine of broiler chicks.

Experiments were conducted to demonstrate the activity of bacitracin as a growth permittant for poultry and to further elucidate the mode of action of antimicrobial agents for that purpose. Supplementing a soybean protein and sucrose-based diet with 2.2, 11, and 55 ppm of bacitracin resulted in significant improvements in weight gain and feed efficiency of chicks fed the higher levels. In a second experiment, graded levels of bacitracin from 1.1 to 55 ppm were fed. A regression analysis of the index scores, the combined effects of both weight gain and feed efficiency, on the log of the significant dose levels of 5.5 to 27.5 ppm gave a linear response line with r = .996. Based on the equation, the ineffective level of the antibiotic was determined to be 4 ppm and the maximum effective level 31 ppm. Supplementing the soybean protein and sucrose-based diet with levels of 5.5, 16.5, and 55 ppm of bacitracin reduced the numbers of Clostridium perfringens organisms in ileal contents of chicks (all P less than .05). Chicks fed a level of 1.1 ppm, a level that did not give a growth response, had numbers of the organism present that were not significantly different from controls. Supplementing a soybean meal and corn-based diet with a level of 55 ppm of bacitracin did not significantly affect weight gain, feed efficiency, or numbers of C. perfringens in the ileum of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the antibiotic thiopeptin on Clostridium perfringens and growth and feed efficiency of broiler chicks.

Experiments were conducted to determine the potential of the antibiotic thiopeptin as a growth permittant for poultry. Thiopeptin as the semipurified antibiotic and as fermentation solids demonstrated activity against Clostridium perfringens at .03 ppm based on suppression of gas production in an anaerobic tube test. Supplementing a soybean protein and sucrose-based diet with levels of 2.2, 11, and 55 ppm of thiopeptin from each of the two sources resulted in significant improvements in weight gain and feed efficiency of chicks fed the higher levels. Computed indexes for each antibiotic treatment showed that the antibiotic as fermentation solids was slightly more active than the semipurified material at the lower levels. Supplementing the soybean protein and sucrose-based diet with 1.1, 5.5, 16.5, and 55 ppm thiopeptin reduced significantly (P less than .01) the numbers of C. perfringens organisms in ileal contents of chicks. Chicks fed 5.5, 16.5, and 55 ppm thiopeptin also had significantly fewer C. perfringens organisms in the intestine than those fed 1.1 ppm. A discussion is presented of the biological responses of thiopeptin relative to the antibiotics efrotomycin and bacitracin.