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UBC Theses and Dissertations

Antibiotics and the nutrient requirements of the chick Smith, David F.


A study has been made on the growth stimulatory-effect of antibiotics when fed to chicks as supplements to different rations. A total of 9 biological tests employing 1280 chicks were carried out. Chicks fed the Connecticut ration and modifications thereof showed a significant growth response to aureomycin supplementation of the rations. The efficiency of feed utilization was improved by the addition of aureomycin to the rations in this experiment. The effect of aureomyoin has been tested in rations in which the protein level has been adjusted to 16%, 17.9%, 19.5% and 22% respectively. The basal rations used consisted of ground corn and wheat as the cereal grain and soybean oil meal and fishmeal as the protein supplements along with additional vitamins and minerals to balance the ration. The results showed that aureomycin did not lower the dietary requirement of the chick for protein. A test was made on the effect of antibiotics on growth of chicks when fed in rations which were deficient in specific amino acids. A wheat ration deficient in lysine and a corn ration deficient in tryptophan have been used. The results showed that antibiotics did not lower the dietary requirement of the chick for either lysine or tryptophan. Antibiotics were fed in chick rations containing different amounts of available carbohydrates. It was found that antibiotics did not lower the dietary requirement of the chick for carbohydrate. A comparison of aureomycin and penicillin showed no difference in growth stimulating properties between the two antibiotics under the conditions of the different experiments. Aureomyoin supplement (aurofac) promoted the same growth response at 0.05 and 1.0% levels. The greatest growth response to antibiotics was obtained when the chicks were fed a diet adequate in available carbohydrates and protein and balanced in amino acids.

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