Effects of Isoniazid, Chlortetracycline, and Copper upon Growth and Gastrointestinal Urease Activity of Chicks

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Abstract
Results are presented from 4 experiments using 72 lots of 15 chicks and 4 lots of 10 chicks fed a sucrose-casein basal diet supplemented with chlortetracycline (100 ppm), isoniazid (50 or 100 ppm), and copper (3.5 ppm) alone and in all combinations over a 4-week experimental period. Chlortetracycline alone or in combination with isoniazid and copper resulted in increased weight gains, improved efficiency of feed utilization, and lowered gastrointestinal ammonia concentration and ureolytic activity. Incorporation of isoniazid, an anti-tuberculosis agent, resulted in greater weight gains, but the efficiency of feed utilization was not increased. Feeding of isoniazid resulted in lowered gastrointestinal ammonia and ureolytic activity. Copper showed similar but less marked effects. Additive or nearly additive increases in growth were observed when either copper or isoniazid was fed in combination with chlortetracycline, but when copper and isoniazid were combined the growth differences were less than additive. In general, increase in weight gain due to additives appeared dependent on overall growth rate. The data demonstrate that, under the experimental conditions used, isoniazid, chlortetracycline, and copper when added to a sucrose-casein basal diet resulted in increased growth of chicks concurrently with lowered gastrointestinal ammonia concentration and ureolytic activity.