Abstract
Three digestibility trials involving 58 sheep were conducted to study the effect of chlortetracycline upon the digestibility of ration components. It was found that a level of 11.8 mg. of chlortetracycline per 100 lb. body weight or 11 mcg. per gm. of feed had no effect upon ration digestibility. When the level was increased to 15.4 mg. per 100 lb. of body weight or 16.7 mcg. per gm. of feed there was a significant reduction in the digestibility of dry matter, crude protein, crude fiber, nitrogen-free extract and energy. The addition of either level of antibiotic had no effect upon nitrogen retention. Rectal temperatures were significantly depressed. The volume of urine excreted by sheep in these trials was increased slightly and consistently. Copyright © . .