Influence of Dietary Chlortetracycline on Incidence of Urinary Calculi in Sheep. ∗

Summary

Two hundred seventy-six wether feeder lambs were divided into 7 lots for 98-day fattening period. The animals were selffed total mixed ground milo-molasses-alfalfa-cottonseed hull diets calculated to contain the same total digestive nutrients with urea or cottonseed meal as a source of supplementary nitrogen. Twenty-six deaths from urinary calculi occurred. There were significantly fewer death losses in groups of lambs fed diets containing 10 mg chlortetracycline/lb of feed than in lambs receiving control diets. Also, fewer deaths occurred among lambs fed diets containing urea than among those receiving cottonseed meal as a source of nitrogen. Observations of calculi in the kidney of 146 of the remaining lambs at slaughter revealed a lower incidence and less calculi in those lambs having received chlortetracycline in the diet. The possibility of a physiological effect of dietary chlortetracycline on the reduction of renal calculi formation and subsequent death from urinary calculi is suggested.