Effects of concurrent metaphylaxis with chlortetracycline and tulathromycin on the health and performance of high-risk beef calves

Abstract

A total of 463 steers and bull calves (average body weight 447 lb or 203 kg) were used to determine the effect of feeding chlortetracycline (CTC) to calves metaphylactically treated with tulathromycin at arrival processing in a research feedlot. Experimental treatments consisted of three growing diets top-dressed with either no pellets (CON) or pellets containing CTC (4 g/lb or 8.89 g/kg) administered at a rate of 10 mg/lb (22 mg/kg) body weight (BW) for two five-day intervals with a one-day break in between (CTC) or pellets containing no CTC fed in the same amount per unit of BW (1.12 lb or 2.46 kg/hd) and for the same time period as the CTC treatment (PP). Calves were enrolled in the study for 41 days. No difference in performance, morbidity or mortality was found among the three treatments.