Antibiotics in Beef Cattle Production

Abstract

It was first reported in 1954 that the feeding of chlortetracycline at a low level (70 to 100 mg per head daily) to growing and finishing beef cattle resulted in an improvement in rate and efficiency of gain. Subsequent experiments have confirmed these beliefs. Effective antibiotics cause an average increase in daily gain of from five to seven percent, with slightly greater increases with higher roughage diets. In addition, the growth stimulatory effect is accompanied by an average improvement in efficiency of feed conversion of four to five percent. Antibiotics which have been shown most often to exert these desirable effects in beef cattle are chlortetracycline, oxytetracycline, and tylosin. Higher levels of either chlortetracycline (350 mg per head, daily for 14 to 28 days) or of oxytetracycline (1 or 2 gm per head, daily for approximately seven to ten days) have been shown to aid newly shipped cattle in overcoming the rigors of the shipping fever syndrome, typically observed in new arrival cattle. Continuous low-level (70 to 100 mg per head per day) feeding of effective antibiotics to feedlot cattle has been shown to reduce the incidence of liver abscesses—and thus liver condemnations—by from 33 to 50% or more.