Injectable vs. Oral Vitamin A for Fattening Steer Calves

Abstract

Two trials were conducted with fattening calves to determine the comparative efficacy of oral (20,000 I.U. per day) and initially-injected vitamin A (1, 4 or 6 million I.U.). Both feeding trials covered a period of 210 days each. The rations contained a level of 1.5 mg. of carotene per kilogram. Both methods of administering vitamin A resulted in significant (P<.05) increases in daily gain and feed consumption. Efficiency of feed conversion was improved by all vitamin A treatments. Periodic serum vitamin A analyses indicated the catle initially administered 1 million I.U. of vitamin A by injection in the biceps jemoris approached borderline vitamin A deficiency after 210 days on trial. Both higher levels of initial injections (4 or 6 million I.U.) resulted in apparently normal levels of serum vitamin A through 200 to 210 days. Liver stores of vitamin A at time of slaughter showed very little storage in the control lots of both experiments and for those injected initially with 1 million I.U. All other treatments (20,000 I.U. orally per day, 4 million I.U. injected initially or 6 million I.U. injected initially) showed from 12 to 34 meg. of vitamin per gm. of fresh liver at time of slaughter. No trend of treatment effect on U. S. carcass grades was detected.