Influence of Antibiotics on the Growth and Protein Metabolism of Young Dairy Calves

Twenty-one two-day-old ealves were used to evaluate the effect of aureomyein and baeitraein on growth and protein metabolism. Calves fed rations containing either antibiotic tended to gain at a faster rate, consumed more calf ~tarter and total feed, and made better utilization of their feed (feed per pound of gain) than did the control calves. None of these differences was statistically significant. Neither antibiotic appeared to reduce the incidence of scours. Both antibiotics significantly lowered the coefficients of dry matter and etude fiber digestibility, but neither antibiotic appeared to have any great effect on the digestibility of other nutrients or on nitrogen retention. Aureomycin significantly increased blood sermn levels of total protein, while baeitracin significantly decreased them; but neither had an appreciable effect on blood levels of urea or nonprotein nitrogen. Both antibiotics significantly increased the relative serum concentration of albmnin and lowered the concentration of alpha-globulin, but had little effect on betaglobulin concentration. Calves fed both antibiotics tended to have lower levels of serum gamma-globulin than did the control calves.