Utilization of corn silage carotene by dairy calves.

p ERRY et al. (1957)and Neumann (1960) reported that steers fed an all-concentrate ration developed vitamin A deficiency even though carotene was present in the diet in excess of requirements (N.R.C., 1958). Jordan et al. (1963) found similar results when steers were fed principally on corn silage. Steers fed a "high" nitrate silage were depleted of their liver vitamin A reserves more rapidly than those fed a "low" nitrate silage; however, at the end of the trial all animals had rather low levels of vitamin A storage in the liver. This research was designed to study the efficiency of utilization of corn silage fl-carotene by young dairy bulls fed a high concentrate ration and to determine if this utilization was affected by added nitrate in the ration. A preIiminary report of this work was presented earlier (Miller et al., 1965).