Influence of Sodium Nitrate, Vitamin A and Protein Level on Feedlot Performance and Vitamin A Status of Fattening Cattle

Abstract

Yearling steers were fed a high-grain ration composed of 80% ground shelled corn and 20% alfalfa hay for 153 or 160 days. Feedlot performance was not improved by increasing the protein content of the basal ration from 10.6 to 11.8%; or by supplementing the rations with about 12,000 I.U. of vitamin A palmitate per head daily. Plasma vitamin A declined from initial values of about 30 mcg. per 100 ml. to 16–18 mcg. per 100 ml. in cattle not supplemented with vitamin A, but to a lesser extent when about 12,000 I.U. of vitamin A were fed daily. Liver reserves of vitamin A were low, being about 1 mcg. per gm. in unsupplemented steers and about 2 mcg. per gm. in steers receiving the additional vitamin A. Initial reserves were not determined, but some indication of gradual depletion is given by the decrease in plasma vitamin A. Dietary carotene (av. of about 42 mg. daily) and body reserves of vitamin A appeared to be meeting the vitamin A needs for growth and prevention of deficiency symptoms under the conditions of this experiment. Adding 1% sodium nitrate to the ration reduced performance, but vitamin A and carotene in the plasma or liver were apparently not affected. Feeding additional vitamin A did not reduce this effect. Clinical symptoms of nitrate toxicity were not evident in any of the steers. Copyright © 1963. American Society of Animal Science . Copyright 1963 by American Society of Animal Science