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Influence of Nitrate upon Carotene Destruction during in Vitro Fermentation with Rumen Liquor¹

Departments of Agronomy and Animal Husbandry, Cornell University, Ithaca, New York

ABSTRACT

Reports of vitamin A deficiency in fattening beef cattle have become numerous in recent years (2, 5, 6). These deficiencies have primarily involved animals on a full feed of corn silage or a full feed of corn and limited quantities of silage, although these rations should supply the presently recognized carotene requirement (1). Reports of vitamin A deficiency in dairy cattle exist, but these reports have seldom been verified by scientific investigations. Deficiencies of vitamin A have been attributed, in part, to the presence of sublethal i levels of nitrate (0.5–1.5% nitrate) in the roughage consumed.The nitrate supposedly destroys carotene or vitamin A, interferes with the conversion of carotene to vitamin A, or interferes with the absorption of carotene and/or vitamin A following consumption.

Carotene destruction during in vitro fermentation with rumen liquor from control and nitrate-fed dairy heifers was studied in this laboratory. The ten donor heifers had been individually fed a diet of alfalfa-timothy hay and 4 lb concentrate (no vitamin A added) per day for ten months, were about 24 months old, and were five to eight months pregnant.

¹ Supported in part by Grant No. GM-07642 of the U. S. Public Health Service, National Institutes of Health.