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Blood Levels of Ascorbic Acid and Vitamin A during Vitamin A Depletion and Effect of Administration of Ascorbic Acid during Terminal Vitamin A Depletion in the Dairy Cow¹

Animal Industries and Animal Diseases Departments, Storrs Agricultural Experiment Station,University of Connecticut, Storrs

L. A. Moore

Bureau of Dairy Industry, Agricultural Research Administration, U.S.D.A., Washington, D. C.

ABSTRACT

Eighteen calves, nine Guernseys and nine Holsteins, 105 days of age and previously raised on a limited-whole milk and dry-calf starter system, were fed a vitamin a depletion ration in amounts adjusted at 7 day intervals for liveweight.

During initial vitamin A depletion, from 105 days of age until each calf's blood plasma level of vitamin A decreased to less than 4.0 percent, there was no significant decrease either in whole blood or plasma ascorbic acid levels. In contrast, both plasma carotene and vitamin A decreased in a relatively uniform manner.

During terminal vitamin A depletion, after blood plasma levels of vitamin A of less than 4.0 were reached, there was a decrease in consumption of the feed allowed, accompanied by decreases in blood levels of ascorbic acid as well as initial appearance of clinical symptoms of vitamin A deficiency. In addition, spinal fluid pressures of greater than 200 mm. H₂0 were observed.

Subsequent administration of ascorbic acid subcutaneously for a 14-day period did not alleviate the anorexia, the clinical symptoms of terminal vitamin A de-pletion or the increased spinal fluid pressure. In contrast, administration of vitamin A orally resulted in complete consumption of the feed allowed, significant decreases in spinal fluid pressure and disappearance or alleviation of clinical symptoms. Upon slaughter, all calves given ascorbic acid had squamous metaplasia in the parotid gland ducts, whereas of those calves given Vitamin A, one showed squamous metaplasia, two had no lesions and three had transitional type epithelium.

¹ Supported in part with funds provided by the Research and Marketing Act of 1946 through a contract between the Storrs Agricultural Experiment Station and Bureau of Dairy Industry and also by the Chas. M. Cox Co., Boston, Mass, and the Big-Y-Foundation, Norwich, Conn.