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The utilization by the chick of vitamin A alcohol and vitamin A esters fed in various types of carriers English, Earl T.

Abstract

The relative utilization by the chick of vitamin A alcohol and vitamin A esters fed orally, by pipette, in aqueous carrier, in cottonseed oil-in-water emulsions varying in the oil content, and in cottonseed oil solution was investigated. The efficiency of utilization was based on liver vitamin A storage as determined by spectrophotometry analyses of isopropyl ether liver extracts. Day-old White Leghorn chicks of both sexes were, placed on a vitamin A-deficient diet until the liver vitamin A stores were depleted. The vitamin A preparations were fed to the depleted chicks at various potency levels over periods of 3 and 4 days. Twenty-four hours after administration of the final dose the chicks were killed; the livers were removed, macerated under carbon dioxide, digested with steam and extracted with peroxide free isopropyl ether. Two aliquots of the ether extract were removed, one being analyzed for the vitamin A content of the whole oil and the other being saponified and analyzed for the vitamin A content of the unsaponifiable fraction. It was demonstrated that the crystalline alcohol was utilized 1.5 times as efficiently as the natural ester concentrate when fed in cottonseed oil solution; in aqueous carrier, however, the natural ester concentrate resulted in 4 times the liver vitamin A storage determined for the crystalline alcohol. When the crystalline alcohol and the crystalline acetate were administered in the 50 percent cottonseed oil-in-water emulsion, more liver vitamin A storage was observed than from administration in either the cottonseed oil solution or the aqueous carrier. When the natural ester concentrate was fed in the various types of carrier, the 50 percent emulsion appeared to be responsible for 2.5 times and the aqueous carrier for 4 times as much liver vitamin A storage as was observed when the cottonseed oil was used as the carrier. The increased utilization of the crystalline vitamin A acetate when administered in the 50 percent cottonseed oil-in-water emulsion over that observed when the vitamin was fed in either cottonseed oil solution or aqueous carrier was attributed, in part at least, to the presence of an extensive preformed-oil-water interface which allowed enzymatic hydrolysis of the ester to proceed immediately. The maximum utilization of the natural vitamin A ester concentrate was assumed to occur for the same reason, since this form of the vitamin was obtained commercially as a mixed animal and vegetable oil solution. Investigation of the degree of utilization of the synthetic vitamin A palmitate and the crystalline vitamin A alcohol when fed in cottonseed oil-in-water emulsions did not reveal any regular increase or decrease in the efficiency of utilization when the oil content of the emulsion was varied in a stepwise manner. It was demonstrated, however, that the efficiency of utilization was increased in all cases when the ester form of the vitamin was administered in an oil-in-water emulsion over that observed when administered in oil solution or in aqueous carrier. The crystalline vitamin A alcohol was shown, to be consistent in showing a maximum, utilization when administered in a 50 percent oil-in-water emulsion but with variations in the oil content of the emulsion the utilization was observed to fall off in an irregular manner. It was shown that the differences in the utilization of the alcohol and ester forms of vitamin A by the chick, when administered orally in large doses, in an aqueous emulsion, were similar to those obtained when the various forms, were fed in the mash. When, however, large doses of the alcohol .and ester forms were fed orally in oil solution the relative utilization was observed to be reversed. Hence it was concluded that, when the forms of vitamin A were fed in an unnatural manner (by pipette), the use of an aqueous carrier resulted in a truer conception of the relative utilization which would be found under normal feeding conditions.

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