A Study of Breed and Seasonal Variations in the Ascorbic Acid Content of Certified Milk from Guernseys and Holsteins

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Abstract
Six hundred and sixty-one samples of certified milk collected at bi-monthly intervals from fifty-five Guernsey and Holstein cows over a 52-week period were assayed for their ascorbic acid content by the dichlorophenolindophenol titration method. The ascorbic acid content of both Guernsey and Holstein milk showed seasonal variation. The February milk contained large amounts of ascorbic acid, 23.37 mg. for the Guernsey and 20.23 mg. per liter for the Holstein milk. A second peak occurred in early November when the ascorbic acid content of the Guernsey milk was 21.96 mg. and late October when the ascorbic acid content of the Holstein milk was 20.44 mg. The average ascorbic acid content of the Guernsey milk varied from 17.76 mg. to 23.37 mg. and for the Holstein milk from 15.72 mg. to 20.44 mg. per liter. The ascorbic acid content was consistently higher for the Guernsey than for the Holstein milk. The total yearly average for the Guernsey milk was 20.54 mg. of ascorbic acid whereas that of the Holstein milk was 18.17 mg. per liter. The data obtained in this investigation indicate that the variation in the ascorbic acid content of raw certified milk produced under commercial conditions is independent of ration and period of lactation. However, it is evident from the above results that the generous consumption of raw certified milk can contribute materially to the vitamin C content of the human dietary.