277. Vitamin A and C in cow's milk, with a note on the synthesis of vitamin C in bovines

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Abstract
1. A simple method is described for the determination of carotene and vitamin A in milk. Figures for the carotene content of milk were higher and those for vitamin A were lower than similar figures reported by Western workers. 2. Figures for vitamin C in milk are similar to corresponding figures of English and American workers. Previous low values for vitamin C, reported by Indian workers, are due to destruction of the vitamin by light. 3. The vitamin C concentration of milk is not subject to great individual variation, probably because cows cannot excrete in milk any vitamin C taken in with the food and because vitamin C of milk is produced by synthesis within the mammary glands from some simple blood constituents. 4. To test the ability of bovines to synthesize vitamin C, young calves were kept for long periods on a strictly vitamin C-free diet. The concentration of vitamin in the blood and other tissues of these animals remained, however, at a normal level. Calves appear therefore to be able to synthesize sufficient vitamin C for their normal growth and activity. 5. Unsuccessful attempts were made to produce vitamin C in vitro by growing bacteria isolated from various parts of the alimentary canal on media prepared from ingesta taken from the regions from which they were isolated.