Factors influencing the vitamin content of milk fat. 5. Changes in vitamin A and carotenoid content of the blood plasma of cows and heifers near parturition in relation to secretion of these substances in the milk fat
Thompson, S.Y.; Micgillivray, W.A.
J. Dairy Res 24: 108-114
For part 1 see Abst. 331, Vol. 22. 5. A group of 4 Jersey cows and another of 6 heifers were selected as due to calve about the same time. Before and after calving all grazed on similar pasture, mainly ryegrass, which provided a carotene intake of from 4 to 7 g. daily. Samples of blood were taken every second day for 3 weeks before the expected calving date and 3 weeks after, and vitamin A ester, alcohol and carotene were estimated.