Relative Value of Vitamin A and Carotene for Supplying the Vitamin A Requirements of Swine during Gestation and Beginning Lactation

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Abstract
In two different trials a comparison was made of the relative values of vitamin A and carotene, when added to a low-carotenoid basal diet at levels of 6500 or 7100 I.U. daily, for supplying the vitamin A for gilts during gestation and early lactation. Results on these animals also were compared with those on gilts of a check lot that received a typical herd ration. Criteria for estimating the relative values of vitamin A and carotene were: concentration of vitamin A in blood serum and in colostrum of gilts, concentration of vitamin A in blood serum and in livers of new-born and of 4-day-old pigs, and condition of gilts and baby pigs. Vitamin A concentrations in blood serum of vitamin A supplemented gilts at parturition, in their colostrum and in serum and livers of their new-born and 4-day-old pigs, were essentially the same as vitamin A concentrations in similar materials from animals of the check lot, the values being significantly lower only for vitamin A in livers of 4-day-old pigs from dams of the vitamin A dietary group in one trial. Vitamin A concentrations in colostrum of gilts receiving crystalline carotene were only one-half to three-fourths of those in colostrum from dams of the other dietary groups. Concentrations of vitamin A in blood serum of carotene-supplemented dams at the time of parturition and in serum of their new-born and 4-day-old pigs were approximately one-half of those of animals of the vitamin A and the check lots. Concentrations of vitamin A in livers of new-born and 4-day-old pigs from carotene-supplemented dams were less than one-fourth of those in livers of similar pigs from dams of the other two lots. Although there was no positive evidence that the carotene-supplemented gilts or their pigs suffered from a vitamin A deficiency, the data clearly shows that unit for unit carotene is less effective than preformed vitamin A as a vitamin A supplement for swine during gestation and early lactation. Vitamin A concentrations in blood serum of the dams decreased as parturition approached and increased during the days immediately following parturition.