Relative Value of Carotene from Alfalfa and Vitamin A from a Dry Carrier Fed at Minimum Levels to Holstein Calves

Vitamin A is a limiting dietary essential in calf nutrition (4,12,19).For the prevention of night blindness, a daily intake between 11 and 16~, of carotene per pound of body weight or between 2.3 and 2.9~ of vitamin A per pound of body weight has been reported to be adequate (16,17,18,25).Similar values for growth were between 11 and 33 or 10.0 and 25.0 (7,13,14,17,22,24,29), for maintenance of blood plasma vitamin A levels of 10.0~ per cent between 34 and 57 or 8.2 (5), and for adequate liver reserves between 71 and 102 or between 5.4 and 29.0 (13, 14, 17, 2~).With the exception of the requirements based on blood plasma levels (.5), the experiments on responses to carotene feeding were not run concurrently with those on responses to vitamin A feeding and consequently cannot be compared directly.Although the carotene requirements for the prevention of papillary edema and the maintenance of normal spinal fluid pressure have been studied and these criteria found more sensitive to changes in the vitamin A status of the calf than night blindness or growth (25,27,28), data with respect to the effect on these of intake of vitamin A per se were not reported.The present study was undertaken to determine quantitatively the relative value of carotene from alfalfa and vitamin A from a dry carrier fed at minimum levels employing as criteria blood and liver values of vitamin A, spinal fluid pressure, occurrence of papillary edema, and tissue alterations in the Holstein calf.