Effect of Initial Vitamin A Status on Subsequent Response of Holstein Calves to Carotene Intake from Artificially Dehydrated Alfalfa

Open Access
Publisher Website
Google Scholar
Abstract
Thirty-six male Holstein calves, 89[plus or minus]9 days of age and partially depleted of their vitamin A stores to an average of 8.9 [plus or minus] 4.0 gamma per 100 ml of plasma, were fed one of 3 initial carotene intakes, 100, 300 or 900 gamma per lb. live weight per day, for 6 weeks and, thereafter 1 of 4 final carotene intakes, 20, 60, 180 or 540 gamma, for 12 weeks. Both plasma carotenoids and vitamin A concentrations responded to current carotene intake, with more rapid changes observed when carotene intake was changed from a high to a low intake as compared with a low or a medium to a high. The initial vitamin A status as indicated by plasma concentrations at the termination of the initial carotene intake period influenced the response of plasma and liver vitamin A concentration observed for the final 12-week carotene intake period, in that greater carotene intakes were required to obtain a desired response in the case of the lower initial plasma vitamin A concentrations. Based on calculated tocopherol intakes, artificially dehydrated alfalfa resulted in increased plasma and liver concentrations of this vitamin.