Conversion of Carotene from Alfalfa to Vitamin A by Guernsey and Holstein Calves

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Abstract
Twelve Guernsey and 12 Holstein male calves whose average age was 83 + 10 days and who were partially depleted of their vitamin A stores to an average plasma vitamin A level of 7.8 [plus or minus]2.5 gamma/100 ml, were fed daily one of 4 levels, 30, 60, 120 or 240 gamma, of carotene from alfalfa per lb. of live weight for 12 consecutive 7-day age periods and then slaughtered. Guernseys had higher concentrations of carotenoids in plasma and liver than did Holsteins. Conversely, Holsteins had higher concentrations of vitamin A. The linear rates of change of either plasma or log liver vitamin A concentrations on log carotene intake for Guernseys and for Holsteins were essentially parallel but Holsteins maintained higher average levels than did Guernseys. Based on this, it was calculated that Holsteins converted carotene to vitamin A 1.4 times more efficiently than Guernseys, when employing plasma vitamin A as the criterion, with 95% confidence limits between 0.8 and 2.5. A similar value when utilizing log liver vitamin A as the criterion was 1.8 with limits between 1.2 and 2.8 and for log liver vitamin A per 100 lb. of live weight 1.7 with limits between 0.8 and 4.5.