Vitamin A and Carotene Requirements for the Maintenance of Adequate Blood Plasma Vitamin A in the Dairy Calf

Summary Studies have been made to determine the blood plasma concentrations and the intakes of carotene and vitamin A necessary for the growing calf. The data obtained showed that the blood plasma vitamin A was a more delicate measure of the state of vitamin A nutrition in the calf than either growth or blood carotene. A blood plasma vitamin A level of 10γ or more per 100 cc. was found to be necessary for adequate vitamin A nutrition of the growing calf. Blood plasma vitamin A levels of 7–8γ per 100 cc. were borderline levels while values below this were definitely inadequate. Daily intakes of vitamin A which would maintain deficient, borderline, and adequate concentrations of blood plasma vitamin A were found to be approximately 6,12 and 18γ per kg. of body weight respectively. The daily carotene requirements necessary to maintain an adequate plasma vitamin A and prevent deficiency symptoms were 75γ per kg. for Holstein yearlings and 125γ per kg. for Guernsey yearlings. The blood plasma carotene levels which would maintain an adequate blood vitamin A were 50–70γ of carotene per 100 cc. for Holsteins and 110–140γ of carotene per 100 cc. for Guernseys.