The vitamin A requirements of dairy cows for the production of butterfat of high vitamin A value. I. Artificially dried alfalfa hay (carotene)

Summary 1.Two feeding experiments have been completed to determine the minimum vitamin A requirements of dairy cows for the production of butter with maximum vitamin A value. 2.Artificially dried alfalfa hay was used as the source of vitamin A (carotene). 3.Under the conditions of these experiments, it was found that dairy cows required approximately 550,000 vitamin A units daily to restore the vitamin A potency of the milk fat to its highest value.