The Vitamin A Requirements of Dairy Cows for Production of Butterfat of High Vitamin A Value. II. Vitamin A Per se

Summary 1.Feeding experiments have been completed to determine the minimum vitamin A requirements of dairy cows for the production of butter of maximum vitamin A value. 2.When the source of vitamin A in the ration was vitamin A per se (fish liver oil), this requirement was satisfied with a daily intake of 200,000 units. 3.In this series of experiments, vitamin A per se was found to be approximately three times as effective as carotene in dehydrated alfalfa hay.