The Milk and Butterfat Production Responses to Shark Liver Oil in the Ration

Reports on the results of feeding shark liver oil to dairy cattle are conflicting.Deuel and co-workers (1, 4) reported that the daily feeding of 30 to 60 ec. of shark liver oil increased the milk and butterfat production of Guernsey cows approximately 10 per cent.This amount of shark liver oil furnished from 700,000 to 1,400,000 I.U. of Vitamin A.Rupel, Boyer and Phillips (8) found that the daily feeding of 25 co. of shark liver oil with a Vitamin A potency of 7,500 I.U.and 15,000 I.U.per gram had no effect on the milk production and fat percentage of Holstein and Guernsey cows.These authors reported that the daily feeding of 90 ce. of a 15,000 I.U.shark liver oil caused a noticeable drop in the amount of 4 per cent fat-corrected milk.More recently Jensen et al. (5) reported that daily feeding of shark liver oil to furnish from 117,500 to 1,350,000 I.U. of Vitamin A resulted in no increase in milk or butterfat production of Jersey, Guernsey, Holstein, and Brown Swiss cows.It was found that the daily feeding of as much as 90 co. of shark liver oil tended to increase the normal rate of decline in milk production with the advance of lactation.In view of these conflicting reports the results presented in this paper are offered as additional information.EXPERIMENTAL Twelve cows, 6 Jerseys and 6 Holsteins, were used in the experiment.These cows were divided into 4 groups ; group I, Holstein supplement, group II Jersey supplement, group III, Holstein control and group IV, Jersey ,control.The groups were so divided that the production of each was approximately that of its control group.All groups were fed the same basal ration, consisting of alfalfa hay, grain mixture and sunflower silage, which was replaced by sweet clover silage after 8 weeks.The grain mixture consisted of barley, oats, wheat bran, linseed oil meal, cottonseed meal, dried molasses beet pulp, iodized salt, and steamed bone meal.All groups were fed the basal ration during a preliminary period of 4 weeks.Beginning with the fifth week the rations of groups I and II were