The Fat Percentage of Milk as Affected by Feeding Milk to Dairy Cows

Abstract

Summary 1.The fat content of the milk of dairy cows was markedly increased when the fat content of the ration was increased during six day periods by feeding butterfat, lard, tallow, linseed oil, cottonseed oil, corn oil, peanut oil, soy-bean oil, or cocoanut oil. 2.The degree to which the fat percentage of the milk was influenced was, to a large extent, proportional to the amount of fat which was fed. 3.The increase in the fat content of the milk was secured regardless of the breed of the cows, stage of lactation, level of production, or season of the year. 4.The increase in fat percentage was due primarily to increased butterfat production, since the milk yield was influenced only to a slight extent, except in the case of cocoanut oil which appeared to cause a depression of milk yield when fed in large amounts. 5.The increased amount of butterfat in the milk was equivalent to but 10 to 20 per cent of the increase in fat intake, the remainder presumably being utilized by the body for other purposes. 6.A period of 12 to 24 hours after the fat was fed elapsed before its influence became observable in the milk. This influence was maintained for 30 to 42 hours after the last fat was fed. This lag apparently corresponds to the time required for the necessary digestive, circulatory, and secretory processes to take place. 7.The influence of the fat was exerted whether it was added to an already adequate ration or whether it replaced an equivalent amount of energy in the form of carbohydrates. 8.It was not found necessary to feed the fat in an emulsified form as it was very effective when fed after melting and mixing with the grain. 9.These investigations give no satisfactory evidence upon the effect of continued fat feeding because of the short experimental periods used.