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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #43161
Title: EFFECT OF DIETARY FAT SOURCE ON MILK FATTY ACID COMPOSITION

Author
item DHIMAN TILAK RAJ - UNIV OF WISCONSIN
item VAN ZANTEN K - CHRISTIAN AG COLL-HOLLAND
item Satter, Larry

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: High producing dairy cows increase their milk production when fat or oil is supplemented to their diet. Consequently, there has been a large increase in the amount of fat or oil fed to dairy cows in the United States within the last 5-10 years. Tallow, soybeans, cottonseed, and palm oil represent the major sources of supplemented fat or oil. These sources differ in the amount of saturated and unsaturated fatty acids and the types of fatty acids (short chain and long chain) present in the oil. It is known that the type of fatty acids consumed by the cow can influence the type of milk fat produced, and this can affect manufacturing properties of the milk fat and its potential impact on the consumer's blood cholesterol level. This study compared the effect of supplemented fat derived from soybeans, tallow and palm oil on milk fatty acid composition. Feeding all fat sources tended to increase the amount of milk unsaturated fatty acids. Feeding whole soybeans, relative to the control and other fat supplements, resulte in milk that was lower in palmitic acid, particularly desirable from a human health point of view. Of the three fat sources compared, oil from soybeans tended to have the most desirable effect on milk composition.

Technical Abstract: Four multiparous rumen cannulated cows and four primiparous cows without rumen cannulae were used in two 4 x 4 Latin squares to study the effect of dietary fat source on milk fatty acid composition. Cows were fed 55% alfalfa silage:45% concentrate diets (DM basis). The four diets were control and fat supplementation (3.2% fat on a DM basis) as either roasted soybeans, calcium salt of palm oil fatty acids (Trademarked as Megalac), o hydrogenated tallow (Trademarked as Alifet). Cows fed supplemental fat (.68 kg/d) as roasted soybeans, Megalac, or Alifet produced 33.8, 32.6, and 32.5 kg/d of 3.5% FCM, respectively, compared to 31.6 kg/d with no fat supplementation. Addition of fat decreased milk protein percentage. Milk fat percentage was increased with Megalac and decreased with Alifet feeding. Ruminal fluid VFA, blood plasma glucose concentrations, and in situ forage DM digestion were not affected by fat supplementation. Feeding gfat decreased the proportion of short and medium chain fatty acids (C6- C14:0) in milk and increased the proportion of long chain fatty acids (C16:0 and longer). Results show that fatty acid profile of milk fat can be changed by changing fatty acid composition of the diet. Roasted soybeans were most effective in reducing C16:0 and increasing C18:1, C18:2 and C18:3 acids in milk fat. Feeding Megalac did not decrease milk C16:0 content, and neither Megalac or Alifet had much effect on C18:2.