Increased Polyunsaturated Fatty Acid Yields In Milk of Cows Fed Protected Fat

Abstract

Three Jersey cows were fed; (1) Control diet (corn silage, alfalfa hay, grain concentrate); (2) Control plus 3.6 kg/ day full-fat soyflour; and (3) Control plus 3.6 kg/day formaldehyde-protected full-fat soyflour. Changes in rumen fatty acids, diet digestibility, and total yield of milk fatty acids were measured. Ether extract digestibility increased when the experimental diets were fed where as nitrogen digestibility was reduced by the protected supplement. Proportion of rumen acetate was lower when the unprotected soyflour diet was fed. Milk and fat yields were increased by the experimental diets. The weight percent as well as absolute yields of milk fatty acids from 6 to 16 carbons were reduced whereas butyrate and all 18 carbon fatty acids were increased by the experimental diets. Linoleic acid weight percent and absolute yield more than doubled in milk fat from animals receiving the protected supplement. Increased mammary gland uptake of 18 carbon fatty acid inhibited de novo synthesis of fatty acids by mammary tissue. © 1974, American Dairy Science Association. All rights reserved.