Lactation performance and fatty acid composition of milk from Holstein cows fed 0 to 5% oleamide

Diets containing 0 to 5% oleamide were fed to Holstein cows to determine linear or nonlinear responses to the fat supplement on lactation performance and milk fatty acid composition. Six rations containing concentrate, corn silage, and 0, 1, 2, 3, 4, or 5% (dry matter basis) added oleamide were fed to six multiparous cows in a 6 x 6 Latin square for 2-wk periods. As the oleamide concentration in the ration increased from 0 to 5%, dry matter intake declined, fiber and dry matter digestibilities remained constant, and digestibilities of protein and fatty acids increased. Milk yield declined as dietary oleamide increased, although yield was not depressed numerically until oleamide exceeded 2% of the diet dry matter. The C18:1 concentration doubled in milk as oleamide in the diet increased from 0 to 5%. Ratios of C18:1 to C16:0 in milk fat were 0.56, 0.83, 1.34, 1.53, and 1.73 for the diets supplemented with 0, 1, 2, 3, 4, and 5% oleamide, respectively. No amide was detected in milk samples taken from cows fed the 5% oleamide diet. Results show that intake of diets containing 2 to 3% oleamide substantially increased the milk C18:1:C16:0 ratio without greatly affecting milk yield or causing detectable amounts of amide in milk.