PREDICTION OF MILK FATTY-ACID PROFILE IN DAIRY-COWS FED DIETARY-FAT DIFFERING IN FATTY-ACID COMPOSITION

The objective of this work was to predict changes in milk fat composition caused by differences in dietary fat. Twenty-two references describing 35 experiments and 108 treatments were used in the analysis. For lauric, myristic, and palmitic acids in milk, proportions in the dietary fat and the total dietary fat concentration were important predictors for their concentrations in milk as well as for stearic and oleic acids in milk. Using model that included these four parameters, the residual standard deviation around the observed versus predicted line within experiments was approximately 10% of the mean for short-chain fatty acids (<C-12); for lauric, myristic, palmitic, and oleic acid; and for total C-18 fatty acids in milk. The model also effectively predicted milk fatty acid profile with respect to lauric, myristic, palmitic, and oleic acid and total C-18 fatty acids across experiments despite differences in breed, basal diet, and milk yield among experiments. The content of short-chain acids, stearic acid, and polyunsaturated fatty acids were less effectively predicted across experiments. Possible explanations for the differing predictabilities for different milk fatty acids are discussed.