Milk Fat Globule in Ruminant: Major and Minor Compounds, Nutritional Regulation and Differences Among Species

Abstract

Recent knowledge is presented on the composition of ruminant milk fat fractions and the nutritional strategies known to alter their amount. The development of lipidomic and proteomic analyses has allowed for the characterization of minor components, such as proteins, liposoluble vitamins, and phospholipids of the milk fat globule (MFG), in addition to the triacylglycerols (TAG), which are the major constituents of the MFG core. Few differences in these components among ruminant species exist, and they have been outlined mainly on the fatty acids (FA) profile of the TAG, whereas comparative data are still lacking on vitamins and proteins. The effects of dietary treatments enriched in n‐3 polyunsaturated FA (PUFA) on the composition of the milk fat fraction are explored. In particular, pasture and plant oilseeds increase milk n‐3 PUFA and cis‐9,trans‐11 CLA and decrease saturated FA, whereas data with new feed resources, such as algae, are still rare. The peculiarities of the response of the milk fat to diets that induce a milk fat depression in cows but in lesser extent in small ruminants are described. The potential effects of polar lipids, proteins, and liposoluble vitamins of the MFG on human health are reviewed, highlighting the nutraceutical properties of milk.Practical Applications: This review provides an overview of the different components of the milk fat fraction in ruminant species and on nutritional strategies to alter their amounts to improve the nutritional quality of milk. Furthermore, this review presents recent data on species peculiarities of the milk fat fraction composition and of its response to nutritional factors, which offers a promising model to identify news levers of regulation of this fraction and foster the identification of new feeding strategies to better control milk fat composition and feed efficiency.This review synthesizes data on the composition of the milk fat fraction in ruminant species, reports advances in nutritional strategies to alter their amounts and species‐specific responses to nutrition, as well as the potential effects on human health of the major and minor components of this fraction.