Effects of nutrition on the contents of fat, protein, somatic cells, aromatic compounds, and undesirable substances in sheep milk

Abstract

This review discusses current knowledge of the main nutritional factors that influence composition of sheep milk and, consequently, its processing into cheese, with special focus on milk fat and protein concentration and characteristics, content of bioactive compounds, somatic cell content, content of aromatic compounds able to improve its organoleptic characteristics and content of toxic substances. Sheep milk composition is strongly influenced by ewe nutrition, especially in highly productive animals. Milk fat concentration is markedly affected by the ewe's net energy (NE) balance, dietary NDF content and dietary supplementation with ruminally protected/inert or unprotected marine and vegetable oils. Milk fat composition can be modified to contain higher levels of human healthy fatty acids (FA), such as conjugated linoleic acid and omega-3 FA. Milk protein content, and its characteristics, are more difficult to change than milk fat, although dietary energy seems to have a major role, while diet protein and amino acid supplementation only marginally affect milk protein level and its characteristics. Nutritional stress, and some vitamins, affect the somatic cell content of milk and this impacts cheese yield and quality. Feeds in the diet can markedly influence milk aroma and, consequently, play a role in determining cheese flavor, especially when ewes are pastured. Possible sources and causes of contamination of sheep milk by heavy metals or dioxins, and mycotoxins, through the diet are also addressed. Overall, quality and safety of sheep milk can be modified and improved by the nutrition characteristics of the diet.