A review of the potential of nutrition to modify milk fat and protein

Abstract

Feeding allows relatively rapid changes to be made in the yield and composition of milk. The largest effects are on the concentration of fat, with only small changes possible in protein and effectively none in lactose. The progressive substitution of concentrates for forage in high-forage diets increases milk protein concentration while fat concentration remains unchanged, but with further substitution, protein concentration, remains constant while fat concentration may fall drastically depending on the type of concentrate, meal frequency and level of intake. Dietary acid detergent fibre concentration together with concentrate intake was found to account for 92% of the variation in fat concentration with such diets. Dietary protein has only small effects on milk composition. Lipid supplements generally reduce milk protein concentration, but can both increase and decrease fat concentration. The fatty acid composition of milk is important for health and processing qualities and can be altered by various dietary means. It is concluded that feeding provides the best means of responding to rapidly changing market demands for milk. However, options for manipulating protein concentration are limited, while the wide variation technically possible in fat concentration is restricted by practical considerations.