Regulating the composition of milk : influence of nutritional factors on the quantity and the fat and protein content of milk

Abstract

The chemical composition of milk depends on factors related to the animal and to its environment. Among the latter factors diet plays an important role. In the short term it can have different effects on fat and protein content. The protein content varies in relation to energy intake (+ 0.6 g/kg per UFL around energy requirements). It may also be improved by the addition of specific amino-acids (lysine and methionine). It is nearly always reduced by the addition of lipids (even when protected) in the diet. The fat content depends on the percentage of concentrate in the diet (and when this is high on the type of concentrate used) and also on the presentation and distribution of feed (particle size, number of distributions, mix of feed). It can be significantly increased by the use of certain dietary constituents (maize silage, beets, lactoserum) or additives (buffers, monopropylene glycol). It is thus possible to modify in opposite ways the fat and the protein contents. In the future, synthetic tools for appreciate the quality of the rations (fibrosity index) should improve regulation in variations in fat and protein contents.