Altering Milk Composition by Feeding

Abstract

Nutrition offers a means of making rapid changes in milk composition, but the relationship between feed constituents and milk composition is complex. The greatest changes can be brought about in the concentration of milk fat. Particularly important dietary factors are the amount of roughage, forage:concentrate ratio, the carbohydrate composition of the con-centrates, lipids, intake, and meal frequency. Far smaller changes are possible in milk protein concentration. The best documented effects are for intake and lipid supplements. Dietary protein has only small effects on either milk fat or protein concentration. Very small changes in lactose concentration occur sometimes in response to diet but they are inconsistent and not of practical value. Exploitation of these possibilities requires repeatable responses and accurate prediction of overall animal performance. Empirical prediction equations have been developed for some factors but the complexity of the interrelationships of the several different responses to a single dietary change suggest that mechanistic models covering complete nutrient utilization by the dairy cow may be necessary. Whatever the technical developments, economic factors will be the final determinant of the uptake of such techniques by the dairy farmer.