There are a number of approaches available to the dairy industry to alter milk composition: genetic selection, identification and manipulation of specific genes controlling milk components, altering the nutrient content and composition of the diet or implementing alternative management procedures. Genetic selection for factors, such as the B variant of _-casein can have a greater long term impact in raising milk protein content than can nutritional manipulation; however, changes brought about by nutritional means generally occur rapidly and may therefore be a more appropriate means of responding to today's rapidly changing market demand of more emphasis on milk protein and less on milkfat. Unfortunately the amount of change possible in protein issmall compared to the change that could be effected in milkfat percentage. Excellent reviews on factors affecting milk composition have been published. This paper will focus on the primary nutritional and management factors affecting milk protein, namely: (1) Energy intake; (2) Feeding of fats; (3) Quantity and quality of protein; (4) Forage quality and type; (5) Feed additives and BST; (6) Management with emphasis on environment, feeding management, milking frequency and pest control; (7) Environmentaland seasonal effects.
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