Feeding and milk protein production

Abstract

This paper reviews the effects of feeding on milk protein production. It deals, first, with the chemical composition of the milk proteins and the extent to which the composition is influenced by diet, the synthesis of proteins in the mammary gland and the effects of variations in the supply of amino acids and of the energy-yielding nutrients that are absorbed from the gastrointestinal tract. There is then an examination of the impact of changes in dietary energy and protein supply on the content and yield of protein in milk and specific consideration of particular features of ration formulation, including supplementary energy concentrate foods, supplementary lipids and amount and type of supplementary protein foods. Finally, it is argued that the effects of diet on milk protein production are evaluated best simply in terms of milk protein yield; some of the pitfalls of interpreting information on milk protein content in practice are pointed out.It is concluded that the yield of milk protein is determined by the dietary supply of energy-yielding constituents and protein but that presently employed systems for ration formulation do not provide a satisfactory means of interrelating milk protein yield and the intake of nutrients in the cow's diet.