Considerations in the nutritional modification of milk composition

The trend to determine milk value on the basis of its components, is becoming global, with increasing emphasis being placed on its protein content (Murphy and OʹMara, 1993). A milk market based on fat appears to be shrinking. Consequently there is a need to increase milk protein content using a combination of nutrition, management and genetics. Nutritional modification to accomplish this must consider impact on the environment, society and animal welfare, as well as economics. Opportunities for doing so may include the development of RPAA products, lipid supplements and improvements in forage digestibility and quality of stored forages. Ability to formulate diets that will change milk composition in a predicted direction requires research to improve the prediction of effects of diet on quantity and balance of absorbed amino acids, ruminal fermentation and DMI. Dynamic, predictive models will be useful in the development of practical diets to optimize yield of milk and its components.