ABSTRACT
This chapter highlights the principles of nutritional requirements of animals for maintenance and production. Diets for productive animals must meet the requirements for energy and specific nutrients for: the formation of milk, eggs, and wool; the growth of tissues, such as skeletal muscle; and work. Nutritional requirements of animals for production are often determined from factorial analysis of their products, and must be considered along with their nutritional requirements for maintenance. The net efficiency of milk production is the ratio of energy in milk to the energy in feed excluding maintenance requirements. The daily requirements of gestating, lactating, growing, egg-producing, or working animals for energy or nutrients consist of maintenance and production requirements. In all cases, the physiology and metabolism of animals must be borne in mind when assessing their energy and nutrient requirements during their life cycle.
