Nutrient requirements of the high yielding cow

Abstract

Critical evidence on the nutrient requirements of the high yielding dairy cow (7000 + kg/lactation) is very limited. A consensus of this evidence plus the histories of well-documented individual animals indicates the high yields to have been achieved without recourse to abnormally high rates of feeding concentrates/kg milk produced. Such animals as these have above average food intakes with an extra 0.16 kg dry matter/additional kg milk produced. A high standard of management — including for instance frequent feeding per day — favours greater food intakes. Even so, their intakes do not match the need for nutrients. Hence high energy density rations (12.5 MJ metabolizable energy with 150–170 g crude protein/kg dry matter) are necessary and the large milk output is accompanied by mobilization of body reserves to bridge the gap between intake of, and need for, nutrients. This role of body reserves and the need to extend intakes as far as possible must be catered for in the nutrition and management, both current and long term of the cow, as must the risks of metabolic disorders attendant on such high outputs.