[Experimental studies of the evaluation of the energy balance of dairy cows. 1. Milk production and milk composition].

Proper assessment of the risk to animal health in early lactation has proved to depend decisively on knowledge of intensity of mobilisation processes as well as of the onset and general pronunciation of subsequent regeneration of endogenic energy reserves. Mere calculation of the difference between estimated energy uptake via feed ration and energy output to sustain milk production would not provide a realistic picture of energy mobilisation and deposition in the organism of a dairy cow. Milk fat levels and quantities but also high milk protein levels and quantities were the milk substances which more clearly than others indicated mobilisation of endogenic fat and protein reserves during the first three weeks of lactation. No information could be derived from milk yield and milk substances as to the onset or level of positive energy balance, following redepositing of energy.