Comparison of methods to evaluate the energy supply in dairy herds

Different methods to evaluate the nutritional and metabolic status in dairy herds are available. The aim of this study was to evaluate three different methods to assess the energy status of the herd: 1) the calculation of the energy balance of the herd with a new method based on the Swiss standard calculations, 2) the "efficiency of the feeding management" based on milk yield and milk protein content (%) obtained from DHI data, and 3) the percentage of cows per herd with an average milk yield (16-25 kg/day), but a low milk protein (< 3.2 %). The study included data from 47 farms enrolled in the herd reproduction survey program of the University of Berne, with a total of 653 cows included in one winter period. A correlation could only be seen between methods two and three. It is concluded that it is insufficient only to calculate the ration as an estimation of the energy status of the herd. A rough calculation of the ration is necessary to have an idea on the energy density. But the calculated ration seems to be considerably different from the amount of energy and nutrients of the diet finally absorbed by the cow. As the ingested ration is relevant for milk production and animal health, the relationship between milk yield and milk protein content as well as the percentage of cows with milk protein < 3.2% are considered to provide good information about the efficiency of the feeding management in dairy herds.