THE DUTCH PROTEIN EVALUATION SYSTEM - THE DVE/OEB-SYSTEM

In 1991 a new protein evaluation system replaced the Digestible Crude Protein (DCP) system in the Netherlands: the DVE/OEB-system. The system was mainly developed with the aim to prevent avoidable losses of nitrogen, by feeding according to more exactly defined requirements of dairy cows. A second aim was to predict milk protein production more accurately. Protein requirements for maintenance, milk protein production, growth, mobilisation, metabolic losses in the digestive tract and gestation are expressed in DVE, the sum of digestible feed and microbial true protein available in the small intestine. In the system each feed has a DVE-value composed of the digestible true protein contributed by feed protein escaping rumen degradation (1), microbial protein synthesized in the rumen (2) and a correction for endogenous protein losses in the digestive tract (3). Each feed also has a degraded protein balance (OEB) reflecting the difference between the potential microbial protein synthesis based on degraded feed crude protein and that based on energy available for microbial fermentation in the rumen. The framework of the new system is based on what are considered strong elements of other recently developed protein evaluation systems. Additionally new elements are introduced, including undegraded starch (USTA), fermentation products (FP) in ensiled feeds, the role of energy balance in protein supply and the way in which requirements change in the course of lactation. Data within the framework of the system are mainly of Dutch origin. This is particularly true for the regression equations developed to predict the protein values of forages and protein values of a number of by-product ingredients.