THE ROLE OF FEED PROTEIN-QUALITY IN REDUCING ENVIRONMENTAL-POLLUTION BY LOWERING NITROGEN-EXCRETION .2. CHOICE OF AN ASSAY FOR MONITORING PROTEIN-QUALITY AND PREDICTING PROTEIN-UTILIZATION

The optimum protein nutrition of farm animals allowing minimum nitroge n excretion is a compromise between performance (weight gain) and effi ciency of protein utilization. The use of highly digestible feed ingre dients allowing maximum nitrogen retention requires assay techniques w hich are suitable for monitoring protein quality of the feed or predic ting nitrogen utilization of the animal. The various assay methods ref lecting the protein metabolism of the animal may give different inform ation according to the criteria, which they utilize. Therefore, a suit able assay should be selected with care, depending on the question to be answered. The various aspects of selecting assays for monitoring th e protein quality of feeds and predicting protein utilization by the a nimals are discussed.