ABSTRACT
High efficiency of nutrient and energy utilization is required to be in line with international commitments on greenhouse gas emissions. The focus in many regions in Europe is the N surplus, which originates from inefficient resource utilization, contributing largely to environmental pollution. In addition, large amounts protein rich concentrates are imported in EU countries, with land use changes in the producing regions worldwide like South America and South Asia. Therefore, increasing the production of home-grown proteins in Europe and quantifying their protein use efficiency is needed. In addition, alternative protein sources originating from home grown proteins in Europe should focus on factors determining the nutritive value of feedstuffs (concentrates, by-products and forages) for ruminants and its causes of variation. Focus on home grown proteins should also consider the contribution of forage production systems for the energy and protein supply of ruminants. The protein and carbohydrate fractionation is helpful for forage characterization and comparison of nutritive value.
