Nutritive value of grassland plants: Energy and protein values

Energy (NEL) and protein values (APIE and APIN) of 10 important grassland species were evaluated based on digestibility of organic matter which was determined by the method of Tilley and Terry. Foxtail had the lowest (5,5 ± 1,0 MJ NEL/kg DM) and white clover the highest energy value (6,4 ± 0,5 MJ). During the first growth of the grass species energy content varied mainly with age, whereas during the regrowths and in legumes the effect was smaller. The highest decrease in NEL-concentration was observed in the first growth in foxtail (-0,54 MJ/kg DM and week) and the lowest in white clover (-0,19 MJ). The influence of age on APIE and APIN was similar to that obtained in energy. The APIN content decreased at a higher rate compared with the APIE content and thereby limited the milk production potential of grass species at an early stage of growth. By contrast legumes and specially white clover have an excess of APIN until a late stage of development. These facts clearly demonstrate the benefits of balanced grass and legumes mixtures.