Effects of harvest delay on nutritive value in four grass and four legume species in binary mixtures

摘要

Information on companion species effects in grass-legume mixtures on quality changes during prolonged growth is lacking while this is relevant in view of delayed harvests that frequently occur in practice. Perennial ryegrass (Loliumperenne) was sown with either red clover {Trifolium pratense), white clover {Trifolium repens), lucerne {Medicago sativa) or birdsfoot trefoil {Lotus corniculatus), and white clover with hybrid ryegrass {Lolium x boucheanum), meadow fescue {Festuca pratensis) or timothy {Phleum pratense). Yield, concentrations of N, neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin (ADL), and in vitro organic matter digestibility (IVOMD) were studied during two years in a cutting trial in Denmark. The dynamic development of compounds was investigated. Herbage digestibility and N concentration decreased during prolonged growth while contents of fibre compounds increased. In May, concentrations of ADF and lignin increased faster in legumes than in grasses; in August, NDF and ADF concentrations increased most quickly in legumes. Generally, N concentrations as well as IVOMD declined at similar rates in grasses and legumes but within each group, differences in yield and development of nutritive value occurred among species. The relationship between weekly growth rate and change in quality parameters differed among species and between functional groups.