Changes in feed quality of different forage legumes during autumn growth

摘要

In autumn growth forage legumes dominate, resulting in high contents of crude protein (CP) in the sward. The aim of the present study was to determine the variation in feed quality of white clover, red clover, kura clover, alfalfa and birdsfoot trefoil harvested on three different dates (approximately 22, 46 and 60 days of regrowth after 5 August) in three years. Swards were established each year as binary swards with perennial ryegrass. CP, CP-fractionation, neutral detergent fibre (NDF), acid detergent fibre (ADF) and energy contents were measured and energy content estimated. Results show a significant species x year x sampling date interaction for the analysed forage quality parameters. Highest CP values were achieved by white clover, alfalfa and red clover with 30% in the early cut. The highest content of fraction A (non-protein N) was also found on this sampling date, decreasing in the later harvests. Red clover had the lowest contents of fraction A and, together with birdsfoot trefoil, the highest contents of fraction C (in ADF-residue-bound N = acid detergent insoluble N). Considering N use efficiency in ruminant nutrition, red clover and birdsfoot trefoil seem to have positive effects, compared with other forage legumes, on effective N use.