关键词: 牧草, 干物质, 粗蛋白, 中性洗涤纤维, 本性洗涤纤维, 降解能力

Abstract: Vegetation is the foundation for Tibetan plateau grassland farming,development of appropriate strategies for sustainable utilization of the grassland resources requires the information about forage quality.High quality forages are crucial for proper ruminant animal feeding since they provide energy,protein,and minerals.Therefore,accurate prediction of forage quality allows producers to manage grasslands to meet specific animal requirements.Some parameters of feedstuff nutritive value determination are based on chemical composition and digestibility,measured either in vitro or in vivo.The objective of the current study was to evaluate the chemical composition and the degradation characteristics of six wild forage species growing in Shannan areas of Tibet using the nylon bag technique with six cannulated wethers.The results show that significant differences were detected in degradability and degradation characteristics of DM,CP,NDF and ADF among the six wild forage species.The nutrient degradation in all the forage samples increased along with the incubation time increasing.During 3-48h,the degradation rate increased relatively fast and slow down after 48 h.At 72h,the degradation rate of Setaria viridis(L.) Beauv.reached to the maximum,the degradation rates of its DM,CP,and NDF exceeded 60%.The S.viridis and Pennisetum centrasiaticum Tzvel.with higher protein and lower fibre contents had higher values than others in rapid degradation fraction,slow degradation fraction,and the effective degradability of DM,CP,NDF and ADF;while Imperata cylindrical(L.) Beauv.and Stipa plareosa P.Smirn.had worse degradation characteristics than others.In view of the nutrient component and degradability,S.viridis and P.centrasiaticum have higher nutritive value,while I.cylindrica and St.plareosa have lower value among the six wild forage species.

Key words: Forage, Dry matter, Protein, Neutral detergent fibre, Acid detergent fibre, Degradability