Grazing effects on the quality and quantity of forage in Inner Mongolian grassland

摘要

The efficiency of utilization of nutrients by ruminants for productive purposes is determined by various factors. In this study, the effect of years and grazing intensity on aboveground net primary production (ANPP) and on nutritional forage characteristics (i.e. the concentration and yield of crude protein (CP), cellulase digestible organic matter (CDOM), metabolizable energy (ME) and neutral detergent fibre (NDF)) were tested in the typical steppe of Inner Mongolia within a controlled grazing experiment during six consecutive years (2005-2010). Grazing effects were tested along a gradient of seven grazing intensities (ungrazed to very heavily grazed). Our results show that years and grazing intensity significantly affect the concentration and yield of forage nutritional parameters. Forage nutritional yields showed higher values in years with higher rainfall. Forage CP, CDOM and ME concentrations increased but ANPP and nutritional yields decreased with increasing grazing intensity. Furthermore, forage nutritional yields were positively correlated with the dominance of major species, but negatively or less correlated with species diversity.