Nutritive value and composition of vegetation selected by steers grazing semi-natural pastures every other year compared with every year

摘要

The herbage selected by two groups of steers grazing different pastures was compared: one pasture was grazed every other year (Intermittent) and had thus been left ungrazed the previous season, while the other pasture was grazed every year (Continuous). Vegetation selected by steers in the two groups was sampled on eleven occasions between 11 May and 5 October. Each sample was sorted into three fractions: grasses/sedges, forbs/browse and senescent herbage. The nutritive contents of all samples were analysed. The results were similar for the two treatments. On a dry matter basis averaged over the season, both pastures consisted of approximately 59% grasses/sedges, 24% forbs/browse and 17% senescent herbage. The nutritive value of selected vegetationin the Intermittent and Continuous treatments, respectively, were as follows (seasonal mean, SE in brackets): 9.7 (0.3) and 9.6 (0.4) MJ per kg dry matter, 157 (7) and 146 (8) g crude protein per kg dry matter, 470 (12) and 483 (13) g neutral detergent fibre per kg dry matter. It was concluded that there were no major differences in either the composition, or the nutritive value, of herbage selected by the steers grazing the pasture that had been left ungrazed the previous season compared with herbage selected by the steers in the Continuous group.