Evaluation of the feeding value of Aries HD perennial ryegrass (Lolium perenne). I. Performance of lactating ewes in spring

The feeding value of Aries HD perennial ryegrass (Lolium perenne) was evalu ated over spring (3 Sep to 1 Dec 1996) using Romney ewes suckling single la mbs, with Yatsyn 1 perennial ryegrass as the control cultivar. There were t hree replicate plots of each cultivar of 0.33 ha continuously stocked with 6 ewes per plot after lambing to maintain a mean sward surface height of 6 cm. Ewes were removed from the area on 5 November at weaning. Ewe liveweigh t gain tended to be higher on Aries HD than Yatsyn 1 over September (94 ver sus 56 +/- 14.5 g day(-1), P < 0.07) which coincided with a significantly h igher herbage intake (1.78 versus 1.37 +/- 0.038 kg DM day(-1), P < 0.04). The percentage of ryegrass leaf was higher in Aries HD pasture, as were ewe bite rate and calculated bite weight. The time spent grazing on these ryeg rass cultivars was between 11.0 and 11.3 hours per 24-h period. There was n o significant difference in growth rates of suckling lambs between cultivar s. Information on herbage nutritive value, herbage intake, and grazing beha viour are discussed in relation to the differences in ewe performance.