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

Abstract

The feeding value of Aries HD perennial ryegrass {Lolium perenne) was evaluated over spring (3 Sep to 1 Dec 1996) using Romney ewes suckling single lambs, with Yatsyn 1 perennial ryegrass as the control cultivar. There were three 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 liveweight gain tended to be higher on Aries HD than Yatsyn 1 over September (94 versus 56 ± 14.5 g day -1 , P < 0.07) which coincided with a significantly higher 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 ryegrass cultivars was between 11.0 and 11.3 hours per 24-h period. There was no significant difference in growth rates of suckling lambs between cultivars. Information on herbage nutritive value, herbage intake, and grazing behaviour are discussed in relation to the differences in ewe performance. A99033

Evaluation of the feeding value of Aries HD perennial ryegrass (Lolium perenne). II. Performance of weaned lambs in summer and autumn

“…Sixty weaned Romney lambs were selected for the summer experiment in late November 1996 (30 ewe lambs and 30 wether lambs). This total consisted of 36 lambs from the previous spring experiment (Bluett et al 1999) plus 24 similar lambs selected from the Research Unit flock. Twelve lambs were allocated to an initial slaughter group and their carcass weights were used to predict initial carcass weight of the remaining 48 lambs at the start of the experiment.…”

“…Measurements of herbage mass, botanical composition, tiller density, and nutritive value (in vitro organic matter digestibility, nitrogen, and neutral detergent fibre) were made using methods described by Bluett et al (1999). Monthly herbage samples were also analysed for concentrations of lolitrem B, peramine, and ergovaline by HPLC (Barker et al 1993).…”

“…All lambs were slaughtered on 25 March 1997 to record carcass weight, dressing out percentage, and fat depth (GR: Kirton 1989). Initial carcass weight of the experimental lambs was predicted from a regression equation based on the 12 lambs slaughtered at the beginning of the experiment (Bluett et al 1999). Carcass weight gain was estimated using the estimated initial carcass weight and the final carcass weight.…”

“…Measurements of herbage intake and grazing behaviour were made in two 4-day periods in both January and March 1997. Herbage intake was estimated using the faecal marker (C^C^) method described by Bluett et al (1999). Chromium release rates were determined by recovering capsules at slaughter in March, and were used for both January and March intake periods.…”

“…A previous weaned lamb experiment over summer and autumn (Bluett et al 1997) showed that contrasts in lamb performance between Aries HD and Yatsyn 1 reflected the interrelated effects of alkaloid concentrations and ryegrass staggers, and better lamb performance on Aries HD pasture could not be attributed to any difference in herbage nutritive value. Bluett et al (1999) reported that for ewes suckling lambs in spring, when the risk of effects on sheep from endophyte alkaloids were low, ewe liveweight gain tended to be higher on Aries HD than Yatsyn 1 over September (94 versus 56 g day" 1 , P < 0.07), which coincided with a higher herbage intake and bite rate. This paper compares the performance of weaned lambs on Aries HD and Yatsyn 1 over the following summer-autumn period, when the concentration of alkaloids was expected to be higher than in spring.…”