Publication Date

1993

Description

ABSTRACT Upland pastures for sheep and beef cattle in the UK typically contain less than 5% clover in the grazed herbage, Use of fertiliser N, low P and K status, low pH and inappropriate choice of grass and clover varieties are implicated in this low pasture clover content, along with temperature constraints. In a 4-year study, swards of tecraploid perenn ial ryegrass (Lolium perenne, cv. Condesa) were compared with swards of a diploid perennial rye grass (cv. Contender) both being maintained at a constant grazing height of 4-6 cm and given 160 kg N/ha/year. Lamb output (kg/ ha) from the Condesa swards was 13.4% higher than from Contender. Swards of N-fertilised Condesa were also compared with swards' based on Condesi + small-leaved clover (Trifolium repens, cv. Aberystwyth Sl 84) given no N which attained sward clover contents (% of dry matter) of 13, 26, 21 and 17% in the 4 grazing seasons after pasture establishment in 1987. Lamb live- weight gain/ha on these pastures relative to Condesa + N fertiliser were 0.76, 1.05, 1.0 1 and 0.96, with reduced relative stocki ng rates of 0.60, 0.86, 0.88 and 0.80 over the 4 seasons. Daily gain of lambs and ewes were significantly increased on clover by 50 and 69 g/day, respectively. Higher stocking rotes and output were correlated with higher sward clover content and the results indicate that with a sward clover content around 20%, N fixation by clover was producing che 'equivalent effect of applying 160 kg of fertiliser N. This exceeds national average application rates on upland grass. Higher seed and fertiliser costs needed for clover establishment, and the time taken for clover to develop, restrict the application to permanent pastures rather than those in an arable rotation.

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Sustainable Clover-Dominant Swards for Lamb Production Under Low Temperatures

ABSTRACT Upland pastures for sheep and beef cattle in the UK typically contain less than 5% clover in the grazed herbage, Use of fertiliser N, low P and K status, low pH and inappropriate choice of grass and clover varieties are implicated in this low pasture clover content, along with temperature constraints. In a 4-year study, swards of tecraploid perenn ial ryegrass (Lolium perenne, cv. Condesa) were compared with swards of a diploid perennial rye grass (cv. Contender) both being maintained at a constant grazing height of 4-6 cm and given 160 kg N/ha/year. Lamb output (kg/ ha) from the Condesa swards was 13.4% higher than from Contender. Swards of N-fertilised Condesa were also compared with swards' based on Condesi + small-leaved clover (Trifolium repens, cv. Aberystwyth Sl 84) given no N which attained sward clover contents (% of dry matter) of 13, 26, 21 and 17% in the 4 grazing seasons after pasture establishment in 1987. Lamb live- weight gain/ha on these pastures relative to Condesa + N fertiliser were 0.76, 1.05, 1.0 1 and 0.96, with reduced relative stocki ng rates of 0.60, 0.86, 0.88 and 0.80 over the 4 seasons. Daily gain of lambs and ewes were significantly increased on clover by 50 and 69 g/day, respectively. Higher stocking rotes and output were correlated with higher sward clover content and the results indicate that with a sward clover content around 20%, N fixation by clover was producing che 'equivalent effect of applying 160 kg of fertiliser N. This exceeds national average application rates on upland grass. Higher seed and fertiliser costs needed for clover establishment, and the time taken for clover to develop, restrict the application to permanent pastures rather than those in an arable rotation.