Effect of lambing date on the utilization of grass/clover and lucerne pastures during mating

N.A. Thomson and K.T. Jagusch

Lincoln College, Canterbury

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Proceedings of the New Zealand Society of Animal Production. 1976, 36: 184-189

The utilization of grass/clover and lucerne pastures grazed by ewes lambing early (August 20) and late (September 20) was investigated through the flushing period. To achieve a positive liveweight response in ewes the average single grazing utilizations were: 58%, lucerne early; 54%, grass early; 43%, lucerne late; and 48%, grass late.

There was a significant linear relationship between utilization of grass/clover pasture and liveweight gain (r= -0.65) with an 80 g/day decrease in liveweight/10% increase in utilization. Ewes maintained liveweight at a utilization of 65%. Total dry matter available/grazing was the major positive factor affecting utilization and liveweight gain with increasing proportions of dead material in the swards having a negative effect. This effect was more marked in the groups flushed later in autumn. Utilization of lucerne for positive liveweight gain appeared to be affected by the low quality of residual material, 12.4% protein and 54.8% acid detergent fibre. Mating of ewes on lucerne resulted in a significant depression in lambing percentage compared with the ewes mated on grass/clover pastures.

Keywords: NZSAPAB;

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