PASTURE MANAGEMENT AND HILL COUNTRY PRODUCTION

Abstract

Pasture and animal production from farmlets rotationally grazed with sheep(RGS), set stocked with sheep (SSS) and rotationally grazed with cattle (RGC) were compared for 5 years. Herbage accumulation rate, herbage mass, tiller and stolen growth and defoliation and sheep diet selection were measured. RGC increased perennial ryegrass (L&urn perenne L.) and white clover (Trifolium repens L.) content. RGS herbage mass was 1000 kg DM/ ha greater than SSS by January. Despite differences in ewe liveweight and herbage mass profiles, grazing management had no effect on total wool production. In the first two years SSS had higher weaning weight per ha than RGS. Under high grazing pressure sheep selected a diet ranging from 85% dry matter digestibility in December to 56% in June. Total leaf growth was similar for RGS and SSS pastures because greater leaf extension rates for RGS were compensated for by higher tiller numbers in SSS swards. The total leaf length grazed was the same for RGS and SSS pastures because the greater leaf length grazed per tiller for RGS was offset by more frequent grazing of more numerous tillers in SSS. Rotational grazing may allow greater conservation in spring and provide extra feed at very high grazing pressures, but at commercial grazing pressures pasture rationing is unlikely to give greater animal production