Grazing management of native pastures in the New England region of New South Wales. II. The effect of size of flock on pasture and sheep production with special reference to internal parasites and grazing behaviour

The effect of flock size on pasture and animal productivity, on parasitic infection, and on grazing behaviour was investigated in a grazing experiment over a period of 3 years. Merino sheep, undrenched, and stocked at the rate of one sheep per acre on native pasture dominated by Bothriochloa ambigua S.T. Blake, were used in five flock sizes, vie. 2, 4, 8, 16, and 30 animals. Flock size did not significantly affect the forage available or the botanical composition of the pastures, but liveweight gains and wool production were significantly lower in the flock of two sheep than in the other flocks. Observations indicated that the reduced productivity of the smallest flock was associated with reduced grazing time consequent on changes in grazing behaviour. No consistent significant differences in worm egg counts were observed in faecal samples from the different flocks. The results indicate that although under fairly extensive grazing conditions a unit of two sheep may be unsatisfactory in some respects, flocks of four sheep could give information on pasture or animal production or on parasitism comparable with that from larger flocks of up to 30 animals.