The effect of paddock size on animal production.

Abstract

THE EFFECT OF PADDOCK SIZE ON ANIMAL PRODUCTION N. M. ELLIOTT* Summary Observations at Bengworden, eastern Victoria, with Merino wethers in 1964 and 1965 showed that Iiveweight and wool production were similar at the same stocking rate on both large (up to 107 acres) and small (5-acre) paddocks. I. INTRODUCTION Subdivision per se, in the absence of grazing management, has been shown to have no effect on liveweight and wool production of animals at low rates of stocking (Southcott, Roe and Turner 1962; Suckling 1962). In the observations described here, comparisons were made of the production of sheep grazing paddocks of 5 acres with production of sheep grazing adjacent larger areas of 40 and 107 acres. II. EXPERlMENTAL Two experiments were carried out at Bengworden, near Bairnsdale, in Eastern Victoria. The climate, pastures and seasonal changes in pasture production have been described by Drake and Elliott (1960, 1963). In Experiment 1, monthly measurements of the liveweight of Merino wethers were made between August 14, 1963 and August 20, 1964 using stocking rates and paddock sizes as in Table 1. Greasy fleece weights were taken at shearing on September 4, 1964 which was 365 days after the previous shearing. Initially, the sheep were one year-old medium-woolled Merino cated to their treatments on the basis of body and fleece weights. used was to rank sheep in class intervals for body weight and fleece ing proportionate representation from each class interval for each In the experiment of the first sheep each, while 240 following year, from September was repeated (Experiment 2) on experiment, and using sheep from selected as in Experiment 1, were were run in an adjoining 40-acre TABLE 1 wethers, alloThe method weight, drawtreatment. 4, 1964 to August 31, 1965, the portion of the 107-acre paddock this paddock. Four groups of 30 run in four new 5-acre paddocks, paddock at six to the acre. Details of Experiment I *Department of Agriculture, Bairnsdale, Victoria. 177 TABLE 2 Mean liveweights and greasy fleece weights-Experiment 1 III. RESULTS The results of Experiment 1, in terms of mean liveweights at the beginning and end of the experimental period and mean greasy fleece weights at shearing, are shown in Table 2. There were no pronounced differences between the groups in liveweights or in greasy fleece weights. In Experiment 2, the average greasy fleece weights of the four small groups on 5-acre paddocks, stocked at six sheep per acre, ranged between 5.10 and 5.22 kg compared with 5.26 kg for the group on the 40-acre paddock. The body weights of the small groups ranged from 51.6 to 53.6 kg as against 50.0 kg for the large group. The reduced body weight of the large group could be largely attributed to a severe and persistent outbreak of sheath-rot just prior to shearing and which was less serious in the small groups. Animals in the small paddocks tended to concentrate and camp along the fencelines around their paddocks, while those in the large paddocks usually camped in a few areas throughout the paddocks. 1V. DISCUSSION The results were characterised by absence of differences in production of the flocks of different size grazing at common stocking rates. They confirm the finding of Southcott, Roe and Turner (1962) who worked at lower stocking rates. The similarity in production of sheep grazed in different sized paddocks suggests that results obtained experimentally in relatively small plots may be extended to large acreages without qualification. Subdivision per se does not appear to increase level of production in the absence of any change in grazing management. Whether it might do so in conjunction with changes in grazing management cannot be decided from these particular observations. V. ACKNOWLEDGMENTS The author is indebted to Messrs. J. S. and M. A. Ballantyne on whose property the observations were conducted. VI. REFERENCES F. R., and ELLIOTT, N. M. (1960). Wool production per acre, rates of stocking trial. The Journal of Agriculture, Victoria 58: 645. D RAKE , F. R. and E LLIOTT , N. M. (1963). Rates of stocking investigated at Bengworden. The Journal of Agriculture, Victoria 61: 553. S OUTHCOTT , W. H., -ROE, R., and T URNER , HELEN N EWTON (1962). 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 int' ernal parasites and grazing behaviour. Australian Journal of Agricultural Research 13: 880. S UCKLING , F. E. T. (1962). Recent trials at the Te Awa Hill Pasture Research Station. Massey College Sheep Farming Annual 1962, page 18 1. D RAK E, 178