Abstract:
Animal Production in Australia Vol. 15 THE EFFECT OF PARTIAL SHEARING ON THE USE OF WINDBREAK SHELTER BY LAMBING EWES J. ROSEMARY DONE-CURRIE*+, J.J. LYNCH** and MANIKA WODZICKA-TOMASZEWSKA* Shearing immediately prior to lambing encourages ewes to use windbreaks and so increase survival of their newborn lambs (Alexander and Lynch 1980). In practice many graziers crutch their ewes prior to lambing and Love et al. (1978) measured voluntary food intake (VFI) as a simple index of cold response on such sheep. They found a VFI level almost equivalent to that of fully shorn sheep and therefore suggested that a small increase in the inguinal shorn area before lambing could be a simple means of improving lamb survival by inducing sheltering behaviour. This experiment examines the effect of partial shearing on the sheltering behaviour of lambing ewes. Four groups each of 16 ewes were studied in two successive winters. In year I the treatments were shorn (S), belly shorn (B), crutch and wig shorn (CW), and unshorn(US) and the approximate areas of skin exposed were 100, 8.8, 6.3 and 0 percent respectively. In year II the treatments were S, crutch, belly, wig and legs shorn (CBWL), udder crutch and wig shorn (UCW) and US with percentage areas shorn being 100, 36.1, 8.9 and 0 respectively. Each shearing group was placed in two of eight separate 40 m x 40 m paddocks with a synthetic windbreak one metre high running at right angles to the westerly wind and down the centre. From 1600h to 900h each day for three weeks during lambing the location of each sheep was observed hourly. Sheep were recorded as sheltering if they were between two m windward and six m leeward of shelter. Weather conditionswere also recorded. Significant linear relationships between transformed data of the percentage (Y) of sheep found in the sheltered areas and the percentage (X) of skin exposed at shearing were found from 1800h to 600h for each year of the experiment and the whole experiment. The lines of best fit were: Year I Year II Whole experiment Y= 0.34X + 24.9 Y = 0.28X + 26.6 Y= 0.31X + 25.6 r = 0.9807 (P < 0.05) r = 0.9809 (P < 0.05) r = 0.9752 (P < 0.001) where r is the correlation coefficient. for the whole experiment. There were 4 points for each year and 8 Thus, the greater the area of skin exposed, the greater the number of sheep using the sheltered area. Exposing the skin around the inguinal region in the B, CW and UCW ewes did not elicit sheltering behaviour to the extent of the CWBL and S treatments. It is not sufficient to crutch, wig and shear around the udder of ewes prior to lambing to maximise their use of shelter and so improve lamb survival during inclement weather. ALEXANDER, G. and LYNCH, J.J. (1980). Proc. Aust. Soc. Anim. Prod. 13: 329. LOVE, K.J., EGAN, J.K. and MCINTYRE, J.S. (1978). 12: 269. Proc. Aust. Soc. Anim. Prod. k Dept. of Physiology, University of New England, Armidale, N.S.W. 2351. +c* CSIRO Pastoral Research Laboratory, Armidale, N.S.W. 2350. *+ Present address: Department of Agriculture, Rutherglen Research Institute, Rutherglen, Vic. 3685. 670