Abstract:
Proc. Amt. Sot. Arh. Prod. 1994 Vol. 20 LIVEWEIGHT AND WOOL PRODUCTION, AND THEIR SEASONAL PATTERN, IN MERINO WETHERS FED A UREA SUPPLEMENT L.C. BUTLERA, G.M. HEADA and H.F. FOSTER B ADcpt of Primary Industry and Fisheries, P.O. Box 46, Kings Meadows, Tas. 7249 B'Mcrton Vale', Campbell Town, Tas. 7210 Wool production and its components vary throughout the year due to combinations of many factors (Birrell 1981) including photoperiod, seasonal feed supply and management. This work aimed to investigate seasonal wool growth and liveweight patterns of sheep fed at pasture with or without a urea supplement block in Tasmania, and to relate these to fleece quality measurements. About 300 fine wool Merino wethers (age 10 months) were drafted at random into 2 treatment groups and offered either no supplement or a Rumevite urea-concentrate-mineral block ad libitu for 2 years. m A sample of 20 monitor animals from within each treatment group were weighed, and dyebands applied, every 2 months. At the July shearings, fleeces were weighed (year 2 only) and dyebands harvested for measurement of periodic wool growth. The wool from each group was baled separately, tested for core and staple measurements and auction price recorded. Despite an unplanned 14% difference in stocking rate in year 1, the liveweights (Table 1) were not different (P > 0.01). However, in the second year when stocking rates were equalised, the supplemented group was 15% heavier (P < 0.01) with 30% heavier greasy fleece weights (P < 0.01) than the unsupplemented group. Other fleece measurements are shown in Table 1. Differences in fibre diameter may have contributed to the price difference in year 2, but not year 1. The minimum wool growth rate and liveweight occurred around July during the period of lowest feed availability, as expected, regardless of supplementation. Table 1. Production data for the control and supplemented sheep for each year of the study Despite the design faults, these data are consistent with a possible response to the supplement, but how much is due to the urea, the concentrates or the minerals in the supplement cannot be determined. Given previously reported difficulties in establishing an effect due to urea supplements (Mulholland 198O), the evidence of a response from this unreplicated trial must be treated with caution. The blocks would not have provided sufficient energy to account for the differences. Seasonal or paddock effects are unlikely given the inconsistency and magnitude of the effect. BIRRELL, I-M. (1981). Aust. J. Agric. Res. 32: 353-70. BUTLER, LG. and HEAD, G.M. (1994). Aust. J. Exp. Agric. 34 (in press). : MULHOLLAND, J-G. (1980). In 'Proceedings of a Seminar on Urea Licks and Blocks for Sheep and Cattle', (Ed D.J. Barker) pp. 36-48 (Australian Society of Animal Production, WA Branch: Perth). 449
