Wool production and quality of three strains of Merino in a semi-arid environment under different grazing strategies
M. A. Friend A B D and G. E. Robards A CA Department of Wool and Animal Science, University of New South Wales, Sydney, NSW 2052, Australia.
B Current address: EH Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
C Current address: 10 Clarence Street, Glenbrook, NSW 2773, Australia.
D Corresponding author. Email: mfriend@csu.edu.au
Australian Journal of Experimental Agriculture 46(1) 37-44 https://doi.org/10.1071/EA04018
Submitted: 12 February 2004 Accepted: 16 September 2004 Published: 9 February 2006
Abstract
Three strains of Merino wethers (strong, medium and fine wool; n = 30 each; 3 years old) were grazed under 3 different management regimes (10 from each strain) in a semi-arid environment to test the hypothesis that attempting to keep liveweight stable at upper and lower levels would improve staple strength relative to sheep in which no attempt was made to limit liveweight fluctuations, and that strength and wool colour would not differ between strains. Sheep in the low grazing regime were managed in an attempt to keep liveweight stable at a level below that of sheep in the high grazing regime, which were managed in an attempt to keep liveweight stable at a level higher than sheep in the low grazing regime. For the control group, no attempt was made to limit liveweight fluctuations through grazing management. Sheep in the high grazing regime had greater liveweights throughout the experiment than sheep in the low grazing regime, while the liveweight of sheep in the control group was usually intermediate. Staple strength did not differ significantly between the strains, but was greater (P<0.05) for sheep in the high grazing regime (58.3 ± 2.2 N/ktex) than for sheep in the control (39.0 ± 2.3 N/ktex) and low (33.8 ± 2.3 N/ktex) grazing regimes, which did not differ significantly from each other. Wool yellowness was not affected by grazing regime, but was lower (P<0.05) in fine wool sheep (1.0 ± 0.1%) than medium wool sheep (1.4 ± 0.1%), which, in turn, was less (P<0.05) than in strong wool sheep (1.7 ± 0.1%). Staple strength was significantly (P<0.05) correlated with mean liveweight (0.27), mean fibre diameter (0.25), minimum fibre diameter (0.36), coefficient of variation of fibre diameter (–0.50), coefficient of variation of diameter along fibres (–0.48) and between fibres (–0.41). The results indicate staple strength was not adversely affected by the choice of strain in a semi-arid environment, and that nutritional management to limit fibre diameter variability can be an effective strategy to improve staple strength, regardless of strain.
Additional keywords: fibre diameter variability, wool growth.
Acknowledgments
The authors thank Messrs Noel Corliss and David Wilson for their care of the sheep and assistance with sampling. The authors also wish to thank Professor John James for his statistical advice and Mr David Petrie for his assistance in wool metrology. Part funding for the work was supplied by Australian woolgrowers and the Federal Government as MAF was in receipt of a postgraduate scholarship from the Australian Wool Research and Promotion Organisation.
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