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RESEARCH ARTICLE
Contents Vol 48(9)

Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 1. Description of traits, model comparison, variance components and their ratios

A. E. Huisman A C , D. J. Brown A D , A. J. Ball B and H.-U. Graser A
+ Author Affiliations
- Author Affiliations

A Animal Genetics and Breeding Unit1, University of New England, Armidale, NSW 2351, Australia.

B Meat and Livestock Australia, PO Box U254, University of New England, Armidale, NSW 2351, Australia.

C Current Address: Hypor, 5830 AA Boxmeer, The Netherlands.

D Corresponding author. Email: dbrown2@une.edu.au

Australian Journal of Experimental Agriculture 48(9) 1177-1185 https://doi.org/10.1071/EA08119
Submitted: 10 April 2008  Accepted: 2 May 2008   Published: 7 August 2008

Abstract

Both wool and sheep meat industries are interested in sheep that have a high reproduction performance and are resistant to internal parasites, in addition to the traditional traits. There is considerable interest in breeding sheep for wool, carcass, reproductive and internal parasite resistance traits simultaneously. The objective of this study was to estimate single trait genetic parameters for 40 traits recorded in Merino sheep, covering bodyweight, carcass, wool, reproduction and internal parasite resistance traits. This also involved determining the appropriate models. The results from this study will be used to review the genetic parameters used in the routine genetic evaluations conducted by Sheep Genetics.

The most appropriate models included a maternal genetic effect and covariance between direct and maternal genetic effects for most of the bodyweight traits, greasy and clean fleece weight, fibre diameter and coefficient of variation of fibre diameter. The permanent environment due to the dam was not included for any trait. There was considerable genetic variation in most traits analysed; lowest heritabilities (0.09–0.10) were found for number of lambs born and weaned per lambing opportunity, and highest heritabilities (0.62–0.77) for fibre diameter. The estimated heritabilities and genetic variances, in combination with the estimated correlations, indicate that there is potential to make genetic improvement in most traits currently recorded in Australian Merino sheep.


Acknowledgements

This research was funded by Meat and Livestock Australia (MLA). The authors would like to thank the Merino breeders and accredited Lambplan scanners who collected the pedigree and performance data used in this study. The work of Stephen Field, the MGS database manager, and that of Bronwyn Clarke, who manages the Merino Validation Project, is acknowledged.


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1 AGBU is a joint venture of NSW Department of Primary Industries and the University of New England.