Genetic evaluation of crossbred lamb production. 4. Genetic parameters for first-cross animal performance
V. M. Ingham A , N. M. Fogarty B F , A. R. Gilmour B , R. A. Afolayan B , L. J. Cummins C , G. M. Gaunt D , J. Stafford E and J. E. Hocking Edwards EA Agrisearch Services Pty Ltd, Orange, NSW 2800, Australia.
B The Australian Sheep Industry Cooperative Research Centre, NSW Department of Primary Industries, Orange Agricultural Institute, Orange, NSW 2800, Australia.
C Department of Primary Industries, Primary Industries Research, Hamilton, Vic. 3300, Australia.
D Department of Primary Industries, Primary Industries Research, Rutherglen, Vic. 3685, Australia.
E South Australian Research & Development Institute, Struan Research Centre, Naracoorte, SA 5271, Australia.
F Corresponding author. Email: neal.fogarty@dpi.nsw.gov.au
Australian Journal of Agricultural Research 58(8) 839-846 https://doi.org/10.1071/AR06368
Submitted: 22 November 2006 Accepted: 3 May 2007 Published: 30 August 2007
Abstract
The study estimated heritability for lamb growth and carcass performance, hogget ewe wool production, and worm egg count among crossbred progeny of maternal breed sires, as well as the genetic and phenotypic correlations among the traits. The data were from crossbred progeny of 91 sires from maternal breeds including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester. The sires were mated to Merino ewes at 3 sites over 3 years (and also Corriedale ewes at one site), with 3 common sires used at each site and year to provide genetic links. These sheep comprised part of the national maternal sire central progeny test program (MCPT) to evaluate the genetic variation for economically important production traits in progeny of maternal and dual-purpose (meat and wool) sires and the scope for genetic improvement. The matings resulted in 7846 first-cross lambs born, with 2964 wether lambs slaughtered at an average age of 214 days, and wool data from 2795 hogget ewes. Data were analysed using univariate mixed models containing fixed effects for site, year, sex and type of birth and rearing, dam source and sire breed, and random terms for sire and dam effects. Heritabilities and genetic correlations were estimated based on variances from progeny of 70 sires by fitting the same mixed models using a REML procedure in univariate and multivariate analyses. Estimates of heritability were low for lamb growth traits (0.07–0.29), meat colour and meat pH (0.10–0.23), and faecal worm egg count (0.10), moderate for carcass fat and muscle traits (0.32–0.47), and moderate to high for wool traits (0.36–0.55). Estimates of direct genetic correlations among liveweights at various ages were high and positive (0.41–0.77) and those between liveweights and most carcass and meat quality traits were small and varied in sign. Liveweights were moderately to highly positively correlated with most wool traits, except fibre diameter (–0.28–0.08). The study indicates that there is genetic variation for wool, growth, carcass, and meat quality traits, as well as for faecal worm egg count, with scope for selection within Australian maternal sire breeds of sheep.
Additional keywords: heritability, genetic correlations, maternal breeds, meat colour, meat pH.
Acknowledgments
The MCPT was run by the NSW Department of Primary Industries, Department of Primary Industries Victoria, and the South Australian Research and Development Institute, with the generous financial support of Meat and Livestock Australia. Commonwealth funding through the Australian Sheep Industry Cooperative Research Centre is also gratefully acknowledged. We also gratefully acknowledge the many other scientists, technical, and other support staff at the Agricultural and Advisory Station, Cowra, Orange Agricultural Institute, the Pastoral and Veterinary Institute, Hamilton, Rutherglen Research Institute, and Struan Research Centre, who have contributed to and supported the work over several years. We especially acknowledge the contributions of Jayce Morgan, Lynette McLeod, Kelly Lees, Tony Markham, Murray Arnold, Kerrie Groves, Trevor Pollard, Greg Seymour, Taffy Phillips, Paul Curran, Jack Rowe, Tamara Starbuck, Liz Abraham, and Elke Hocking. The support of ram breeders who entered sires is also greatly appreciated.
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