2010-Perez-Cabal_et_al - Analysis of the existence of major...

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M. A. Pérez-Cabal, I. Cervantes, R. Morante, A. Burgos, F. Goyache and J. P. Gutiérrez Analysis of the existence of major genes affecting alpaca fiber traits doi: 10.2527/jas.2010-2865 originally published online July 23, 2010 2010, 88:3783-3788. J ANIM SCI http://jas.fass.org/content/88/12/3783 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by guest on December 12, 2011 jas.fass.org Downloaded from
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ABSTRACT: The aim of this study was to determine the presence of major genes for fiber diameter (FD), SD of FD (SDFD), CV of FD, and comfort factor (CF) in Huacaya (HU) and Suri (SU) Peruvian alpaca breeds. Bayesian segregation analyses with relaxed transmis- sion probabilities were performed using 1,906 and 6,592 available records for SU and HU breeds. Evidence for the presence of major genes was statistically supported when the 95% posterior density did not include zero. Significant major genes were found associated with de- creased FD, SDFD, CV values, and increased CF val- ues. Additive effects of the major genes were 4.18 and 4.23 μm for FD, 1.67 and 1.61 μm for SDFD, 3.32 and 3.76% for CV, and 15.03 and 14.90% for CF in HU and SU breeds, respectively. Dominance effects were −1.98 and −2.03 μm for FD, −0.88 and −1.11 μm for SDFD, −1.37 and −2.17% for CV, and 13.0 and 11.8% for CF in HU and SU breeds, respectively. Major gene variance was larger than the polygenic variance for all traits. Major gene allelic frequencies for FD, SDFD, and CV ranged from 0.81 to 0.86 for HU breed and from 0.70 to 0.77 for the SU breed and were 0.24 and 0.36, re- spectively, for CF. It can be concluded that a major gene affecting these traits could be segregating. Then, molecular identification and monitoring of animals car- rying favorable genes throughout the worldwide alpaca population would allow for a quick genetic improve- ment. Key words: alpaca, fiber, major gene, mixed-inheritance model, segregation analysis ©2010 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2010. 88:3783–3788 doi:10.2527/jas.2010-2865 INTRODUCTION The alpaca is the most important fiber producer of South American camelid species. Its fiber production is the main income for many rural Andean communities because alpaca flocks can graze at more than 4,000 m above sea level with daily temperature ranging from −15 to 20°C (Morante et al., 2009). There are 2 alpaca breeds with different fleece characteristics: Huacaya ( HU ) and Suri ( SU ). The HU breed represents more than 85% of the alpaca population in Peru (Quispe et al., 2009). Few genetic selection programs have been imple- mented to improve fleece characteristics. The Pacomar- ca S.A. research farm has developed some technological improvements and is becoming an elite alpaca flock. It developed a selection program for the HU breed using a textile value index as the selection criterion. Genetic parameters estimated from both breeds at this farm showed that estimated heritabilities for fiber traits were moderate for HU and high for SU (Gutiérrez et al., 2009; Cervantes et al., 2010), which may suggest segre- gation of a major gene (Zhang et al., 2000).
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2010-Perez-Cabal_et_al - Analysis of the existence of major...

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