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2009-Vergara_et_al - Direct genetic maternal genetic and...

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O. D. Vergara, M. F. Ceron-Muñoz, E. M. Arboleda, Y. Orozco and G. A. Ossa Colombian multibreed beef cattle population Direct genetic, maternal genetic, and heterozygosity effects on weaning weight in a doi: 10.2527/jas.2007-0636 originally published online Oct 24, 2008; 2009.87:516-521. J Anim Sci http://jas.fass.org/cgi/content/full/87/2/516 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by on February 2, 2011. jas.fass.org Downloaded from
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ABSTRACT: The (co)variance components of BW at weaning (WW) were estimated for a Colombian multibreed beef cattle population. A single-trait ani- mal model was used. The model included the fixed effect of contemporary group (sex, season, and year), and covariates including age of calf at weaning, age of cow, individual and maternal heterozygosity propor- tions, and breed percentage. Direct genetic, maternal genetic, permanent environmental, and residual effects were included as random effects. Direct, maternal, and total heritabilities were 0.23 ± 0.047, 0.15 ± 0.041, and 0.19, respectively. The genetic correlation between di- rect and maternal effects was −0.42 ± 0.131, indicating that there may be antagonism among genes for growth and genes for maternal ability, which in turn suggests that improving WW by direct and maternal EPD may be difficult. A greater value for the direct heterosis ef- fect compared with the maternal heterosis effect was found. Furthermore, the greater the proportion of An- gus, Romosinuano, and Blanco Orejinegro breeds, the less the WW. Key words: beef cattle, genetic variable, heterozygosity ©2009 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2009. 87:516–521 doi:10.2527/jas.2007-0636 INTRODUCTION Animal models allow us to obtain variance compo- nents and predict breeding values for individuals in a population (Henderson, 1988). According to Rodriguez et al. (1997), and depending on the characteristics con- sidered in the evaluation and on the data structure, different models can be used for prediction of breeding values of individual beef cattle, which is the reason why specific animal models have been developed. According to Arnold et al. (1992), the use of animals with different genetic composition in diverse production systems creates the need to develop evaluation proce- dures that include genetically diverse cattle. This need may include evaluations for composite breeds, commer- cial crossbred cattle, and synthetic breeds. It is known that preweaning traits reflect a combina- tion of factors such as the genetic growth potential of the calf, the milk yield and maternal behavior of the dam, the environment, and their interactions (Meyer, 1992). To conduct a genetic evaluation of those traits, it is necessary to estimate the relative importance of factors involving direct and maternal additive genetic effects. The objective of this study was to estimate the direct and maternal additive genetic variances, the per- manent environmental variance, and the heritability for weaning weight ( WW ) in crossbred calves located in a Colombian tropical humid forest.
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