Contribuição do componente genético de touros da raça nelore avaliados pelo desempenho de suas progênies em teste de desempenho de touros jovens
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Data
2012-03-02
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Universidade Federal de Goiás
Resumo
Performance testing of young bulls are instruments of great utility in breeding
programs and is aimed to evaluate the ability of individual animals regarding weight
gain,, earliness, yield and carcass finishing, providing support for selection based on
individual information of each animal. The objective of this study was to understand
and define the relationships between genetic and quantitative genetic merit of Nellore
bulls evaluated and their progenies in Performance Testing of Young Bulls(PTYB). In
the present study, we analyzed the characteristics of weight calculated at 210 (W210),
365 (W365) and 450 days of age (W450), pre-weaning and post-weaning average
daily gain (PREDG and POSTDG), scrotal circumference at 365 and 450 days of age
(SC365 and SC450), ribeye area (REA) and carcass finishing (FIN) that were
measured during the Weight Gain Tests (WET). The analyzed data set came from the
Nellore participants in the Performance Testing of Young Bulls, which includes weight
gain on pasture tests, from integrated crop and livestock production, coordinated by
Embrapa Rice and Beans and Embrapa Cerrados. For data statistical analysis, we
used statistical procedures available on the Statistical Analysis System (SAS)
application and for obtaining (co)variance estimates, we used the Derivative-Free
Restricted Maximum Likelihood method (DFREML), using univariate animal models
and the Multiple Trait Derivative Free Restricted Maximum Likelihood (MTDFREML)
application. Estimates of heritability for all traits showed moderate to high magnitudes.
For direct and maternal additive effects, the heritability estimates were 0.37 ± 0.13 and
0.32 ± 0.15 and 0.35 ± 0.12 and 0.36 ± 0.16, for W210 and PREDG, respectively. As
for W365, W450, POSTDG, SC365, SC450, REA and FIN, the additive heritability
estimates were 0.33 ± 0.12, 0.53 ± 0.14, 0.54 ± 0.13, 0.36 ± 0.12, 0.54 ± 0.13, 0.26 ±
0.13 and 0.28 ± 0.14, respectively. Therefore, these results indicate the possibility of
improving these characteristics by the use of breeding animals with superior genotype.
Over the years there has been a significant entry of new bulls in evidence of weight
gain on pasture, resulting in marked variation in predictions of genetic breeding values.
However, there was positive and growing relationship between genetic value of bulls
and their progeny. Thus, the results show that the selection of the best bulls based on
genetic evaluations was efficient in terms of genetic progress.
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MAMEDE, Mariana Márcia Santos. Contribution of genetic component of nellore bulls evaluated for performance of their progenies in performance testing of young bulls. 2012. 66 f. Dissertação (Mestrado em Ciências Agrárias - Veterinaria) - Universidade Federal de Goiás, Goiânia, 2012.