Estimativas de parâmetros genéticos para características de crescimento em bovinos da raça Canchim utilizando modelos de dimensão finita

Abstract

RESUMO -Os objetivos neste trabalho foram avaliar diferentes modelos, em relação aos efeitos maternos considerados, para características de crescimento e estimar os parâmetros genéticos para essas características em bovinos da raça Canchim, por meio de análises uni, bi e multicaracterísticas. As características peso ao nascimento, peso ao desmame, pesos padronizados para 12, 18, 24 e 30 meses de idade em machos e fêmeas e peso adulto de fêmeas foram analisadas utilizando-se quatro modelos com os efeitos aleatórios adicionados em sequência. Os efeitos maternos influenciaram os pesos do nascimento aos 2 anos de idade e o peso à desmama foi o mais afetado pelos efeitos maternos. As estimativas de herdabilidade direta obtidas das análises bi e multicaracterísticas foram superiores àquelas obtidas das análises unicaracterísticas. As estimativas de herdabilidade do efeito genético direto obtidas usando análise multicaracterística foram 0,39 para peso ao nascer; 0,31 para peso à desmama; 0,29 para peso aos 12 meses; 0,28 para peso aos 18 meses; 0,26 para peso aos 24 meses; 0,30 para peso aos 30 meses; e 0,38 para peso à idade adulta. As correlações genéticas estimadas entre pesos obtidos em idades jovens com peso à idade adulta foram altas, acima de 0,79. A seleção com base em características de crescimento em qualquer idade pode promover ganhos genéticos moderados no peso corporal de animais da raça Canchim em todas as idades-padrão, inclusive nos pesos ao nascer e à idade adulta das fêmeas. É importante considerar nas análises os pesos prévios à seleção para estimar parâmetros genéticos para pesos após a seleção. A análise multicaracterística é a mais indicada.Palavras-chave: análise multicaracterística, bovinos de corte, correlação genética, herdabilidade, peso padronizado Estimation of genetic parameters for growth traits in Canchim cattle with finite modelsABSTRACT -The objectives of this work were to evaluate different models, regarded to considered maternal effects, for growth traits and to estimate genetic parameters for these traits in Canchim breed bovine, by one, two and multitrait analyses. The weight traits at birth, at weaning, standardized weight for 12, 18, 24 and 30 months of age in males and females, and mature female weight were analyzed using four models with random effects added in sequence. Maternal effects influenced birth weight at 2 years of age and weaning weight was the most affected by maternal effects. Direct heritability estimates obtained by two-and multitrait analyses were higher than those obtained through one-trait analyses. Estimates of direct genetic effect heritability obtained using multi-trait analyses were 0.39 for weight at birth; 0.31 for weight at weaning; 0.29 for weight at 12 months of age; 0.28 for weight at 18 months of age; 0.26 for weight at 24 months of age; 0.30 for weight at 30 months of age and 0.38 for weight at mature age. Genetic correlations estimated among weights at early ages and mature weight were high, above 0.79. Selection based on growth traits at any age ...

The influence of animals from embryo transfer on the genetic evaluation of growth in Simmental beef cattle by using multi-trait models

“…Likewise, the phenotypic variance (σ 2 p ) also increased almost linearly with age in both models. This finding agreed with the results of Marques et al (1999), Baldi-Rey et al (2010), Menezes (2010) and Boligon et al (2010), who reported a similar linear behavior for other beef cattle breeds.…”

Genetic analyses on bodyweight, reproductive, and carcass traits in composite beef cattle

“…The observed average for bodyweight, reproductive, and carcass traits (Table 2) are in agreement with previous studies of the Canchim breed (Andrade et al 2008;Baldi et al 2010;Barichello et al 2010;Buzanskas et al 2010;Meirelles et al 2010;Borba et al 2011). The variance components and heritabilities estimated in single-trait analyses are presented in Table 3.…”

“…A substantial proportion of the variation in the bodyweights, scrotal circumferences and carcass traits was associated with the additive genetic term indicating that these traits may respond to selection in Canchim cattle. For BW, WW, YW, and SCW the direct heritability estimates were in the range found in the literature for the Canchim breed, which ranged from 0.25 to 0.41 (BW), 0.23 to 0.48 (WW), 0.24 to 0.29 (YW), and 0.17 to 0.52 (SCW) (Alencar et al 1993;Silva et al 2000;Gianlorenço et al 2003;Andrade et al 2008;Baldi et al 2010;Buzanskas et al 2010;Borba et al 2011). Direct heritability estimates for BW obtained by Boligon et al (2011), El-Saied et al (2006), and Meyer (1995) were equal to 0.30 AE 0.01, 0.36 AE 0.04, and 0.38 for Nellore, Charolais, and Australian Angus cattle.…”

Genetic evaluation using multi-trait and random regression models in Simmental beef cattle

“…Starting at this age, a new and more marked increase in these variances occurred (Figure 3). Baldi et al (2010b) and Menezes (2010) obtained linear increasing in the estimates of residual variances along the growth trajectory. In RRM, the same behavior reported in MTM was observed.…”

“…Several studies in beef cattle have demonstrated the importance of including maternal effects in the analysis (Meyer et al, 1993;Baldi et al, 2010b;Nobre et al, 2009;Menezes, 2010). Meyer (1997) reported that the models that rule out maternal effects lead to overestimates of direct heritability.…”