Efeito da endogamia sobre características de crescimento de bovinos da raça Gir no Brasil
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Data
2000-08-01
Autores
Queiroz, Sandra Aidar de [UNESP]
Albuquerque, Lucia Galvão de [UNESP]
Lanzoni, Neli Aparecida
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Zootecnia
Resumo
Esta pesquisa foi conduzida com o objetivo de avaliar o efeito da endogamia e suas possíveis influências sobre o crescimento de bovinos de corte. Foram utilizadas 27.406 observações de peso à desmama, padronizado aos 205 dias (PD), e 14.317 informações de peso ao ano, padronizado aos 365 dias (PA), de animais da raça Gir, no período de 1970 a 1995. As análises foram feitas pelo método dos quadrados mínimos, incluindo-se o efeito aleatório de grupo contemporâneo e os efeitos fixos de geração (discreto), idade da vaca ao parto e taxa de endogamia do bezerro e da vaca como variáveis contínuas, considerando-se os efeitos linear e quadrático. Apenas 11,65% das vacas, 19,84% dos touros e 9,23% dos bezerros da raça Gir estudados apresentaram algum grau de endogamia e as estimativas das médias de endogamia foram de pequena magnitude, constatando-se valores de 1,04; 0,96; e 1,66% para vacas, touros e bezerros, respectivamente. O efeito da endogamia do animal foi significativo e quadrático para as duas características estudadas. Os resultados mostraram depressão endogâmica para ambas as características (PD e PA). Recomenda-se evitar os acasalamentos, intencionalmente, endogâmicos e monitorar os acasalamentos com base no parentesco entre os indivíduos, visando manter baixas as taxas de endogamia.
This research was carried out to evaluate the inbreeding effects and its possible influence on the beef cattle growth. Data with 27,406 observations of weaning weight, standardized to 205 (WW), and 14,317 observations of yearling weight, standardized to 365 days (YW), from Gyr breed animals, from 1970 to 1995, were used. The analysis were made using the least square method that included the random effect of contemporary group and the fixed effects of generation (class), age of cow at calving, calf and cow inbreeding as regressions, considering linear and quadratic effects. Only 11.65% of cows, 19.84% of bulls and 9.23% of the studied calves from the Gyr breed presented some degree of inbreeding. The estimates of the inbreeding means were of low magnitude and the values were of 1.04, 0.96 and 1.66% for cows, bulls and calves, respectively. The animal inbreeding was significant and quadratic for both studied traits. The results showed inbreeding depression for both traits (WW and YW). Intentional inbreeding matting should be avoided and matting should be planed also taking into account the relationship between the animals, in order to keep inbreeding in low degree.
This research was carried out to evaluate the inbreeding effects and its possible influence on the beef cattle growth. Data with 27,406 observations of weaning weight, standardized to 205 (WW), and 14,317 observations of yearling weight, standardized to 365 days (YW), from Gyr breed animals, from 1970 to 1995, were used. The analysis were made using the least square method that included the random effect of contemporary group and the fixed effects of generation (class), age of cow at calving, calf and cow inbreeding as regressions, considering linear and quadratic effects. Only 11.65% of cows, 19.84% of bulls and 9.23% of the studied calves from the Gyr breed presented some degree of inbreeding. The estimates of the inbreeding means were of low magnitude and the values were of 1.04, 0.96 and 1.66% for cows, bulls and calves, respectively. The animal inbreeding was significant and quadratic for both studied traits. The results showed inbreeding depression for both traits (WW and YW). Intentional inbreeding matting should be avoided and matting should be planed also taking into account the relationship between the animals, in order to keep inbreeding in low degree.
Descrição
Palavras-chave
Gyr cattle, Inbreeding, weaning weight, yearling weight, bovinos Gir, Endogamia, peso ao ano, peso à desmama
Como citar
Revista Brasileira de Zootecnia. Sociedade Brasileira de Zootecnia, v. 29, n. 4, p. 1014-1019, 2000.