Endogamia na Raça Holandesa no Brasil

• Autor(a) principal: Paiva, André Luis da Costa
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5576
• topic: Endogamia; Gado Holandês; Consagüinidade; Inbreeding; Holstein breed; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

This study aimed to evaluate the Inbreeding trends on Holstein breed and study it s effect on milk yield. The pedigree data contained 248.141 Holstein animals born between 1960 e 2002. Data set was edited to maintain cows with age of calving between 18 and 24 months, year of born between 1981 and 2002, year of calving between 1984 and 2004, breed composition with purebred and grade bred resulting in 98.524 observations of first lactation. Inbreeding coefficient was calculated by using MTDFREML software. In addition, effective size population (Ne) and generation interval were calculated. To study the Inbreeding trend, a superposition of generations is frequent on cattle being necessary infer to which generation the individual belongs by calculating the generation coefficient. A model was proposed considered fixed effects of herd-year, breed grade and season of calving; and Inbreeding and age of calving as covariables. Solutions of fixed effects were obtained by software BLUPf90. After verifying significance on Inbreeding effect, a regression analysis was made to milk yield on first lactation including linear and quadratic effects of the Inbreeding coefficients. Results indicate that out of 320.712 animals with 0,38% Inbreeding coefficient (F), 53.411 showed positive F values with 1,30% of average F varying from 0,01% to 31,20%. F has decreased considering just inbred animals when analyzed by year or generation. Only 16,65 % of the animals (53.411) in population were inbred. There was an increasing on inbred animals when evaluating the evolution on number of inbred animals in relation to total population by year or generation. By year of born, the higher percentage of inbred animals (43,50%) appeared in 1998 trending to reduce until 31% in 2002. Ne was higher than recommended (40 per generation) on first four generations. Sire son generation interval was higher than the others (Sire daughter, Dams son, Dams daughter). A higher average F was found (6,23%) when only animals with yield data were analyzed. Only quadratic effect on Inbreeding grades was not significant from all the sources of variation used on the proposed model. A linear coefficient of 22,60 kg was found for each 1% of increasing on Inbreeding. The average Inbreeding for Holstein animals in Brazil can be considered low for the total population and inbred animals. Although current levels of Inbreeding are considered low, milk yield on first lactation was significantly affected.