Estrutura Populacional e Depressão Endogâmica em Características de Crescimento de Bovinos da Raça Nelore Criados no Bioma Amazônia.

Abstract

This study aimed to investigate the genetic diversity, population structure, addition to the effects of inbreeding on the growth characteristics of the breed Nelore created in the Amazon biome. The database used for analyzes contained records of 1,402,287 animals born between the years 1950-2012. The population structure and genetic diversity were investigated by estimated parameters with the information and pedigree records made available by the Brazilian Association of Zebu creators. Inferences about the effects of inbreeding were carried out by comparing models using Bayesian methodology, the Deviance Information Criterion (DIC) was the test statistic used. The completeness of the pedigree was 73.75%; 32.89%; and 11.69% in the first, second and third generation respectively. The effective number of founders and ancestors, the reference population, was 639 and 617, respectively. Assuming an effect "bottleneck", virtually nil, estimated at 1.04. A contingent of 829 animals, founders or not, explained 50% of the genetic variability of the population. The mean generation interval, 7.46 years, can be considered high. The average coefficient of inbreeding among the 18,647 inbred animals was 8.74%, being higher in the second generation in the study. The effective population size ranged between 16.15 and 1810.8 animals over the evaluated periods. Estimates of weights at weaning, a year and to yearling were 178.4 kg, 233 kg and 292.14 kg respectively. The comparison between models with or without inbreeding allowed the conclusion that the inclusion of this effect explains better the variation of the studied traits. Therefore, it is important to monitor the mating to prevent that an increase in inbreeding can result in decreased performance of the herds.