Características avaliadas em programas de melhoramento genético de bovinos de corte

Abstract

The Brazil has excelled in cattle since the mid-1990s, especially in beef cattle, where the country stands out as the largest exporter of beef in the world. One reason for this focus is the success of breeding programs, especially in Nellore because of the large number of animals evaluated. The objective of study was to analyze the main characteristics evaluated in breeding programs, compare the importance given to each of the different programs, evaluate the selection index, the number and importance of each characteristic in the formation of the index graph and evaluate of genetic trend of the index. A review of the main characteristics evaluated in the main programs of genetic improvement of beef cattle. Then the description has been made the characteristics and its importance in each breeding program, and for each specific. We performed an approach to the selection index of the program, taking into account the number and characteristics involved in it. We evaluated the characteristics of eight programs of genetic improvement of beef cattle. The features were grouped into a spreadsheet, being classified in weight and performance characteristics, reproductive traits, characteristics assessed by visual scores and carcass characteristics. Evaluations were made based on comparisons between programs for each trait and its importance given to each one. It was observed a great diversity of characteristics, some common to several programs generating EPDs, others being only quantified without information of genetic merit. It was also observed a great diversity of characteristics evaluated in breeding programs, where different programs that assess and evaluate the same race give different amounts for certain characteristics. In evaluating the selection index was observed that some programs have selection index valued at more than one time, thereby generating a single index and other indexes in two stages during selection, generating two indices. The programs are getting good genetic gains expressed by genetic tendencies, even those in which different races are evaluated with the same weighting in the index. However, if any difference in weights for some characteristics in different breeds, these gains may be higher.