Genetic associations among average annual productivity, growth traits and stayability: a parallel between Nelore and composite beef cattle

• Grant number: 13/06091-8
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: May 01, 2013
• End date: October 31, 2013
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Joanir Pereira Eler
• Grantee: Joanir Pereira Eler
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil

Abstract

This study was conducted to examine the relationship among average annual productivity of the cow (PRODAM), yearling weight (YW), postweaning gain (PWG), scrotal circumference (SC) and stayability in the herd for at least 6 years (STAY) of Nelore and composite beef cattle. Measurements were taken on animals born between 1980 and 2010 on 70 farms located in seven Brazilian states. Estimates of heritability, genetic and environmental correlations were obtained by Bayesian approach with five-trait animal models. Genetic trends were estimated by regressing means of estimated breeding values by year of birth. The heritability estimates were between 0.14 and 0.47. Estimates of genetic correlation among female traits (PRODAM and STAY) and growth traits ranged from -0.02 to 0.30. Estimates of genetic correlations ranged from 0.23 to 0.94 among growth traits indicating that selection for these traits could be successful in tropical breeding programs. Genetic correlations among all traits were favorable and simultaneous selection for growth, productivity and stayability is therefore possible. Genetic correlation between PRODAM and STAY was 0.99 and 0.85 for Nelore and composite cattle, respectively. Thus, PRODAM and STAY might be influenced by many of the same genes. The inclusion of PRODAM instead of STAY as a selection criterion seems to be more advantageous for tropical breeding programs, because the generation interval required to obtain accurate estimates of genetic merit for PRODAM is shorter. Average annual genetic changes were greater in Nelore than in composite cattle. This was not unexpected, because the breeding program of composite cattle included a large number of farms, different production environments, genetic level of the herds and breeds. Thus, the selection process has become more difficult in this population. (AU)