ESTIMATION OF GENETIC PARAMETERS TO DETERMINE THE BIRTH AND WEANING WEIGHT IN BRAHMAN BOVINES

Objective. To estimate the heritability and genetic environmental and phenotypic correlations of birth and weaning weight in Brahman bovines. Materials and methods. 612 values for birth weight (BW) and weaning weight (WW) were analyzed for Brahman Bovines born form 1996 to 2003. The data derived from “Pradera” and “Mundo Nuevo” farms in Sucre department (Colombia). Data were analyzed using the mixed SAS V 8.0 system. The proposed mathematical model included the fixed effects: year, time, sex, number of calves, and farm and suggested the random effect of bull for both characteristics. Results. It was found that the effects farm and bull were statistically significant for the (BW). For WW, the year was statistically significant (p?0.05); sex, number of calves and bull effects were highly significant (p?0.05) and time and farm effects were not significant (p?0.05). The estimated heritability was 0.16 and 0.37 for BW and WW, respectively. Genetic, phenotypic and environmental correlation values were -0.2, 0.14 and 0.26 respectively. Conclusions. Values found for heritability indicate that the phenotype is not a good indicator of genotype, and that it is necessary to use tests of progeny or pedigree for selection. The value of the genetic correlations allows the affirmation that calves with better birth weight will not be those that reach higher weights at weaning.