Genetic Associations between True Fertility Index and Growth and Reproductive Traits in Beef Cattle

Abstract Text: The objective was to estimate genetic correlations between the index of true fertility (TF) and age at first calving (AFC), calving interval (CI), and weaning weight (WW) in Brangus (BA), Braunvieh (BR) and Salers (SA) cattle populations of Mexico. The TF index was computed as the WW multiplied by 365, and divided by the CI. Bivariate animal model analyses were carried out using the DFREML program. Estimates of heritabilities across breeds ranged from 0.05 to 0.08 for TF, 0.01 to 0.10 for AFC, 0.05 to 0.12 for CI, and 0.18 to 0.23 for WW. Genetic correlations in BA, BR and SA were -1.00, -0.76 and -1.00 for TF-AFC; -0.88, -0.93 and -0.85 for TF-CI; and 0.17, 0.17 and 0.15 for TF-WW. These favorable correlations suggest that the use of TF index could cause joint genetic progress in growth and reproductive traits.

Keywords:

genetic parameters

animal model

bivariate analyses