Copyright (c) 2025 Journal of Agricultural Research

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Having genetic resources that are well adapted to local environmental conditions is of great importance for achieving better productive performance with lower costs and ensuring animal welfare. The objective of this study was to estimate the genetic (co)variance components for birth weight (BW) and weaning weight adjusted to 205 days (WW205) in Charolais cattle under the tropical conditions of Chiriquí, Panama. A total of 1,895 records from animals born between 1998 and 2019 were used. The data were analyzed with a bivariate animal model considering the fixed effects of contemporary group (year–season), sex, dam age at calving, and the covariate age at weaning for WW205, all of which were highly significant. Random effects included the animal and the dam’s permanent environmental effect. Heritability estimates were 0.39 ± 0.10 for BW and 0.24 ± 0.08 for WW205, with a genetic correlation of 0.80 ± 0.12 between both traits. Repeatability was 0.41 ± 0.15 for BW and 0.33 ± 0.15 for WW205. The model solutions allowed the estimation of breeding values for each trait, and these results were subjected to a principal component analysis (PCA). The first two eigenvectors were used as weighting factors in a selection index. It was observed that the PCA-based index would yield only a slight improvement compared with the independent use of breeding values; however, the high correlation between traits limits the response. It is recommended to use PCA as a complementary tool to build selection indices for the traits evaluated in this Charolais population, although studies with larger populations are still needed.