Estimation & Prediction

Breed, Heterosis, Recombination, and Genomic Information Effects on EPD-Based Ranking of Tropical Composite Beef Cattle

---

Abstract

Montana Tropical is a composite beef breed designed to produce beef under extensive grazing conditions, in tropical and subtropical environments based on exploitation of the complementarity between breeds and retained heterosis. The animals breed composition was computed grouping them into four biological types: N (Bos indicus animals), A (Bos taurus animals adapted to the tropical environment), B (Bos taurus/British origin) and C (Bos taurus/continental origin). The objective on this paper was to compare 10 different models, considering the inclusion of effects: M1: No breed group composition; M2: the same as M1, with genomic information; M3: direct and maternal breed group effect, direct and maternal heterosis; M4: the same as M3, including genomic information; M5: Same as in 3 plus breed group specific recombination; M6: same as M5, including genomic information; M7: Same as M5, plus breed specific heterosis; M8: same as M7, including genomic information; M9: including direct and maternal breed group effect, specific direct and maternal heterosis and recombination; M10: same as M9 including genomic information of 3.912 animals. The dataset analyzed had 126,424 observations on weaning (WW), post weaning weight gain (PWG), and yearling weights (YW), while the pedigree data has 188,000 animals and analysis used BLUPF90 family programs to estimate EBVs. The models were compared by the Spearman correlation among estimated ted breeding values of animals for these traits. correlations among the 9 models compared with the most complete one, M10 were: WW: varied from 0.94251 (M1 and M2), 0.95352 (M3), 0.98531 (M4), 0.95615 (M5), 0.96961 (M6), 0.96074 (M7), 0.99200 (M8) and 0.96799 (M9). Considering PWG, the correlations were: 0.80099 (M1 and M2), 0.85420 (M3), 0.97203 (M4), 0.84960 (M5), 0.96768 (M6), 0.86063 (M7), 0.97544 (M8) and 0.87031 (M9). The Spearman correlations among EBVs for YY were: 0.92064 (M1 and M2), 0.95290 (M3), 0.99668 (M4), 0.95074 (M5), 0.99540 (M6), 0.95432 (M7), 0.99692 (M8) and 0.95828 (M6). Ranking correlations between breeding values predicted with the different models were higher for WW, followed by YW and lower for PWG. The WW trait was the most robust, showing the lowest sensitivity when breed composition was included in the model, whereas PWG was the most sensitive. Higher model parameterization without genomic adjustment for relationship tends to cause greater instability in ranking due to less accurate estimation of fixed effects, as specific recombination among biological types are limited in the dataset. The inclusion of genomic information resulted in a significant increase in the ranking correlation with the more comprehensive model, highlighting the importance of this variable in improving the model's accuracy. Overall, incorporating breed composition, heterosis, and recombination effects modified the ranking of all traits, emphasizing the importance of assessing their influence in selection decisions for breeding programs in composite cattle.

Keywords: 2026

How to Cite:

Ferraz, J. B., Baldi, F., Medeiros, G., de Mattos Oliveira, E., Giacomini, G., Nuñez-Dominguez, R., Espigolan, R. & da Gama, L. T., (2026) “Breed, Heterosis, Recombination, and Genomic Information Effects on EPD-Based Ranking of Tropical Composite Beef Cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2284204. doi: https://doi.org/10.31274/wcgalp.23556

Rights: 1