Copyright (c) 2024 Revista investigaciones agropecuarias
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The results of 84222 records of Test Day (TD) belonging to 1390 daughter of 72 Holstein (Ho) sires and their crosses with Brown Swiss (Bs) (proportion between 50 and 100% of Ho) restricted to those Ho sires with at least 2 progeny and 10 TD both in pure breed and in each of at least two crosses. A quadratic multiracial random regression model (RAMR) was applied to estimate the evolution of the (co)variance components, and genetic parameters of TD along the lactation. Heritability (h2) results were h2 ? 0.12 to 0.25 in the different crosses in the lactation trajectory, while genetic correlations were positive between pure and crossbred animals, but different from unity. With the solution of this model, the breeding values (BV) of each animal were estimated, which were expressed as deviation (dVG) from the BV of pure Ho, with dVG and the corresponding coefficients of additivity (adi) and dominance (dom) a system of equations was created whose solution provided the BVadi and BVdom for each animal. This will be useful in breeding programs where there are animals of different proportions of genes from parental breeds, since it would allow the general and specific combinatorial ability of these breeds to be exploited. The small size of the available data sets precludes a generalization of this alternative, it’s suggested other studies to corroborate the procedure applied.
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