Variabilidad genética en rasgos de interés económico en sementales Holstein en Panamá y Estados Unidos

A total of 4898 observations were analyzed for milk in 305 days (L305), services for gestation (SG) and interval between calving-to-gestation (PG) of 1699 Holstein cows calving between 1996 and 2023 under the Panamá environmental conditions, daughters of 898 mothers and 225 sires from which 171 had their breeding value (BV) available in the USA. The database was analyzed using a multicharacter animal model, the heritability estimates (h2) for L305, SG and PG of 0.19±0.10, 0.06±0.16, 0.11±0.10, while repeatability were s 0.23±0.10, 0.091±0.08 and 0.13±0.10 respectively. The GBVs for each trait in Panama, as well as for the BVs in the common sires in the USA, expressed in a standardized way, were analyzed by Principal Component Analysis and the indices (Iimp) and (Iexp) were formed using the corresponding coefficients of the eigenvalues as a weighting factor. The correlation between the estimated BV in Panama and the USA was 0.02, while it was 0.19 between Iexp and Iimp. This indicates the existence of antagonism and therefore the existence of genotype-environment interaction between milk production and reproductive behavior in the conditions of Panama with respect to the USA. It is concluded that the selection of sires and introduction of semen in the tropics in general and more specifically in Panama should receive greater attention in the breeding strategies of the region.