Caracterización de los toros padre evaluados genéticamente en las poblaciones Angus y Hereford de Uruguay

Uruguayan cattle production has undergone a process of transformation since the second half of the nineteenth century with the introduction and consolidation of the Hereford (1864) and Aberdeen Angus (1888) breeds; initially, selection was based on subjective criteria, later incorporating objective information through population genetic evaluations from the 1980s onward, which allowed the estimation of breeding values using Expected Progeny Differences (EPD), although the performance of imported genetics may be affected by genotype × environment (G×E) interaction, since international evaluations do not always consider local production conditions; the objective of this study was to determine the origin of sire bulls of the Aberdeen Angus and Hereford breeds recorded in the population genetic evaluations of INIA Uruguay and to compare their genetic values; for this purpose, data from Genética Bovina (INIA & ARU, 2024a, 2024b) were used and complemented with genealogical records from the Asociación Rural del Uruguay (ARU), reconstructing pedigree trees to identify the country of origin of ancestors and classifying animals according to the combination of origin of their paternal ancestors (sire, grandsire, and great-grandsire), followed by statistical comparison of mean EPDs for several productive traits; in the Angus breed, although 68% of the sires were born in Uruguay, a predominance of foreign ancestry was observed, mainly from the United States and Argentina, with the purely U.S. origin combination showing, on average, the most favorable EPD values for growth and carcass traits, whereas the purely Uruguayan combination showed the best averages for lower birth weight and higher milk ability; in the Hereford breed, a lower diversity of origins and a higher proportion of animals with purely national paternal genetics were observed; the results indicate that most Angus sires show foreign ancestry, although the increasing presence of animals with Uruguayan ancestors and the identification of nationally bred animals with superior EPDs for certain traits demonstrate progress in local genetics and highlight the importance of considering genetic origin according to the specific productive objectives of each production system.