The Spanish Merino is the most important worldwide breed due to be the origin of all the Merino and Merino‑derived breeds. Its genetic improvement began with the Roman people in the Iberian Peninsula with a clear selection objective: the fineness of the wool. However, in the last six decades, it has been common practice in Spain to cross animals from this breed with other breeds with greater meat aptitude in a clear change of the selection criteria resulting in the existence of a large ovine population (Merine‑type) which remains out of the official flock-book. Nevertheless, there are still herds considered as historical strains that maintain the ancestral genetics and are therefore registered as pure. In the present work, 13,484 animals belonging to the Donoso, Granda and Hidalgo historical genetic lines, together with animals registered as pure in the flock-book and animals from the Merino Negro lineage were genotyped with 19 microsatellite markers for their genetic characterization. The Correspondence Factor Analysis (CFA) and the analysis of inferring the population structure showed a clear genetic differentiation between each of the strains that, except for the Granda line, most of the animals were correctly classified to their group. On the other hand, the variability values showed that the populations do not present risk of genetic drift despite many centuries of closed-matted flocks. The results obtained showed that the historical Merino strains, due to their purity and genetic "healthy", are the optimal basis for the "remerinization" of the national sheep population, which for decades has been losing the identity that made the Spanish Merino the most valuable livestock breed in the world.

Anaya G., Granero A., Alcalde M.J. (en prensa). Situación genética de las principales líneas puras del merino español. ITEA‑Información Técnica Económica Agraria. Vol. xx: YY-YY. https://doi.org/10.12706/itea.2023.020