HERDBOOK ANALYSES OF THE ASTURIANA BEEF-CATTLE BREEDS

Data from 2 Asturiana breeds' herdbooks were analysed to study their genetic structure. Herds were assigned to 3 levels by the use of herd sires. Generation intervals averaged 5.3 (Casina) and 5.4 (Carrenana) yr, and for both breeds sires were significantly younger than dams. Determination of the important herds shows the contribution of Caso county (60%) to the total herd appearance of the Casina breed. The overall mean Wright's inbreeding coefficients were 1.2 and 0.2% and the increases of inbreeding level per generation were 0.7 and 0.24% for Casina and Carrenana, respectively. Those low values of inbreeding increase can be partially explained by a relatively low centralization reflecting a high degree of diversity.