Genetic history of Palas Merino breed during 1930-2003.

Palas Merino breed was homologated in 1960. It developed since 1935 as a population almost isolated in the reproductive point of view, the isolation being total during 1940-1950 and 1970-2003. During its evolution, there were 8 migrations. After each migration, the genetic similitude of the breed with this raised the similitude with previous immigrations being diminished. During 1930-1940 the genetic similitude of the breed with Ramboiullet Merino was of 42.3-40.0%, this being decreased at 2.26% in 1970, disappearing in the breed evolution after this year. The genetic similitude with German Semiprecoce Merino progressively increases after 1930 (14.9%) reaching the value of 47.72% in 1950, and then decreases to the value of 12.78% in 1970. Diminishing the genetic similitude with this breed continued also 1970 reaching the zero value after 1980. Beginning with 1953 Palas Merino suffers the influence of Merino of Stavropol and Caucasian Merino breeds, imported from the former USSR. After1970 Palas Merino has also suffered the influence of Australian Merino breed. It can be shown that the present Palas Merino have cca. 92% of the genes of the population that was homologated in 1960 and 5% from the genes of Australian Merino breed. During the whole studied period (1930-2003) the medium interval between generation was of 4.11 years, being bigger on mother-son and mother-daughter filiations; the selection was made on own performance and mother’s performance (the sheep retained for reproduction consisted of older sheep „good at wool and milk”). The total inbreeding of Palas Merino breed increased from the value of 2.75% in 1940 to 7.24% in 1970, then decreasing to the value of 2.03% in 2003. These data show that during breed’s evolution the practice of inbreeding was systematically avoided.