Abstract :
At present, the Assaf is the main dairy sheep in Spain. The Spanish Assaf (Assaf.E) was
formed by male-mediated absorption of native Spanish sheep. Here we assess the genetic
relationships among the Assaf.E andmajor native Spanish dairy breeds using microsatellites
to contribute to the knowledge of the formation and within-population genetic variability
of the breed. Blood samples from 44 unrelated Assaf.E individuals from 23 different
Assaf.E flocks spread throughout 6 different Spanish provinces were obtained and genotyped
using 14 microsatellites. Up to 312 additional samples belonging to the Awassi and
Milchschaf sheep breeds and to six native Spanish dairy sheep breeds (Castellana, Churra,
Latxa, Manchega, and Rubia de El Molar) as well as samples from Merino individuals to be
used as the outgroup were also analysed observed (Ho) and expected (He) heterozygosity,
rarefacted number of alleles per locus and distances based on molecular coancestry information
were computed. Probabilities of assignment of the Assaf.E individuals to native
Spanish dairy sheep breeds and cryptic genetic structure in the whole dataset were also
assessed. It can be concluded that the Assaf.E breed has low genetic variability and high
genetic distance with respect native Spanish dairy sheep breeds. From our results, the formation
of the Assaf.E breed basically occurred via the absorption of individuals belonging to
the Entrefino type, particularly to the Castellana and Manchega populations. Furthermore,
Churra individuals may have participated in the formation of the Assaf.E breed at an early
moment of the introduction of the breed into Spain.
