This study aimed to analyze genetic diversity in a conservation nucleus of Santa Inês sheep using thirteen microsatellite loci on chromosome 20 (where the Sheep Major Histocompatibility Complex - Ovar-MHC - is found). Seventy three animals from one herd born from 2004 to 2006 were evaluated as a principal nucleus. Seventy one animals from two other herds were used as control comparison. There was a reduction in heterozygosity over the years in relation to the whole population. This may be due to the repeated use of the same sires. The estimates of molecular coancestrality also indicated an increase in genetic similarity between individuals with the herd over the years. A high number of alleles occurred exclusively in the principal nucleus herd, but with a frequency lower than 10%. The Ovar-MHC region of chromosome 20 was shown to be highly polymorphic. Monitoring of the herd over time should be implemented as additional tool for genetic management within the herd.
animal genetic resources; genetic diversity; Ovar-MHC; Ovis aries; molecular coancestrality; SSR
