Research Article

Genetic diversity and assessment of 23 microsatellite markers for parentage testing of Santa Inês hair sheep in Brazil

Published: May 08, 2012
Genet. Mol. Res. 11 (2) : 1217-1229 DOI: https://doi.org/10.4238/2012.May.8.4

Abstract

Santa Inês is the most common hair sheep breed in Brazil and probably has the highest genetic diversity among sheep breeds in this country. Successful breeding programs for Brazilian sheep breeds are not common for various reasons, including a lack of control of parentage in the flocks. We developed an allele frequency database for 23 STR loci for the Santa Inês breed based on 285 animals sampled from five populations distributed across the central-western and north-eastern regions of Brazil. The marker set included seven microsatellites used in the 2011 International Society for Animal Genetics sheep genotyping comparison tests and all eight microsatellites currently approved by the Brazilian Agricultural Ministry laboratory accreditation guidelines for sheep identification. The microsatellites had an average of 10 alleles and a mean expected heterozygosity of 0.745. Combined paternity exclusion probabilities when no parent or one parent was known were >99.99%. A small proportion (5.8%) of the existing genetic variation was found to be among the Santa Inês populations, possibly derived from genetic drift and selection. We found that the marker panel proposed by the Agricultural Ministry, although generally useful, should be enhanced by including more markers for improved exclusionary power in parentage testing. This database provides a useful tool for parentage testing of this major Brazilian breed, contributing to improved management and breeding of existing herds.

Santa Inês is the most common hair sheep breed in Brazil and probably has the highest genetic diversity among sheep breeds in this country. Successful breeding programs for Brazilian sheep breeds are not common for various reasons, including a lack of control of parentage in the flocks. We developed an allele frequency database for 23 STR loci for the Santa Inês breed based on 285 animals sampled from five populations distributed across the central-western and north-eastern regions of Brazil. The marker set included seven microsatellites used in the 2011 International Society for Animal Genetics sheep genotyping comparison tests and all eight microsatellites currently approved by the Brazilian Agricultural Ministry laboratory accreditation guidelines for sheep identification. The microsatellites had an average of 10 alleles and a mean expected heterozygosity of 0.745. Combined paternity exclusion probabilities when no parent or one parent was known were >99.99%. A small proportion (5.8%) of the existing genetic variation was found to be among the Santa Inês populations, possibly derived from genetic drift and selection. We found that the marker panel proposed by the Agricultural Ministry, although generally useful, should be enhanced by including more markers for improved exclusionary power in parentage testing. This database provides a useful tool for parentage testing of this major Brazilian breed, contributing to improved management and breeding of existing herds.