Estudo de associação entre microssatélites localizados no cromossomo OAR3 e características de crescimento e resistência aos nematódeos gastrintestinais em ovinos

Abstract

The sheep production has been growing surprinsingly in the last years in Brazil, but in despite of this, it can not be considered competitive yet, principally because the lack of structure and organization of the sector. Among the problems faced by the Brazilian sheep producers we could cite the gastrointestinal parasites and the relatively low productivity of the native breeds when compared with the exotic ones. The knowledge of the genetic factors controlling these traits can help in the improvement of then without impair the correlated traits. Through molecular biology and statistical technics is possible to identify genes/chromosomal regions associated with these traits and once the region is confirmed as really important in the control of the characteristic this information could be used in breeding programs through marker assisted selection. Many regions were identified as candidate for growth and nematode resistance traits in sheep and other ruminants, and among of them is the Q arm of the sheep chromosome OAR3. Because of this, the aim of this study was to investigate three microssatelite markers located in the Q arm of the OAR3 and its relationship with growth and nematode resistance traits in sheep from three genetic groups: Santa Inês X Santa Inês, Dorper X Santa Inês e Suffolk X Santa Inês. The association analysis revealed two alleles of the BL4 marker with significative effect in the Santa Inês x Santa Inês genetic group and one allele form the same marker with significative effect in the genetic group Dorper x Santa Inês on birth weight. It was also observed one allele from the BL4 marker associated with slaughter weight in the Santa Inês x Santa Inês genetic group. We did not observe any association between the markers studied and nematode resistance. Our results suggest that there are one or more genes in the studied region related with growth traits, but more studies are required to confirm the importance of this region in the control of these traits and to identificate the candidate genes.