RESUMO
Conservation and improvement strategies in farm animals should be based on a combination of genetic and phenotypic characteristics. Genotype data from 30 microsatellites were used to assess the genetic diversity and relationships among five Cuban cattle breeds (Siboney de Cuba, Criollo Cubano, Cebú Cubano, Mambí de Cuba and Taíno de Cuba). All microsatellite markers were highly polymorphic in all the breeds. The expected heterozygosity ranged from 0.67 ± 0.02 in the Taíno de Cuba breed to 0.75 ± 0.02 in the Mambí de Cuba breed, and the observed heterozygosity ranged from 0.66 ± 0.03 in the Cebú Cubano breed to 0.73 ± 0.02 in the Siboney de Cuba breed. The genetic differentiation between the breeds was significant (p < 0.01) based on the infinitesimal model (F(ST)). The exact test for Hardy-Weinberg equilibrium within breeds showed a significant deviation in each breed (p < 0.0003) for one or more loci. The genetic distance and structure analysis showed that a significant amount of genetic variation is maintained in the local cattle population and that all breeds studied could be considered genetically distinct. The Siboney de Cuba and Mambí de Cuba breeds seem to be the most genetically related among the studied five breeds.
Assuntos
Cruzamento , Variação Genética , Repetições de Microssatélites/genética , Animais , Bovinos , Conservação dos Recursos Naturais , Cuba , Heterozigoto , FilogeniaRESUMO
The bovine transferrin gene (TF) is located at 125 cM on bovine chromosome 1 (BTA1); it codes for transferrin, a glycoprotein that is highly conserved in many species and that is responsible for iron transport. The TF gene has been located in several QTL regions, and some transferrin classes have been associated with fat and milk yields. We analyzed by means of allele-specific oligonucleotide real-time PCR the c.1455A>G SNP in exon 12 of the TF cDNA sequence (accession number U02564), which induces an Asp/Gly substitution at position 469 of the peptide. The c.1455A>G SNP was assayed in eight Spanish cattle breeds, as well as in two groups of Holstein-Friesian animals that had the highest and lowest estimated breeding values for milk fat yield. Analysis of the cSNP showed balanced frequencies in all breeds, with a mean of 0.44. Evaluation of a potential association between the cSNP and the groups of Holstein-Friesian animals selected for milk fat yield showed a significant association (P < 0.0006); the G allele was associated with high fat production. Significant differences in genotypic frequencies between the groups were also detected (P < 0.0028). These results lead us to suggest that the TF gene has an effect on milk fat yield.