Estudos genômicos aplicados ao melhoramento genético de bovinos

Abstract

The search for increasingly productive seedlings has led to the use of different tools, among them, the use of molecular markers in genetic improvement. However, since the cost of the genotyping technique is still considered high, an alternative is the use of the imputation technique (prediction of genotypes not interrogated in genotyping). Thus, in the first chapter of this dissertation, genotypes of Nellore animals were analyzed with the objective of evaluating the potential of imputation of 3K and 7K panels, both customized. For the imputation, the FImput program was used. The panels were produced from markers that passed the quality control, considering the distance between markers and those with higher allele frequency. The results demonstrated that the use of customized panels for imputation of markers can be applied to achieve values of at least 90% accuracy. The customization of the 3K and 7K panel together with the imputation technique can contribute to improve the cost-benefit of the use of genomic studies in animal breeding. In the second chapter, a broad genomic association study (GWAS) was carried out, using imputed data from Canchim animals, aiming to identify genes associated with navel length, coat and scrotal circumference phenotypes. GWAS was performed using Bayesian inference using the GenSel program. Thirty-one regions were found in association with umbilicus length, one coat region and four EC-related regions. In these regions, quantitative loci (QTLs) and genes related to the characteristics studied were identified. The identification of genes and QTLs, previously described in the literature, reinforce the evidence of association. This knowledge may contribute to the understanding of the genetic architecture involved in the expression of these characters in Canchim cattle.