STUDY OF ALLELIC AND GENOTYPIC FREQUENCIES OF LOCI ASSOCIATED WITH CARCASS CHARACTERISTICS EVALUATED BY ULTRASONOGRAPHY IN NELORE ANIMALS.

• Grant number: 25/01225-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Josineudson Augusto Ii de Vasconcelos Silva
• Grantee: Maria Gabriela Sanches Lopes
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Research into meat and carcass quality in Nelore cattle is still limited and challenging, as these traits are polygenic and difficult to measure. Several candidate genes, such as DGAT1, CAPN5, TG and MADH3, have previously been associated with meat quality in taurine breeds. Identifying these genes and estimating their allelic (fa) and genotypic (fg) frequencies in the Nelore breed will provide valuable information for understanding the phenotypic variation of individuals and selecting sires with the potential to improve meat and carcass quality in the breed. This study will use genotypic and phenotypic data from 9,789 Nelore animals (85% bulls) belonging to the Nelore Qualitas® Genetic Improvement Program. The traits ribeye area, subcutaneous fat thickness of the loin and hip and marbling, measured by ultrasonography, will be associated with SNPs in order to identify animals with superior performance for these traits. Data analysis will be carried out using the programs R, for data preparation, descriptive statistics, analysis of results and graphic visualization, and PLINK v1.9, for quality control of SNPs and calculation of fa and fg. Quality control will consider the criteria: Hardy-Weinberg equilibrium assessed by the chi-square test (¿², p < 0.05), call rate below 90% and minor allele frequency (MAF) below 5% for excluding SNPs and removing animals with pedigree conflicts. Candidate genes will be identified using genomic information from the Gene database (2020) and validated using the National Center for Biotechnology Information (NCBI). In addition to generating relevant results for genetics and the improvement of meat quality in the Nelore breed, the project will encourage the academic development of the student, promoting her initiation into scientific research. The findings obtained will be submitted to scientific events and published in an international journal of relevance in the field.