Abstract
The objective of this study was to perform a genome-wide association study (GWAS) to detect chromosome regions associated with indicator traits of sexual precocity in Nellore cattle. Data from Nellore animals belonging to farms which participate in the DeltaGen® and Paint® animal breeding programs, were used. The traits used in this study were the occurrence of early pregnancy (EP) and scrotal circumference (SC). Data from 72,675 females and 83,911 males with phenotypes were used; of these, 1,770 females and 1,680 males were genotyped. The SNP effects were estimated with a single-step procedure (WssGBLUP) and the observed phenotypes were used as dependent variables. All animals with available genotypes and phenotypes, in addition to those with only phenotypic information, were used. A single-trait animal model was applied to predict breeding values and the solutions of SNP effects were obtained from these breeding values. The results of GWAS are reported as the proportion of variance explained by windows with 150 adjacent SNPs. The 10 windows that explained the highest proportion of variance were identified. The results of this study indicate the polygenic nature of EP and SC, demonstrating that the indicator traits of sexual precocity studied here are probably controlled by many genes, including some of moderate effect. The 10 windows with large effects obtained for EP are located on chromosomes 5, 6, 7, 14, 18, 21 and 27, and together explained 7.91% of the total genetic variance. For SC, these windows are located on chromosomes 4, 8, 11, 13, 14, 19, 22 and 23, explaining 6.78% of total variance. GWAS permitted to identify chromosome regions associated with EP and SC. The identification of these regions contributes to a better understanding and evaluation of these traits, and permits to indicate candidate genes for future investigation of causal mutations.
Highlights
Reproductive traits, including female sexual precocity, are directly associated with the profitability of beef cattle production systems. [1], studying economic values for reproductive traits, found that these traits can be up to 13 times more important than growth traits
The objective of this study was to perform genome-wide association study (GWAS) to detect chromosome regions associated with indicator traits of sexual precocity in Nellore cattle using a single-step method
The single nucleotide polymorphism (SNP) windows obtained in the second iteration that explained the highest proportion of variance can be observed in Figs 1 and 2, where Manhattan plots are shown for the traits early pregnancy (EP) and scrotal circumference (SC), respectively
Summary
Reproductive traits, including female sexual precocity, are directly associated with the profitability of beef cattle production systems. [1], studying economic values for reproductive traits, found that these traits can be up to 13 times more important than growth traits. Indicator traits of sexual precocity, such as the occurrence of early pregnancy of heifers and scrotal circumference, are obtained more in the herd since they are part of routine data collection and can be used as selection criteria. These traits can be measured in a large number of animals and show high heritability [5,6,7,8], they are sex-limited traits. These evaluations are costly and increase the generation interval, reducing annual genetic gain
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
