|OLIVEIRA JUNIOR, GERSON - Universidade De Sao Paulo|
|PEREZ, BRUNO - Universidade De Sao Paulo|
|SANTANA, MIGUEL - Universidade De Sao Paulo|
|SILVEIRA, JULIANO - Universidade De Sao Paulo|
|GIANLUCA, MAZZONI - University Of Copenhagen|
|VENTURA, RICARDO - University Of Copenhagen|
|JUNIOR, MARIO - Universidade Federal De Mato Grosso|
|KADARMIDEEN, HAJA - University Of Denmark|
|GARRICK, DORIAN - Iowa State University|
|FERRAZ, JOSE BENTO - Universidade De Sao Paulo|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2017
Publication Date: 11/9/2017
Citation: Oliveira Junior, G.A., Perez, B.C., Cole, J.B., Santana, M.H., Silveira, J., Gianluca, M., Ventura, R.V., Junior, M.L., Kadarmideen, H.N., Garrick, D.J., Ferraz, J. 2017. Genomic study and Medical Subject Headings enrichment analysis of early pregnancy rate and antral follicle numbers in Nelore heifers. Journal of Animal Science. 95(11):4796-4812. https://doi.org/10.2527/jas2017.1752.
Interpretive Summary: Zebu cattle, such as Brazilian Nelore beef cattle, are adapted for performance in hot climates under low-input production systems. However, they achieve reproductive maturity later and have lower fertility than breeds adapted to temperate climates, such as Holstein dairy cattle. This paper describes research that used DNA marker information to identify regions of the genomes of Nelore cattle associated with heifer pregnancy rate and antral follicle count. Cows that are able to produce many healthy follicles and become pregnant earlier in life are more profitable, and knowledge of the genes and chromosomal regions associated with those traits may be useful for better understanding fertility in high-producing dairy cows.
Technical Abstract: Zebu animals (Bos indicus) are known to take longer to reach puberty when compared to taurine animals (Bos taurus), limiting the supply of animals for harvest or breeding and impacting profitability. Genomic information can be a helpful tool to better understand complex traits, and improve genetic gains. In this study, we performed a Genome-wide association studies (GWAS) to identify genetic variants associated with reproductive traits. Genes in linkage disequilibrium with the associated variants can be used in functional enrichment analysis using medical subject headings (MeSH), in order to identify biological mechanisms involved in fertility. The estimated heritabilities for heifer pregnancy (HP) was 0.28±0.07 and for number of antral follicles (NF) was 0.49±0.09, with the genomic correlation being -0.21±0.29. The average LD between adjacent markers was 0.23±0.01, and GWAS identified genomic windows that accounted for >1% of total genetic variance on chromosomes 5, 14 and 18 for HP and 2, 8, 11, 14, 15, 16 and 22 for NF. The MeSH enrichment analyses revealed significant (p < 0.05) terms associated with HP: “Munc18 Proteins”, “Fucose” and “Hemoglobins”, and with NF: “Cathepsin B”, “Receptors, Neuropeptide” and “Palmitic Acid”. The genomic analyses contributed to a better understanding of the genetic control of the reproductive traits HP and NF and provide new selection strategies to improve beef production.