Genome-wide Association Study of First Service Conception Rate in Brangus Heifers using Probit, Robit and Logit models

Thursday, August 21, 2014
Posters (The Westin Bayshore)
Sunday O Peters , Berry College, Mount Berry, GA
Kadir Kizilkaya , Adnan Menderes University, Aydin, Turkey
Dorian J. Garrick , Iowa State University, Ames, IA
Rohan L Fernando , Iowa State University, Ames, IA
James M Reecy , Iowa State University, Ames, IA
Ikhide G Imumorin , Cornell University, Ithaca, NY
Milton G. Thomas , Colorado State University, Department of Animal Sciences, Fort Collins, CO
Abstract Text:  First Service Conception (FSC) is an important trait in cattle reproduction. Genome-wide association study (GWAS) was conducted using BayesC probit, robit and logit model and marker genotypes from the Bovine SNP50.  Yearling heifers were estrus synchronized, A.I and pregnancy verified by ultrasound. Model treated SNP effects as random with an assumed fraction pi=0.9995 having no effect on phenotype. Fixed effects were year, location of birth, calving season, dam age and contemporary group. Results showed there was concordance among the three models for 9 out of the 15 top SNP windows associated with variation in the phenotype. The concordant regions were found on chromosomes 1, 6, 8, 16, 23 and 26 and they explained 10.9% of the variance. Seventy positional candidates were identified within 1Mb upstream and downstream of the flanking SNP  but only 34 were expressed in the pre and post pubertal hypothalamic transcriptome.