|Ortega, M Sofia - University Of Florida|
|Denicol, Anna - University Of Florida|
|Hansen, Peter - University Of Florida|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2015
Publication Date: 7/12/2015
Citation: Ortega, M., Denicol, A., Null, D.J., Cole, J.B., Hansen, P.J. 2015. Single nucleotide polymorphisms in specific candidate genes are associated with phenotypic differences in days open for first lactation in Holstein cows. Journal of Dairy Science. 98(Suppl. 2)/Journal of Animal Science 93(Suppl. 3):648–649(abstr. W85).
Technical Abstract: Previously, a candidate gene approach identified 51 single nucleotide polymorphisms (SNP) associated with genetic merit for reproductive traits and 26 associated with genetic merit for production in dairy bulls. We evaluated association of the 77 SNPs with days open (DO) for first lactation in a population of Holstein cows grouped based on predicted transmitting ability for daughter pregnancy rate (DPR): <= -1 (n=1220) and >= 1.5 (n=1053), and located in 11 farms in Florida and California. Cows were genotyped using Sequenom MassARRAY®. To evaluate phenotype, farm records were retrieved and complemented with records from the national evaluation system. The association of the genetic variants with days open was evaluated using the MIXED procedure of SAS V9.4 (SAS Institute, NC). The model included farm, number of copies of the minor allele and the pedigree relationship matrix to account for relationships among animals. For each SNP, genotype was considered as a categorical variable to estimate additive and heterosis effects. Days open was lower (P<0.0001) for cows in the high DPR group as compared to the low DPR group (97.8 +-2.6 d vs 163.0 +-2.9 d). There were 6 SNPS with significant additive effects (P<0.05) on DO (COQ9, FCER1G, FST, GPLD1, MRGPRF and OCLN) and an additional 6 SNPS with a tendency (P<0.10) for an association (ACAT2, CD14, PCCB, PMM2, RABEP2 and SREBF1). For example, DO for cows with 0, 1 or 2 copies of the minor allele for COQ9 averaged 139.4 +-3.5, 134.3 +-2.8 and 123.6 +-3.5 d, respectively. The DO for cows with 0, 1, or 2 copies of the minor allele for FST averaged 124.9 +-3.3, 134.8 +-2.6 and 135.8 +-4.4 d, respectively. For 9 of 12 genes, the favorable allele for DO was also the favorable allele in the earlier report for DPR. SNP related to genetic and phenotypic estimates of fertility are likely to be good markers for genetic selection. Moreover, study of the role of the genes could lead to new insights into physiological regulation of fertility in dairy cattle (USDA AFRI 2013-68004-20365).