Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 2012
Publication Date: June 28, 2012
Citation: Dikmen, S., Cole, J.B., Null, D.J., Hansen, P.J. 2012. Genomic evaluation of rectal temperature in Holstein cattle. Journal of Dairy Science. 95(Suppl. 2):401(abstr. 327). 2012. Technical Abstract: Heat stress negatively impacts the production, fertility, and health of dairy cattle. Rectal temperature (RT) has unfavorable genetic correlations with production, longevity, economic merit, and somatic cell score in Holstein cows. The objectives of the current study were to perform a genome-wide association study (GWAS) for rectal temperature in dairy cows under heat stress conditions, and to determine if single nucleotide polymorphisms (SNP) are associated with genes related to heat stress. Rectal temperature was measured between 1500 and 1700 h in 5,590 lactating Holstein cows sired by 3,322 bulls during the summer in north central Florida. Rectal temperature averaged 38.8 ± 0.57 degrees C, and ranged from 37.0 to 41.6 degrees C. The model included fixed effects of parity; random effects of herd-year, animal, and permanent environment; and regressions on temperature-humidity index and test-day milk yield. The pedigree included 886 animals with Illumina BovineSNP50 BeadChip (Illumina, Inc., San Diego, CA) genotypes. After SNP edits for call rates < 0.90, minor allele frequencies < 0.05, and Mendelian conflicts, 30,0018 markers remained. Genotypes for nine animals were dropped due to low call rates. (Co)variance components and breeding values were calculated using the AIREMLF90 and BLUPF90 software packages from the University of Georgia (Athens). The GWAS was performed with a one-step procedure as implemented in the POSTGSF90 software. The heritability and repeatability of RT were 0.06 and 0.22, which is lower than recent estimates, possibly because most sires had only a few daughters with records and pedigree ties were limited. The 20 SNP with the largest solutions were examined to determine if they were located in or near genes that could account for heat stress effects. Five SNP were located in introns: C1H21orf59 on Bos taurus autosome (BTA) 1, INADL on BTA3, ZNF335 on BT13, VPS13 on BTA16, and FTO on BTA18. The third-ranked SNP was located in an exon of CCT6B on BTA12. These results will help identify genes involved in physiological responses to heat stress. Additional phenotypes are needed to improve estimates SNP effects.