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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING GENETIC PREDICTIONS IN DAIRY ANIMALS USING PHENOTYPIC AND GENOMIC INFORMATION

Location: Animal Improvement Programs

Title: Genome-wide association mapping for identification of quantitative trait loci for rectal temperature during heat stress in Holstein cattle

Authors
item Dikmen, S -
item Cole, John
item Null, Daniel
item Hansen, P -

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 6, 2013
Publication Date: July 23, 2013
Citation: Dikmen, S., Cole, J.B., Null, D.J., Hansen, P.J. 2013. Genome-wide association mapping for identification of quantitative trait loci for rectal temperature during heat stress in Holstein cattle. PLoS One. 8(7):e69202.

Interpretive Summary: Heat stress negatively affects the production, fertility, and health of dairy cattle. One possible way to reduce the harmful effects of heat stress is to select individuals that are genetically resistant to heat stress. Most of the negative effects of heat stress on animal performance are a consequence of either physiological adaptations to regulate body temperature or the adverse consequences of failure to regulate body temperature. Selection for ability to better regulate body temperature during heat stress could increase thermotolerance. In the current study, a genome-wide association study for rectal temperature (RT) during heat stress in lactating Holstein cows identified several DNA markers that are associated with genes that may have large effects on RT. The largest proportion of variance (7 to 44%) was consistently explained by markers flanking the region between 28,877,547 and 28,907,154 bp on Bos taurus autosome (BTA) 24, which is flanked by the U1 spliceosomal RNA and NCAD genes. The SNORA19, RFWD2 and SCARNA3 on BTA 16 were also important, as were regions on BTA 16 (close to CEP170 and PLD5), BTA 5 (near SLCO1C1 and PDE3A), BTA 4 (near KBTBD2 and LSM5), and BTA26 (located in GOT1). These markers may prove useful in genetic selection for thermotolerance, and for identification of genes involved in physiological responses to heat stress.

Technical Abstract: Heat stress negatively affects the production, fertility, and health of dairy cattle. One strategy to reduce the magnitude of heat stress is to select individuals that are genetically resistant to heat stress. Most of the negative effects of heat stress on animal performance are a consequence of either physiological adaptations to regulate body temperature or the adverse consequences of failure to regulate body temperature. Thus, selection for regulation of body temperature during heat stress could increase thermotolerance. The objective of the current study was to perform a genome-wide association study (GWAS) for rectal temperature (RT) during heat stress in lactating Holstein cows and identify SNPs associated with genes that have large effects on RT. Records on afternoon RT where the temperature-humidity index was > 78.2 were obtained from 4,447 cows sired by 220 bulls, resulting in 1,440 useable genotypes from the Illumina BovineSNP50 BeadChip with 39,759 SNP. For GWAS, 2, 3, 4, 5, and 10 adjacent SNP were averaged to identify consensus genomic regions associated with RT. The largest proportion of variance (7 to 44%) was consistently explained by markers flanking the region between 28,877,547 and 28,907,154 bp on Bos taurus autosome (BTA) 24. That region is flanked by a U1 spliceosomal RNA (28,822,883 to 28,823,043) and NCAD (28,992,666 to 29,241,119). In addition, the SNP at 58,500,249 bp on BTA 16 explained 7.6% and 10.6% of the SNP variance for 1- and 2-SNP analyses, respectively. That contig includes SNORA19, RFWD2 and SCARNA3. Other SNPs associated with RT were located on BTA 16 (close to CEP170 and PLD5), BTA 5 (near SLCO1C1 and PDE3A), BTA 4 (near KBTBD2 and LSM5), and BTA26 (located in GOT1). In conclusion, there are QTL for RT in heat-stressed dairy cattle. These SNPs could prove useful in genetic selection for thermotolerance and for identification of genes involved in physiological responses to heat stress.

Last Modified: 4/16/2014