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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #315432

Research Project: Improving Genetic Predictions in Dairy Animals Using Phenotypic and Genomic Information

Location: Animal Genomics and Improvement Laboratory

Title: Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress

Author
item Dikmen, Serdal - Uludag University
item Wang, Xian-zhong - Southwest University
item Ortega, M. Sofia - University Of Florida
item Null, Daniel
item Cole, John
item Hansen, Peter - University Of Florida

Submitted to: Journal of Animal Breeding and Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2015
Publication Date: 7/21/2015
Citation: Dikmen, S., Wang, X., Ortega, M., Null, D.J., Cole, J.B., Hansen, P.J. 2015. Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress. Journal of Animal Breeding and Genetics. 132(6):409-419.

Interpretive Summary: Dairy cows with increased rectal temperature during heat stress experience lower milk yield and reduced fertility. Because rectal temperature during heat stress is heritable, genetic selection for regulation of body temperature should reduce the effects of heat stress on production and reproduction. The goals of this study were to validate the relationships between heat tolerance and DNA markers previously related to resistance to heat stress, as well as to identify new DNA markers related to resistance to heat stress. Thermotolerance was studied by measuring rectal temperature (a direct measurement of body temperature regulation), respiration rate (an indirect measurement of body temperature regulation), and sweating rate (the major evaporative cooling mechanism in cattle) in 455 lactating Holstein cows during the hottest part of the day in summer. DNA markers previously related to heat tolerance on chromosomes 4, 6, and 24 were related to rectal temperature, regions of chromosomes 6 and 24 were associated with respiration rate, and regions on chromosomes 5, 24, and 29 were associated with sweating rate. New markers were identified for rectal temperature (n=12), respiration rate (n=8), and sweating rate (n=3), including markers in the CAST and PGR genes related to rectal temperature, the ARPL61P and TSHB genes related to respiration rate, and the SERPINE2 gene, related to sweating rate. These genetic markers may prove useful in genetic selection for heat tolerance in Holstein cattle.

Technical Abstract: Dairy cows with increased rectal temperature during heat stress experience lower milk yield and fertility. Given that rectal temperature during heat stress is heritable in dairy cattle, genetic selection for regulation of body temperature should reduce effects of heat stress on production. One goal of the study was to validate the relationship between genotype and heat tolerance for SNPs previously related to resistance to heat stress. A second goal was to identify new candidate gene SNPs related to resistance to heat stress. Thermotolerance was assessed in 435-455 lactating Holstein cows during the hottest part of the day in summer by measuring rectal temperature (a direct measurement of body temperature regulation), respiration rate (an indirect measurement of body temperature regulation) and sweating rate (the major evaporative cooling mechanism in cattle). Thermotolerance was related to genotype for 19 SNPs previously related to rectal temperature from a genome-wide analysis study (GWAS), 4 SNPs previously related to change in milk yield during heat stress from GWAS, 2 candidate gene SNPs previously related to rectal temperature and respiration rate during heat stress (ATPA1A and HSPA1A/HSPA1B) and 66 SNPs in candidate genes that were previously related to reproduction, production or health traits in Holsteins. For SNPs previously related to heat tolerance in GWAS, regions of BTA4, BTA6 and BTA24 were related to rectal temperature, regions of BTA6 and BTA24 were associated with respiration rate and regions on BTA5, BTA24 and BTA29 were associated with sweating rate. New candidate gene SNPs were identified for rectal temperature (n=12), respiration rate (n=8), and sweating rate (n=3). Among these SNPs were ones for CAST and PGR, related to rectal temperature, ARPL61P and TSHB, related to respiration rate, and S SERPINE2, related to sweating rate. These genetic markers may prove useful in genetic selection for heat tolerance in Holstein cattle.