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Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress
Author(s) -
Dikmen S.,
Wang X.z.,
Ortega M.S.,
Cole J.B.,
D.J.,
Hansen P.J.
Publication year - 2015
Publication title -
journal of animal breeding and genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 51
eISSN - 1439-0388
pISSN - 0931-2668
DOI - 10.1111/jbg.12176
Subject(s) - single nucleotide polymorphism , respiration rate , snp , biology , heat stress , genome wide association study , thermoregulation , genotype , zoology , genetics , respiration , endocrinology , gene , botany
Summary Dairy cows with increased rectal temperature experience lower milk yield and fertility. Rectal temperature during heat stress is heritable, so genetic selection for body temperature regulation could reduce effects of heat stress on production. One aim of the study was to validate the relationship between genotype and heat tolerance for single nucleotide polymorphisms ( SNP s) previously associated with resistance to heat stress. A second aim was to identify new SNP s associated with heat stress resistance. Thermotolerance was assessed in lactating Holsteins during the summer by measuring rectal temperature (a direct measurement of body temperature regulation; n = 435), respiration rate (an indirect measurement of body temperature regulation, n = 450) and sweating rate (the major evaporative cooling mechanism in cattle, n = 455). The association between genotype and thermotolerance was evaluated for 19 SNP s previously associated with rectal temperature from a genomewide analysis study ( GWAS ), four SNP s previously associated with change in milk yield during heat stress from GWAS , 2 candidate gene SNP s previously associated with rectal temperature and respiration rate during heat stress ( ATPA 1A and HSP 70A ) and 66 SNP s in genes previously shown to be associated with reproduction, production or health traits in Holsteins. For SNP s previously associated with heat tolerance, regions of BTA 4, BTA 6 and BTA 24 were associated with rectal temperature; regions of BTA 6 and BTA 24 were associated with respiration rate; and regions of BTA 5, BTA 26 and BTA 29 were associated with sweating rate. New SNP s were identified for rectal temperature ( n = 12), respiration rate ( n = 8) and sweating rate ( n = 3) from among those previously associated with production, reproduction or health traits. The SNP that explained the most variation were PGR and ASL for rectal temperature, ACAT 2 and HSD 17 B 7 for respiration rate, and ARL 6 IP 1 and SERPINE 2 for sweating rate. ARL 6 IP 1 was associated with all three thermotolerance traits. In conclusion, specific genetic markers responsible for genetic variation in thermoregulation during heat stress in Holsteins were identified. These markers may prove useful in genetic selection for heat tolerance in Holstein cattle.