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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING GENETIC MERIT OF RUMINANTS THROUGH GENOME SELECTION AND ANALYSIS

Location: Animal Genomics and Improvement Laboratory

Title: The SLICK Locus derived from Senepol cattle confers thermotolerance to Intensively-Managed lactating Holstein cows

Authors
item Dikmen, Serdal -
item Khan, Firdous -
item Huson, Heather -
item Sonstegard, Tad
item Moss, James -
item Dahl, Geoffrey -
item Hansen, Peter -

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2014
Publication Date: N/A

Interpretive Summary: The SLICK haplotype in cattle confers animals with a short and sleek hair coat. Originally, identified in Senepol cattle, the gene has been introduced into Holsteins. Holsteins with slick hair had superior thermoregulatory ability as compared to non-slick animals and experienced a less drastic depression in milk yield during the summer. Results support the utility of introgression of the SLICK haplotype for reducing the impact of heat stress on dairy production.

Technical Abstract: The SLICK haplotype in cattle confers animals with a short and sleek hair coat. Originally, identified in Senepol cattle, the gene has been introduced into Holsteins. The objectives of the current study were to determine whether lactating Holsteins with the slick phenotype have superior ability for thermoregulation as compared to wild-type cows or half-siblings not inheriting the SLICK haplotype and whether seasonal depression in milk yield would be reduced in slick cows. In the first experiment, diurnal variation in vaginal temperature in the summer was monitored for cows housed in a free-stall barn with fans and sprinklers. Vaginal temperatures were lowest in slick cows, intermediate in siblings and highest in wild-type cows. In the second experiment, acute responses to heat stress were monitored after cows were moved to a dry lot in which the only heat abatement was shade cloth. The increase in rectal temperatures and respiration rates caused by heat stress during the day was lower for slick cows than siblings or wild-type cows. Moreover, sweating rate was higher for slick cows than cows of the other two types. In the third experiment, effects of season of calving (summer vs. winter) on milk yield and composition were determined. Compared with winter, milk yield during the first 90 days in milk was lower for cows calving in the summer. However, this reduction was less pronounced for slick cows than wild-type cows. In conclusion, Holsteins with slick hair have superior thermoregulatory ability as compared to non-slick animals and experience a less drastic depression in milk yield during the summer. Results support the utility of introgression of the SLICK haplotype for reducing the impact of heat stress on dairy production.

Last Modified: 10/22/2014
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