|Chase, Chadwick - Chad|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 8/16/2007
Publication Date: 2/6/2006
Citation: Olson, T.A., Chase, C.C., Marasegaram, M., Lucena, C., Godoy, E. 2006. A history of the evaluation of the slick hair gene [abstract]. Journal of Animal Science Supplement.84(2):Paper No. 34.
Technical Abstract: Study of the Slick hair gene began with determination that Senepol cattle were more heat tolerant than Angus and Hereford cattle. Rectal temperatures of Senepol cattle under heat stress were often 0.5º C lower than Angus and Hereford cattle. Crosses of Senepol with Angus were subsequently found to be similar in heat tolerance to Senepol. Observation that calves of Senepol X Angus crossbred cows generally possessed either the short, sleek hair of the Senepol or normal, longer hair led to the conclusion that a major gene for hair type was responsible. Comparisons of the heat tolerance of slick- and normal-haired 25% Senepol cattle of the same breed composition showed that slick-haired animals were able to maintain rectal temperatures approximately 0.5º C lower than those of normal-haired animals. Also, respiration rates of normal-haired animals were higher (P<0.01) than those of slick-haired animals. In Venezuela, under drylot conditions in a hot, but desert-like environment, 109¾ Holstein: ¼Carora (a Venezuelan slick-haired dairy breed) cows were compared to a group of 110 of their normal-haired paternal half-sisters. The slick-haired cows produced 984kg more milk (P<0.01) in their first lactations and had calving intervals 43 days shorter (P<0.01) than their normal-haired sisters. The rectal temperatures, Respiration rates, and grazing activities of 87.5% Holstein: 12.5% Senepol young bulls, with and without slick hair were evaluated in Florida and the slick-haired sibs gained faster on pasture, maintained slightly lower rectal temperatures and had lower (<0.01) respiration rates than their normal-haired siblings. Recently we mapped the slick hair gene to the bovine chromosome 20 using linkage analysis. We expect a haplotype to be determined soon that can be used as a definitive test for both the slick phenotype and homozygous animals in Senepol and composite populations of slick-haired cattle.