Pinpointing the chromosomal location of the “slick” gene identified by Agricultural Research Service (ARS) scientists could help breeders develop cattle with shorter, slick hair that helps keep them cool in the subtropical heat.

In central Florida, excessive summer heat can take its toll on cattle, leading to reduced milk production from dairy cattle and higher death rates among beef cattle. But the discovery of the slick gene by scientists at the ARS Subtropical Agricultural Research Station (STARS) in Brooksville, Florida, should help deal with these heat-related issues.

Breeders could move the gene into other economically important breeds, such as Holstein, to improve their heat tolerance. The black-and-white Holstein is the world’s top-producing dairy animal. The typical Holstein herd produces more than 21,000 pounds of milk, 775 pounds of butterfat and 683 pounds of protein per year. Studies at Brooksville led by animal scientist Chad Chase have shown slick-haired animals to have internal temperatures about 1ºF lower during the summer than other cattle with normal hair coats.

Mapping the gene’s location on the chromosome is the first step towards identifying the mutation responsible for the shorter, slick hair. Chase and his STARS team have found a strong association between at least two closely positioned markers on chromosome 20 and the slick-haired phenotype. Microsatellite markers were used in these studies.

These results suggest a role for marker-assisted selection to identify bulls that will produce only slick-haired progeny. Some Senepol bulls were tested using these markers, and the results indicated excellent potential for identifying bulls that will produce only slick-haired offspring. The same gene also appears to be responsible for the slick-hair coat in Romosinuano cattle.   PD

—Excerpts from USDA Agricultural Research Magazine, August 2008

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