The Rat-tail Riddle

A question at a loading chute last fall elicited some digging into why “rat-tail” calves are discounted by buyers.

Rat-tail calves have short, curly, malformed, sometimes sparse hair and lack tail switch development. They're usually a mouse-gray color. Research shows ranch and feedlot performance are usually lower for rat-tail cattle.

The syndrome is caused by crossing some Continental breeds that have the diluter gene (yellow in color) with cattle that are black in color, says Ron Torell, Nevada Extension livestock specialist.

Simmental × Angus and Simmental × Holstein are the most common crosses producing this congenital defect. To a lesser extent, there is also incidence in Gelbvieh and Charolais crosses.

In one study by Kansas State University and the U.S. Meat Animal Research Center, Clay Center, NE, the rat-tail condition had no effect on birth weight, weaning weight or gain from birth to weaning. However, rat-tail calves had significantly lower rates of gain during the winter months from weaning to yearling, resulting in significantly lighter yearling weight.

Steer gains from yearling to slaughter weren't significantly different, but rat-tail steers were lighter and older at slaughter than non-rat-tail steers.

To prevent rat-tails in a cross breeding program, identify and cull cows that have or have had rat-tail calves. Buy only bulls without the gene. Breed associations have worked hard to identify bulls that are diluter gene free.
— Nevada Extension Coffee Shop extentioncoffeeshop@unr.edu

Targeting T-cells

USDA is betting that genetic research at Montana State University (MSU) will increase knowledge of bovine health relatively soon.

“We think we can make a lot of headway in a short time,” says Mark Jutila of MSU's veterinary molecular biology department.

He plans to target different immune cells than have been studied in the past. This work on a set of newly discovered “T-cells” should zero in on the genes needed to develop new vaccines or breed healthier cattle.

The three-year, $1.8 million research project was the largest animal genome project funded by the USDA competitive grants program this year. It includes the vet medicine programs at the University of Minnesota and Washington State University.

“Once we start to understand the genes that control the function of these cells, specific genetic traits that are important in resistance to infectious disease might be identified that could be followed in breeding,” says Jutila.

Up to 70% of the circulating T-cells in newborn cattle are the “gamma/delta” type, which are distinct from alpha/beta T-cells.

“We know very little about what the gamma/delta T-cell does. Maybe this is why we haven't been able to develop cattle vaccines any faster than we have,” says Jutila.
— Montana State University

Canuk Back Scratchers

Canadian cattle feeders are taking a new look at the effectiveness of back scratchers in cattle pens for controlling cattle lice.

“For most of the year, cattle can generally control lice populations themselves just by grooming,” explains Doug Colwell, Lethbridge, AB. The exception is in the winter when coats get very heavy.” In winter, providing animals with something to scratch on that can penetrate the thicker hair coat, can reduce louse populations.

The idea for a study on back scratchers came from a producer in Saskatchewan who designed and built them after noticing how feedlot pens provide limited access to scratching areas.

“He found that when commonly used insecticides like malathion are used with the back scratchers, louse populations disappeared within 10 days and didn't come back,” Colwell says. “It's an inexpensive way to provide additional control over and above the regular parasite control program.”
— Ag Canada

Compiled by Clint Peck, BEEF Associate Editor. Contributions welcome: 406/896-9068, 406/896-9069 (fax), cpeck@intertec.com.