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Rounding Up The Genes For Twinning In Cattle

Beef and dairy producers who want to control twinning rates may soon get some help. Researchers have identified three regions of the cattle genome that contribute to an increased frequency of double ovulation in the animals.

“Our work has now confirmed the existence of at least one gene on cattle chromosome 19 that affects ovulation rate,” says Brian Kirkpatrick, a University of Wisconsin-Madison animal geneticist who led the study. “We also have strong evidence for genes with similar effects on chromosomes 5 and 7.”

Kirkpatrick, Becky Byla and Keith Gregory published their research in a recent issue of Mammalian Genome. Kirkpatrick and Byla are with the Department of Animal Sciences in the College of Agricultural and Life Sciences. Gregory is now retired from the USDA Meat Animal Research Center in Clay Center, Neb.

The frequency of twinning is typically about 1 percent in beef herds and about 4 percent in dairy herds. Although environmental factors and the age of cows both affect twinning, multiple births are in large measure under the control of genes, according to Kirkpatrick. His goal is to identify genes that increase double ovulation and twinning in cattle.

The research is leading to DNA tests so producers can accelerate the development of herds with a high or low frequency of twinning. Later this summer Kirkpatrick expects to offer producers the first DNA test to detect animals with a high frequency of twinning.

“Our new DNA test specifically identifies the form of chromosome 19 associated with high ovulation rate,” he says. Cows that test positive for that DNA have about a 10 percent chance of producing twins at each birth. The forms of chromosomes 5 and 7 that the researchers identified can increase twinning frequency by a total of another 13 percent.

Kirkpatrick knows that most producers aren”t interested in seeing more twins. Twins often create extra problems for cows during pregnancy and calving. Twin calves are more likely than singl