Meat from cattle having two copies of the myostatin gene. This cut has more meat, less fat, and less marbling than meat from cattle having no copies or one copy of the gene. Click the image for more information about it.

Read the magazine story to find out more.

Sorting Out the Genes Behind Leaner Beef

A lean cut of beef, low in saturated fat, that's also flavorful and tender? Sound too good to be true?

It may not be, according to animal scientists and geneticists with the Agricultural Research Service who are studying cattle genes that may contribute to leaner cuts of beef. They've been especially interested in a gene that codes for the protein known as myostatin.

Myostatin limits muscle growth in mammals, including humans. But when the gene responsible for producing the protein is altered or suppressed somehow, the result is enhanced muscle growth and reduced fat deposition. Researchers achieve this muscularity in cattle through selective breeding strategies.

Scientists at the ARS Meat Animal Research Center (MARC) in Clay Center, Neb., have found that a key benefit of inactivated myostatin in cattle is the creation of beef that's tender and lower in saturated fat. All cuts of beef from cattle possessing the inactivated myostatin have improved tenderness, according to MARC food technologist Tommy L. Wheeler.

Despite the promise of breeding systems that manipulate myostatin, researchers are aware of possible drawbacks. When animals inherit copies of the altered myostatin gene from both parents--instead of just one--they are born with a condition that's known as double-muscling.

Double-muscled animals often require additional birthing assistance and sometimes Caesarean delivery, according to MARC animal geneticist Timothy P.L. Smith. These cows may also experience reduced fertility and lower stress tolerance.

ARS researchers, including Michael D. MacNeil, an animal geneticist at the agency's Fort Keogh Livestock and Range Research Laboratory in Miles City, Mont., are looking to other breeds--like Limousin and Charolais--that are also well-muscled and trim. These cattle may achieve their lean physiques through the collective action of several genes, each exerting a small effect.

Read more about the research in this month's issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.