Focusing on steak marbling

Tuesday, February 17, 2009

Researchers at Iowa State University say beef cattle can be a more efficient link in the food chain simply by managing fat content through selective breeding programs.

According to an ISU animal science professor, as cattle grow, fat is a late-maturing tissue that follows the normal body development of organs, bones and muscle.

Fat is deposited in four places in cattle - internal fat surrounds the organs, seam fat is found between the muscles, subcutaeous fat is just under the hide, and intramuscular fat occurs within the muscle.

The intramuscular fat is generally referred to as marbling and is considered the "taste fat" versus the other three fats referred to as the "waste fat." During the animal's finishing phase, when most of the fat is deposited, 10 pounds of waste fat are deposited for every pound of taste fat. This results in excess fattening because producers often feed cattle longer to ensure the carcass will have enough of the desired marbllng.

The big question then becomes: How does the cattle industry provide adequate levels of "taste fat" without the added expense of "waste fat?"

Carcass data from various cattle breeds show that the genetic correlation between subcutaneous fat and intramuscular fat in finished cattle is low. Researchers then conclude that the two fat deposits are controlled by a different set of genes, making it possible to select cattle with more favorable rates of taste fat relative to waste fat. They've tested this theory as part of the ISU beef cattle breeding project.

Through ultrasound scans, the researchers learned that bulls with increased intramuscular fat and lower levels of subcutaneous fat produced offspring with the same characteristics.

The bottom line, according to the professors, is that cattle producers who want to "manage fat" in their herds can do so.

"They need to identify and feed cattle with the genetic potential for increased intramuscular fat and less subcutaneous fat," said one. "The result will be less feeding just to ensure adequate marbling and lower production costs."

For cattle producers and steak lovers everywhere, this has to be music to the ears.