17 November 2000

Muscle gene work

AN MLC-funded project looking at variation in the myostatin gene, which affects muscle development in some breeds of cattle and sheep, is under way at Roslin Institute.

This gene results in exaggerated muscling, most frequently seen in Belgian Blues, says project leader John Williams. He says that a mutation of the gene fails to stop muscle development at an appropriate point.

"This muscling also appears in South Devon cattle, but it is not as extreme. Examining this, we have found that when there is one copy of this deleted gene then South Devons show an increase in muscling and a decrease in fat, which is an advantage.

"However, when two copies of this deleted gene are present there is slightly more muscle growth and more associated problems with calving."

This phenomenon has occurred because in South Devons extra muscling has not been selected for, as premiums for this are small in Great Britain, says Dr Williams.

Consequently, most breeders have selected for easy calving rather than muscling and currently about 40% of South Devon cattle carry the gene. This compares with Belgian Blue cattle, where the trait has been heavily selected for and it is 100% heritable. As a bonus it improves meat tenderness, he says.

"Belgian Blue meat is very tender because there is more muscle fibre and less fat." But he adds there is a cost to this, through calving difficulties and associated losses.