Americans' increasing demand for lean beef produced without supplemental growth hormones is adding significance to an Australian discovery.
Researchers at Adelaide University have identified a gene that explains a large increase in retail beef yield. It is a modification of the myostatin gene called �myostatin F94L,� and it frequently occurs in Limousin cattle but rarely in other breeds. The scientific journal Animal
Genetics published the research this summer.
The modified gene explains a large proportion of the Limousin breed's advantage in retail yield, earning the �Limousin muscling gene� moniker. It is not the same modification of the myostatin gene that causes double muscling and lowered fertility in some breeds. Additionally, the F94L variation does not have any adverse effects on birth weight or calving ease.
�This discovery raises the prospect of a commercial genetic test for significant muscularity,� said Kent Andersen, Ph.D., executive vice president for the North American Limousin Foundation (NALF). �That is good news for Limousin and Lim-Flex� breeders and commercial cattle producers because they could use F94L to select for the efficient production of lean red-meat yield, and the associated benefits are economically important in today's marketplace.�
While myostatin F94L is not the only gene that influences retail beef yield, it has a large effect. Homozygous animals have 13 percent larger ribeye areas (REAs) and 4 percent more total retail yield.
The gene's high-yielding form occurs in 83 percent of the Limousin breed � compared to 3 percent in Belgian Blue, 0.6 percent in Angus, and zero in Hereford and Jersey. That means 68 percent of Limousin animals are homozygous for the trait and 28 percent are heterozygous.
�This gene appears to explain a much larger proportion of the genetic variation of the trait than any of the currently available gene markers for marbling, tenderness or feed efficiency,� said Alex McDonald, general manager of the Limousin society in Australia. �The discovery of what appears to be a major gene, which can be used to increase retail beef yield in all breeds of cattle throughout the world, is an exciting breakthrough.�
McDonald added negotiations are underway with an Australian laboratory to provide a commercial genetic test for the F94L modification.
