Love me tender, genetically

By PHILIPPA STEVENSON

Don't blame or credit the chef. That steak is liable to be tough or tender because of the breed of cattle it came from.

AgResearch Ruakura scientist Dr Chris Morris says a gene in cattle, known as Calpain 1, is responsible for meat tenderness.

A six-year research trial by AgResearch and Adelaide University has discovered the tenderness gene in Jersey-Limousin-cross cattle.

It follows year-old US research which showed the gene in Piedmontese-Angus-cross cattle.

Dr Morris said finding the tenderness gene in different breeds and crosses suggested it was likely to be present in many cattle breeds. That promised major benefits for the New Zealand meat industry, he said.

"Farmers may be able to breed the gene into their cattle herds, enabling a bull carrying two copies of the gene to produce offspring with more tender meat. This in turn would allow a meat processing plant to reduce the time required for chilled storage of steaks before sale, or produce more tender steaks if they are stored for the usual time."

Richmond chief executive John Loughlin said it suggested opportunities for greater value from meat rather than cost reductions.

"It could give a marketing edge if the reliability of product could be increased," he said.

"A lot of our steer beef is already reliable in terms of tenderness. That's why it is very popular with chefs, particularly in Asia. But the world's consumers get more demanding every year and certainly anything we can do to improve the tenderness, and the reliability of the tenderness really is a value creator."

The Ruakura trial, in which 400 Jersey-Limousin-cross cattle were treated the same way, showed that Calpain 1 was responsible for just over 20 per cent of the differences in tenderness measured in a large sample of the animals' steaks.

"Clearly there are other genes controlling tenderness and this is only one of them. So we've still got more work to do but it's a good start," Dr Morris said.

"It's just one piece in the puzzle, but nevertheless a very significant first step in finding the causes of meat tenderness. Those involved in the table beef industry in New Zealand are likely to be very excited at implications of this discovery."

He said the Calpain 1 gene had two forms, one for tough and one for more tender beef. Both forms may already be widespread in New Zealand beef cattle, although it was not known at what frequency either gene version occurred.

"We already know two breeds likely to have lots of the tender form and two likely to have the tough form; so we need to analyse the other common beef breeds in New Zealand to find the relative frequency of the tough and tender form in those breeds."

Dr Morris declined to say which of the breeds tested in the trials had the tough form but said the frequency of the tender form could be raised in cattle by increasing the number of bulls carrying the tender gene in herds.

There are about 40 beef breeds in New Zealand, but fewer than 10, including Angus, Hereford, Charolais, Limousin, Simmental, Piedmontese, Belgian Blue and Shorthorn, account for over 90 per cent of the table beef consumed.

AgResearch is to offer a DNA test which will enable farmers or breeders to identify carriers of the tender gene.

Bulls carrying two copies of the tender gene would produce more tender offspring but animals with one copy of the gene would also influence meat tenderness.

Calves or yearlings that carry at least one copy of the tender form of the gene would be better prospects for the fresh meat trade. Animals carrying no copies of the tender form could be consigned to the hamburger trade, Dr Morris said.

The presence of the tender gene in an animal could not substitute for management practices that might also lead to a more tender product. However, animals otherwise treated alike during grazing, trucking and slaughter were more tender if they carried the gene, he said.

Dr Morris said the actual purpose of the gene was to break down structural proteins during the life of an animal. Calpain 1 gene codes for part of a protein called microcalpain, which is one of a family of proteins known as proteases. Their role during an animal's life meant that after slaughter they continued to reduce the structural integrity of meat, or tenderise it.