AS many as half of the nation’s sheep producers are playing with danger, researchers now say – and the results could well prove tough to swallow.
They claim that in the pursuit of lean lamb, many stud breeders have inadvertently culled intramuscular fat – the key trait for tenderness – raising the risk of a consumer backlash.
Stud breeders and commercial producers were taken aback by this revelation, announced at the final Sheep Co-operative Research Centre grower update in Glen Innes last Wednesday.
Meat and Livestock Australia (MLA) sheep geneticist, Dr Alex Ball, Armidale, told the gathering the correlation between fat covering (PFAT) and intramuscular fat (IMF) was far greater than anybody had imagined – in fact, three times greater than the link in beef.
“Up until three months ago we (the industry) didn’t know what it was doing (to tenderness),” he said.
The data had come straight out of the sire nucleus (comprising every bloodline available to commercial producers), half of which fell within the dry-eating-to-tough territory.
The sire nucleus had provided the data for researchers to collate the eating quality of 190 sires from 2007 to 2008.
And this had potentially wide implications for commercial breeders.
“There is not a bloodline you can buy this year we don’t know about,” Dr Ball said.
From previous studies the industry had found the best eating lamb contained between 4.4 per cent and 5.1pc IMF, with lower concentrations requiring more shear force (ie, chewing).
“Anything less than four per cent and consumers will call it tough and anything less than 4.3pc is getting a little dry – half the sire nucleus falls into this territory,” Dr Ball said.
“If you want to know how tough four is, take off your boot and bite the end of it.”
One sire had returned a 3.7pc IMF.
Dr Ball said the trend was potentially damaging.
“Consumer surveys tell us if someone eats a tough piece of lamb they won’t try it again for six months,” he said.
The findings would perhaps resonate with terminal sire users most, which the study had revealed were “most lean”, with maternal breeds being “less lean” and Merinos the least affected of all.
To gauge how quickly tough lamb could invade the consumer psyche one only had to look at how fast PFAT had declined, Dr Ball said.
In the 10 years from 1999, breeders had increased average liveweights by more than five kilograms and in the process stripped more than two millimetres of fat – or the equivalent of half a fat score.
More research was needed to underscore these findings and help the industry produce a better product.
The Sheep CRC would this year sample the loin and topside of 750 lambs to test what consumers thought in relation to what laboratory testing had revealed in terms of tenderness and shear force.
Dr Ball said in most cases correlations were manageable – especially in terms of PFAT and IMF.
The Sheep CRC was working to release information in July to help the production of lean, moist lamb, including an Australian Sheep Breeding Value for IMF and shear force, and part of this process would see studs restrict the use of some bloodlines that were at risk.
As a rule of thumb Dr Ball said he and his fellow researchers did not want breeders selecting PFAT less than -1 “and we would prefer it to be -0.5 or greater”.
“Consumers might start to find problems in those sires that are moving down toward that -2 PFAT.
“At the moment there aren’t any problems for consumers.”
Sheep CRC chief executive officer, Graham Truscott, Armidale, said the IMF breed value had been long awaited but was still timely.
“We’ve probably caught it in time and now we have the parameters to work with to maintain the tenderness of our lamb,” he said.
“We don’t want to scare the industry into thinking we’re heading down a path into dry, tough lamb, we can prevent that from happening.”
Other good news was research into the heritability of positive gains in essential fatty acids, zinc and iron.
Email a friend