Chris Cummins, owner of Breakout River Meats, Cowra, NSW, recently condemned the "lanky" and "wayward" direction the lamb industry had taken in the last decade.

But this week he said results from a five-year study that could potentially increase the muscle mass in lambs by up to 10pc and decrease fat content by up to 20pc, was "needed change".

"The push for more muscle is a big plus as we need to thicken our carcasses up," Mr Cummins said.

"You can liken a lamb to an inch by an inch and a quarter rubber band that they have stretch out to an inch and a half.

"They have lost the middle, leg and forequarter and they need to wind the clock back."

Mr Cummins said he was cautious of pushing fat too low, sighting that some lambs were already difficult to fatten.

"You can't have good meat without some fat," he said.

The five-year study conducted between Department Primary Industries, The Australian SheepGenomics program and scientists at Utah State University in Logan, USA, identified pathways that affect muscle growth and leanness in a rare naturally occurring mutation in a sheep found in the United States known as Callipyge.

Callipyge sheep have a naturally occurring genetic mutation that results in a dramatic increase in leanness and mass across the muscle groups at the hind end of the sheep.

DPI scientists believe there is potential to mimic these desirable traits in Australian sheep breeds to increase the leanness and overall weight of the animal.

Project research scientist Dr Matthew Knight, DPI, Attwood, said the study identified the specific muscling pathways identified in Callipyge sheep in a range of British breeds trialed in the study.

Once the gene was identified the second phase of the project manipulated the diet of lambs to ascertain increase in muscle and decrease in fat.

"I was not surprised to find increased muscling, but the amount of the increase was probably a bit higher than we expected," Dr Knight said.

While unable to divulge the ration mix, Dr Knight said lambs were fed on pellets with supplements for eight weeks.

The next phase of the work will be to trial lambs in the paddock in feeding trials.