The Armidale-based researcher, who was speaking at the recent Beef CRC Maternal Efficiency Project update at Struan, says producers will buy heavily muscled sires to progress their herds, but in their replacement females are only looking at maternal traits rather than also placing some emphasis on carcase traits.

"We have a tendency to have females produce a calf and grow that calf as quickly as possible, but are not really interested in selecting females for meat quality traits," he said.

"We should be selecting cattle for all traits including meat yield."

Within breeding herds strong emphasis is placed on fertility and weight gain but Mr McKiernan, who has been researching muscling in beef cattle since the early 1980s, said increased muscling can have a far greater benefit to producers' bottom line.

A five per cent improvement in fertility or weight gain produced only a 6-7pc increase in gross margin per cow, compared with selling progeny with a higher muscle score which can lead to a 24pc boost in gross margin.

Analysis of the two to three million cattle sold through saleyards across Australia each year has shown buyers are paying a premium of between 15 and 25c/kg for animals with more muscle content.

Mr McKiernan said there was still a misconception from the early introduction of the European breeds, that heavily muscled cattle were associated with calving troubles, and there has been a lot of difficulty differentiating between muscling and masculinity.

But in his long-time research he has found muscle score is a direct reflection of meat yield, and there is no drop in overall fertility or growth rate breeding from higher muscled females.

The only differences are the progeny of the higher muscled cattle are half a frame score smaller than the lower muscled cattle, and are slightly leaner at the 10th rib.

"If animals are the same size and grow at the same rate there is a fair bit of efficiency to be gained at the farm level and you are satisfying the market better at the end of the day," he said.

To date Mr McKiernan says there has been no difference in calving ease using heavy muscled bulls over high muscle females, but he said it had taken a long time to achieve good divergence between the high and low muscle female groups.

He said he was confident there was no weight difference at weaning of the progeny from high and low muscle females or time for the high and low muscle females to get back in calf, but would need another calving season to confirm calving ease in heifers.

Mr McKiernan said one of the major hurdles with breeding for muscling was producers were not financially rewarded in over the hooks selling, despite the advantages in the boning room with a larger percentage of high value hindquarter cuts from higher muscled cattle.

He said the processing industry still needed to be convinced of the value of investing in technology such as VIASCAN to measure eye muscle area in carcases, but was confident it would eventually be adopted in line with grading systems in Europe and the United States.

"The US has had a quality grade and yield grade for many years and now we have quality grades in Australia with MSA, yield grading will be the next step," he said.

Mr McKiernan's latest research project is investigating the effect of the Myostatin gene (the gene for double muscling) by mating high muscle females to Myostatin carrier bulls, and Myostatin carrier females to high muscle bulls.

It complements the Beef CRC III's Maternal Efficiency Project, which is looking at another determinant of meat yield, levels of fatness and its affect on maternal performance in two research herds at Struan Research Centre and Vasse in Western Australia.