Marble score doesn't have to come at a cost to carcase

With that comes new skills that can filter back down the supply chain to the benefit of the commercial producer - no matter what breed grazes on the farm.

At Gloucester this two-pronged approach has yielded commercial qualities that lead the field. A crop of calves born in the drought and finished on feed for more than 400 days delivered the consistently highest marble score for their brand Jack's Creek. At the same time, carcase weight ticked the box for retail buyers.

Processing and feedlot manager with Jack's Creek, Victor Rixon, said the ability to maintain marbling while growing out a carcase would add value to any breed.

"In Wagyu there is a heavy focus on marbling and of course that's a key focus," he said. "But the customer wants a decent carcase."

A bell curve plotted over a typical Jack's Creek cohort of 200 steers yields an average marble score of 7.5, ranging from 4 and 5 to 8 and 9. Average carcase weights are 420kg with a yield of 58 per cent.

At Gateway Wagyu there was an early investment in a bull that shows a combination of those desirable traits - Sumo Michifuku F154, bred by now deceased veterinarian and world Wagyu pioneer Dr Simon Coates. This horned full-blood cross of Tajima and Shimane blood lines show the ability to go both ways with an average 8.6 marble score and 462kg over 21 analysed carcases.

Back in South Africa Gateway director Carl Erasmus used to breed water buffalo to supply paying hunters for a prize and recalled breeding for traits that tended to be naturally opposed - like horn width versus "boss", or skull plate. Nature usually provides one aspect or the other but by carefully selecting for traits the Erasmus family achieved their goal of providing both.

"There's no such thing as a bargain when it comes to breeding," says Mr Erasmus. "Success is not guaranteed. You've got to push on."

Livestock research officers at the Animal Genetics and Breeding Unit, part of the University of New England at Armidale and partnered with DPI, continue to develop their estimated breeding value program for Wagyu, as they do for all the commercial breeds they study.

"At the most basic level trying to breed for two traits is as simple as selecting on each," explained a spokesperson. "In the case of Wagyu, they seem to have a useful amount of data driving their carcase and marbling EBVs, so getting increases in both seems like an achievable thing if the two EBVs are used appropriately, even though the natural relationship might be for more marbling in smaller carcases.

"The success of this selection is, however, a direct function of the amount of data that is recorded and used in the genetic analysis to drive the EBV estimation. If low amounts of data are recorded for one or both traits, then it will be harder to drive them in different directions."

"Is the marble score EBV highly accurate? That depends on from what angle you are asking," said the spokesperson.

"At the individual animal perspective that depends on the data that is driving its EBVs.

"If a bull has a number of progeny recorded for carcase marbling, they will have a higher accuracy for their marbling EBV than a bull that has no progeny recorded for marbling.

"At the breed level it depends on how many records the breed's evaluation contains for marbling. It also depends on accuracy."

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