The “Myomax” gene is a trait carried by the Texel breed, contributing to increased meat yield on shoulders, loins and leg cuts, but is now delivering benefits across all breed types.
Recent research work by AgResearch scientist Patricia Johnson has shown lambs with a double copy of the gene are delivering significantly increased yields to those without the gene.
Long time Southland Romney breeder Andrew Tripp of Nithdale Station in eastern Southland has been involved in identifying the gene since 2005 when the science was still developing. Figures from his commercial flock back up Johnson’s research.
Tripp has stuck with the gene screening process for Myomax as the science was commercialised, and is now delivered through Pfizer Animal Genetic’s MyoMAX technology service.
The IP was originally developed through AgResearch, with Ovita commercialising it prior to being purchased by Pfizer.
While the gene is associated with Texels and composite breeds containing Texel bloodlines, it is also now capable of being detected in more traditional terminal and maternal breeds containing traces of Texel bloodlines, including Romneys, Coopworths and Perendales.
“Our Romneys have gone from a 52% yield through Alliance’s VIAscan grading to 55% and I would say they average one copy each now. We would still be four to five years off a double copy of the gene through the flock,” Tripp said.
Johnson’s research of 1000 lambs involved lambs randomly selected from mobs without information on breed, age or origin available.
Those animals carrying a double MyoMAX gene, known commercially as MyoMAXGOLD, averaged a yield of 58% and those with a single gene averaged 55%, compared to animals with no gene averaging 52.9%.
Tripp estimates it takes a commercial flock around eight years to achieve double copies of the Myomax gene throughout.
With 3000 lambs processed last year, his figures sit closely to those calculated through Johnson’s trial which analysed lambs passing through Alliance’s Lorneville and Mataura plants over 2008-09.
Increasing the frequency of the gene is a simple matter of using more and more double gene sires.
However, Tripp cautions a downside are the genetic faults other Texel genes accompanying the Myomax gene can also bring. These include twisted feet, black spotting in the wool, lower wool production and fertility.
“They are just faults you have to be aware of, and breed out.”
In addition to yield gains, another upside for commercial farmers is a gene that also causes a bald patch around the tail area, helping reduce dags.
The Myomax gene effect can be passed on to lambs through the ram, dam or both, and lambs containing two copies of the mutation in the DNA are shown to be even more likely to benefit from higher yields.
A second part of Johnson’s research compared the incidence of animals with Myomax single gene, versus Myomax double gene.
Only a quarter of the animals had the double and single genes, but over half the mobs had at least one lamb with a Myomax mutation.
However, there was a random diversity to the animals’ genetics, indicating a wide spread of Myomax-Texel genetics within all flocks.
Pfizer Animal Genetics technical manager Sharl Liebergreen said the initial economic benefit to farmers like Andrew Tripp of bringing MyoMAX genetic scanning technology into a flock was valued at $1.90 worth of more meat per lamb in 2006.
“Economic values used in that analysis have changed considerably with the value per kg carcase weight almost doubling over that period, and carcase weights have also increased over that period.
“Cost benefit modelling shows the use of a MyoMAXGOLD ram over commercial ewes without the Myomax gene will produce $3.02 more meat directly to the producer,” he said.
Tripp said the direct gains were exciting to see and he fully expected to achieve the 58% yield figure, after which future gains would be more incremental.
“With our stud clients it has been an education, they used to shy from the Texel content. But with blood testing we know we can breed back to 85-95% Romney with all the positive traits of fertility, wool and worm resistance and get that Texel meat yield factor there.”
