Robert Hodgkins  -  Using genomic selection technology to advance the development of a ovine maternal breeding line

South of England Agricultural Society

31 year old Sheep farmer from West Sussex.

Locks Farm is a tenanted 1,400 acre farm, most of which is situated within the South Downs National Park. 90% of our grassland in permanent pasture and is the farmed under the South Downs ESA regime where no fertiliser or chemical is permitted, therefore there is very little we can do to manipulate or extend our grazing season.

Productivity of some of the swards would be considered very low – the ESA agreement stipulates an annual maximum stocking rate of 3 ewes per acre. The farm rises up to 783ft above sea level, and field contours range from flat ground at home to steep banks upon the downs.

We are large commercial family run sheep farm running 3000 plus NZ Romney ewes. The farm is a spread out unit (25 miles round trip to visit every flock) on good to mediocre grassland, land class 3-5. We operate a single breed, closed flock and take great care and interest in selecting future progeny to make shepherding as enjoyable and stress free as possible.  We are one of the largest Signet recorded flocks in the country, single sire mating and recording over 1500 ewes and there progeny per year.  We sell high quality, NZ Romney rams and females, this year we have sold around 110 2 tooth rams, and all of the breeding females (800+) we had for sale.

Nithdale Genetics

Farm using Gene markers to advance Romney Breed

Posted by Robert Hodgkins on November 26, 2012

Appears in Livestock

Nithdale Genetics is a Romney and Suffolk Stud owned By Heather and Andrew Tripp the farm covers an area of around 1450ha with an effective grazing area of 1400ha, carrying around 7300 Sheep with a separate Dairy herd and Parlour.

They have invested substantial capital in new DNA technology, for example although they lambed commercial ewes on the hill un-shepherded for a number of years, until 2009 they had lambed stud ewes in the paddocks so as to tag lambs and determine the dams parentage. Because of DNA parenting technology they made the decision to lamb them on the hill un-shepherded also. By blood testing sires and ewes it enabled them to determine the parentage of the lambs through their own DNA. This approach reflected more what many clients were doing yet still enabled performance recording of stock to occur.

As mentioned previously there is a gene (predominately) in the Texel breed that has been shown to increase lean meat yields on a Carcass. In 2005 after extensive research the genes responsible was discovered and a blood test was released.  This test is called Myomax.  

Sheep identified with the MyoMAX gene tend to display increased muscling in the leg and loin, less carcass fat and an improved carcass weight compared to their contemporary’s. A lamb that receives one copy of the gene will have 5% more muscling in the leg and loin and 7% less carcass fat. An animal with Myomax from both parents will have up to 10% more muscling and 14% less carcass fat.

In 2007 Nithdale began work to introduce the Myomax genes into the Romney breed to increase its attractiveness as a dual purpose animal whilst retaining the core Romney traits of high maternal ability and low shepherding requirements.   In other words a sheep that effectively has the all the traits traditionally bred for in the Romney with the meat traits of the Texels.  Because all Lambs were being DNA tested for parentage anyway it was only a small incremental cost to apply the Myomax test as well. 

A Texel was crossed with high index Romney ewes and all the progeny were blood tested to see who was carrying the gene.  Those who were carriers where breed back to a Romney and again the progeny was tested, over the generations by testing for the presence of the double muscling gene and then back crossing to a Romney.  The objective was to breed a sheep that is 7/8 — 15/16 Romney with two copies of the Myomax gene.

This process was expected to take at least 17 generations as to move forward each generation had to not only carry a copy of the gene but be tested for maternal ability, and survival in the harsh climate and minimal shepherding environment.

Since the launch of the Pfizer 50K chip in 2010 Rams carrying the Myomax gene are routinely tested via the 50K chip, by increasing the accuracy on desirable traits Rams fulfilling the criteria can be identified much earlier in their life meaning you can work them easier with a higher degree of confidence.  It also means you are less likely to use Rams who are not suitable due to poor core Romney Traits. Moving to 50K has enabled the Tripps to significantly reduce the amount of time they think they will need to fully ingrate the Myomax gene, by using superior ram lambs much earlier in their life to speed up genetic gains and take years off the process.



Recent posts

Mark Swift

Dorper and Cropping enterprise

Posted by Robert Hodgkins on November 21, 2012

Appears in Crops, Livestock