Breeding Sheep With Myomax

[Newby]

I was sat wondering so I thought I'd stop wondering and ask on here.
Could someone explain please how myomax passes on to progeny from a double carrier and a single carrier tup? And does it make a difference if the ewe is also a carrier? Cheers

 

[Paul E]

I'm sure someone will correct me if I'm wrong..........
The lamb inherits the gene from its parent, but needs 2 copies to express it (1 from each parent) so if both parents have 2 copies the lamb will have it, if parents only have 1 copy each, there is statistically 50% chance of having it.
Obviously if neither parent has it, its a swaledale !!!!!
I don't know if its dominant, like polling, where one polled parent can trump the other one.
Hope this makes sense.

 

[Woolless]

Let me try and get this right: A sheep can have a maximum of two copies of myomax, one inherited from each parent. If a sheep has two copies, then its offspring will definitely have at least one copy. If a sheep has one copy, it has a 50% chance of passing a copy to its offspring. Sheep with one copy will express the gene by carrying approximately 7% more muscle than if it did not carry the gene. A sheep with two copies will carry 14% more muscle. A sheep carrying one copy would be expressed in shorthand as T+T-, two copies T+T+. The possible combinations are:

Tup T+T+, ewe T+T+ = 100% lambs T+T+

Tup T+T+, ewe T+T- = 50% T+T+, 50%T+T-

Tup T+T-, ewe T+T- = 25% T-T-, 50%T+T-, 25%T+T+

What breed are you you working with?

 

[GrannyAching]

As per Mendel. Interesting, great explanation @Woolless . I'v also seen it done with coins where you start with 2 heads up and 2 tails up.

 

[andybk]

isnt myomax a texel meat marker ?(similar to the H in scrapie genotype) , there is another different marker in other breeds (charollais for one ) for extra muscling , in fact the hind leg muscle is a different shape , So myomax isnt necessarily a black and white marker for meat so dont get to hung on breeding for it ,

 

[Woolless]

isnt myomax a texel meat marker ?(similar to the H in scrapie genotype) , there is another different marker in other breeds (charollais for one ) for extra muscling , in fact the hind leg muscle is a different shape , So myomax isnt necessarily a black and white marker for meat so dont get to hung on breeding for it ,

The vast majority of Texels have two copies, one of the reasons they look like Texels I suppose. I think most Charollais have two copies too. @neilo? Some of the big Romney studs in NZ are introgressing it into their sheep. It's not the whole story but it makes a difference.

 

[neilo]

The vast majority of Texels have two copies, one of the reasons they look like Texels I suppose. I think most Charollais have two copies too. @neilo? Some of the big Romney studs in NZ are introgressing it into their sheep. It's not the whole story but it makes a difference.

'Some' Charollais have 2 copies, but a very long way from 'most'. From my investigations/testing over the last 10-12 years, lots of the sheep that have been selected for extreme muscling in the breed, have been carriers. Many of those shown up as having the best hind quarter muscularity on CT scanning (a measurement, rather than a subjective assessment) over the last 20 years, have been carriers. They were selected without the use of DNA test results, as the test wasn't available back then.

There seems to be little appetite for MyoMAX testing or selection in the breed, with very few of us actually doing any work with it. For me, it's a no-brainer. If you can get 10% extra hindquarter fleshing with no obvious detriment elsewhere, then what's not to like?

I might add that the original Rams that I identified with it here (which Innovis used in their trial work to establish that 'extra 10%' stat in their promotional literature when they were selling the gene test) were homebred over several generations, and I can be 100% sure that there was no funny business going on with regards to breed purity. I have no problem with cross breeding at all, so long as they are sold as such. It is a pet hate of mine, when folk sell something that has been 'improved', as something it's not.

It could be suggested that the REALLY valuable genetics are those that have top ranked muscularity, but no MyoMAX. Add 10% to those by using over MyoMAX carrying females for a couple of generations, and you make some real gains.

 

[Woolless]

'Some' Charollais have 2 copies, but a very long way from 'most'. From my investigations/testing over the last 10-12 years, lots of the sheep that have been selected for extreme muscling in the breed, have been carriers. Many of those shown up as having the best hind quarter muscularity on CT scanning (a measurement, rather than a subjective assessment) over the last 20 years, have been carriers. They were selected without the use of DNA test results, as the test wasn't available back then.

There seems to be little appetite for MyoMAX testing or selection in the breed, with very few of us actually doing any work with it. For me, it's a no-brainer. If you can get 10% extra hindquarter fleshing with no obvious detriment elsewhere, then what's not to like?

I might add that the original Rams that I identified with it here (which Innovis used in their trial work to establish that 'extra 10%' stat in their promotional literature when they were selling the gene test) were homebred over several generations, and I can be 100% sure that there was no funny business going on with regards to breed purity. I have no problem with cross breeding at all, so long as they are sold as such. It is a pet hate of mine, when folk sell something that has been 'improved', as something it's not.

It could be suggested that the REALLY valuable genetics are those that have top ranked muscularity, but no MyoMAX. Add 10% to those by using over MyoMAX carrying females for a couple of generations, and you make some real gains.

This is why I have an Easycare family family which I am slowly pushing for eye muscle depth (whilst maintaining ease of lambing etc) plus an unrelated Myomax family.

 

[neilo]

isnt myomax a texel meat marker ?(similar to the H in scrapie genotype) , there is another different marker in other breeds (charollais for one ) for extra muscling , in fact the hind leg muscle is a different shape , So myomax isnt necessarily a black and white marker for meat so dont get to hung on breeding for it ,

As you will know, Texels & Charolais have a similar genetic origin, so given similar selection pressure (for confirmation) there's no reason that similar genetic mutations shouldn't occur in both.
With the physical variation in both breeds, down to selection in different directions by different breeders, I'd question whether there is a definitive hind leg muscle shape in either breed.

There is a suggestion that there is a different myostatin variation in Charollais, but the research work on that at Roslin ran out of steam/funding when the Kiwis patented the MyoMAX test first. I was taking part in that research, providing bloods from many high muscularity sheep, as described by CT scanning in the early days. The sheep that Roslin identified as carrying the 'Charollais' myostatin mutation also carried the same number of copies of the MyoMAX mutation, when I tested them. I'm not convinced that it is necessarily a seperate thing.

 

[NZDan]

It's a gene that's probably floating about in a few breeds. It's been found in Romneys and I owned a Dorper ram who carried it.

 

[Man_in_black]

Sure some Lleyn have the gene too.

 

[Tim W]

Lleyns, Easycare, Exlana,Dorper, Romney, Wiltshires (belonging to a Texel breeder)
----the list goes on. Very few genes are exclusive to a particular breed
With a couple of crosses within a controlled breeding program you could put it into any breed

 

[neilo]

The same gene mutation exists in several cattle breeds, to varying degrees too. I understand South Devons test for it and actively select against it on the assumption that it negatively impacts on maternal calving ease.

Wasn't the mutation first found in humans?

 

[NZDan]

The same gene mutation exists in several cattle breeds, to varying degrees too. I understand South Devons test for it and actively select against it on the assumption that it negatively impacts on maternal calving ease.

Wasn't the mutation first found in humans?

Yes its present in humans, mice, whippets.
Heard a rumour some bloke managed to breed it into some Finns.[emoji6]

 

[neilo]

Yes its present in humans, mice, whippets.
Heard a rumour some bloke managed to breed it into some Finns.[emoji6]

On that point, it should perhaps be noted that it doesn't make an animal well muscled, just more so than it would have been without the mutation. I had an extreme growth rate ram a few years back, that I stopped using as he was just too plain/late maturing. It turns out he was a carrier. Lord knows how poor he'd have been without it.

 

[NZDan]

On that point, it should perhaps be noted that it doesn't make an animal well muscled, just more so than it would have been without the mutation. I had an extreme growth rate ram a few years back, that I stopped using as he was just too plain/late maturing. It turns out he was a carrier. Lord knows how poor he'd have been without it.

14% of f**k all is better than 0% mind. I can tell most of my carriers by sight probably 80% accuracy.

 

[neilo]

14% of fudge all is better than 0% mind. I can tell most of my carriers by sight probably 80% accuracy.

I have a friend that claims he can tell by sight too. He claims that those sheep with short ears are generally carriers......

 

[NZDan]

I have a friend that claims he can tell by sight too. He claims that those sheep with short ears are generally carriers......

With the Finns I find that looking at their bums is generally a good guide. Most of mine are half sibs and sired by single carrier rams so its pretty simple to split them into best half and worst half, there is normally three distinct groups poor, average and good bums. I've never had a carrier in the poor group and never had a non carrier in the good group. Its the middle group that tend to muddle things.

But just to show its not the be all, by current Texel stock sire is ranked 2nd in NZ on SIL (Texels) for Terminal sire index and ranked third for meat yeild index but only carries a single copy of Myomax.

 

[jamie]

I've got some tups to test for myomax. Who is best to do the testing?

 

[Woolless]

https://tlbiolabs.co.uk/