Lambing ease gestation length

[CopperBeech]

It is a gene which was isolated, which adds 0.6 % prolifacy in the next generation. It can also throw over sized singles and infertile ewes.

Excuse my ignorance, what is an Inverdale?

 

[unlacedgecko]

Excuse my ignorance, what is an Inverdale?

It's a prolificacy gene as explained above.

My rams are texel/Cheviot composites from @MJT.

 

[unlacedgecko]

It is a gene which was isolated, which adds 0.6 % prolifacy in the next generation. It can also throw over sized singles and infertile ewes.

Where are you getting this info on oversized singles?

I'm not aware of them being any more predisposed to it than any other breed.

 

[unlacedgecko]

G1 dry ewe hoggs.

100 in the for sale section.

 

[CopperBeech]

Where are you getting this info on oversized singles?

I'm not aware of them being any more predisposed to it than any other breed.

It’s in a couple of papers on the subject. I haven’t got them to hang but seem to remember one of them was by Lincoln university.

I think the more worrying thing was the potential for breeding infertile females though ?

 

[CopperBeech]

If I remember correctly the gene was first identified in a family of Romney’s in NZ, descended from one ewe. About 1984. Over the next five years they found it in her male descendants on the X chromosome. The problem is it’s normally used in ewes to go to a terminal because as said above 1 copy increases prolifacy by 0.6 (ovulation by 1.0) but two copies give small non functional ovaries which render the female infertile and which often end up with tumours developing. Interesting stuff.

 

[George C]

Where are you getting this info on oversized singles?

I'm not aware of them being any more predisposed to it than any other breed.

We have a slightly different version of this gene in our pure Lleyn. It is inherited in exactly the same way.
We test our ewe lambs from carrier ewes so we know who our carriers are.
I have never heard of any problems with big singles and it would be really unusual for a carrier to have a single.
As long as you have decent records and test any rams you want to use who could potentially be carriers, you could manage it without so much testing. Just only use a carrier ram on your least prolific ewes.

 

[CopperBeech]

What’s the point though ? Other than to grade up a closed hill flock to have a better scan %? I would think on most decent commercial flocks suited to most outdoor lambing systems, there wouldn’t be a huge advantage ? Around 180% is probably enough. Lamb survival is by far a more important trait.

 

[George C]

What’s the point though ? Other than to grade up a closed hill flock to have a better scan %? I would think on most decent commercial flocks suited to most outdoor lambing systems, there wouldn’t be a huge advantage ? Around 180% is probably enough. Lamb survival is by far a more important trait.

Without it pure Lleyn can dip below 180%. Having around 1/3 flock carriers keeps my scanning % where I want it.

 

[CopperBeech]

Without it pure Lleyn can dip below 180%. Having around 1/3 flock carriers keeps my scanning % where I want it.

That’s fair. But sure I’d want to be chasing it too much with a composite outdoor maternal flock ? But I suppose folk like it.

 

[gatepost]

Yes. Gestation length and birth weight are highly correlated in both sheep and cattle. Same for birth weight and ease of birth, hence breeding lines selected against birth difficulties (history shows this is generally how it is done) have shorter gestation hence lighter birth weights, as well as physical differences such as wedge shape lambs/calves and dam's pelvic aperture and innate vigour.

Mean lambing dates between same breed sires joined with ewes at the same time can vary by 5 days if not previously selected on anything related to birthing difficulties if not related. Likewise sires from different breeders can vary by a similar magnitude if a breeder has put emphasis on easy birthing while the other have not, irrespective of breed name.

One older NZ Texel ram had outstanding Lamb Survival figures and was exported to the UK. The exporter claimed his progeny were born 4 days ahead of other sires as he was an AI donor sire. Lamb vigour soon makes up for the kilo of extra birth weight when much of the birth trauma is eliminated by slipping out easier.

Thanks, excellent comment, this highlights one of the major problems associated with the wholesale use of ET as a business model in some breeds, maternal traits thrown away, the only assessment made, being visual on ''breed points'' generation after generation.

 

[Global ovine]

Thanks, excellent comment, this highlights one of the major problems associated with the wholesale use of ET as a business model in some breeds, maternal traits thrown away, the only assessment made, being visual on ''breed points'' generation after generation.

With the majority of UK breeders across all breeds not recording, there is a void in data on how good a ram is for passing on the essential trait for Survival.
This is accentuated by the extensive use of Terminal bred sires, selected for carcass traits which sire daughters to be used as crossbred ewes. These represent 58% of all ewes mated compared to 48% of pure breed matings. (see 2020 Pollott report); https://projectblue.blob.core.windo...ef & Lamb/SheepBreedSurvey4295_130821_WEB.pdf

Improving Survival traits reduces costs in labour and vet/medicines and increases output/income. The forecasted reductions and phasing out of production subsidies will act as an incentive to improve this efficiency driving trait.
Those breeders recording and ranking animals now will be establishing a big lead over those who are guardians of the status quo.

 

[unlacedgecko]

It’s in a couple of papers on the subject. I haven’t got them to hang but seem to remember one of them was by Lincoln university.

I think the more worrying thing was the potential for breeding infertile females though ?

I can't find those papers. Post a link when you find them.

Sterile females only occur from an inverdale ram going over inverdale ewes. Simple recording (via ear notching if necessary) can avoid that.

 

[unlacedgecko]

Inverdale x Shetland lambs in for marking. I'm pretty pleased with growth and shape. Ewes currently rearing 138%.

 

[CopperBeech]

This isn’t meant as a dig at @unlacedgecko just in case it sounds like one. Because I’m aware I have an unfortunate tone!

But are not some of these genes, partly now being used to make a sh!t sheep, a better sh!t sheep? Or perhaps just accelerating advancement is a better way to look at it, I know.

But like the myomax thing, you get a sheep with feck all meat on it, and myomax will give (7%) more back end muscling. So a sheep with feck all back end now has a little bit more, but still less than a decent sheep.

Same with inverdale, a sheep that scans really badly, now scans marginally better, but not as well as a sheep which just has better prolifacy.

And could it be argued that the reason some breeds have a lot less shape and a lot less lambs is because that’s what they are suited to ?

Although I suppose change of environment (ie from higher ground to low ground) is perhaps the answer to the last statement.

It’s a bit like the NZ Romney, a wise man recently pointed out to me that it’s not a fantastic sheep, it’s just a good version of a sh!t sheep. The kiwis had very very little choice of breeds at the point they chose the Romney, and so chose the beat of a bad bunch. And made a much much better sh!t sheep.

Now they appear to be seeing the light.

Right, where’s that Tin hat.

 

[unlacedgecko]

This isn’t meant as a dig at @unlacedgecko just in case it sounds like one. Because I’m aware I have an unfortunate tone!

But are not some of these genes, partly now being used to make a sh!t sheep, a better sh!t sheep? Or perhaps just accelerating advancement is a better way to look at it, I know.

But like the myomax thing, you get a sheep with feck all meat on it, and myomax will give (7%) more back end muscling. So a sheep with feck all back end now has a little bit more, but still less than a decent sheep.

Same with inverdale, a sheep that scans really badly, now scans marginally better, but not as well as a sheep which just has better prolifacy.

And could it be argued that the reason some breeds have a lot less shape and a lot less lambs is because that’s what they are suited to ?

Although I suppose change of environment (ie from higher ground to low ground) is perhaps the answer to the last statement.

It’s a bit like the NZ Romney, a wise man recently pointed out to me that it’s not a fantastic sheep, it’s just a good version of a sh!t sheep. The kiwis had very very little choice of breeds at the point they chose the Romney, and so chose the beat of a bad bunch. And made a much much better sh!t sheep.

Now they appear to be seeing the light.

Right, where’s that Tin hat.

Yes

 

[Gulli]

This isn’t meant as a dig at @unlacedgecko just in case it sounds like one. Because I’m aware I have an unfortunate tone!

But are not some of these genes, partly now being used to make a sh!t sheep, a better sh!t sheep? Or perhaps just accelerating advancement is a better way to look at it, I know.

But like the myomax thing, you get a sheep with feck all meat on it, and myomax will give (7%) more back end muscling. So a sheep with feck all back end now has a little bit more, but still less than a decent sheep.

Same with inverdale, a sheep that scans really badly, now scans marginally better, but not as well as a sheep which just has better prolifacy.

And could it be argued that the reason some breeds have a lot less shape and a lot less lambs is because that’s what they are suited to ?

Although I suppose change of environment (ie from higher ground to low ground) is perhaps the answer to the last statement.

It’s a bit like the NZ Romney, a wise man recently pointed out to me that it’s not a fantastic sheep, it’s just a good version of a sh!t sheep. The kiwis had very very little choice of breeds at the point they chose the Romney, and so chose the beat of a bad bunch. And made a much much better sh!t sheep.

Now they appear to be seeing the light.

Right, where’s that Tin hat.

Surely making a sh!t sheep into a better sh!t sheep is the point of selective breeding?

You'll make much more impressive genetic gains if you start with rubbish!

 

[CopperBeech]

Surely making a sh!t sheep into a better sh!t sheep is the point of selective breeding?

You'll make much more impressive genetic gains if you start with rubbish!

I get that.

But you can do a lot of selection, to end up with a sheep that is less of a good sheep than the less selected sheep, from a better flock. If that makes any sense.

And the speed of gain is cool, but it’s the end point that’s important ?

 

[MJT]

I get that.

But you can do a lot of selection, to end up with a sheep that is less of a good sheep than the less selected sheep, from a better flock. If that makes any sense.

And the speed of gain is cool, but it’s the end point that’s important ?

But Is selecting sheep with a gene that causes prolificy not getting exactly the same end product as selecting sheep that are prolific ?

 

[Gulli]

I get that.

But you can do a lot of selection, to end up with a sheep that is less of a good sheep than the less selected sheep, from a better flock. If that makes any sense.

And the speed of gain is cool, but it’s the end point that’s important ?

That's true, although how would you know unless the flocks cross over at some point? Myomax, inverdale etc. Can be useful and if you're going to add them in then it doesn't matter at what point you do it.
I would suspect that breeders aren't getting to a point where they have inverdale or myomax carriers and then stopping any further advancement.

Tongue in cheek about genetic gain but if you can put your genetic gain in an advert then a bigger number looks better