Genomic recording of Sheep

[Gulli]

We were taught about drift lambing at uni. Seems to contradict the point of outdoor lambing but then some people lamb outside and then bring the fresh lambs in each day. So maybe its a step in the right direction.

 

[d.iainm]

Works ok for me moving them once they are a day or two. but like I said small scale every place has their own reasons for doing things the way they do.

 

[Global ovine]

Drift lambing was a pain for all involved (sheep and man) ---used it once or twice but sheep are best left alone at lambing

GO---you just need to improve your sheep a bit so they don't need tailing

Removing tails is only one part of the exercise, ear marking, maybe Pulpy Kidney vaccinating, long acting vit B12 injection, DNA blood sampling for many breeders, etc.
Regarding breeding no or bare tails; yes great, but the trade off in introgressing these genes and diminishing those traits that pay the bills would really hurt.

 

[Tim W]

.
Regarding breeding no or bare tails; yes great, but the trade off in introgressing these genes and diminishing those traits that pay the bills would really hurt.

Don't agree there i'm afraid----
We have bare tailed animals that perform very well---the only extra difference between my cleanskin sheep and the NZ Romneys (for example) I have seen are that the Romneys are not quite as prolific and have all that damned wool
My sheep are just as functional---bred for worm resistance/footrot/good mothering abilities/grass conversion etc and the results are there to see
In fact many of the great qualities that breeders historically rejected but have become desired in the last 30 years (ability to survive with minimal human input) are to be found in abundance in 'less improved' hair sheep'----unrivalled lamb vigour, cold tolerance, mothering ability, locomotion traits etc
Of course the only way for you to find this out for sure is to try it ---you will just have to wait until we get those export protocols up and running

 

[neilo]

Drift lambing---having a set of fields for lambing in and drifting the sheep around them

So, start with 100 ewes in field #1 , after a couple of days when say 15 have lambed you open the gates and let the un-lambed ewes drift through to field # 2, when 15 of them have lambed you let the un lambed ewes through to field # 3 etc

The idea being that you have less mis-mothering due to the lambed ewes being left with lots of room ---tried this and found it to be more hassle than it was worth. You end up with plenty of mis mothering when you 'drift' the ewes

Some people do it with success

The guys I have heard doing 'drift lambing' are moving the in lambed ewes once or even twice a day, avoiding mismothering. The ewes soon get into the routine and run through to fresh grazing, whilst the freshly lambed ones stick with their lambs, so you shut the gate and go round ringing etc then move them out separately the next day, before the lambing ewes come round again. If you leave them longer between moves, some ewes will run off through the gate with the mob.

Agreed it sounds like making work, and I quickly dismissed the idea in favour of set stocking. I know several that swear by it though. I suppose it means you need less area of lambing paddocks?

 

[SteveHants]

Removing tails is only one part of the exercise, ear marking, maybe Pulpy Kidney vaccinating, long acting vit B12 injection, DNA blood sampling for many breeders, etc.
Regarding breeding no or bare tails; yes great, but the trade off in introgressing these genes and diminishing those traits that pay the bills would really hurt.

I hadn't realised that kiwi breeders give a prophylactic shot of B12 - why not breed sheep that can tolerate lower levels of it?

 

[KNconsulting]

I hadn't realised that kiwi breeders give a prophylactic shot of B12 - why not breed sheep that can tolerate lower levels of it?

To answer your specific question: there are two things.
1) It depends on whether there is genetic variation for the trait and to the extent of this variation
2) It probably isn't cost-effective to select for genetic differences. Each time you put selection pressure on one trait you have to reduce it for another. Where the traits have high economic worth then it is viable to put selection pressure on it. For example, for some disease traits it is worth looking at a genetic approach but when there are cheap prevention/treatment options then it is not cost-effective to use a genetic approach.

I think I've made sense!

 

[JD-Kid]

depends on the year etc etc for colbolt some areas high some low so hard to breed just for one area depending on where rams sold

used to do sheding off great way of makeing work out of thin air to try and belive you are going forward to be fair you would make better gains takeing the wife away for 6 weeks and tie all the gates back .. i know people will say can't do it i would say question the rams you buy the ewes you run or even if you should have sheep in the frist place

 

[SteveHants]

To answer your specific question: there are two things.
1) It depends on whether there is genetic variation for the trait and to the extent of this variation
2) It probably isn't cost-effective to select for genetic differences. Each time you put selection pressure on one trait you have to reduce it for another. Where the traits have high economic worth then it is viable to put selection pressure on it. For example, for some disease traits it is worth looking at a genetic approach but when there are cheap prevention/treatment options then it is not cost-effective to use a genetic approach.

I think I've made sense!

I see your point, but I would have thought that it is highly unlikely that there is no genetic variation for this trait. I would guess (but I could be wrong) that a minority do, and if that is the case then surely it is worth removing them from the genepool. If they all need that shot, then isn't it better looking at the soil instead?

"Each time you select for one trait you have to reduce it for another" depends on the variability of traits and if they have an influence on how others are expressed. I would say in most cases that is simply not true. For example, you could be selecting for milkiness and susceptabilty to footrot at the same time - using your logic the milkiest animals would also have the highest incidences of rot, wheras in reality both probably follow a normal distribution within the population. Yes, you would end up with fewer replacements, but I don't see that as a problem.

 

[Tim W]

I think what Catherine means is that the more traits you pick for the less progress on these traits you make

So if I select on 1 trait = muscle---then progress will of course be fast but if I select for animals that have lots of muscle, low fat, high litter values, low FEC, foot rot resistance, mastitis resistance and high IQ (not sure if that is applicable in sheep) then progress will be much slower?

Measuring Vit B deficiencies in a flock of sheep would also be expensive and time consuming I assume

 

[SteveHants]

It might be, but it also might be that those animals you are selecting for have better traits in a number of areas. What I'm saying is that it doesnt nescessarily follow that selecting for multiple traits is slower, it might be, but it isn't nescessarily a logical step to assume it will.

 

[KNconsulting]

It might be, but it also might be that those animals you are selecting for have better traits in a number of areas. What I'm saying is that it doesnt nescessarily follow that selecting for multiple traits is slower, it might be, but it isn't nescessarily a logical step to assume it will.

Agree to a point - where there are positive genetic correlations between traits of interest then this will actually increase selection rates as you say but for some there are unfavourable genetic correlations or at the very least neutral relationships. With one of the main drivers of 'genetic improvement' being effective population size then a larger population will make it easier to select for the traits required. Speed of genetic improvement will also be influenced by heritability and with many of the traits of interest having low heritability this will also slow down the rate of change. Bringing in disease traits may also slow the rate of change with the risk of unfavourable correlations with production (sometimes but not always and will vary according to the trait). There may also be unfavourable relationships between disease traits. With the acquired immune response being generally either cell-mediated or antibody based then if one of these mechanisms has a larger impact upon disease resistance then resistance to another disease could be reduced