[Richmond]

Just out of curiosity ..... if a ewe has always had twins, will she continue to have twins?
Equally, if a ewe has only ever had singles, is she likely to have twins in the future?
I have a ewe atm who is the size of a small planet, but she's only had a single lamb in both her previous pregnancies. Just wondering if she might have twins this time. If it is another single, it's going to be enormous ...

[Rosemary]

Big ewe doesn't always equal big lamb - some carry a lot of fluid.
In my time, I had ewes that had the same number of lambs every year and some that had a single one year and twins or triplets the next. It's partly determined by genetics but also by external factors like weather and nutrition.
Litter size tends to increase with age of the ewe.

[Richmond]

OK thanks. I'll keep watching and waiting and see what pops out 

[SallyintNorth]

Lambing pattern if all other things are constant does seem to have a genetic component - I've a line of sheep always have a single first time then twins always or sometimes thereafter, and one line just has singles, except the one and only time the founding ewe had two - which was when we discovered half her udder didn't function.  

So how I look at it is that knowing the history helps with probabilities, but you absolutely mustn't bank on it! 

And I also have had ewes so big and square you could have sat a family of 6 down to eat a roast dinner off her back, some of which have had triplets, many twins, and one or two have just had one.  A much more reliable predictor of "litter size" is ewes body condition (BCS), but even at that, you can have a large but thin ewe produce a single, a fat ewe produce triplets, just like a ewe you thought might be empty can have quads, a big ewe a tiny single, and so on! 

[Richmond]

Thanks Sally. I'll report back. She's getting close now I think. She always looks larger than either of her sisters, who both have twins each year, but only has had two singles so far. So I was just curious whether she would produce another single despite being, as you so accurately describe it, "big enough to seat a family of 6"!

[PK]

I have a Wiltshire Horn ewe which produces singles and this year, as in previous years, has an enormous girth compared to the other ewes. Her condition at tupping time was fine so I wonder if it is the amount of fluid as Rosemary suggests.

[Richmond]

I'd forgotten you had WHs PK - mine are WHs too 
Yes this particular girl is a bit of a fatty tbh - not sure why as our pasture is very poor and they only get extra feed for a short while pre and post lambing plus a bit of hay over winter, and she always looks as round as a barrel whatever the season!

[Richmond]

Update: She had twins last night in the howling wind and rain! Didn't want to use the shelter provided and chose to give birth in the middle of the field. Hastily erected temporary shelter out of hurdles and bales. Checked on them through the night but mum and both babies ok so far this morning