How old are they?
Why are they not on pasture with the rest of the flock?
What breed?

I leave mine run with the flock and they are on pasture all the way till its time for the freezer.

I see no reason not to just let the lambs run with the flock till its time to butcher. I dont grain out or hay feed. All pasture, all spring, summer and fall.

Sudden changes in diet and care right before slaughter sounds like a set up for failing lambs. It takes time for change to happen. All change should be done slowly. I cant see finishing with grain if they are not already use to grain. And it sounds like yours are not use to it and they will scour and have probs.
If your going to grain out, you would need to start at weaning, slowly so they adjust.

I personally cant see the efficiency in grain as it cost so much and sheep/lambs do extremely well on pasture with nothing else, at least mine do.
And other farms around here do it the same way as I do....all pasture.

Rule here for lambs....Teat, pasture, pan.

 

Sounds like they were dealing with worms. After worming they may need a sulfa (Scour guard or halt or a sulfa methazine) to counter a flush of cocci. Costs are all relative, sure grain is pricey but so is predation and disease (and a fast maturing pasture dropping potein from way too much rain!) Good thing lamb prices are up too.

 

My daughter and my sheep come from the same flock-she took 15--I took 15. She weans her lambs and grain feeds them--I leave mine on the ewe to wean naturally and they are only on grass pasture. her lambs-my lambs all born about the same time--she takes my lambs to market for me along with hers but keeps them separated. her lambs averaged 65# my lambs averaged 76#.
This tells me--wean naturally and forget the grain.

 

Have you checked their eyelids? Your symptoms sound a lot like barber pole worms, although barn raised lambs are less likely to have such an infestation as to cause these symptoms. I'd check their eyelids for color anyway. Red or darker pink is what you want. Light pink, gray or white means serious problems.
Remember, just because you worm doesn't mean you don't have worms. 80% of sheep farms in the US have barber pole worms that are resistant to at least one of the commonly used sheep wormers, and more often they are resistant to more than one. All you are doing by worming sheep with resistant worms is killing what few sensitive worms there are, and leaving the resistant ones to reproduce like crazy.
That being said, without being on any pasture, it's unlikely, but not impossible that these worms are causing the symptoms. Check the eyelids and/or get a FEC done.

 

I am not a sheep breeder or raise a farm of them, however we raise a couple for 4-H. Our's are in a separate pens and we finish them out as market animals. I am no expert but maybe something I share will help you?

We have to alternate our wormer's monthly, we use a safeguard one month and use valzban the next. I also use Apple Cider Vinegar. This routine seems to keep our's worm free. I have also used Diatomaous Earth because it is a natural,

We feed a finisher feed, of course that's probably very expensive for you to do. It is a higher protein feed.

When our lambs scour we use sulmet. You do have to read the label, there is a time period that you have to wait to slaughter, so we use it when absolutely necessary !

Vitamin B complex seems to keep eating and helps build muscle versus fat.
We use a liquid, but there are a couple of granules on the market that have no copper in them.

 

In my area of ontario we have recieved about as much rain each month so far than we usually recieve all summer. This means our pastures are not recovering well after grazing. We removed our lambs so that there would be less pressure on the pastures. Also our ewes are going to be rebred in August and needed a little extra time to recover this year. Some are getting old. Everone has there own management issues.
We have wormed them. I think we had a combination of acidosis and some of the lambs had pneumonia. We lost 3 lambs (they were all small bad doers) and still have one or two that are teatering, but the rest seem on the road to recovery. We have a bank barn and the circulation is not the greatest. We have to work on that. Our ussual method of production would keep the lambs on pasture until August. We would rebreed the ewes in August for easter lambs. Worms are big issue here because if the high moisture, but luckily the Great Pyrenese dogs keep preditors away.