[MaxiB]

My Valais X has just had a nasty bout of fly strike which he was treated for… however, once sheared I was mortified to see his body condition is very poor… how did  I miss that! I am feeling seriously guilty about it…. he has had ad-lib access to hay as well as grass… he is now on his own to allow his wounds to recover. How can I get some weight on him? 

[twizzel]

A feed of cake each day will help, given he is a he you must make sure it is suitable for wethers/rams and has ammonium chloride included, lamb finisher nuts probably best bet. But I would also look at why he is thin, check his teeth, do an egg count to see if worms are an issue, run bloods for iceberg diseases MV johnes etc. Given we’re in summer he should be at his fittest really so there may be an underlying condition that is causing the lack of condition.

[Rosemary]

What Twizzel says. An don't rely on visuals to assess condition in future. A fleece can hide a lot, as you now know. You need to get regular hands on to assess condition. Hope he recovers.

[Bywaters]

If you are on poor ground, it's hard to get condition back.

From what I have read (not from personal experience so stand to be corrected) this breed are particularly susceptible to bad feet, on poor ground. This will also put them off eating. Easy to spot 1 sore foot but when they have 2 or even all four, it's harder

All good advice already stated. On the positive, at least you are aware now, before it's too late