Originally Posted by netty83
Should I be letting her gain weight before trying to turn it to muscle and condition or should I be trying to do it both together?
Since I don't know what type of concentrates (grain or hard feed) you have available in the UK I'll pass on answering that part of your question. Depending on just HOW underweight she is would determine whether I fed her up first and conditioned later or did both simultaneously.
If she's a body condition score of 3 or less I'd feed her up quite a bit before I tried any conditioning as that burns calories and she needs everything she can get if she's down this far.
From 3-5, I'd start conditioning her right along with the weight gain, but slowly and light exercise only. Once she's up to 4-5, then you could start to ride her lightly (5-7 considered optimal condition) and build as she builds up stamina and muscle.