Any foods containing molasses WILL eventually grow mould on them...take it from me, don't use any horse mixes or other mixes containing lots of molasses. I have learned the hard way. I lost a lot of pigs a while back and it took ages to find the problem. It was traced back to a gut bug that grew out of control when they had sugary foods...I took horse-mixes out of their diets and the deaths stopped. Last year, I stupidly used some horse mix again, and after a while some of my pigs looked a bit odd...then I lost the most loved of all my pigs (Milky Mouse) through severe diarrhoea that was linked (by my vet) to yet another gut bug that was feeding on the rich molasses. It killed my girl...
About 2 months after Milky died, I thought I'd use a tiny bit of the left over horse mix in my chaffmix, just to use it up. Honestly, it was only a couple of handfuls...and the next few days, I had 5 bloat pigs - two died despite emergency vet care, I pulled the other girls through with day and night care for a week. Again, traced back to the food - I hadn't noticed at the time that a very fine, almost invisible to the naked eye, mould had grown on some of the molasses loaded foods, and even this tiny amount was enough to make my piggies sick. I found the mould later using a microscope.
I've learned my lesson, finally - I thought that it can't be that bad as other shelters have used horse mixes for years (including Jess) - but every single time I let my defences down and use the stuff, I end up losing pigs. And I wouldn't be surprised if some of the piggy-deaths that Jess has experienced with sick rescue pigs are simply because their guts are not able to handle the rich, molasses-loaded horse mixes in her chaff mix hence they can't get better despite all other treatments given to them!
Pigs don't need molasses. They can live a perfectly healthy life on a diet of good grassy hay (one that has all sorts of grasses and herbs in it, not just one type of grass), vegies and fresh grass. Chaff mixes are really just a way to alleviate boredom as they keep my lot occupied for a while. I never use horse mixes, just a mix of oaten chaff, lupins, rolled oats, and jack-rabbit micropellets (not too many as they are made with lucerne). And if you don't want to make a chaff mix like mine, then simply use oxbow cavy cuisine along with their hay and vegies - yes, cavy cuisine has some molasses in it but only a tiny amount that is carefully measured - the key is to give them only the recommended amount of the pellets.