Lucerne/Alfalfa… if it is really fresh and green it will often cause scouring/diarrhea. We don’t know (as far as I’m aware) what causes the scouring, BUT my observation over the years is that once it is stored for a few months the problem goes away (hence the old advice to always feed ‘shedded’ hay)… so whatever it is in lucerne/alfalfa that causes the issue seems to be volatile and disappears after a while.
The issue at the moment for many of us is hay is in such short supply that all we can get is very fresh lucerne! We don’t have the luxury of waiting a couple of months for it to lose whatever it is that makes our horses scour… here is what you can do!
Take your bales, open them up and spread the pieces (biscuits, flakes, leaves… we call them all sorts of funny things depending on where you are in the world!) apart and let them sit for about a week (longer if you have the luxury of time) to air out. You should find that your horse’s gut will be much happier with it once it has had this chance to air out. If your hay seems particularly rich and is making horses scour badly try also sitting it in the sun.
I have dealt with lucerne/alfalfa in a polo stable in Asia actually bursting horses’ stomachs! ? was horrible!! But once we got them to start airing and sunning the hay like this (it was imported from the USA) the problem thankfully stopped. Its the only time I have heard of that with lucerne/alfalfa and hopefully the only time!
Anyway, if you are dealing with soft manure in horses on fresh lucerne/alfalfa give this a try. Would love to know what happens if you have time to leave a comment on Facebook.