I use Bio-care mix which has them in and it's helped my mare she is much calmer had much more solid poos, i did try youghurt though and it made her worse (poo wise)
I use 'pink powder', I think it's by NafNaf but I could be completely wrong. My old mare can get a bit 'loose' when the grass come through in autumn and winter. Had the vet out two years ago and he could find nothing wrong so I just stick her on this for a few weeks and it seems to work.
I'm feeding NAF pink powder at the moment, since my horse had flatulent colic after worming on the last 2 occasions.
I emailed NAF to ask if they thought this the most appropriate product and I thought it would be worth posting their helpful reply:
"Thank you for your enquiry, and I'm sorry to hear of the problem you're having with your mare. Pink Powder is an ideal product for supporting digestion on a daily basis, but it may be that your mare needs a little extra help in particular circumstances, in her case, when being wormed. I would advise keeping her on Pink Powder daily, and adding Synbiozyme - a concentrated pre and probiotic - for a day before, during and a couple of days after worming. Synbiozyme can be safely fed to pregnant mares, and would be ideal alongside Pink Powder, just to give her an additional helping hand when she most needs it. Personally, I would also suggest going down the worm counting route, as you may well find she doesn't need worming as often as you have been doing.
Synbiozyme is available from any NAF main dealer, though some may have to order it in for you. If you do not know your nearest NAF main dealer please contact us again with your town or postcode and we'll be happy to advise you."
An old stallion on the yard has also been colicky lately and his vet recommended Yea-Sacc.
Equimins pro bio - excellent and very reasonable - made a huge difference to my TB - she stopped dropping weight and my feed bill was considerably reduced.
Used to feed it to Cairo and Jemima - both who would get upset guts on change of diet - now they eat anything and everything. Cairo is now on blue chip, linseed and brewers yeast so I have dropped the pro-bio as the stuff I feed seems to do the trick.
Started Chancer on it as a youngster - he too never gets any colic problems (to date) and is now on brewers yeast and linseed which have natural probiotics in them.