It depends why you need it nomis and where the problem is. Many commercially available supplements claim lots of things but results are variable. Coligone is not really designed to aid digestion - it is designed to soothe and line the gut and so prevent colic in stressy, colicky horses.
My rescued mare Angel had severe liver damage from ragwort poisoning and has been on Yea Sac ever since I took her on 18 months ago. (She's doing brilliantly by the way!) Yea Sac aids hind gut digestion which is often compromised in liver damaged horses. It contains the B vits that such horses struggle to absorb and acts as a mild appetite stimulant too. So that might help if your ned has liver probs or lack of B vits, but not necessarily otherwise!
Why does your ned need help nomis? If we know a bit more, we can be more helpful x
You could use the protexin 6 day syringe boost. Simple systems might help but its a complete diet change to a high fibre diet with extra things like yeast added to aid digestion. my friend has just ut her 19yr old on Spillers senior maintainence which has all the pro and prebiotics in it and is cheaper. has all the glucosamine in too so a good all round feed. you have to feed the recommended amount though. he is a 16hh irish draught and gets 3/4 scp and heaped scp hifi light twice a day. works out to about 500g hifi and 1.6kg of mix. if you want to put wieght on the they have a senior condiotoning mix too that has higher protein, starch and oil to get the wieght on with all the added good stuff too. My friends boy is looking great with it, poos better and more consistent through the day and so a healthier digestive system.