We used Red Cell temporarily on the advise of a Veterinarian a couple years ago when a horse was recovering from an illness and blood work showed she was anemic. I wouldn't use it all the time unless there is a need as too much iron can cause problems.
Vets reccomended haemavite b plus to me, it's a fantastic tonic, helps raise the immune system, battle anaemia, aid digestion and enhance: rehab, performance and also enhances appetite. Very reasonable too, really rate it
As othbsits said too much iron can cause problems as horses cannot excrete excess iron. If I thought my horse was aenemic I would have her tested to make sure she actually needed the supplement first.
thanks I was just wondering as I have heard of people feeding to help with energy levels (such as in competition horses) and just wanted to see what you all used it for