Do horses like potatoes?

Actually, potatoes aren't a good thing to feed horses. Green and raw potatoes are poisonous (The toxin, solanine, is destroyed by cooking, at least in the tuber part). Potatoes are also likely to get stuck causing choke. Finally, potatoes are too starchy for horses - they can make them fat.

Solanine poisoning can cause excitability, decreased heart rate and respiration, gastric problems, convulsions, muscle weakness and coordination difficulties. So, no potatoes. Especially not uncooked.