Horses and donkeys are now in TFC. They work similarly to vanilla Minecraft.
Horses and donkeys will spawn in plains and warm plains, ie. not in mountain or hill biomes. For plains, temperature must be between 0-30, and rainfall 100-500.
See familiarity for up-to-date info for version 79.
Horses are peaceful mobs that don't flee when the player approaches. They will follow the player as long as you hold grains in your hand. To tame a horse or a donkey, leash it by using a rope on it (ropes work the same way as leads in vanilla minecraft). Then, with an empty hand, right-click the horse to ride it. After a few seconds, the horse will throw you off, and small puffs of smoke will appear. Try riding it again, until small hearts float up from the horse (this takes usually 5-6 tattempts, but can take more). This means the horse is tamed, and will not throw you off anymore. To release the horse from the rope, hold down Left Shift and right-click the horse.
To control the horse while riding it, you'll need a saddle. Hold Left Shift and right-click the horse to open its inventory. Place the saddle in the saddle-slot, and close the screen. Your horse will now be wearing a saddle. Right-click the horse to ride it, and control it the same way as riding in vanilla Minecraft. Dismount by pressing Left Shift.
The health of the horse is shown above your hunger bar. It appears this health bar is not optimised for TFC, as it only displays the last few hitpoints of the horse (ie. it will only decrease when the horse is near death). There doesn't appear to any easy way to replenish health for horses, but they will slowly regenerate health on their own. Though once attacked, it appears to be impossible to calm them down again.
Feeding horses with grains will allow you to mate a male and female horse together. Right-clicking the female will show if it has become pregnant. It takes several months of gestation before a foal is produced, and additional months before the foal grows into an adult horse.
When killed, the horse will drop a Large hide, a bunch of horse meats, and some bones. It will not drop any equipped saddle.