When a horse has a temper of 100 the player can still feed it client-side. However once the inventory is updated, the item count corrects itself.
Glitched items in hand when trying to feed a llama
lamas cant be tamed
This bug doesn't let me use objects and makes them invisible until I click the space they were taking in my inventory
Untamed horses continue consuming food after reaching 100% tameability (100 temper)
Client can always use carrot on a stick, ignoring pig's food state