Minecraft wiki entry for Breeding, associated text: Baby animals take 20 minutes to grow up. This can be accelerated by feeding them their breeding item. Green sparkles appear similar to those caused by bone meal. Each feeding reduces the remaining time before the animal grows up by 10%. The less time remains, the less time is saved by each feeding, making it inefficient to feed an animal continuously until it becomes an adult. After the ninth feeding, the time saved by one feeding is less than a minute, as shown in the graph. Horses, donkeys, and llamas have different mechanics: different breeding items grow babies by different amounts, and each item ages babies by a constant time rather than a percentage of the remaining time.