I'm interested to know more about reasons for deciding at what age it's okay to have a foal and how that compares to backing - interested, not looking to start any sort of argument! My current view is that I wouldn't want to back before 5 because vertebral growth plates don't fuse until at least then, possibly later. Backing involves relatively sudden introduction of weight ie that of a person. Obviously being in foal also involves carrying a weight, but it builds up very gradually. Given that sexual maturity in female horses is around 2-3 years, presumably wild horses can become pregnant at 2 and give birth at 3, which is earlier than I'm suggesting. I know that selective breeding have changed things a bit in that the horses are much bigger but does the wild argument count for anything? If I did breed, it would just be for me - I'm hopelessly sentimental about my animals and couldn't let anyone else have one of them! I can understand the practical point about breaking before breeding, but surely it's possible to tell how trainable a horse is from doing groundwork?