How old does a kid have to be to ride bulls in the rodeo?

The horse can barrel race as soon as it is trained to barrel race. You can start training it once it is ready to ride and take it to barrel races or I know someone who has a barrel racing 4 yr old. It just depends on when the horse is trained to barrel race. So you could have a 10 yr old not ready or a 3 yr old racing an winning!