Herding dogs don't automatically know how to herd properly, they just have a strong chase instinct that is particularly suited to being molded and trained into being a proper herding dog. Without proper herding training all you will have is a dog that randomly chases, scatters, nips, and potentially harms the animals.
I adopted an Australian Shepherd that had been locked up indefinitely in an outbuilding on a farm (his previous home) because he would endlessly chase, nip, and harrass the horses. Even after his leg was shattered by an angry horse, in the absence of any training or supervision, he continued to chase and chase and chase them. That is what he is driven to do, and if I wanted him to become a herding dog it would take a lot of hard work to harness and channel that energy into what you would think of when you think of herding: seamlessly collecting, driving, and seperating stock on command, under complete control of the shepherd.
If you do want to get into herding, though, it can be great fun as well as practical if you have livestock to move (livestock other than horses). There is a place here in WA that teaches owners how to teach their dogs to herd; Perhaps there is a similar facility in your area. Don't underestimate the amount of time and training that goes into a good herding dog, but if you want to do it go for it.