Kids fed my horses 30 lbs if Timothy pellets?

Keep a close eye on the horses and if any of them start showing signs of illness immediatly take them to the vets. if you are still concerned there is not harm in talking to a vet. With the kids you need to explain to them in detail how dangerous it is , if this continus you will have to speak to the childrens paretnts as it could be fatal for the horses.