Also, take water from home for the goat to drink. Goats don't like different smelling or tasting water. If your goat is not drinking, or it is extremely hot, you need to drench him with water or electrolytes to prevent dehydration. Probiotics and B Complex vitamins are always good to give during times of stress. Keep track of what your goat eats and drinks before and after weigh-in.
Many shows require a weigh-back.
A half-gallon of water weighs 4 pounds. Give your goat a chance to drink, just limit the water. Don't keep a 5-gallon bucket full of water in the pen at show time. Familiarize your goat with the new surroundings. Take the goat out and walk him calmly in the arena.