I don't think one pumpkin would bloat them...but it might be a little "rich" on their digestive tracks. Try cutting it in half, wait a day or two and then feed the other half. If it's REALLY big, you could quarter it.
Greenhorn Acres - Nubians, Boers, and Unclassified Goats
My goats get pumpkins by the wheelbarrow with no ill effects. We have an orchard and sell produce, including pumpkins for Halloween. Any that start to get soft, get pitched into the goat pen. The leftovers at the end of the season go to the goats, several at a time. I have four goats and they share with the chickens, but I have never had any bloat. Pumpkin seeds are also said to be a natural dewormer. I have no worm issues in my goats, but I'm not sure if it is the pumpkins they eat or the fact that the chickens are constantly scratching and eating anything that moves in the dirt and in the goats' stalls.