Give him very very small treats. Think of something about half the size of the visible lead on a sharpened pencil. It shouldn't intefere with his appetite. GIve him a few day to get adjusted to his new home. Its common for dogs not to eat much for 3 or 4 days after moving to a new home. Don't worry about him. He will be ok. The less you worry and make a fuss over him the quicker he will adapt. Just let him sniff, expore, and get used to things on his own.