There was enthusiastic cheering and stamping of feet. Napoleon was so gratified that he left his place and came round the table to clink his mug against Mr. Pilkington's before emptying it. (10.28)
"Gratified" is just a fancy word for pride. Napoleon is proud of the fact that these human farmers are accepting him as one of their own. Unfortunately, "one of their own" means that he's a conniving, tyrannical overlord. So, you know, good luck with that.