Back at the Barnyard (2007)

Season 2: Episode 46

Otis finds a giant chicken egg and decides to hatch it so they can have a fifth for polo. The giant chicken egg turns out to be that of a dinosaur, which proceeds to wreak havoc wherever it goes. The animals want to get rid of it, but Otis has paternal feelings and begs the animals to give him a chance. They relent, but things truly go awry when the dinosaur quickly grows a thousand times its size and falls in love with Mrs. Beady.