Activities that lend well to doing at home include: going to the library and borrowing books/puzzles/puppets about the farm, using farm puppets in play in place of a baby (feed the cow, wash the cow's ears, etc), hiding puppets or farm toys and finding them (adding a flashlight can suddenly make kids interested when their attention wanes), adding farm toys to bath time (the concepts of clean/dirty are great to add), download animal coloring pages, and watching You Tube videos of animals in their environment (always pre-watch to be sure the content is appropriate).
Have fun!!