Did you know you can search Google for animal sounds? Just search for [what sound does a cow make] or other variations. It also works for a search on [animal noises].
19 animal sounds were added to Google including monkey, cat, cow, duck, elephant, horse, lion, moose, owl, pig, raccoons, rooster, sheep, tiger, turkey, turtle, bowhead, humpback whale, wolf, zebra.
Here is a screen shot:
This works on desktop or mobile.
There were some reports that this feature would go live in mid-January but the first I've seen of it was yesterday on Google+ via the Google Australia channel.
It doesn't look like it works for Penguins or Pandas. :-/
Forum discussion at Google+.