Yes, happy birthday even though I don't know what these cows are all about.
Not to be a buzzkill, I strongly recommend not doing these global changes without having a clear, easy way to disable the features. It is incredibly irritating and distracting, especially for mobile. If I were a first time or even recent visitor, I would never come back.
Edit: I noticed the annoying cows disappeared after making a post here. I sure hope it wasn't a coincidence because making people post just to remove an aesthetic nuisance is a pretty underhanded tactic. If that's not the case, then ignore this. Just my two cents.