In survival mode, animals do not drop items no matter how many killed.

In survival mode I was attempting to collect items from all kinds of animals to get the resources I needed and none of the animals dropped anything. That included sheep, cows, pigs, chicken, bunnies, etc. I tried using different weapons and kept killing more to see if I just needed to destroy more. But still nothing. It's getting very frustrating and really is hindering me from playing.