Animals suffocate in walls

Whenever you put animals in tight spaces they push eachother in the walls surrounding them and they suffocate.

What I expected to happen was...:
The animals would not push eachother in the walls and dont die.

What actually happened was...:
the animals pushed eachother in the walls and died.

Steps to Reproduce:
1. I put 2 cows in a 1x2 hole for a animal farm with hoppers.
2. they were standing on stone hals slabs
3. whenever i cheched the chest that the hoppers led to there was leather and uncooked steak and i realized one of my cows died
4. I also put 2 chickens in a 2x2 hole in the ground and had them breed and the same thing happened with them.