version 131. Not sure if this is intended but its a little strange that spawn eggs would create new animals that are already too old to breed.

Not a bug, but also shouldn't be 50%. Random spawns (including spawn eggs, but not on chunk generation since there is another spawn logic there to accommodate group of animals) will always be adults, but has a random age from 1 day being adult and full old, which would imply that the chance of getting an old animal should be very slim. Anyway, i will take a look.

Should've been fixed by build 142.