** Animals do not have to be "fat" to breed, only "no longer interested in food" (when trying to feed them). Grass eaters will typically be in this state after a minute or 2 on grass or crops.
**If too hungry or low on fat animals can die when giving birth.
** Animals can have miscarriages which may kill the mother with no offspring spawned. StarvingStarvation, being off-deed, or being ona deed with an animal-to-tile ratio of 15 or less (see character > settlement > info to see current deed below 15 ratio ) are known as the reasons for miscarriages.
** Tamed animals who are pregnant can lose the baby if they go offline when you do.
** Neither animal should be of same gender.