Real forced landings with animals in the field
While it is asking for trouble to practice a forced landing to low level once you see animals in the chosen field, do they make it a no-go for a real forced landing? They are more likely to get out of your way than trees. I would probably continue with sheep, or even cattle, if the only option was almost certainly hitting something solid.
AAIB bulletin 1 2010. G-LNYS Cessna 177 engine failure
“As the aircraft approached the pilot’s initial choice of field, it became apparent to him that it contained livestock and was, therefore, unsuitable.”