Change type of livestock names

How do I change the name a type of animal is allocated (e.g. Male is a Bull, female is a heifer)?

To change the name given to males, females and their progeny, go to Setup > Livestock Types.

Select your livestock type and click Edit. 

You are then able to edit the names that are given to the males, females and prgeny of that livestock type. Once you have made the changes, click OK.