The animal that mates the most is the male brown antechinus which has sex and mates with as many female antechinus as possible for up to 14 hours at a time.
That is a lot of time for sex from one animal.
The antechinus is a mouse which is also known as Stuart's antechinus and Macleay's marsupial mouse, is a species of small carnivorous marsupial of the family Dasyuridae.
The male antechinus mouse die after their first breeding season, and the species holds the world record for being the world's smallest semelparous mammal.
Cats and dogs are also a pretty high on the list of a mating animal when it comes to mating most.
And lastly the human which is also an animal mates quite a bit as well although most humans do not mate as much as the mouse does.