This is sometimes formulated "animals mate only for reproduction".

Attenborough objected, explaining he thought it unlikely given that the animals only mate underwater and it is unlikely that the recording could have been made there.

By checking female mice for the presence of a plug it is possible to determine whether the animal has mated.

When these animals mated, some of the offspring carried the functional YAC DNA in every cell, the researchers reported.

The animals will not mate.

The animal inside him mated with hers until she'd ridden both to exhaustion.

Needless to say, Gulliver is violently disgusted by her, but must admit that he can no longer pretend he isn't a Yahoo (animals mate naturally only within their own species).