The verb is "is." The relative clause is "that
is not unheard of etc."
It would be helpful if you could include the whole sentence. You're showing us neither the subject of the sentence nor the main verb. It sounds like a headline, followed by
another long subject with no verb.
The missing part could be something like, "
Joe is now going to explain to us a bit of animal husbandry etc." This would make it all work.