Doubt it all you like, but multiple reports from news media say otherwise. I'm not saying the news is always right but there are multiple sources. You can search for it yourself. There is nothing there that says it is illegal to drink it or to sell it.
Not that far fetched from people eating mountain oysters, etc.
I can confirm it is (well, was) 100% true. I visited said pub - but didn't partake.
Funnily enough it was very much targeted at females, sort of as a "dare you!" kind of novelty. They originally offered apple-infused stallion semen (tiny amount) mixed with other spirits as a shot. Once it got later into the night, LOADS of girls were up for the challenge.
When you think about it, for the reason alone, probably more New Zealand women have had horse sperm in their digestive system than anywhere else in the world.
We Kiwis DO like to punch above our way in any per-head-of-population stakes!
Men could, of course, buy them too - but there was a definite air of it being "for the ladies" so any guy ordering one was going to have their sexual orientation questioned.
A couple of years later they began offering stag semen mixed with stout beer. It was promoted like an exclusive gourmet "wild food".
All donations came from "Hannibal, a 7-year-old Geraldine sire stag with impeccable DNA".
But after a while they stopped. Novelty just wore off. It stopped being daring and funny. Just became kind of cringe.
But I absolutely promise you, all true.