The first male rabbit I had spayed (well it was actually castrated) after he fathered 3 litters. I took him to the vet (at an animal "clinic") in the afternoon and picked him up the next morning. Withing a week he had developed a urinary track infection, so I took him back and she gave him an injection and a course of antibiotics.
What I will say is that - after the operation and from then onward - he never regained his fully happy demeanor; there was always "something missing" from his life, and at times he would look at me as if to say - well you can imagine.
Some time later, his grand daughter gave birth to twin boys. All was fine and dandy for the first 2 months; then they were continually "bothering" their mother - but not (yet) fighting. By this time, I had changed "vets" to a rabbit doctor at the "animal hospital", so booked to have them both "done".
This time, the whole business (for both of them) was done in under 2 hours and when I collected them they were both fine; one a little drowsy obviously. The doc said I had to bring them back in one week. When I did this, and had a look at each one (in turn) on the operating table, I noticed that they still had their testicles; what the doctor had actually done is what I call a vasectomy!!!
So, if possible DON'T GET YOUR RABBIT CASTRATED; get the other option. They both stopped "bothering" their mum, and were absolutely normal and still very affectionate. However, they started fighting like hell a couple of months later, so I separated them; they live either side of a gate - they can see each other but cannot get close enough to fight.