he took care of the cows during their pregnancies, and also, um, inseminated them with semen collected from bulls... semen that was collected by someone else, who was a breeding expert with the bulls. Collected manually.
This is a weird thing to know.
I knew a few students who went to UC Davis and talked about how there were the days in class where everyone was excited and got to do something really interesting like when you first see the Milking Machine, or even getting a chance to inseminate the cows. But the morning where you have to do the collecting everyone was very quiet and the tone was much more "Well... I guess this is what we're doing today isn't it? No going back now!"