You should give up farming, last month the roosters you had didn't lay eggs for your egg farm, now the bulls won't produce milk. You have no luck as a farmer, take my advice, leave it to the experts! Perhaps you could be a shepherd.
With bulls timing is everything. Just like the cows, the milk pressure has to build up to make the animal uncomfortable and agitated. Then the will see you as a friend doing them a favour by relieving the pressure.
Just look for these signs before you attempt to milk the bull... 1. The eye balls will bulge. 2. The neck will arch up. 3. They will swing their head. 4. They will paw the ground.
When you see these signs, approach the bull, crouch down, grab the testicles with one hand and the single teat with the other.
This crouching position is also very convenient for kissing your arse goodbye.