At 6 yrs your cow will yield mediocre beef. It would be best to have it made into ground beef. Also per the USDA, after 3 yrs of age, all nerve tissue has to be removed from the meat, due to BSE, or Mad Cow disease.
You will also want to separate the bull from the steer, or the bull will fight with, and possibly injure the steer.
If your bull breeds with any of females, you will not enjoy eating it, as the male hormones will give the meat an off flavor. Bulls used for breeding are generally used to make bologna and hot dogs when they are butchered.