While I don't have a lot of experience in that area, I would have to say that it would have depend on each individual cow. Some cows are *old* and have bad teeth at 10 years of age, while other cows are still going strong and pumping out a calf every year at 15. I have a yearly heifer that came out of a cow that was well past 20.
I would judge whether a cow is too old by her condition rather than her cronological age -- if she is in good physical condition, has good hips, and good teeth, I'd chance it with her. (without good teeth, she can't eat enough to produce the milk the calf needs -- if you can hear grinding in her hips when she walks, she has a good chance of becoming a "downer" when she calves)
> AT what age would you reccomend
> not to breed a cow anymore?