We keep our good older cows until they have a problem. saskcattle is basically right. Do you pregnancy check? We apply these rules. If she has had good calves, doesn't get thin or run down, if she is getting around okay, and is stil breeding back. We also keep heifers out of these good old cows, the longevity gene is the best for being a profitable gene to want to have in the animals you have. If they have trouble getting around, if they start to look thin or poor, they finish out that calf and go. If they are not bred at preg check, they go. We don't bury them if we can help it, they get sold. Even with the cull cow prices at .50/ lb. or so, that is still $4-600 that you can put towards another, or just put back into the ones you have as a kept replacement heifer.