With increasing production costs, producers really need to evaluate each and every ewe and decide whether she’s really productive. Marginal ewes (and rams) should not be maintained in the flock. According to an article in Agriview (an ag newspaper in Wisconsin), there are seven good reasons to cull ewes. The reasons are equally applicable to does.
Open: start your cull list with open ewes. They are the most costly in terms of feed, labor,and management.
Health issues (footrot, foot scald, mastitis, etc.). Unhealthy ewes can be a large drain in terms of labor.
Udder quality and/or soundness. Ewes that have lost all or part of their udder function create a management diffculty because they generally cannot produce enough milk to meet the nutritional needs of their lambs. Structurally unsound ewes, i.e. those with few teeth left and hard-keeping emaciated ewes, are also candidates for culling.
Late lambing. Lambs born in the early part of the breeding season will usually be the most productive members of the flock.
Age, though you should not automatically cull a ewe that is six years old, if she is still productive.
Genetic progress, though most genetic improvement is made through the ram.
Poor disposition: females that are difficult to maintain in a grazing system should be culled. Ewes that step on or lay on their lambs because of a poor and/or flighty disposition should be culled.
While it is recommended that 15 percent of the flock be culled annually, the decision to cull ewes (and does) varies from year to year.