Removal of cows from the herd is largely an economic decision, because it has limited influence on genetic improvement. In most cases, it has been recommended that nonpregnant cows routinely should be culled. However, systems analysis studies have not always shown this to be a profit-maximizing decision, particularly for young cows and when the difference in value between cull cows and replacement heifers is large.
Functionally unsound cows should almost always be culled. Cows with impaired mobility or unsound mouths are unlikely to harvest sufficient nutrients to maintain body condition and be productive. Newborn calves may have difficulty nursing from large teats or pendulous udders. In either case, economic consequences of the unsoundness are profound. However, few commercial cows should be culled for low productivity. Only in extreme cases will income lost due to low future production be greater than the cost of developing a replacement heifer. Record keeping that includes production information could be valuable in years when extra culling is necessary.
Calf weaning weights typically begin to decrease when cows reach about eight years of age. Several studies indicate that in commercial production, the optimal economic culling age is between eight and 11 years. When calf prices are low, the optimum culling age decreases. When calf prices are high, there is some advantage to keeping slightly older cows.