When space is limited, cows will attempt to displace cows standing at the feed bunk by head butting. Animals in a group may be classified as those who are “less successful” at displacing others (they are more often displaced), “moderately successful” (they are as likely to displace others as to be displaced) or “highly successful” (displace others more often than they are displaced). In a mixed group, the low success group is generally heifers. The low success group has higher cortisol levels and is the group that will benefit the most from regrouping or lower density.
Short-term overcrowding may be necessary in expanding herds or when heifer calf births are high. Cattle can compensate to some degree for these times unless they are vulnerable for other reasons. Transition groups should be considered high risk and overcrowding either the feed bunk or stall space should be avoided. Close up dry cows may not be able to compensate or recover from competition for feeding or lying space.
It can be tempting to overcrowd groups regularly, but we are learning more about the negative impacts on cow health, welfare and ultimately cow productivity and profitability. Give your cows the space they need, and they will give you the performance you need. Management should change in order to reduce the impacts of overcrowding. More frequent feeding and pushing up of feed, more frequent scraping of manure and good bed maintenance should be priorities.