The behavioral and physiological consequences of overstocking dairy cattle

Abstract

Overstocked group pens continue to be a challenge for many dairy producers. There are many reasons why overstocking may occur, including an unexpectedly busy calving month, too many replacement heifers, or herd expansion before barn expansion. While overstocking may be a short-term solution to a management challenge, a growing body of science demonstrates that overcrowding results in both behavioral and physiological changes that could compromise future performance, productivity and animal welfare. Overstocking interferes with normal behavioral time budgets of dairy cows, disrupting both feeding and lying activity. Aggressive competitive interactions are also more frequent when cows are crowded at the feed bunk or lying stalls, particularly for socially subordinate animals. More recent research has found that overstocking can affect physiological processes, including energy metabolism and glucocorticoid secretion. This research has dramatically improved our understanding of the ways in which overstocking affects dairy cattle health and welfare, and collectively will enable improved science-based recommendations on how best to manage intensively housed dairy cattle.