Implications of overstocking on the behavior, health, and productivity of dairy cows in the Southeast
The survivability of dairy farms across the Southeastern United States is being challenged by a variety of factors, such as high costs of production and aging housing and milking facilities. One common response to this is to attempt to increase revenue by increasing herd size, yet keep costs low by not investing in related infrastructure. This approach may be counterproductive to the overall performance of the farm as there is a growing body of evidence that suggests there are negative consequences on lactating dairy cows that are required to compete for resting and feeding resources. This presentation reviews the current understanding of: 1) the relationships among overstocking, behavior, health, and productivity; 2) the behavioral strategies that dairy cows utilize to mitigate the effects of overcrowding and the potential consequences of these strategies on health and productivity; 3) factors that are specific to the Southeast that may impact the relationship among stocking density and other considerations of housing management; and 4) current gaps in our knowledge that should be addressed with future research. Overall, the behavioral changes that were evident in overstocked freestall-based housing facilities included a decrease in the number of hours spent lying per day, an alteration of the feeding times and overall time spent feeding, and increased antagonistic behaviors occurring at the freestalls and feed barriers. From a performance perspective, there were indications that both milk production and reproductive success might be altered by overstocking either the freestalls or feed barriers of a housing facility. The hot, humid summers, which typify the region, and the age, design, and management of freestall facilities represent two factors with the potential to compound the overall impacts of overcrowding in the Southeast. On the other hand, the commonality of pasture access in the overall housing strategy across the region might mitigate some of the negative effects of overstocking on lactating cows. The extent to which these interactions are detrimental or successful when associated with overstocking reflects a major gap in our current understanding of managing dairy housing systems in the Southeast. Beyond freestall-based housing facilities, there is a growing interest in the use of composting bedded pack housing in the region. However, there is little empirical data to support recommendations for the space required per cow within these housing systems.
Keywords: Dairy cow, housing, behavior, overstocking