Don’t Overdo Lock-up Times

Self-locking head-lock stanchions have become a management staple on most U.S. free stall dairies. But their convenience can become too much of a good thing, according to a review paper published recently in the journal Veterinary Quarterly.

A research team from Texas A&M University evaluated published studies that examined the effects of lock-up times on various aspects of dairy cow health, welfare, behavior, and performance. While lock-ups are now integral on dairies for performing pregnancy diagnosis, artificial insemination, veterinary-related treatments and exams, vaccinations, heat detection, and some feeding purposes, they also have been deemed a source of “management-induced stress.” The studies evaluated showed far-reaching impacts on cows, including:

• Elevated cortisol levels – Blood cortisol is a common measure of stress, and elevated levels can lead to immunosuppression, increases in size of the adrenal gland and spleen, and higher circulating epinephrine – all of which can contribute to reduced mammary blood flow and subsequent milk production. Dairy cows locked up more than 4 hours per day have shown significantly elevated cortisol levels.
• Decreased feed intake – Cows locked up away from feed for other management practices miss out on critical ration bites and water intake. One study comparing cows locked up for management tasks versus no-lockups showed those in headlocks had a 3-6% reduction in dry-matter intake compared to those without lockups.
• Reduced milk and component production – The authors noted that chronic stress can lead to suboptimal performance of alveoli in the mammary gland, resulting in lower milk yield, higher mastitis incidence, and lower milk quality. Studies supporting this include one in which cows locked up for more than 4 hours per day produced about 4 pounds less milk per day. Another showed a drop in protein production percentage from 3.27% down to 3.19% when cows were restrained.
• Altered time budgets – Excessive lock-up time of greater than 4 hours per day has been shown to induce an increase in natural behaviors like grooming, eating, and resting immediately after release from lockups. Another study bore out cows’ natural inclination to rest versus eating when they are tired. In that study, cows locked up for 2 hours per day lost part of their normally allocated feeding time for 24 hours. For cows locked up for 4 hours, it took 41 hours before their normally budgeted feeding-time length was restored.
• Increased aggression – Cows with prolonged lock-up times also have been shown to demonstrate more aggressive behavior. This is believed to be the result of frustration or discomfort during the lock-up period. Aggressive behavior has been associated with lower reproductive performance, including lower conception rates for heifers at first service.
• Foot health issues – The authors theorized that excessive standing during lock-up could lead to development of poor hoof conditions, papillomatous digital dermatitis, and claw horn lesions. One lameness study cited in the paper showed that non-lame cows stood for 0.73 hours per day; slightly lame cows stood 2.3 hours per day; and moderately lame cows stood 4.3 hours per day.
• Increased heat stress – Heat stress has a multitude of negative effects on cows. Studies evaluating cortisol levels revealed greater stress levels among cows locked up in hot climates versus mild conditions.

The Texas A&M researchers concluded that – based on present research -- 4 hours per day is the upper acceptable bound for lock-up times, with less lock-up time being more desirable. They also stressed the importance of minimizing lock-up times in extreme heat environments, especially late morning and early afternoon in hot weather.

They urged additional studies to evaluate the effect of different lock-up time periods on the health and production of dairy cows, calling the issue of lock-up times “one of the major issues in the dairy industry that needs immediate attention.”