Lameness is an important disorder affecting dairy cows in the U.S., not only for economic reasons, but also from an animal welfare point of view. Prevalence of lameness in the U.S. has increased in recent years. We conducted a field study in 50 Minnesota dairy herds (and 5,626 Holstein cows) and found the average prevalence of lameness in those herds was 24.6 percent. Lameness status was evaluated by using a 1-to-5 scale locomotion scoring system, with cows scoring 3 or greater considered lame. Our goal in this study was to collect a lot of information from these herds to evaluate what could be potential risk factors for lameness. Farms were randomly selected, without any previous knowledge of lameness status of the herd and without any enrollment criteria besides cows being housed in freestalls. In a field study, we are looking at a whole system in the “real world.” Data of this kind are needed in order to better understand dairy systems, but they can be difficult to interpret.

Results

Parlor type, parlor size, number of cows in the farm, number of cows per FTE (full-time-equivalent employee), TMR crude protein and NDF content, feeding frequency, pen stocking rate (number of stalls per 100 cows), pen space per cow, linear feedbunk space per cow, type of feed barrier (headlocks or post and rail), total daily distance between pen and milking parlor, frequency of use of a footbath, pen type (2-row or 3-row) and cud chewing index (measured as percent of cows lying down in stalls chewing their cud) were not associated with the prevalence of lameness.

Time away from the pen for milking was associated with the prevalence of lameness. That association was positive, meaning that the longer the cows spent away from their pen, the greater the prevalence of lameness. The top quartile groups for lameness prevalence (lowest prevalence) averaged 160 minutes away from the pen, whereas the bottom quartile groups averaged 351 minutes. It has been suggested that cows stay away from their pen for 3 hours a day. The average time for the herds in our study was 4.1 hours per day.

Hoof trimming frequency was significantly associated with prevalence of lameness. There was a greater prevalence in dairies that trimmed hooves only when the manager decided cows needed it because of hoof overgrowth or lameness (33.7 percent lameness), compared to dairies that had a maintenance trimming scheduled (once or twice a year for all cows), plus when needed (22.9 and 21.3 percent lameness, respectively).

Cow comfort quotient (CCQ is measured as number of cows lying down in stalls divided by total number of cows touching a stall) was negatively associated with prevalence of lameness and it averaged 76 percent across groups in our study. That means that the greater the cow comfort quotient, the lower the lameness prevalence. The minimum recorded group average CCQ in our study was 52 and the maximum was 92 percent, with the top and bottom quartile groups averaging 87.5 percent and 63 percent, respectively. This indicates that the goal of 85 percent CCQ can be achieved in well-managed herds that have comfortable stalls. Average lameness prevalence in the CCQ top quartile groups was 18.7 percent, whereas in the bottom groups it was 33.7 percent. Type of stall surface was significantly associated with prevalence of lameness. Cows housed in barns with sand-bedded stalls had a lower prevalence of lameness (17.1 percent) than cows housed in barns with mattress based stalls (27.9 percent).

There was an association between height of the brisket board greater than 6 inches and prevalence of lameness. That association was positive, meaning that the higher the brisket board the greater the prevalence. There was also an association between lameness prevalence and the presence of the area behind the brisket board filled with concrete at the same height as the brisket board. We hypothesize that having these types of lunge obstruction make it more difficult for cows to rise normally, especially if they are already lame. We recommend the brisket board be preferably no higher than 4 inches above the stall surface, be smooth and rounded and that the area behind the brisket be at the same level as the stall surface.

General recommendations to reduce the prevalence of lameness include:

•Reduce management risk factors for lameness.

•Build or redesign stalls to meet cows’ needs so that cows can rise and lie down normally.

•Use adequate amounts of bedding and follow optimum bedding management protocols.

•Move lame cows to a dedicated bedded pack where they can recover faster. PD