Strategic sampling for dairy lamenessLocomotion scoring of all cows on a regular basis can be an onerous task. So, Washington State University researchers are looking at different sampling scenarios to get a good handle on lameness in a herd, while also making it do-able for the producer.

“A large herd could look at several pens a month to get an idea of what is happening on the farm,” says Dale Moore, director of veterinary medicine extension at Washington State University.

Washington State University researchers tested sampling strategies on five farms and determined a few methods that can be used to sample cows for locomotion scoring that accurately (within 95 percent confidence) estimate herd lameness prevalence:

1. Score all the cows. This can be done as cows exit the milking parlor or by releasing cows individually from the lock-up if the pens are small enough. This is time-consuming in a large herd. However, scoring all the cows allows for identification of severely lame cows that need treatment. Additionally, it allows for epidemiologic analysis of lameness for the individual farm, which may be useful in determining problem areas.

2. Score the middle third of the pen as they exit the milking parlor. The advantage of this strategy is that it can determine pen level prevalence. The disadvantage is that it depends on milking parlor times, and requires the observer to be present for the milking of the entire herd if all pens are to be locomotion-scored.

3. Calculated sample size of cows, distributed throughout the herd: This strategy is the one employed by the National Dairy FARM (Farmers Assuring Responsible Management) Program. A calculated sample of cows is weighted across pens and distributed evenly within each pen. The advantage of this strategy is that it does not rely on the milking parlor times. In some cases, it may be difficult to observe cows walking freely in pens while keeping track of which cows have been scored already. This strategy has been easily implemented while the herd is locked up for regularly scheduled herd checks, but requires an assistant releasing individual cows from the headlock as needed to allow for locomotion scoring. The disadvantage of this strategy is that it does not accurately estimate pen-level prevalence, only herd-level prevalence.

And, certainly it is good for farm personnel, including cowpushers, to keep an eye on cows that may need immediate attention.

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