Two dunks are better than one, and three are better yet. That’s why Nigel Cook, a University of Wisconsin veterinarian and humane cow care specialist, is recommending that footbaths be at least 10' in length. Twelve-foot baths are even better.
"With a 6' bath, half the rear feet of cows get only one dunk in the footbath solution as cows stride through," he says. "A 10'-long bath ensures cows get at least two dunks per rear foot. And if you extend the bath to 12', 40% of the time the rear feet will get three dunks each."
How does he know? Cook and his graduate students set up a video camera on the exit lanes of parlors and taped cows as they strode through footbaths. Time and again, cows walking through 6' baths had half of their rear feet dunked only once. Extending the baths to 10' and 12' ensured multiple dunks.
While Cook has no proof that two dunks are better than one, or that three are better than two, it only makes sense. And since the whole point of a footbath is to ensure that hooves are covered with solution, multiple dunks increase the chances for that to happen, he says.
Extending the footbaths 4' to 6' without narrowing their width means a lot more solution is needed. So Cook and his graduate students narrowed the baths down to 18" or 20" to see if cows would have any trouble walking through. They didn’t. Plus, narrowing a 12'-long bath to 20" means 50 gal. of solution is about 4" deep, an ideal dunking depth.
Cook decided to slope the sidewalls of the footbath area outwards so that they "V" out to a 36" width at 36" above the floor. He also installed solid sidewalls along the footbath alley (either plywood or concrete).
"The solid sidewalls is a Temple Grandin idea that assumes cows will look straight forward and keep moving through an alleyway with solid panels," he says. "It works."
Cook recommends a step-in and step-out curb height of 10" or 11". Though this doesn’t affect the stride of cows, it does prevent solution from splashing out of the footbath, he says.
He also recommends eliminating the rinse bath prior to the footbath. Because cows naturally start to defecate as soon as they step into water, they foul not only the rinse bath, but the footbath as well. A better use of that space would be for a longer footbath area, he says.
Next summer, Cook hopes to do further research on how often footbath solution must be changed. Right now, the recommendation is to flush out the footbath and fill it with fresh solution every 200 cows. The key, he says, is to keep the solution clean enough so that the active ingredients can actually be effective.