News from the Midwest Sectional Meetings, March 16-18, 1998, Des Moines, Iowa
Contacts:
Leo Timms, Iowa State University, (515) 294-4522
Tom Jirik, ASAS/ADSA Media Coordinator, (701) 231-9629
Dairy Researchers Probe Cold Weather Teat Lesions To Cut Mastitis Infections
The phenomenon that makes your fingers and lips sore and irritated during cold weather affects the teats of dairy cows the same way, research at Iowa State University suggests.
ISU researcher Leo Timms in cooperation with researchers at ISU’s College of Veterinary Medicine and the USDA National Animal Disease Center spent the last two years studying cows’ teat-ends, looking for hardening, cracking, bleeding and other wounds. They adopted a teat-end rating system to evaluate lesions on cows in the university dairy herd and in herds of cooperating private producers.
Sudden cold snaps in October and March this winter confirmed Timms’ conviction that the lesions are akin to those suffered on fingers and toes. The number of cows with lesions and cracks went from 12 percent to 50 percent in two days in October.
"We used to think these things got progressively worse during the winter. But we saw significant change literally overnight," Timms said. "Viruses don’t come and go that fast."
Those cracked and irritated teats provide an ideal environment where mastitis-causing bacteria can gain a foothold for infecting the rest of the udder. In fact, Timms says, the presence of those lesions are probably the single biggest factor influencing mastitis infection rates, especially during winter or harsh weather.
Timms explains that, like fingers, the teat end is an extremity far outside the body cavity and is very sensitive to temperature changes. The tissue reacts by slowing down blood flow and may undergoe a process called hyperkaratosis or thickening to form a callous. Also, the teat end may dehydrate, forcing the tissue to split or crack, greatly enhancing the chances for bacterial entry and infection.
Initially, teat-end lesions appear as small white circular or horseshoe-shaped rings around the teat opening. As the lesion worsens, the teat opening appears to turn inside out or protrude and vertical cracking appears. Dark scabbing over and inside the teat orifice may follow. Some lesions can be confused with mild frostbite. Timms research shows that the tissue cracking, especially during winter, may be independent of the degree of hyperkaratatosis, or teat end callous.
"Currently, there’s no way to absolutely prevent the lesions, given the environmental conditions of typical dairy housing," Timms says. "The best we can do is minimize the conditions that result in the lesions."
That means providing windbreaks and adequate bedding and feeding cows indoors during cold weather. Timms advises keeping tissue disinfected and conditioned while minimizing irritation to the teat ends. "That’s difficult considering that cows must be milked twice daily," he notes.
"A key is to have a milker unit that milks the cow out cleanly and quickly, yet still provides adequate yet not excessive massage," he says. "There’s a temptation to reduce vacuum and slow down pulsation, but this just prolongs irritation to the teat ends by increasing the time the milking unit is on the cow. In many herds, the best strategy may be to turn vacuum and pulsation speed up." Producers should work with an equipment supplier to evaluate changes in equipment adjustments.
Timms also advises teat dipping before and after milking with a dip that disinfects and conditions skin. Germicidal dips that contain from 5 to 12 percent skin conditioners or the skin-conditioning equivalent are preferable. Avoid teat washing with water in cold weather because it removes the skin’s natural oils and washing and drying can be abrasive. Dipped teats should be blotted dry before and after milking if post-milking conditions expose teat tissues to cold weather. New post-dip alternatives such as powders and glycol-based products are currently available, but data on their effectiveness is incomplete. Salves, if used at all, should be germicidal and used sparingly with a focus on the teat end.
"For years we’ve heard reports of teat-end lesions. There was no thorough research on how the lesions formed and under what conditions, but field reports indicated a fairly significant problem," Timms said. Short-term studies on the effect of various teat treatments didn’t document the link to cold temperatures or provide enough information on how untreated lesions healed.
Timms said he and other researchers first suspected the lesions were caused by a virus similar to those that cause cold sores that are triggered by cold weather and other stress. Tissue samples ruled out that possibility and the changes in tissue were far more rapid than those typically caused by viruses.
That led the researchers to suspect that cold trauma was even more to blame for the problem. "Our question now is how can we insulate teat ends from those effects?"
Timms said efforts have been complicated by the emergence of salves, dips and other treatments that promise to solve the problem. "We’ve been shocked at how rapidly things can change. Teat ends heal as rapidly as they become irritated," Timms noted. "No matter what you do, even if you do nothing, you’re likely to see improvement."
The researchers have also found that from five to eight percent of cows have sensitive tissue that can be irritated even by normal milking. Timms expects dairy researchers to take the research one step further, to find ways to better manage cows with sensitive tissue and to reduce the number of lesions in the rest of the herd. The result will be improved production, fewer cows culled and less antibiotic used to treat mastitis infections.
Researchers in England, the Netherlands and at the University of Illinois, the University of Wisconsin and the University of Minnesota are also studying teat-end lesions.
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