Articles

Stress in feet can lead to lameness in the future
Maureen Hanson

Have you ever noticed you tend to have a lot more lameness in the fall? Or that your fresh cows start having foot problems just as they start to hit peak milk production?

That’s not a coincidence, said international hoof care consultant Karl Burgi. “The cows are telegraphing that they experienced a period of stress earlier – usually about 4 to 6 weeks before you see lameness set in,” he said.

Burgi, owner of Dairyland Hoof Care Institute, Baraboo, Wis. trains hoof trimmers and consults with dairy herds all over the world. He said no matter where they live, cows can have healthier feet, and thus stay healthier in general, with properly balanced feet and low-stress living.

The “lameness-later” trifecta starts with heat stress      

Burgi identified three primary incidences that can trigger lameness events down the road:

  1. Heat stress
  2. Any episode of cows standing too long
  3. Transition

Heat stress affects the feet? Yes, said Burgi, because hot cows stand more to try to cool off. When cows are standing, blood does not flow as effectively to the feet, and there is naturally more pressure and compaction on the pedal bone and joints in the hoof structure.

At the same time, the cow’s internal cooling mechanisms also cause blood to be redirected away from her extremities, including the feet and legs. “With poorer circulation, cows are not able to resolve inflammation in their feet, and the hoof corium is deprived of oxygen and nutrients,” Burgi explained. That opens the door for sole ulcers and white line lesions to start to develop, and makes it harder for the cow to regenerate healthy horn tissue, leading to thin soles.

Lack of oxygen creates ideal conditions for another lameness scourge to develop: digital dermatitis, often referred to as hairy heel warts. The bacteria that cause heel warts thrive in an anaerobic, or low-oxygen, environment.

There also are nutritional factors related to heat stress and lameness, according to Chad Mullins, PhD, owner of Dairy Strong Consulting, Maryville, Mo. “Cows may periodically go off feed during heat stress, and their salivation increases,” he noted. “The saliva then is less available to buffer the rumen, and irregular intake can further upset the rumen microbial balance.”

The result can be subclincal rumen acidosis (SARA). This condition has long been associated with lameness or “laminitis,” although the mechanisms for how it occurs are not fully understood.

“I’ve gotta get off my feet…”

Mullins pointed out a connection between two of the three major lameness instigators. “Cows standing too long not only causes pressure and wear on the feet, but often creates heat-stress spells,” he explained. “Think of two of the main culprits of prolonged standing – waiting in the holding pen to be milked, and standing in lock-ups for breeding or veterinary procedures. Both are situations in which cows are crowded together and get hot, even if the ambient temperature is relatively mild.”

Social dynamics and stall use also can dramatically impact the amount of time cows spend on their feet. “When you walk into a free stall barn and see a lot of cows perching in stalls or wandering around looking for a place to lie down, it’s a telltale sign that the herd also has significant lameness problems,” shared Mullins.

He cited data from the Miner Institute in New York that measured lying time versus lameness incidence. The researchers found that cows with greater lying time had significantly less lameness. Milk production also increased, with 2.0 to 3.5 lbs. more milk produced per hour of rest beyond a minimum resting time of about 12 hours.

That makes sense, said Mullins, because resting not only improves blood circulation to the feet, but to the mammary system as well. It also is the time when most rumination takes place. A recent Dutch study showed that rumination activity dropped appreciably at night shortly before cows were diagnosed as lame, further demonstrating how interconnected the issues are.

Burgi added the structure of modern dairies can keep cows on their feet too long. “As herds get larger, walking distance between the parlor, barn, eating and drinking areas often becomes longer,” he said. “Even when their feet are perfectly healthy, cows only regenerate 3/16 of an inch of new horn tissue per month. When walking wear exceeds that growth, we have serious problems.”

He added dairies that bed with sand often have more hoof wear, even though sand does offer beneficial traction at the same time.

Transition troubles  

The third leg in the three-legged stool of lameness initiators is transition. During the months immediately before calving, Burgi said circulating hormones and enzymes cause the body’s ligaments to loosen. “If cows’ feet are not trimmed properly, ligaments in the feet can stretch, leaving them prone to infection and injury,” he noted.

Late in pregnancy, foot angle also changes slightly, with greater tilt to the bones inside the claw. Again, if the feet are not properly trimmed and balanced, they are vulnerable to lameness.

Overwhelmingly, the most common cause of lameness in the first 60 days of lactation is foot rot. Burgi attributes this to lower immunity in the transitions period, coupled with potentially less sanitary housing conditions compared to the lactating herd. The skin integrity may be compromised in such situations, opening the door to bacterial invasion. Unfortunately, immunosuppression and lower skin integrity also creates the bacteria that cause heel warts to set up shop.

Steps to head off lameness at the pass

The multiple and overlapping causes of lameness call for a multi-pronged approach to prevention. The experts suggest:

Keep cows cool – Shade, misters, soakers and fans all can promote cow cooling. “I’ve seen dairies in Saudi Arabia where it is 125˚F. The cows all lie down and they have no lameness spikes,” said Burgi. “It can be done.”

Minimize standing time – Aim to free up as much time in possible in cows’ 24-hour daily time budget for resting, by monitoring parlor through-put efficiency and minimizing the time they spend in lock-ups. A minimum of 12 hours of rest per day is needed, but up to 14 is ideal.

Don’t forget about heifers – First-calf heifers need 6 to 8 weeks to adjust to concrete and free stalls, especially if they were reared on pasture or dry-lot corrals. “They need time to develop enough digital cushion to withstand concrete after they calve,” shared Burgi. He also recommends the first functional trim for heifers at 3 to 8 weeks before anticipated calving. Monitoring for heel warts should start at about 10 months of age. “In herds where we get heel warts under control in the heifer pen, we often don’t have much of a problem with the disease in the lactating herd,” said Burgi.

Trim before transition – It is critical for every cow to have a functional trim at dry-off. “In herds with a lot of wear, we actually don’t remove a lot of hoof tissue – we install a lot of blocks instead,” said Burgi. “The point is that we want the feet to be well-balanced going into the transition period.” Mullins added it takes vigilance to make sure a trim happens for every cow. “There’s a difference between being aware that it needs to be done, and make sure it actually does get done,” said Mullins. “Even during busy times on the dairy, this step is a ‘must-do.’”

Build for the feet – “We build dairies to last several decades, then put floors down that last a couple of years,” Burgi lamented. “Concrete installation should not be rushed, and it has to hold up under the traffic of several hundred or thousand cows walking over it every day.” He said it is important to match tensile strength to the location. A holding pen, for example, needs to bear more weight and wear than a free stall barn floor. A smooth surface with ample grooving also necessary. Grading no steeper than 5% also is advised.

Treat timely – When a cow is detected lame, a dairy’s protocol should be to have her on a trimming table within 24 hours. Hooves should be trimmed or blocked as needed, and systemic antibiotics and/or supportive therapy administered according to veterinary protocols. Heel warts should be treated with a topical, veterinarian-prescribed antibiotic gel and bandaged to ensure contact.

Use preventative hoof baths – Hoof baths are important to control foot rot and digital dermatitis, but should not be viewed as a treatment. Ideally, cows and heifers should start using hoof baths 1 to 2 weeks before calving. If heel warts are a serious problem in the heifer pen, it also is appropriate to use them there. Consult your veterinarian for hoof bath solutions that are safe, effective and will not compromise skin integrity.

Like so many things on a dairy, Mullins said lameness prevention requires open communication between many people. The dairy manager, employees, hoof trimmer, veterinarian and nutritionist all have an important job to do, and need to keep the rest of the management team informed. “Keeping feet healthy is not a periodic chore, but rather is the result of what happens every day,” he stated. “It takes the right people to get it done.”

Foot health advice and ideas

The Dairyland Initiative from the University of Wisconsin-Madison has developed a “Guide to Welfare-Friendly Dairy Cattle Housing.” This housing module includes plans, advice, calculators and virtual tours for heat-stress abatement; free stall design; flooring; stocking density; transition housing; foot bath design and more. A comprehensive lameness-prevention module also is coming soon. You can access the modules at Dairyland Intitiative after completing the site’s free registration.

 

Source: Dairy Herd Network

 


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