Taking a whole-herd approach with footbathing, to include heifers and dry cows, is key to tackling digital dermatitis. A leading cattle-lameness vet and a Fife-based producer tell us more.
TEXT LIZ SNAITH
Digital dermatitis is producers’ number-one disease concern, while lameness has the greater impact on herd welfare and productivity, according to a recent Ruminant Health and Welfare grassroots survey. Digital dermatitis (DD) is present in the majority of UK dairy herds and, consequently, this begs the question: how do we strive to achieve zero lameness?
Adopting a whole-herd approach to controlling DD is endorsed by the University of Liverpool Vet School’s George Oikonomou, whose research group ran a largescale farm study among heifers, which were less than 12 months old. The work revealed DD incidence levels of up to 45%.
The benefits of routine footbathing the whole herd – heifers, dry cows and milkers – twice daily, were shown in a recent Hoofcount survey. “Visits to the farms reporting the lowest levels of lameness uncovered a common theme – routine footbathing the whole herd,” says the company’s Anthony Marsh. The survey also revealed that 92.5% of producers reported a reduction in digital dermatitis following the installation of an automatic footbath.
“Digital dermatitis is a disease that is commonly overlooked among youngstock for various reasons, including lack of awareness and biosecurity,” says Professor Oikonomou. “And footbathing in formalin in a plastic footbath is a messy, time-consuming job for the milking herd, without adding heifers into the mix.
“But, once infected, heifers retain the digital dermatitis causing treponemes anaerobic bacteria in the skin, often in a dormant phase. These localise mostly around the heel and in a pocket between the heel bulbs, but they can spread throughout the hoof, both under the horn and under the dew claws.
He adds that while in-calf heifers may suffer small lesions prior to calving, the stress of calving means these issues can get worse. “And these lesions could create significant infection pressure on the rest of the herd.”
The University of Liverpool Vet School study involved intensively monitoring foot health in 2,756 Holstein cattle across four herds. DD lesions were scored according to differences in length of time there had been an infection and severity. Overall disease incidence was high, with 45% of the studied animals showing lesions.
“The work also highlighted that 41% of heifers were already showing lesions two months before first calving. This suggests they became infected early in life,” explains Professor Oikonomou. “We then examined an additional 530 10-to-12-month-old heifers and found that 45% were either already infected or became infected within three months from the start of monitoring. And 50% of them subsequently became chronically infected.
These findings underline the need to control DD in heifers since first infections can occur early in life.
“Minimising exposure to slurry and wet conditions is vital as those will compromise skin integrity and also potentially increase exposure to the digital dermatitis-causing pathogens,” he explains.
“Remember to adhere to biosecurity principles. Disinfecting foot-trimming equipment, particularly after handling infected cattle, could potentially reduce transmission. And isolating cattle with active digital dermatitis infection while treating them could also help. But this may be impractical to implement on farm.” He also urges producers to identify and treat infected cattle, particularly those with active lesions. “Regular walks among cattle when they are feeding, possibly aided by the use of a small mirror glued at the end of a long stick, could help producers to spot infection. It’s worth investing some time here because infected heifers are most likely a main source of DD-infection pressure.
“Routine footbathing also helps to control DD in milking herds, so it should also be used for heifers and dry cows. Consistency, use of appropriate solutions, and cleanliness are all integral aspects of successful footbathing protocols.” Finally, he urges producers to select bulls with high (positive) DD genetic index scores.
“We have recently investigated the association between the estimated genomic breeding value for the DD index, as calculated by AHDB, and the actual frequency of foot lesions, as recorded by our research team, in a population of Holstein dairy cows.
“The chance of DD infection was 2.5 times greater for every one-point reduction in the animal’s DD genetic index. So the probability of an animal being infected was 60% for animals with a DD index of –1 and only 20% for animals with a DD index of +1.”
Brian Weatherup manages a 210-cow pedigree Holstein herd, near Dunfermline, and was recording a DD incidence among heifers of 10% during the housing period until 2022, when he agreed to take a belt-and-braces approach to the disease. This has resulted in DD infection levels falling to less than 2%.
“While youngstock were always kept separate from the main herd, the slatted floors remained clean and dry, and we treated any lesions at least three times with tetracycline spray – a dangerous job that put us at risk of getting a kick,” he says. “DD only became apparent during the housing period and there were no cases during the grazing season.”
After investing in five Hoofcount automatic footbaths, he thought footbathing could also be the solution to tackle the problem in heifers. “It had already proved a success with the milking herd, where DD levels had fallen from 10% to less than 3% after introducing a Hoofcount footbath at the exit of each of our four robotic milking units.”
Bespoke design: the Weatherups are pleased with their heifer footbaths
He commissioned Hoofcount to design two, 2.5m x 2.3m bespoke footbaths to fit into their unit’s refurbished cubicle youngstock accommodation, where all replacement heifers are housed from 12-month olds until three weeks prior to calving. “The footbaths are portable and every three or four weeks, we lift them into the shed and leave for a week. We fill for five days with a 1% formalin solution, followed by Hoofcount Extra F – a formaldehyde, copper, zinc and aluminium solution – for one day, and then a final day of just water.”
He says that the footbaths’ dimensions allow for two dips per hoof and the heifers can walk through one of the baths several times a day. “We still keep a close watch for lesions and, if we find any, they are usually cleared up within one week of footbathing.