With dairy herds increasing in size and spending a greater proportion of their lifetime housed, the issue of digital dermatitis is becoming increasingly problematic to control and eradicate.

It is estimated that in the average dairy herd, around 30% of cows will be affected by lameness. Along with the additional expense of treating affected animals, it also affects milk production and cow fertility.

Milk yields can be reduced by as much as 200 to 500 litres. Therefore, an outbreak of lameness in a 100-cow herd, could reduce overall milk output by as much as £4,200, at current milk prices.

In terms of fertility, lame cows will be slow to return to heat after calving and because of the level of discomfort, lame cows show extremely weak signs of standing heat which can be easily missed. Handling them for artificial insemination (AI) increases stress levels and reduces conception rates.

Causes

Digital dermatitis is caused by bacteria and is highly contagious. Once established in a herd, it can spread quickly to other cows especially during the housing period.

The bacteria thrive in damp, dirty conditions and foot contact with slurry is a key method of transmission.

The problem mainly affects the heel of the cow with lesions mainly forming around the border of the skin and the horn of the hoof. It can also spread to the area between the digits and along the coronary band.

An infected foot can be quickly identified by applying pressure to the rear of the hoof as the cow will instantly raise her foot in an agitated motion.

Prevention

Management is key to getting dermatitis under control. Foot-bathing, foot-paring and isolating severely lame animals can help to minimise the effects on a herd.

In addition, the following is advised:

To help determine if the problem is getting worse, or coming under control, it can also be beneficial to assess cows regularly as they pass through the milking parlour, or footbath, and assign a mobility score.

Cows can be scored from zero (no lameness) to three (severe lameness).

Changing herd management to help eradicate dermatitis

Andrew Dale runs a dairy herd of 110 Fleckvieh cows near Limavady on approximately 170 acres. Milk yield is approximately 6,300 litres on a 12-month rolling average and rising, with Andrew aiming to get cows up to 7,000 litres.

Last week, he hosted a farm walk organised by animal health company Provita, which focused on how he has changed herd management to eliminate the incidence of digital dermatitis in his cows.

Milk from forage is a key part of the system, with cows grazing as much as possible. However, with a limited grazing platform surrounding the yard (after the loss of some rented land), Andrew has had to house cows by night and offer buffer feeding after milking to ease the pressure on grazing ground.

As a result of cows spending more time in the house, he has seen a rise in the incidence of dermatitis.

Cows were being routinely foot-pared two to three times annually and run through a footbath regularly, but the problem was still spreading.

Action

In July 2017, Andrew decided to take a different approach and with the aid of a farm consultant, he has been mobility-scoring all cows on a six- to eight-week interval to monitor the effect of the changes made to herd management.

Cows that are showing early symptoms of dermatitis are treated with a spot spray in the parlour. Andrew also decided to change the footbath setup by replacing the old one with two plastic baths, both measuring two metres in length.

The baths are placed between the exit of the parlour and the entry to the cubicle house where cows are buffer-fed after each milking.

Baths are laid out in the handling race, with the first bath filled with clean water. The second bath has the treatment solution (Provita Hoofsure) mixed through. The solution is mixed at 5% dilution during winter and 2% in summer when cows are grazing.

The first bath is now used to clean the cow’s feet before entering the solution. Cows also tend to soil the water bath with dung and urine, leaving the second bath clean.

Both baths are emptied and re-filled every two days. All cows pass through the bath on a daily basis. Previously, cows were footbathed twice weekly.

Results

The change in management has led to a massive fall in the incidence of dermatitis in the herd. At its peak, Andrew reckoned as many as 70% of cows would have shown some level of dermatitis during the year, from mild swelling to more severe ulcerations.

Around 7% of the herd now show symptoms and Andrew hopes to improve on this in 2018. He is already seeing tangible benefits from the change in management.

Milk yields are up on last year and cow fertility is improving. The breeding season got under way at the turn of the year and submission rates are higher than previous years.

January is the month when lameness seems to affect the herd most, with a high percentage of freshly calved cows present. As such, Andrew is more vigilant when monitoring cows.

He continues to observe cows in both the parlour and along the feeding face for early signs of dermatitis.

A problem cow will be spot sprayed immediately and her tag number recorded. Foot trimming is carried out regularly with cows rarely needing more significant intervention.

The change in herd management has now extended to young stock on farm with replacement heifers passing through the footbath on a weekly basis to train them on the system.

Andrew is also using sexed semen to increase the number of available replacements to choose from, allowing him to cull any persistently lame cows in the herd.