HFV News DECEMBER 2021

Breaking the cycle of Digital Dermatitis

Digital Dermatitis (DD) is a very common infectious cause of lameness in UK cattle - many of you will recognise the characteristic painful skin lesion between the heel bulbs in the hind feet.

Once a cow is infected with DD, she's very likely to be infected for life unless you treat her promptly with appropriate topical antibiotics.

Treponemes are the bacteria thought to cause DD - there are many strains which can cause varying severity of disease. Once a cow is infected the bacteria can become dormant if the conditions aren't quite right for it to grow - and it is these carrier cows that are the main source of continuous infection in the herd spreading it via slurry where the Treponemes can survive for up to 3 days.

FOOTBATHING

Footbathing plays a vital role in the prevention and control of DD - mainly to prevent the resurgence of the inactive, chronic DD lesions, but also to keep the feet cleaner which helps to reduce new infections.

WHO TO FOOTBATH?

Often we prioritise the milking cows for footbathing - but it is really important to consider a protocol that includes dry cows and youngstock too or these will simply become the new source of infection on your farm.

Heifers infected with DD before they calve are 2x more likely to have DD in their first lactation, give 350kg less milk and take longer to get back in calf compared with uninfected milking heifers

WHEN TO FOOTBATH?

How often you will need to footbath is very farm specific - but generally the more frequently the better! Where risk is high, some farms footbath daily. If farms are purchasing stock - these should be footbathed before joining the herd to reduce the risk of buying in a new strain of DD.

FOOTBATH DESIGN

Good, calm cow flow through the footbath is essential to avoid muck contamination, reduce splash-out of the chemical and ensure there's minimal disruption to the cow flow if they are footbathed after being milked. Although very popular, the rigid plastic footbaths with pronounced ridges on the bottom are uncomfortable for the cows to walk through and will hinder cow flow.

Permanent built in footbaths provide better cow comfort and flow - here are some tips for optimal footbath design:

1. Cows don't like to step up or down into the footbath so the bottom of the bath should be at the same level as the entry/exit points
2. The base of the footbath should provide grip as she walks through - rubber matting can be an ideal solution as it provides grip and comfort for her
3. Each foot needs 6 seconds contact time or to be dunked at least twice, if not three times so the footbath needs to be 3.7 - 4 metres long - you can reduce the width to 60-70cm to reduce filling costs
4. Fixing sloping side panels to the edge of the bath reduces splash-out and makes sure every footfall is in the footbath solution
5. The footbath fill needs to be at least 10cm deep to ensure the whole foot is being submerged - this is also true for the last few cows going through so check how the footbath looks for those last few cows
6. Make sure it is easy to fill, empty and clean - the easier it is to maintain, the more frequently it will be used! A wide bore bung, good water pressure and handy supply of chemical really help make to make footbathing easy if you do not have a fully automated one.

SHOULD I USE A PRE-WASH BATH?

There are mixed opinions on having a pre-wash bath - it is probably more effective to have a longer chemical bath or two adjacent chemical baths.

Studies have shown:

• the pre-wash bath actually increases faecal contamination of the chemical bath
• if the foot is wet on entry to the chemical bath it is less able to absorb the solution
• a pre-wash bath adds a significant amount of water to the chemical bath - reducing its concentration

WHAT TO USE IN A FOOTBATH?

It is a common misbelief that the chemicals you add to a foothbath act as a "treatment" - they don't - they are being used as a disinfectant. Any active lesions need to be lifted and treated with topical antibiotics.

EFFECTIVE* DISINFECTANTS:

*there are only a few good studies on the effectiveness of the various chemicals that are currently being used in footbaths.

The only clinically effective disinfectants from studies are:

• 2-4% Formalin
• 5% Copper Sulphate

Peracetic acid and hypochlorite parlour washings have not been found to be effective forms of controlling DD.

Whilst Formalin and Copper Sulphate are both effective for DD - there are a number of precautions that must be considered before use:

• Formalin is a cancer risk so gloves and a respirator MUST be used to avoid exposure to staff who are filling / mixing the product. Formalin should only be used in a footbath if it is a well ventilated area - ideally outside.
• Safe disposal of the footbath chemical must be considered too - especially with copper sulphate which can build up in the soil if it is disposed of in slurry which is then spread onto pasture.

THE IMPORTANCE OF A CLEAN FOOT

Regardless of the disinfectant you use in the footbath, it can only work if it contacts the skin of the foot and so a clean foot is essential before entry into the footbath and each foot will need 2-3 dunks.

As a rule of thumb: you'll need 1 litre of solution for every cow to pass through - so a 200 litre footbath needs to be changed every 200 cows

KNOW THE VOLUME OF YOUR FOOTBATH

Accurate measurements of your footbath are essential to determine its volume when full so you know how much chemical to use to get the right concentration.

FORMALIN 2-4%

COPPER SULPHATE 5%

HOW EASY IS FOOTBATHING ON YOUR FARM?

An easy fill, easy empty, easy clean footbath can really help get DD under control - but footbathing that is poorly done can cause more problems than it solves.

Automatic footbaths are included in the Farming Investment Fund grants that are currently available and can make a big difference to foot cleanliness and hygiene.

Although DD is highly contagious, it can be controlled effectively in a herd by:

1. Improving foot hygiene by better slurry management
2. Early and effective treatment of new lesions with topical antibiotics
3. Footbathing to reduce infection pressure and prevent shedding by the carrier cows

Feeding calves in a cold snap

It's been a cold few weeks and we've all been layering up - but should we be doing more to protect our calves?

Newborn calves are not great at maintaining their core temperature and have a thermoneutral zone between 14°C and 25°C - this means outside these temperatures they have to use extra energy to keep warm or stay cool. When it's below 14°C this means calves use energy from their milk which was intended for growth, and divert it to keeping themselves warm. As the calf gets older, the temperature range they can tolerate widens so by 4 weeks old they are better able to withstand temperatures down to freezing point.

The traditional way of feeding 2 litres of 20/20 milk replacer twice a day just doesn't suit the nutritional needs of a newborn calf any more, and especially not during the winter months. Using bigger volumes, or a higher solids milk replacer, or pasteurised whole milk, definitely helps buffer the calf when temperatures drop - and on some farms adding in a third midday feed can make a huge difference to growth rates and disease levels in a prolonged cold snap.

If calves are fed twice a day at 8am and 4pm then a newborn calf is going 16 hours over night just as temperatures fall. What do they use when they're short on calories? They start to use protein in their bodies as an energy source - from both their muscles or blood proteins. Albumin and globulin are proteins in the blood and both of these are needed for immune response. So not only are these calves nutritionally stressed and losing muscle, but their ability to fight off infections can be affected too.

As always, milk feeding calves is a delicate balance between giving them enough milk to maximise their incredibly efficient early growth rates but without giving too much milk that you discourage early concentrate feeding. Remember that their rumen is useless at birth and takes 6 weeks to become functional and capable of feeding the calf after weaning so they need to be nibbling in those first few week.

Feed an extra 50g of milk replacer per head for each 5°C drop in temperature below 10°C

Most farmers are now using calf coats on calves which definitely help core temperatures stabilise without the calf dipping into the energy in its milk to keep warm - but don't forget the need for a 24/7, deep, dry straw bed too which allows them to nest and insulate themselves with warm air. This means the straw needs to be deep enough that you can't see their legs when they are lying down.

Any poorly draining areas need to be addressed to stop damp spots forming which drain body heat away from the calf, increase humidity at the calf nose and allow bacteria and viruses to survive. A 15 second knee drop test (without waterproofs!) in the calf pens is a quick way to assess how dry the beds really are!

Please get in touch if you're struggling with calf health or poorer growth rates over winter.

GET IN TOUCH:

Paula: 07764 747855 paula@haywoodfarmvets.com

Tom: 07837 291097 tom@haywoodfarmvets.com

Enquiries: mail@haywoodfarmvets.com

Website: haywoodfarmvets.com

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