By the end of next month it is hoped 95 per cent of UK dairy herds will have committed to a Johne’s control plan, and biosecurity plays an important role in controlling the disease.
Biosecurity plays a big part in Johne’s disease control and Dr Wendela Wapenaar, associate professor of cattle health and epidemiology at Nottingham Vet School, sees two key areas where improvements can be made on many UK dairy units.
Cattle movements is the first.
Dr Wapenaar says: “Buying stock has to be one of the biggest threats to disease control. If we stopped moving cattle from farm to farm it would make a significant difference, and not only for Johne’s disease. Buying a seemingly great looking animal does not guarantee you she is disease free.”
Dr Wapenaar urges producers, and their vets, to look at the herd history rather than individual cow data when buying and moving animals.
“This applies to all disease control, but particularly to Johne’s. The bacteria which cause Johne’s are very clever. They can hide inside the animal and do not cause visible disease or evoke an immune response. If the immune system weakens because the animal is under stress, then the bacteria, in effect, wake up.”
This will then generate an immune response which can be picked up with an ELISA test, which is the test used to identify common diseases such as Johne’s, neospora, IBR and BVD.
So a cow, which was most likely infected as a calf, that appeared ‘negative’ on a test, can turn ‘positive’ under stress.
“This is why we must look at the herd history and find out what the prevalence of Johne’s is in the herd, instead of relying on one individual animal’s test result.”
NMR’s HerdWise records will provide the herd data required here. Screening the whole herd through individual milk samples and on a routine basis increases the chance of finding infected animals.
In 2010, the Dutch introduced a compulsory Johne’s control programme for commercial dairy herds.
This included 97 per cent of herds and each herd was allocated an A, B or C rating, based on routine annual test results. In 2014, 75 per cent of the herds had status A, meaning all cows had tested negative.
Dr Wapenaar says: “These herds may not be completely Johne’s-free, but buying from a status A herd is reducing your risk of buying a Johne’s infected animal.”
Dr Wapenaar’s second biosecurity hotspot is general cleanliness on our dairy units, especially around calving pens and young calves where the risk of infection, especially of Johne’s, is particularly high.
“These areas should be covered in the Johne’s control plan, but producers should ensure they use clean equipment, wear clean boots and have a dedicated calving pen, rather than a combined sick cow/calving area.”
She says general cleanliness varies among UK farms.
“First impressions are important. The entrance should be tidy and as free from mud and slurry as possible. I would encourage producers to visit colleagues who run biosecure units and learn from them; there are some great farms in the UK to look at. And we are not talking about a big spend, it is about committing the time to cleaning up and adopting tidier habits.”
Dr Wapenaar has seen biosecurity standards increase on units worldwide and urges the UK to keep up.
She cites dairy units in China, Chile, Sweden and the Netherlands where cleanliness is typically much higher on the agenda than it is on many UK units.
“I have been on units in China where the staff who work with the milking herd never go near the calf houses, and vice versa. Smaller units may not be able to go to these lengths, but dairy staff should not be walking into the calf area with slurry on their boots.”
Likewise, it is compulsory for every visitor to a Dutch dairy unit to put on overalls and wellies provided by the farm. Often visitors must leave their vehicle at the farm entrance, further reducing the risk of disease transmission from between farms.
She admits there are no direct tangible benefits alongside ‘cleaner’ dairy units.
“But improving biosecurity will reduce the risks of disease spread. Good hygiene protocols around the farm are part of this.”
She encourages producers, with their vets, to prioritise key risk areas.
“I might suggest cattle movements and cleanliness as the top risk areas, but these may be good and other risk areas, such as vaccination schemes, staff training and wildlife and pest control might be key.”
Gill Whitehurst from Glenthorne Vets, Uttoxeter, reinforces the importance of high biosecurity on-farm, especially in an area where most herds have some Johne’s-infected cows adding, because of TB, totally closed herds are impractical if producers are looking to maintain or expand cow numbers.
She says vets should be reinforcing biosecurity measures on-farm.
“There is a lot more we can do to dramatically reduce the risk of Johne’s spread and gain some disease control. For example, if I am asked to look at a sick calf at the end of a routine visit, I make the point of thoroughly cleaning off, disinfecting and putting on clean gloves before going into the calf house. Ideally, producers should flag up any calf visits before we look at adult cows.”
She also says hygiene in the maternity unit is a priority.
“Staff should have their own protective clothing which stays on-farm, and those in charge of the young calves should have clean clothing, gloves and boots. Calf feeding buckets are for feed only and not to be handed to people to wash their boots.
"There should not be any adult cow faeces anywhere near the calf unit. And manage colostrum carefully. Use a quality calf milk replacer rather than take any risks.”
She also highlights the need to keep disinfectant footbaths at calf house entrances clean and refreshed.
“Too many are left dirty. Feeding utensils should be clean and disinfected after use too and used exclusively in the calf unit. Essentially, treat your baby calf house how you expect your own child to be treated in a maternity unit.”
She also says slurry spreading is an area which sometimes falls off the biosecurity radar.
“Do not spread farm slurry onto youngstock grazing pastures as you could be spreading infection. Use it for arable or maize land.”
By October 31, 2018, all producers supplying buyer members of the NJMP will need to have assessed their risks and herd status and have a written Johne’s management plan in place.
This must be confirmed by a declaration of compliance with their BCVA-accredited Johne’s veterinary adviser.
Milk collected by buyer members of NJMP account for more than 85 per cent of UK milk production. The target is to have 95 per cent of UK dairy herds committed to a Johne’s control plan by this date.