With this year’s winter shaping up to be mild and wet for many, cases of pneumonia in calves appear anecdotally high. Farmers Guardian provides a round-up of top tips on how to combat the disease.
Building resilience in calves and lowering disease incidence is central to profitable calf rearing, however, Bovine Respiratory Disease (BRD), or calf pneumonia, continues to pose a major threat to the cattle industry.
Defined by AHDB as a respiratory disease which usually occurs in young housed calves aged five weeks to five months old, susceptibility of pneumonia in calves is dependent on a number of factors including stress, concurrent disease, environment, and insufficient colostrum management.
Emily Simcock, veterinary advisor at NADIS, says: “It is unsurprising that farmers are experiencing higher levels of pneumonia in their housed stock this winter, as housing coincided with high rainfall and mild weather.
“In wet conditions, high relative humidity in buildings increases the survival of respiratory pathogens and when the weather is mild there is less differential between indoor and outdoor temperatures, slowing air movement in naturally ventilated buildings.
“These scenarios combined are ideal conditions for the survival and spread of the viruses and bacteria which cause pneumonia.
“Farmers need to assess all the factors which contribute to higher risks of both clinical disease and production impacts of subclinical disease.
“For pneumonia this should involve working with vets and other advisors to assess animals, the environment and pathogens.”
Ms Simcock highlights the NADIS online risk assessments, which she says can be used by farmers to take a preliminary look at the risks of pneumonia for their herds and to highlight areas further advice could be sought on.
With it said that prevention better than cure when it comes to profitable calf rearing, several experts have spoken to Farmers Guardian up to now around the best approach to dealing with the issue.
Placing more focus on colostrum management could lead to improvements in calf immunity.
Speaking to Farmers Guardian in autumn last year, Kat Hart, of The George Vet Group, Wiltshire, said many farmers could benefit from placing more importance on feeding quality colostrum, at the right time.
Ms Hart explained that, ideally, calves should receive a first feed of four litres or 10 per cent of bodyweight within four hours of birth.
Using a refractometer or colostrometer, available to buy online or via agricultural suppliers, to establish colostrum quality was also suggested.
And it was recommended that only colostrum with a reading of more than, or equal to, 22, was fed.
She also explained that e.coli would typically double every 20 minutes if colostrum was stored in a non-refrigerated, non-covered bucket, and said that high quality colostrum could be stored and frozen in a package with a large surface area [such as a sandwich bag] and defrosted as it was needed.
Mixing calves from more than 10 sources resulted in more than 70 per cent being treated for pneumonia, according to results from an AHDB study.
Discussing the findings in an AHDB webinar, Nick Gibbon, from Belmont Farm and Equine vets, Herefordshire, said the extra costs associated with pneumonia were not just down to the cost of treatment and potential losses, but also through lost efficiency and slower growth.
Mr Gibbon said: “When you mix calves from a large number of farms, there are many more viruses and bacteria which the calves will be naive and not immune to, increasing their risk of illness.
“Pneumonia is the biggest reason for antibiotic usage in the calf rearing system and presents challenges to costs and welfare, the focus has to be on preventing it."
Good air quality and ventilation in calf housing should be closely monitored.
This was also highlighted by Mr Gibbon who outlined research by Kenneth Nordlund, University of Wisconsin, in the same webinar.
This research found a strong relationship between air quality and respiratory diseases.
Mr Gibbon said: “Poor housing leads to poor air quality. Dust and ammonia will cause damage to the hairs lining the windpipe which will allow secondary infection as it is easier for bacteria and viruses to invade."
Consistent veterinary advice is that good ventilation is vital to remove moisture and heat and prevent build-up of pathogens which can cause disease.
Calves are usually reared in a relatively intensive environment, which means the spread of disease is often quick.
Speaking to Farmers Guardian in the autumn, James Anderson, Shropshire Farm Vets, said milk buckets or bottles and teats must be thoroughly cleaned between each feed using a chlorine-based detergent and scrubbed to break down milk residues, fatty build-ups and biofilms.
Mr Anderson said: “We recommend that housing and equipment is easy to clean, with smooth, non-porous surfaces which are less likely to harbour dirt and bacteria, and they are much easier to keep clean.”
Industry figures have shown that vaccination against pneumonia is on the rise.
With various vaccines available to help protect the calf from pneumonia, it is advisable to discuss appropriate strategy with your vet.
Farmers Guardian reported at the end of last year that analysis of data in an AHDB report showed almost 10 million doses of vaccine were sold for use in cattle in 2018.
Derek Armstrong, lead vet at AHDB, said the big rise had been in vaccines to protect against pneumonia in calves, which many vets would have otherwise treat with antibiotics.
Mr Armstrong said: “Sales here have risen 35 per cent since 2011, with two-fifths of animals receiving vaccinal protection in 2018. Vaccines for infectious bovine rhinotracheitis have also gone up 50 per cent over the same period.”
When it comes to managing pneumonia in beef calves, vaccination could also bring benefits.
Giles Bramwell, of Bakewell Vets, Derbyshire, told Farmers Guardian: “Given that very few of our clients have bespoke youngstock housing, he calves get brought in during the autumn after spending the summer outdoors on pasture.
“It is a stressful time and putting groups of spring-born suckler calves into housing which has poor ventilation often means you get outbreaks of pneumonia.
“If you can get a vaccine into these calves before the risk period, so they are primed to fight off any viral challenge before they go into the shed, they will have much better chance of surviving the winter unscathed and growing on to be productive.
"You will also spend less money on antibiotic treatment.”