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Bovine Respiratory Disease

Bovine Respiratory Disease

BRD can happen at any time of year, but the cold, damp weather of autumn and winter can stress the animals and lead to invasion of the respiratory system by the pneumonia pathogens.

Experts estimate that 30% of dairy calvesare affected by BRD and up to 90% of suckler calves are affected at a cost of approximately £80 million to UK industry.

On an individual animal level the costs can be broken further:

In dairy heifers, BRD can cost £43:

  • 26%     Slowed growth
  • 22%     Medicines
  • 20%     Vet costs
  • 11%     Labour costs
  • 7%       Mortality (replacement costs, loss of genetic potential)
  • 14%     Other costs 

  In suckler calves, BRD can cost £82:

  • 40%     Loss of live weight gain/ production
  • 31%     Medicines
  • 14%     Mortality
  • 10%     Vet costs
  • 5%       Other costs

 These costs are solely for the treatment of a clinical case: Long term problems can result from the poor growth rates and permanent lung damage.

On average there is a two week delay in first service of affected heifer calves. At a cost of £1.65 per day not served (2004 value) this means a cost of £23.10. The first lactation yield is also affected by up to 2.2%. In a 6000 litre heifer at 25ppl this results in a loss of £33 bringing the whole cost of disease in heifer calves to £99.10

The infectious agents involved include viruses (PI3, RSV, BVD & IBR), bacteria (Pasteurella & Haemophilus) and Mycoplasmas. But as 90% of UK herds carry at least one of the respiratory viruses the animal’s susceptibility to disease is often a response to management problems.

Good colostrum intake after being born is extremely important for minimising disease. Colostrum provides important antibodies to the viruses on the farm to prime the calf’s immune system and preventing infection.

• Stresses to the calves can check their immune system and make them more susceptible to infection. This includes weaning, mixing stock and concurrent disease such as scouring.

Poor housing is often one of the biggest factors with BRD.

• Highly stocked sheds with little or no moving air create an ideal environment for virus multiplication.

• Having mixed age groups in a single airspace allows younger, weaker calves to come into contact with large numbers of pathogens.

• Draughts and fluctuating temperatures can stress calves and check their immune response.

• Deep wet bedding releases ammonia into the air. As well as being ideal breeding ground for pathogens, this ammonia can irritate the respiratory system in calves making it easier for the pathogens to invade.

Ideally animals should be kept in sheds of less than 20 animals. Animals less than 150kg require at least 1.5m2 floor space each. Air space allowance should be a minimum of 6m3 for up to 60kg calves and 15m3 for larger animals.

Calves need good ventilation without draughts to remove dust and bugs. However, excessive air movement around the calves may drop their body temperatures and predispose them to infection. The ideal ventilation rate for an 8 weeks old calf should be 50 cubic feet per minute in mild weather and 100 cfm in hot weather. Air flow should be above the height of the animals and can easily be checked using smoke bombs – ask one of the vets.

As well as providing good housing for your calves, the best way to prevent bovine respiratory disease is by vaccination. There are various vaccines available and choosing the right one depends on the pathogens on your farm and your management system.

If young calves are affected the intranasal vaccines are useful as immunity kicks in within 5 - 10 days of vaccination. These are also useful for calf rearers as the animals can be vaccinated as they’re brought on to the farm. Rispoval Intranasal® is the best of the intranasal vaccines and covers RSV and PI3 and can be used from 9 days old.

The most complete vaccine available is Rispoval 4® which covers RSV, PI3, IBR and BVD. The course of 2 vaccines can be started from 3 weeks and should be completed 2 weeks before housing or any stressful events, e.g. weaning.

To guarantee effective immunity when vaccinating, ensure that the drugs are stored correctly and try to minimize stress to the animals.

Treatment involves the combined use of antibiotics and anti-inflammatories. The anti-inflammatories are essential to open the airways and reduce the fluid in the lungs. They also act as painkillers so will improve feed intake and recovery times. Antibiotics are used to treat Pasteurella and Haemophilus and prevent secondary bacterial infections.

Affected animals should be removed from the group to prevent spread to the rest of the animals. If more than 30% of the group are affected “metaphylactic” (blanket) antibiotic therapy may be considered to treat subclinical infection and prevent spread.

Antibiotic choice is often affected by personal experience. The newer antibiotics have longer durations of action, meaning that calves only need to be injected once. The newest of all, “Zuprevo®”, also claims to have the fastest onset of action, meaning that it starts to act on the bacteria within 1 hour. Please contact one of the vets to discuss the best option for your farm.