29 August 1997

BAD HOUSING COURTS RISKS

Poor housing conditions and mixing stock contribute to pneumonia concerns. Emma Penny reports

INADEQUATE ventilation, housing stock of mixed ages together and putting calves in the cosiest part of buildings all contribute to increase risk of pneumonia.

So says SAC researcher Jamie Robertson, who warns that for every calf at risk, producers stand to lose £22, and for every calf showing symptoms, the loss increases to £75 a head.

"Theres a high probability that most animals will be exposed to the pathogens causing pneumonia. They may not appear to be ill, but there will be a reduction in growth rate and calves will be more susceptible to scour."

Trials funded by the Scottish Office and carried out by SAC and its veterinary services division found that, of the 30 farms where calves were blood tested, all had evidence of previous exposure to at least three of the five viruses whether they showed symptoms or not.

"That means that on a unit of 100 calves, a niggling pneumonia concern – which might not be apparent – could add up to losses of £2200."

Inadequate ventilation, which increases relative humidity within buildings, is a key difficulty, he says. "In new buildings, poor ventilation can often be a result of architect specifications being changed by builders or producers so the inflow and outflow of air is not balanced."

Most buildings work on a pressure principal; air heats up and rises, dissipating through the open ridge – the buildings chimney. As this air exits the building, cool air is pulled in through the space boarding.

"Bear in mind that buildings are designed for a set number of cattle – if stocked at only a quarter of intended density the ventilation system will work at only a quarter of its capacity.

"It is possible to work out how many animals a building should contain to work efficiently. How-ever, we have found that over a third of naturally ventilated cattle buildings wont work, whatever you put in them," he warns.

Producers may be tempted to try fans or blowers, but these can often do little more than stir air – and dust – around. "If you do fit fans, ensure they are the correct size or you could exacerbate difficulties."

Cattle which are likely to be most susceptible to pneumonia should be housed first, advises Mr Robertson. "Mixing stock from different herds, or of different ages, increases risk. Its best to keep groups separate, but where this must be done, house the youngest first."

And when calves are housed, they should be penned in the airiest areas of the building – not the cosiest, which can often have inadequate ventilation, he says.

"Also, ensure you use the best straw for the youngest animals. Poor quality straw bales – particularly big bales – contain massive concentrations of bacterial spores which can penetrate lung alveoli." &#42

Dont be tempted to house calves in the cosiest parts of sheds, says SAC researcher Jamie Robertson.

BUILDING CHECKS

&#8226 Adequate ventilation.

&#8226 House most susceptible first.

&#8226 Use best straw for calves.