14 November 1997

Tracing causes of pig blue ear

FLUCTUATING temperatures, poor ventilation and poor isolation of replacements could be behind an increase in blue ear disease.

East Yorks pig vet John Carr suggests that clean replacements are most likely to be affected.

"As successive batches are bought in, so the proportion of the herd which has no immunity grows. Then when blue is introduced, large numbers go down with the disease," he explains.

Although it is common practice to mix gilts and cull sows so that gilts can develop their own immunity before they join the productive herd, Dr Carr suggests that sows will have developed immunity to the disease. They will not be shedding enough bugs to challenge the gilts immune system.

"It is better, therefore, to expose gilts for six to eight weeks to culls from the growers which are between 10-40kg because infection should be at its highest," he says.

Improved environmental control is also vital to reduce the diseases impact. "Temperatures can vary by 25C at this time of year. This is sufficient to effect the temperature inside accommodation.

"Ventilation systems must be working efficiently to maintain an even temperature."

which will allow the pig to fight off the disease or recover more quickly," he adds.