Bovine proteins discovered in chicken breast by inspectors from the Food Safety Authority of Ireland (FSAI) raised the possibility yesterday [Wednesday] that BSE could be in chickens.

The FSAI was asked by the UK's Food Standards Authority (FSA) to conduct sensitive tests on 30 samples of chicken that had been imported from the same Dutch companies whose chicken fillers were found to contain undeclared pig proteins earlier this year.

The FSAI scientists found that 17 of the samples contained foreign DNA. Seven had bovine DNA, seven had pig DNA and the remaining three samples contained DNA from cattle and pigs. Eight of the samples containing pig protein were actually labelled as "halal", while most carried false declarations as to their contents.

Experts have suggested that the DNA material found itself in the chicken because a process employed by the Dutch poultry called tumbling. This involves bulking up chicken meat by adding water, additives or hydrolised collagen.  

The technique of hydrolysis meanwhile sees proteins extracted from animal parts that may be too old to join the food chain. Extraction is completed either chemically or at high temperatures, but the prions associated with BSE are not destroyed.

In this way, it is theoretically possible that chickens can carry BSE, admitted Wayne Anderson, chief specialist in food science at the FSAI.

"The presence of bovine proteins in chicken is disgusting," he said to the Guardian: "We would be very concerned if the bovine protein source cannot be explained."

Dutch authorities responded to concerns yesterday by insisting that bovine DNA could have found its way into the chicken through injected milk proteins. Anderson added however that there is still not enough evidence yet about the origin of the bovine DNA to make a public safety announcement.

The UK imports large quantities of Dutch chicken breast, much of it is tumbled and a lot of it is used in the foodservice industry.