Tiny rodents may hold clue to cattle deaths mystery

RESEARCH work on small mammals in West Limerick may, after several inconclusive studies, lead to a definitive explanation of the mysterious death of over 170 cattle in the Askeaton area.

Scientific studies to date, including investigations by the Environmental Protection Agency and the Department of Agriculture, have found no indication of significant pollution in the area,

They have also found no evidence to suggest a link between the deaths and the presence of the Aughinish Alumina plant and two ESB plants - Moneypoint and Tarbert. These are in the general vicinity and have been proven to emit significant amounts of sulphur dioxide.

Research teams at the departments of biochemistry and zoology at University College, Galway have, however, discovered that certain small mammals, particularly bank voles - which look like very small field mice - are deficient in two related enzymes which have a vital role in the liver function of both rodents and larger animals.

This may be an indication of pollution in the area and opens up the possibility that the source may be traced, according to Dr John Donlon, a biochemist at UCG.

In humans, a deficiency of one, of the enzymes, phenylalinine hydroxylase, leads to a condition known as phenyl keto uria (PKU). The enzyme which converts an amino acid - a protein building unit - into another amino acid is absent, leading to a build up of phenyl alinine.

This can cause severe brain damage and metabolic disorder. A genetically inherited condition, it affects one in 16,000 children.

Many of the small mammals examined in west Limerick during 1995 were deficient in this enzyme and in glutathione peroxidase, which is required for phenylalinine hydroxylase to work.

The mammals feed on grass and foliage, a diet not dissimilar from that of cattle. Those in a control experiment with a different diet were not deficient, indicating that some dietary factor in the area may have been responsible.

Dr Donlon told The Irish Times that he did not wish to comment in detail, pending the study's publication in a scientific journal. But he confirmed "the distinct link, with animal health problems in the area."

The significance of the research is the discovery of a novel parameter which could be employed as an effective monitor of environmental change in the area. This not only raises the possibility of finding the source of that change, such as a pollutant, but of monitoring any alleviating measures implemented in the future.

The Department of Agriculture was aware of this study, yesterday's Sunday Tribune reported, and has commissioned its own study of rodents in the area. This is likely to lead to an evaluation of the enzymes in cattle there.

Some 156 cattle have been lost on two farms over a seven year period. This led in 1995 to the Department acquiring one of the farms and leasing the other.

The Green Party spokeswoman on food and agriculture, Ms Paula Giles, said the study would give the lie to the view that farm mismanagement was responsible for the deaths.