By ELIZABETH BINNING
A Waikato scientist's study of the bowel habits of cows debunks a long-held belief of farmers that cows always pause to defecate when they walk through streams.
The study by Dr Caroline Bagshaw shows that while cows have little need for bowel control they do not go as
soon as their feet hit the water.
The Hamilton-based researcher has been working with AgResearch and Auckland University to try to find a way to stop livestock from polluting stream water.
"Even a small amount of faeces can have a huge impact on stream quality. Other researchers have found that an amount as small as 100 millilitres of bovine faeces contained 10 million bacteria."
After three years of research Dr Bagshaw has still not found a cost-effective or practical way to stop livestock from polluting the water.
What she has done, however, is clarify beliefs about cows and water.
"Some people think cows defecate as soon as they put their feet in the water. Fortunately this is not the case."
Dr Bagshaw and her colleagues spent the first part of their study looking at why cows spent so much time near streams and what impact features such as alternative water sources had on stream pollution.
They found that the number of times a cow defecated was proportional to the length of time it stayed in an area.
"The study has shown that polled angus cows on hill country spend on average 4 per cent of the day in the stream area and defecate 4 per cent of their faeces in this area."
Many farmers have believed stream pollution could be reduced by providing an alternative water supply.
The study found this had little impact.
"Unfortunately when cows are given the choice of trough water at the top of a hill or stream water, they drink a bit more, and use both."
Dr Bagshaw said fencing off streams was not fool-proof either.
"Cows still defecate along the fences and you are still going to get run-off and urine going into the water."
"More alternative water, with less effort for the cows to reach it, may be the answer."
Herald feature: Environment
