Most cows would rather go hungry than eat pasture contaminated with dung, an Australian researcher has found — but he had to put the cows in nappies to find out.

Dr Michael Friend, a lecturer in Animal Production at Charles Sturt University, conducted an experiment which monitored the eating patterns of cows in fields contaminated with dung.

The research was undertaken to get better models for predicting intake of pasture, said Dr Friend, who worked with researchers from the Scottish Agricultural College in Dumfries and the Macaulay Institute in Aberdeen.

One of the most important factors influencing the productivity of grazing animals is the amount of pasture they consume. Broadly speaking, the more a cow eats, the more milk it produces.

"So the aim in dairy production is to maximise input," explained Dr Friend.

"We know how much cows will consume from a uniform pasture but when we have a variable pasture, like one contaminated with dung, we have trouble estimating how much pasture a cow will eat."

Over a six-month period, Dr Friend placed cow pats with monitors buried in them in strategic positions in fields that were otherwise free of dung.

The buried monitors could detect cows that came within a certain range, thanks to a 'reader' device around each cow's neck — similar to the security swipe systems in many buildings.

Each contaminated patch was also sprayed with a natural marker, which allowed Dr Friend to observe whether or not the cattle had grazed there.

The rest of the field was kept free of further contamination by means of nappies fitted to the cows' rears. The cows were Holstein-Friesians, the main dairy breed in Australia, although the breed isn't really significant to the experiment, said Dr Friend.

The cows were allowed to graze the field for four days. After three days they had eaten all the uncontaminated pasture, and on day four had had to make a decision whether to graze on the contaminated areas or go hungry.

The initial results were mixed. Most cows avoided the contaminated patches for as long as possible, while some cows avoided them altogether, preferring to go hungry. Only one cow grazed on the contaminated patches straight away.

Cow dung takes between a week and a month to break down, depending on weather conditions and how active dung beetles are in the area.

Unfortunately, preventing contamination by keeping the nappies on the cows isn't an option.

"We had a lot of trouble getting them to wear the bag," Dr Friend said. Only eight of the original 12 test cows were included in the experiment because of this difficulty.

The bags were also high-maintenance because they had to be emptied every three hours. "But the dairyman thought it was great, he didn't get crapped on," commented Dr Friend.

Dr Friend will be giving a paper on the research at a conference in Reyjavik, the capital of Iceland, next month.

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