Farming Practises May Increase Risk Of Disease

April 3, 2006

Changing Farming Practises May Increase Risk Of Coliform Mastitis

Trends towards the use of more European and North American farming methods in New Zealand may see the incidence of coliform mastitis increase.

Sometimes referred to as E.coli mastitis, coliform mastitis is responsible for between 50-70 percent of all mastitis in the Northern Hemisphere, but currently only about two percent in New Zealand.

Mastitis specialist Jane Lacy-Hulbert of Dexcel says changing farm practices such as housing cows indoors, feed pads and supplementary feeds could increase the risk of coliform mastitis.

Coliform mastitis is caused by the pathogen Escherichia coli, commonly known as E.coli. The bacterium is commonly found in the cow's environment, especially those areas contaminated by faeces.

Lacy-Hulbert was involved in a trial three years ago where there was an outbreak of coliform mastitis.

"The trial was conducted with a group of New Zealand cows and overseas genetic cows. They were fed either pasture or a total mixed ration (TMR) with zero grazing. Over the three-year trial period we watched coliform mastitis take off in the TMR cows."

The trial results were consistent with what happens in the Northern Hemisphere, where cows are kept in smaller confined areas and fed high carbohydrate supplements that increase the numbers of E. coli in the faecal matter. These two things combined are known to increase the risk of coliform mastitis.

"For those of us who went through the coliform mastitis outbreak during the trial, it was a steep learning curve. We knew from our colleagues in other research establishments overseas and from textbooks what to expect, but to actually experience first hand the situation was a valuable learning curve. We learnt that when the rain came down we could expect to have coliform mastitis breaking out in the TMR cows for the next two or three days – some of them would get it long term and were still experiencing problems up to a year after the trial ended"," Lacy-Hulbert says.

"Some of the cows that got coliform mastitis dropped their milk yield by 50 per cent and didn't regain it for the rest of lactation."

When cows are affected by coliform mastitis, . the onset tends to be sudden and develops rapidly, with some animals showing a high fever and a swollen, painful quarter. Loss of appetite, dehydration and muscle weakness are other possible symptoms. If not treated appropriately coliform mastitis can result in the cow's death.

Dairy Business Manager David McDonnell of animal health company Intervet says New Zealand farmers who use feed pads or stand-off pads could be at a higher risk of coliform mastitis.

"There has definitely been an intensification of the dairy industry in the last 20-30 years. Farmers are feeding increased amounts of maize and pasture silage, as well as by-product feeds.

"Combining the changes in feed with the use of feed pads may see coliform mastitis become more prevalent in New Zealand. E.coli is found in cow faeces, so if they are standing on concrete feed pads day after day the intensification of the bacteria starts to build up. Even if the pad is washed down regularly E.coli can still build up."

ENDS

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