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