LARGER herds, higher stocking rates, heavy traffic areas on laneways and around troughs, and the use of calving pads are all contributing to an increasing incidence of environmental mastitis caused by Streptococcus uberis bacteria.
Dairy Australia’s Countdown Downunder project leader Dr John Penry said mastitis caused by Strep. uberis had been increasing in Australia and New Zealand to the point where 60 to 70pc of mastitis infections where a pathogen can be cultured in the lab are caused by the bacteria.
"Strep. uberis is found in cattle manure and can survive for up to two weeks in fresh dung or contaminated mud and straw," Dr Penry said.
A number of factors are contributing to the growing prevalence of Strep. uberis infections.
"The management of dairy herds has changed significantly in recent years, creating an environment where cows have increased exposure to Strep. uberis," he said.
"Farms are running larger herds on bigger farms and using higher stocking rates, resulting in heavy traffic areas such as laneways, gateways and around water troughs. Management changes also now include calving pads and loafing areas on some farms.
"Transition management now means we can have cows dripping milk before calving. The teat canal is open when the cow lies down to calve and can be exposed to mud and manure."
The key to controlling Strep. uberis involves minimising environmental exposure and controlling the cow to cow transmission.
Dr Penry said Strep. uberis needed to be controlled across three stages of the lactation – at drying off, over the transition period and during lactation.
At drying off cows should be treated with an antibiotic dry cow therapy to remove existing infection and prevent infections early in the dry period before the teat canal seals.
During the second stage – transition and calving – the aim is to minimise the exposure of susceptible cows to faecal material and maximise cow immunity. Most infections occur within the first few weeks of calving when a cow’s natural defences are low and the udder has been in contact with mud and manure during calving.
"It’s important to ensure that cows are milked as close to calving as possible and to monitor closely for signs of clinical mastitis," Dr Penry said.
During the third stage –lactation –the aim is to minimise teat end damage and reduce the incidence of bacteria on the teat skin. Important practices for preventing the spread of infection include putting cups on clean dry teats and taking cups off carefully, post milking teat disinfection and milking machine maintenance.
"It’s worth talking to your advisor about environment mastitis as an effective control program can take more than a year. Each control program needs to be tailored to an individual herd as exposure to infection varies between farms," Dr Penry said.
The Countdown fact sheet What are the keys to controlling Strep. uberis mastitis in dairy herds is available at dairyaustralia.com.au or contact Countdown Downunder on 03 9620 7283.
