Rotate dry cows at pasture to drive down mastitis
Rotating dry cows at pasture and getting the balance between standing times and time for teat closure is a must for effective mastitis prevention, as Debbie James reports
Dairy producers could reduce the risk of clinical mastitis infection post-calving by resting pastures grazed during the dry period.
According to a study commissioned by DairyCo, dry cows at pasture have a lower rate of clinical mastitis when a farm has a pasture rotation policy in place. The study found this to be the case when dry cows grazed fields for a maximum of two weeks and the pasture was then allowed to rest for four weeks.
The research
The randomised clinical trial was carried out in 52 commercial dairy herds in England and Wales to determine whether a well-specified mastitis control plan, implemented in herds with an increased incidence of clinical mastitis, would reduce the prevalence of disease as well as the occurrence of increases in somatic cell counts in individual cows.
Martin Green, professor of cattle health and epidemiology at the Nottingham University Vet School, was involved in the study. He says the findings indicate rotation might reduce pasture contamination on some systems.
“When cows are at grass there is a build-up of infection on the pasture, but when those animals are moved the pathogens are probably removed by environmental factors such as temperature and sunlight,” Prof Green explains.
The peak time for contamination with new environmental mastitis-causing bacteria is often the dry period. Infection during the dry period is usually not apparent until the cow develops mastitis after calving.
Contamination risk
The risk of cows at pasture contracting mastitis is very high, Prof Green emphasises. E coli and Streptococcus uberis are the two most common environmental mastitis pathogens and these thrive in damp conditions. The bacteria are particularly prevalent in the summer if weather is damp and warm.
E coli comes from the gut so anywhere where cow faeces can come into contact with the udder will provide a potential source of coliform mastitis.
Dry cows can be more at risk than milkers because they tend to be rotated less frequently. Although rotation won’t eliminate mastitis it will reduce cases quite significantly, says Prof Green.
But he warns that this advice does not apply to all systems; it is appropriate to farms running pasture-based systems and to those grazing dry cows. “Research clearly shows not all herds have the same problems. It is really important to identify the right issues in individual herds.”
Records
Analysing clinical mastitis and individual cow somatic cell count (SCC) records are the ideal way to consider this.
This can be done through a network of 260 vets and farm advisers who have been trained to deliver the DairyCo Mastitis Control Plan and have the expertise to identify the main causes of clinical mastitis using milk records, clinical records and on-farm questionnaires.
“It is very easy for farmers to work out if they have a problem by working with these people,” says Prof Green.
Preventing mastitis in milkers
Advice on preventing mastitis in milking cows is also changing, Prof Green suggests. Farmers were historically advised that to reduce the risk of infection, a cow should be stood post-milking to allow her teats to close up to prevent infection.
Prof Green says thinking on this has now altered because standing cows for long periods after milking may have a negative impact on foot health.
He advises offering cows fresh feed in a clean area immediately after milking. “The cows will stand to eat and this gives a chance for the teats to close up in a clean area.”
It is essential the area where the cows are standing to eat is clean so dirt isn’t splashed on to their teats. Prof Green recommends scraping yards before cows have access to them post-milking.
Cows should also have access to a clean lying area, particularly when there are lame cows in the herd.
Key considerations for preventing mastitis infection in dry cows at pasture
- Rotate paddocks on a regular basis with a time gap of one month before returning cows to the same paddock
- Avoid overgrazing and overstocking
- Ensure that shady areas, such as those around trees, are large enough so that they don’t become too contaminated
- In wet conditions, cows should be in well-drained paddocks
- Pay particular attention to management around troughs and feeding areas
- Choose calving paddocks carefully
Found out how one Wiltshire dairy producer has benefitted from a DairyCo Mastitis Control Plan