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Mastitis: tighter controls in Holland

by
01 January 2014, at 12:00am

Veterinary Practice reports on some of the presentations at the 2013 British Mastitis Conference

BRIAN Pocknee, as chairman, welcomed more than 90 delegates to the 25th British Mastitis Conference at the Sixways stadium near Worcester.

The opening speaker was Tine van Werven, a veterinary surgeon at Utrecht University, who outlined the Dutch dairy industry experience in reducing antibiotic usage. There was a national decrease of 50% in 2012 in the use of antibiotics in total including pigs, poultry, veal calves and dairy cattle. The dairy sector reduced antibiotic use by 40%.

In 2008 an EU table showing the ranking of the prudent use of antibiotics in humans indicated that the Netherlands was second but veterinary use was very high. Concerns about multiple resistant organisms led to a political drive to reduce antibiotic use in food producing animals.

A large study was undertaken to gain more insight into the total use of antibiotics and the routes of administration and to motivate farmers and increase awareness of a more prudent use of antibiotics. The developed programme has been successful and a target of a 70% reduction from 2009 is set for 2015. The use of 3rd and 4th generation cephalosporins and fluoroquinolones has been banned.

If the UK were to follow the Netherlands example, then the term “animal daily doses of antibiotics per year” will become familiar. If the aDD/aY is 5.3, it means that on average each cow in the herd is exposed to antibiotics for 5.3 days per year.

Ban in Holland

Trials have shown that more than 65% of the total antibiotic use in dairy cows is intramammaries, with dry cow therapy accounting for 45% of the total. Now in place in Holland is a ban on blanket dry cow therapy. Emphasis is placed on a preventive approach rather than curative, management not medicines. Cows with a proven infection may have dry cow therapy prescribed by a vet.

The speaker observed that the “days of treatment” figures have been well received and understood by the farmers. A figure of over 6 requires action (red), between 3 and 6 attention (orange) and below 3 is target (green). These figures for cows will now also include youngstock.

Only medicines that are specified in the herd health plan are permitted to be kept on the farm and only one supplier of medicines is allowed, with a central database for all prescribed antibiotics. 

For 2014 all treatments will be carried out by vets except for farm-specific use under the direction of a vet. A clinical guideline for selective dry cow treatments is due to be released by the Royal Dutch Association for Veterinarians.

Transferring infections

The feeding of non-saleable milk to calves is also a concern for transferring infections, resistant organisms and antibiotics. The risks were highlighted by Karen Bond of the RVC. For her PhD Karen is studying Johne’s Disease and Mycobacterium avium paratuberculosis (Map) transfer in milk is one of her areas of study. Infected cows shed viable Map and Salmonella spp. into their colostrum and milk. Additionally, faecal contamination is a source of these bacteria and also E. coli, Listeria monocytogenes and Campylobacter spp. There are current concerns about Mycoplasma spp. mastitis with pneumonia, otitis media and polyarthritis in calves possibly linked to feeding with mastitis milk.

The neonatal calf is most susceptible to Map with 80% of infections occurring in the first month of life. Map is shed into the milk by clinically and subclinically infected cows and the infection has been recovered from the colostrum of 22% of clinically normal cows. Research has shown that pasteurisation on farm at 60°C for 60 minutes is sufficient to eliminate Map.

The potential for antibiotic residues in milk fed to calves has been well recognised for years. Risks to calf health are a concern. Antibiotics in prepared calf feed are now tightly controlled. The consumption of unknown and varied antibiotic residues by calves, in non-saleable milk, is viewed as a potential risk to humans.

Research updates

There were four short research updates from Peter Down (University of Nottingham), Andrew Bradley (Quality Milk Management Services), Abhijit Gurjar (Cornell) and Roger Blowey (Wood Veterinary Group).

Peter has investigated the many parameters that make up the costs of clinical mastitis. He has concluded that in order to minimise the economic impact, great emphasis should be placed on the reduction of pathogen transmission from cows with clinical mastitis to uninfected cows. A doubling of the transmission rate increases the cost of clinical mastitis in a herd by 60%.

Andrew has identified staphylococcal isolates from over 6,000 samples submitted from over 500 farms. Twenty different staph species were identified with Staph. aureus the highest incidence, accounting for 36% of clinical and 37% of subclinical staph isolates. More coagulase negative species were isolated in later lactation.

The percentage of antibiotic- resistant Staph aureus was lower than previously reported and cell counts were significantly higher than other staph species. Staphylococci haemolyticus at 17% clinicals and 13% subclinicals showed a higher incidence than previously recognised.

Abhijit presented the results of a study showing that the combination of antibiotic plus corticosteroid in the treatment of coliform intramammary infections demonstrated a synergistic effect. Cows were treated with antibiotic alone and in combination and slaughtered for tissue analysis. Full inhibition of bacterial growth in the udder was recorded at 36 hours with the antibiotic alone and at 18 hours with the combination therapy.

The addition of prednisolone to cefapirin resulted in a lower density of leukocytes in tissue and milk. No immune suppressive effects with 20mg of prednisolone were recorded. Homoeostasis in the udder was more quickly restored with the combination therapy.

Roger has been considering the benefits and risks associated with recycled manure as dairy cow bedding. The manure has high levels of bacterial contaminants but offers a low cost material that is comfortable for the cows. Having passed through a “squeezer”, the bedding is 65% dry matter and dries out further when put onto cubicles.

The manure should be used on the day of production and not stored. It is important to understand the risks of the material and gather the experiences of on farm use. It may be that the addition of a premix to raise the pH would reduce the infection risks.

Sensor technoloy

Neils Rutten of Utrecht University is studying sensor technology and an initial literature search has shown that comparisons of different applications and technologies are difficult. “Sensors do not outperform farmers,” he said.

No sensor systems have been found to match the ISO standard for sensitivity and specificity but sensor systems are essential to allow effective cow management with automated milking. In developing sensors, a clear aim is to know what information about the cow’s health is being detected. For clinical mastitis, sensor research is needed to indicate cases requiring treatment.

Detection of the changes in cow behaviour have the potential to accurately predict the onset of a clinical mastitis event and Jenny Gibbons of DairyCo explained the role of behavioural and physiological indicators in monitoring animal health.

Mastitis is painful for cows and indicators of pain have the potential to improve mastitis detection and early treatment. Lying time, lying side preference, stepping during milking, gait, weight shifting and eating behaviour have been studied. A combination of physiological changes (e.g. temperature) and behavioural patterns offer improvements for the future.

Robotic systems

The final presentation from Frederick van Essen of Lely outlined that with robotic systems 85% of mastitis cases are detected. There is continuous cell count monitoring and a change in viscosity means the cow is automatically diverted to a treatment pen and the milk separated from the bulk tank.

Globally there are 15,000 robots in use and the largest number on one farm is 22. Yields increase, not least because the cow is milked more often. Early research showed that cell count increased when a robot was installed but modern installations show a fall.

Posters

There were 10 poster presentations and the best poster award was collected by Neal Thornber of the Dairy Group. The Dairy Group, jointly with Ambic Equipment Ltd, assessed teat coverage and concluded that the objectives for mastitis control are not being achieved.

The conclusion is that an automatic system, applying the product consistently to cover the teat barrel and teat end, would be advantageous. n Proceedings, including the national mastitis survey 2013, are available – e- mail bmc@thedairygroup.co.uk.