Warrnambool Veterinary Clinic

"We aim to deliver superior veterinary services to our clients and their animals."

Dairy Cows

Home

From our DAIRY Newsletter ...

Mastitis at Calving

Dr. Steve Jagoe B.V.Sc  MVS

Last year mastitis around the time of calving provided some of the biggest headaches on many farms in the district. The main organism cultured from the milk of mastitis cases submitted to Warrnambool Veterinary Clinic was Streptococcus uberis. This organism appears to be increasing in frequency, and is now the most frequently isolated of the bacterial causes of mastitis on local dairy farms. A similar pattern is being observed in other dairying districts in Victoria, especially in the Maffra Irrigation Area and the northern irrigation district.

Recently Dr Bryan Mackay of Te Awamatu Animal Health Centre in New Zealand spoke to a group of local vets, and provided results of some research he and others had undertaken on the North Island. Some of the interesting findings are listed below.

In New Zealand 50% of all mastitis in the first 30 days of lactation is caused by Strep.uberis. A similar rate occurs in Western district herds. The organism behaves as an environmental infection where it originates but once in a herd can also behave as a contagious or cow associated organism. Therefore it exhibits different behaviour to other mastitis causing organisms. It has replaced Staph. aureus (golden staph) as the most important cause of mastitis. Some of the risk factors for the presence of Strep. uberis in New Zealand herds are:

 

bulletHeifers: heifers were 5 times more likely than cows to suffer Strep uberis mastitis
bulletAge: the risk of mastitis is increased by 30% for every calving a cow has;
bulletPrevious mastitis: if a cow had mastitis the previous lactation she is 2.6 times more likely to have Strep. uberis mastitis this lactation.
bulletPoor conformation: cows with poor conformation were 3.7 times more likely to have mastitis than cows with good conformation;
bulletLeaking milk: cows leaking milk before calving have 1.8 times more likely to have mastitis due to Strep. uberis;
bulletFarm: some farms are more likely to have a problem than other farms;
bulletDry cow treatments: cows that receive dry cow therapy are 3 times less likely to have Strep. uberis mastitis than those cows which don’t get dry cow treatments.

 

Therefore the risk factors identified were being a heifer, or an older cow, a previous history of mastitis, cows leaking milk at calving and the farm. The protective factors included cows with average or good udder conformation, and the use of dry cow therapy.

There was also evidence from the study that cows with short teats, those with engorged udders at calving and those milked for the first time more than 12 hours after calving had a greater risk of Strep. uberis mastitis.

 

Things that dairy farmers can do to reduce the risk of mastitis include the following.

 

  1. Dry cow therapy- as well as removing subclinical infections, dry cow treatment appears to aid in the formation of a teat plug soon after the cow dries off. This helps protect against dry period new infections.
  2. Select for cows with good udder conformation (sound teat placement and strong suspensory ligaments, as well as management to prevent flag in springing cows). Udder conformation is also assisted when cows are aligned correctly with the milking machine (ie the cups sit evenly below the udder when milked).
  3. Milk fever prevention strategies will improve smooth muscle tone around calving, so that the risk of leaking milk is reduced. Cows with hypocalcaemia have been found to have much higher stress hormone levels than cows without hypocalcaemia. High stress hormone levels reduce the cow’s ability to fight new and existing infections.
  4. Environmental infections such as Strep uberis mastitis also appear to be associated with the presence of an organism called C. bovis. This bacteria appears when dry cow treatments are not used, or when teat spraying is ineffective.

 

The Countdown Downunder guidelines make the following recommendations aimed at reducing the incidence of Strep uberis mastitis.

 

bulletCows due to calve should be managed to minimise exposure to contamination, especially with faeces. When calving pads are used it is recommended that sand is used instead of organic materials like rice hulls or sawdust. The ability of the pad to drain properly must be considered if this option is used on local farms;

 

bulletIf cows have engorged udders, or are leaking milk before calving disinfecting teats then milking out will reduce mastitis risk;

 

bulletThe milking machine should be serviced and functioning correctly, with particular attention to pulsator function, liner length and vacuum level and stability;

 

bulletUse of blanket long acting dry cow therapy to prevent new infections.

 

As well as these recommendations, prevention of over milking and using impeccable teat spraying or teat dipping techniques after milking will help slow the spread of the organism.

 

Mastitis due to Strep uberis causes significant udder damage which results in lower milk production for the total lactation. Somatic cell counts are greatly elevated in clinical cases and take a long time to return to normal after successful treatment. Therefore the bulk milk cell count is also elevated, leading to lower milk prices. We have found on some farms that the mastitis can be difficult to cure, or returns after apparent successful treatment. Therefore it will is important that the management practices listed above are implemented so that Strep uberis mastitis is minimised this season.

 

Like last year, Warrnambool Veterinary Clinic is recommending that milk from mastitis cases be collected prior to treatment, and stored in the freezer. We employ the services of a qualified pathologist to culture milk samples, identify the organism and do tests to determine the most appropriate treatment. This allows you to have the problem investigated more fully if a mastitis problem occurs in your herd. It also allows us to provide advice on the preferred management to prevent new infections, and treatments to successfully treat cases of mastitis.

 

As well as Strep uberis, we still see a lot of mastitis cases that are due to other organisms. However because the behaviour of Strep uberis is difficult to manage it is important that the management practices listed above are implemented so that the threat of Strep uberis to your herd is reduced.

 

 

 

This is the body of the announcement ...

For More Information Contact:

Warrnambool Veterinary Clinic
514 Raglan Parade, Warrnambool. Victoria. 3280 Australia.
Tel: 03 55612255
FAX: 03 55613297
Internet: mail@warrnamboolvet.com.au

[ Home ] [ Up ]

Send mail to mail@warrnamboolvet.com.au with questions or comments about this web site.
Copyright © 2002 Warrnambool Veterinary Clinic
Last modified: November 21, 2006