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Mastitis pathogens in cows: contagious or environmental?

Mastitis is always an unwelcome guest on your farm. It disrupts your daily routine because the sick cow needs to be treated and requires extra attention. The cow also has to be milked separately. Furthermore, there is always uncertainty whether the cow will fully recover.

04-05-2020, updated on 07-01-2021
udder cow

It is unrealistic to think that you can completely eliminate mastitis from your farm. However, you can make a targeted effort to drastically reduce cases of mastitis. The starting point of this is bacteriological research into the nature of the mastitis pathogens in your herd – a simple process that can be achieved via milk sampling. Because there is always a chance of not getting relevant data or a contamination in the samples, it is important to take enough samples. Discuss the results in detail with your vet: they will tell you whether the results indicated contagious or environmental mastitis pathogens.

Contagious mastitis pathogens

Contagious mastitis pathogens are passed from cow to cow during milking, with new infections caused by bacteria being transferred from one cow to the next via the milking cluster. Contamination can also be spread by dirty hands, equipment and inadequately cleaned milking cloths. With contagious mastitis pathogens, take a good look at the milking routine, the maintenance of your milking machine, hygiene and milking protocols. Streptococcus agalactiae (SAG) is an example of a pathogen that is extremely contagious.


Environmental mastitis pathogens

Environmental mastitis pathogens are mainly found in faeces, soil, water and bedding with the areas that cows spend most of their time (cubicles and aisles) acting as the primary sources of infection. Another risk for infection is dirt on lower legs and feet which can come into contact with the udder and teats when the cow is lying. Dirty milking equipment and wet or muddy areas in fields are also potential sources of infection. Visible signs of mud or faeces on any part of the cow give a clear indication of the potential for infection. Because bacteria are invisible, they can also be present in large numbers in clean bedding. Cows that are visually clean can therefore also lie in bacteriologically contaminated bedding, which further increases the chance of infection.

Hygiene is the key

Cubicle hygiene is very important for dairy cows, but also for dry cows and pregnant heifers. Approximately two months before calving, 60 percent of teat canals in pregnant heifers are "open". It goes without saying that proper hygiene in the housing of heifers therefore plays an important role in the prevention of mastitis. The situation is similar for dry cows: many mastitis cases that occur in early lactation are caused by infections by environmental pathogens that occur during the dry period.

For lactating cows, care must be taken to protect the udder prior to milking as the teat canals will partially open as the cow waits to be milked: this partial opening places the teat canal at risk from infection caused by faeces splashing on the udder.

Keep an eye on cubicle cleanliness

According to the Royal GD animal health, bacteria prefer to reproduce in moist and warm conditions. Therefore, it is very important to ensure all bedding remains as dry as possible. Organic material, such as sawdust, straw and separated manure, is used by bacteria as a growth medium, especially when these materials are contaminated with excess milk from the udder. In order of speed of multiplication, bacterial growth is fastest in separated manure, followed by straw, hardwood shavings, white sawdust and finally paper pulp. Softwoods (eg pine and fir) contain more resinous substances, which somewhat inhibit bacterial growth and are therefore more suitable than hardwood or oak.

The E.coli bacteria is one of the most important environmental pathogens. Virtually all udder infections by E.coli originate from the environment. Faeces are rich in E. coli, so there is a good chance that the teats will come into contact with E. coli in the cubicle, especially if hygiene is not up to standards.


Mastitis pathogens that are both contagious and environmental

Some bacteria can occur in both contagious and environmental circumstances to some extent. Examples of these are Staphylococcus aureus and Streptococcus dysgalactiae.

Learn how to support the immune capability of dairy cows for optimised udder health.

Arnout Dekker
Arnout Dekker
Arnout Dekker is the Marketing Manager Europe of Phibro and has 7 years experience as a veterinarian. He is passionate about cows, dairy farm advisory and farm management. Helping farmers with advice and proven products to keep their cows healthy, produce better, be more profitable and sustainable is what drives and motivates him.

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