1. Housing and environment
Housed cows are at greater risk for environmental mastitis than cows on pasture. However in the summer oubreaks of environmental mastitis often occur, these are due to either high rainfall or very hot weather which causes the cows to shelter under trees and produce a very contaminated area. Sources of environmental pathogens include manure, bedding, feedstuffs, dust, dirt, mud, and water.
Bedding materials are a significant source of teat end exposure to environmental pathogens. The number of bacteria in bedding fluctuates depending on contamination (and, therefore, availability of nutrients), available moisture, and temperature. Low-moisture inorganic materials, such as sand or crushed limestone, are preferable to finely chopped organic materials. In general, drier bedding materials are associated with lower numbers of pathogens. Warmer environmental temperatures favor growth of pathogens; lower temperatures tend to reduce growth.
Finely chopped organic bedding materials, such as sawdust, shavings, recycled manure, pelleted corncobs, peanut hulls, and chopped straw, frequently contain very high coliform and streptococcal numbers. With clean, long straw, coliform numbers are generally low; but the environmental streptococcal numbers may be high.
Attempts to maintain low coliform numbers by applying chemical disinfectants or lime are generally impractical because frequent, if not daily, application is required to achieve results. Total daily replacement of organic bedding in the back third of stalls has been shown to reduce exposure of teat ends to coliform bacteria.
Environmental conditions that can increase exposure include: overcrowding; poor ventilation; inadequate manure removal from the back of stalls, alleyways, feeding areas and exercise lots; poorly maintained (hollowed out) free stalls; access to farm ponds or muddy exercise lots; dirty maternity stalls or calving areas; and general lack of farm cleanliness and sanitation.
Control of environmental mastitis is achieved by decreasing teat end exposure to potential pathogens or by increasing the cow’s resistance to mastitis pathogens.
2. Teat Dipping – Germicidal Dips
Premilking dipping is advocated for the control of environmental pathogens and is certainly recommended in herds where there is a high risk of either E.coli or Strep uberius infections.
Postmilking teat dipping with germicidal dips is recommended. A degree of control over the environmental streptococci is exerted, but there is no control of coliform intramammary infection.
3. Teat Dipping – Barrier Dips
Barrier dips, postmilking, are reported to reduce new coliform intramammary infections. Their efficacy against the environmental streptococci and the contagious pathogens appears to be lower than that of germicidal dips.
4. Dry cow therapy and teat sealants
Dry cow therapy with the use of teat sealants of all quarters of all cows is recommended. Dry cow antibiotic therapy significantly reduces any infections carried over from the previous lactation and the teat sealant prevents new environmental infections.
5. Backflushing or use of germicidals sprays between cows
Ensure the product you are using is licenced to be used in this way. This proceedure is usefull in preventing the spread of cow-adapted strep uberis infection, However it does not prevent initial environmental mastitis infection.
6. Milking Machine Problems
Malfunctioning milking machines that result in frequent liner slips and teat impacts can increase cases of environmental mastitis. Ensure your machine is cheched by a technician regularly and any faults rectified as soon as possible. Also make sure your liners are replaced at the correct time – a simple calculation is shown below:
Liner life = 2,500 x number of milking units
Number of cows x 2*
* milked twice daily.
A poorly maintained milking plant will cause teat end lesions which allow infections to enter the teat canal.
7. Udder preparation
Milking cows with wet udders and teats is likely to increase the incidence of environmental mastitis. Teats should be clean and dry prior to attaching the milking unit. Washing the teats, not the udder, is recommended.
There is a vaccine available for mmunizing cows during the dry period against Escherichia coli J-5 bacterin. This vaccine will reduce the number and severity of E.coli clinical mastitis cases during early lactation.
Feeding diets deficient in vitamins A or E, beta-carotene, or the trace minerals selenium, copper, and zinc will result in an increased incidence of environmental mastitis. The supplementation of the dry cow diet with Selenium has been shown to be of benefit.