Mastitis is an inflammation of the mammary gland and the presence of an intra-mammary infection (IMI) is not required for mastitis to exist. However, the vast majority of mastitis cases are due to an intra-mammary infection caused by microorganisms. Over 100 different microorganisms have been shown to cause IMI but most of the economic losses are associated with species of staphylococci, streptococci, and the coli-form bacteria.
| Major Mastitis-Causing Pathogens and sources of infection | |
| Pathogen | Source and Control |
| Staphylococcus aureus | Lives in the udder or on wounds, milkers hands, Transferred to the teat by milking machine or milking practices. Can be controlled by hygiene, milking procedure and culling. Often resistant to treatment. |
| Streptococcus agalactiae | Lives in the udder and spreads from cow to cow, usually by poor milking practices. Can be controlled by strict hygiene and dry cow therapy. Can be treated successfully during lactation. |
| Environmental Streptococci (Str. uberis or Str. dysgalactiae | Lives in the environment and can be controlled by good sanitation and hygiene, clean stall and environment management. Responds to lactation and dry cow therapy. |
| Coliform (E coli, Klebsiella) | Lives in manure, or dirty, wet and muddy areas; polluted water, dirty milking equipment. An environmental problem, which can be tackled by good sanitation and hygiene. Infections can occur between milkings and may also be caused by poor milking practices. |
The infectious agents can be divided into two main groups – contagious and environmental including skin flora. The contagious agents spread from cow to cow primarily during milking while the environmentals infect cows mostly from their growth locations in the bedding and surrounding areas.
Despite considerable research on bovine mastitis the disease still remains an economically relevant problem to the dairy industry. Economic losses are estimated to be approximately $250 per cow per year in the U.S, which includes milk lost & discarded, veterinary costs, labor costs etc. Additional costs incurred by the processing industry in terms of reduced cheese yields, and the manufacture of products with reduced shelf life and consumer acceptance, which are normally not taken into account.
Mastitis is the most expensive disease in dairy cattle and good mastitis control program will enhance the profits on the farm. Farmers often think that a cow with clinical mastitis is the problem, and do not realize the full impact of mastitis on the herd. For every one cow that has clinical mastitis, studies have shown there will be 15 to 40 more cows in the herd with subclinical mastitis – and this often goes undetected.
If the Somatic Cell Count (SCC) is less than 200,000 cells/ml, then there is a likely hood that the problem does not exist, but the farmer still needs to be aware of mastitis and continue to implement practices that will keep mastitis out of the herd. Herds that have a count of more than 300,000 cells/ml are considered to be problem herds and farmers should implement mastitis control measures. A herd where more than 3 cows per 100 cows show clinical mastitis over a month’s time has a costly mastitis problem because of significant lost milk production and reduced economic returns. Subclinical mastitis infections may cause permanent destruction of milk secretory cells which permanently lower milk producing ability.
Contagious infections are caused by S. aureus, Str. agalactiae, or mycoplasma and are usually spread from infected to non-infected cows during milking. S. aureus organisms colonize abnormal teat ends or teat lesions. Milker’s hands, wash cloths, teat cup liners, and flies are ways in which the infection can be spread from cow to cow. The organisms penetrate the teat canal during milking. Irregular vacuum fluctuations impact milk droplets and bacteria against the teat end with sufficient force to cause teat canal penetration and possible development of new infection
The first step in a mastitis control program thus is to use proper milking Hygiene. This means the teats should be clean & dry when the milk is harvested. Individual towels should be used for each cow so as not to transfer bacteria or microorganisms from one cow to another. Proper cow preparation is a very important step in preventing mastitis causing microorganisms from entering the teat end.
Milk with clean hands and wear sterile gloves if needed. Pre-dip if allowed and necessary and allow 30 seconds contact time. Dry teats thoroughly, using single service paper or cloth towels. Examine fore-milk for clinical mastitis (flakes, clots, watery milk). Wash teats with only as much water as necessary to get clean; using paper or cloth towels to scrub teats when dirty. (This step may be eliminated if teats are reasonably clean).
Milking machines can serve as a vector for transferring mastitis organisms from one cow to another, or they may propel droplets of milk back into the teat end, contributing to mastitis. Ensure milking machines are well maintained and the equipment is functioning correctly. Be sure to apply the machines quickly and remove the machines only when the vacuum has been shut off. Listen to the milking machine for air leaks that can cause droplets of milk to be impacted back into the udder of the cow. Avoid over-milking.
Dip teats after milking (iodine solution) covering at least the bottom half of teat. This will kill the microorganisms that are on the teat and aid in closing the sphincter muscle. If environmental mastitis is prevalent in the herd, pre dipping (dipping the teats before milking) and removing the dip completely can assist in the reduction of mastitis. Avoid allowing the dip to become contaminated with manure or other bacteria laden material. Use dip cups that have a small reservoir that will contain enough dip to treat one cow at a time.
Until the sphincter recovers and closes tightly (30-45 minutes), the mammary gland is at high risk for new infections if the teat end is place on bedding or in manure. By providing fresh feed and water after milking, the cows will remain standing to eat while the sphincter closes thus reducing the risk of infection.
The treatment of every quarter of every cow with a specially formulated long lasting antibiotic is essential for providing the cow with protection during the dry period. Most new cases of mastitis occur in the cow during the first two weeks after drying off and the two weeks prior to calving. At these times the infection will go unnoticed and will increase the number of cows that have mastitis early in lactation. This step is essential in reducing the number of new cases in the herd, and is the only way to effectively treat and eliminate contagious mastitis from the herd.
Cows infected with contagious mastitis must either be culled, segregated from the milking herd and milked last, milked with separate milking units, or teat cup liners must be rinsed and sanitized after milking infected cows (backflushed). Treated cows should be milked last to avoid antibiotic contamination of the bulk tank, even when a special milking unit is used.
It is very important to make a conscious effort by the persons milking the cows to detect all mastitis cases, and treat them promptly. Only approved and recommended mastitis treatments should be used to treat cows. It is important the full treatment regime be followed. It is also important that withdrawal times be observed to insure antibiotics are not permitted to contaminate the milk being sold to processors. Milk from treated cows, or cows with mastitis should not be fed to heifer calves.
Cows that do not respond favorably to treatment, or that continue to become infected should be culled from the herd. The continued presence of these cows in the herd can contribute to the infection of other cows in the herd. Cows that do not respond to treatment or continue to become infected are not economic and will cost the dairyman money. When making the decision to cull a cow, make sure the withdrawal time for the antibiotic is observed.
Developing and following good bio-security system takes time and planning, but the cost to the farm enterprise for not having these systems can be considerable. It is also important to remember that developing bio-security plans decreases the risk of introducing health problems to the herd, but there is no guarantee that it will completely prevent the introduction of disease to the herd. Monitoring bulk tank SCC and bacteria, individual cow SCC, and clinical mastitis rates are ongoing tasks and essential for maintaining high levels of herd health and milk quality.
Information courtesy - Mr.Lindell Whitelock, Consultant, WWS; Mastitis Basics - Dr.John Kirk; Virginia Cooperative Extension Publication (Mastitis pathogen and control) and others.
Amit Sachdev
India Consultant
World Wide Sires
email: indiawws@gmail.com
No comments:
Post a Comment