Economic losses related to mastitis is estimated to be around $2 billion each year in the U.S.
Mastitis continues to be a common and economically important disease, even with extensive research in this area. Losses associated with this disease are not restricted to decreased milk production, discarded milk, missed quality premiums, and cost of labor and treatment — mastitis is also a frequent cause of a cow’s culling, death and reduced milk quality (which, for the processing industry, means reduced cheese yields).
In addition, an increasing number of people today recognize mastitis as a food safety and animal welfare problem as well. It is estimated that the average cost of a clinical case of mastitis is $180, and economic losses related to this disease to be around $2 billion each year in the US, making mastitis a significant issue for the dairy industry.
Blame the bacteria
Most of the time, mastitis is caused by bacteria that can be divided in two categories based on their source: contagious or environmental organisms. Examples of contagious pathogens are Staphylococcus aureus, Streptococcus agalactiae and Mycoplasma spp.
In general, for those contagious pathogens, the infected gland is the main source and transmission from cow to cow occurs mainly during milking time.
For environmental pathogens, as the name implies, the main reservoir is associated with where cows live (bedding, manure, dirt, mud, water). Some examples of environmental organisms are coliforms as e.g. Klebsiella sp., E.coli or streptococci other than Strep agalactiae.
This distinction between environmental and contagious organisms is important for the measures that should be taken to help prevent and control mastitis. In general, control is based on decreasing the exposure of the teat end to bacteria while we increase the cow’s resistance to mastitis organisms by boosting the immune system.
Here are the basics dairymen should know to control this disease.
Controlling contagious bacteria
First of all, practice biosecurity.
- Know the farm from where you are buying. Test cows entering the herd, as newcomers can bring infection with them.
- Ask for past bulk tank culture results, past bulk tank somatic cell counts, past records for clinical cases; this will help you to know if the farm where you are buying animals is free of contagious organisms.
- Know the animal that you are buying. Ask for animal history (somatic cell counts, number of clinical cases, previous culture results).
- Do a California Mastitis test (CMT) on those animals you would like to buy if SCC and culture results are not available.
- Take a look at the udder, milk quality, teat ends, teat conformation. Are they similar to what you have in your farm now?
- Keep the recently introduced cows housed in a separate pen if possible; make sure that the cow has not been treated with antibiotics, milk them with separate milking equipment or before the infected cows.
- Infected cows should be milked last or separated from the herd so their milk does not enter the bulk tank and you limit the spread from infected cows to uninfected cows.
- Milk infected cows often — milk is a good nutrient for us and excellent media for bacteria to grow as well.
- Use teat dipping and make sure the teats are clean and then to dip the whole teat using an iodine solution (0.5% for pre-dip and 1% for post-dip). Give time (30 seconds) for germicide to act. Wipe well, milk as usual, and apply post dip covering the whole teat after detaching the milking unit.
- Treat infected cows. With the support of your veterinarian, choose the better antibiotic and pay attention to keeping milk from treated cows out of the bulk tank until after the withdrawal period.
- Use dry-cow therapy with approved commercial products under indication of your veterinarian.
Control environmental bacteria
The saying “keep cows in a dry, clean and comfortable place” works well here. In case animals have access to pasture; muddy areas and ponds should be avoided.
- Maintain clean environment and adequate housing conditions for cows; avoid soiled bedding, manure on bedding and floors, muddy areas, overcrowding pens.
- Teats should be clean and dry before milking to decrease potential for milk become infected during milking.
- Use approved pre-dip on teats, and use pre and post dipping to reduce or prevent spread of infection.
Management practices or factors can also have an influence on how many cases of mastitis you have in your farm:
- Milking machines should be functioning well, and be tested and serviced by a qualified technician.
- Healthy teat skin is the first line of defense against mastitis organisms, thus lesions, cracks, or chapped teats can increase the exposition of the teat to microorganisms that cause mastitis.
- Free-stalls poorly designed or over crowded will favor large numbers of cows to be standing around or lying in alleyways instead of eating and resting as indicated.
- Nutrition — deficiency of vitamins (A, D, E) or trace minerals (selenium, copper, zinc) — can result in increased cases of mastitis. Work with your nutritionist to provide a balanced diet.
- Proper nutrition and good water quality are essential for a good immune system so your cows can fight and win the battle.
(The author is an assistant professor and Extension dairy veterinarian at the Ohio State University. Send comments or questions in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)
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