If one or more of your cows is affected by mastitis then you have a cause to worry. Why? Because some mastitis infections are difficult to cure making treatment and control one of the leading costs to the dairy farmer. Losses arise from milk thrown away for being unfit for consumption due to contamination, damages to the udder, reduced milk yield, extra labor to care for the sick cows, veterinary cost, and early culling or even death of the animal. Continued use of antibiotics and other chemicals eventually become counterproductive due to resistance, leaving prevention as being the best option.
Knowledge of what causes the disease, how it is contracted and transmitted is basic towards an effective control program. You will want to put comprehensive measures that ensure your cows are safe from the disease at all times. Indifferent farmers have considered these measures needlessly frustrating but once the disease sets in the alternative has always been long protracted fights which were mostly unsuccessful, ending up in the losses mentioned. This disease must be taken seriously and consultation with a veterinarian is highly recommended.
Mastitis is the inflammation of the mammary gland or udder characterized by changes in milk and the udder. It is a complex disease caused by any combination of the following: microbes such as bacteria, viruses, yeast and fungi or physical and chemical agents. According to a study by Klastrupand his coworkers, 25% of the susceptibility to infection is attributable to environmental factors, 20% to genetic factors, and 50% to herd management.
The main bacteria causing contagious mastitis are Staphylococcus aureus and Staphylococcus agalactiae. They mostly live inside udders or on teat skin. S. agalactiae is very sensitive to penicillin, so there are relatively high cure rates. Other Staphylococcusspp that cause mastitis include S. aureus which forms pockets of infection protected from antibiotics by scar tissue and therefore difficult to cure. S. uberis usually responds to treatment, but can also be difficult to cure. Coliform bacteria damage through toxins released after the bacteria die and antibiotic treatment may not be needed; however they do not usually persist in lactating udders. Pseudomonas is virtually impossible to treat and cows that survive must be culled.
It is spread by contact of teats with contaminated milking machines, hands, buckets, wiping towel, beddings and housing and other milking equipment and materials. Contamination is brought about by poor milking procedures, inefficiency of milking personnel or milking machines and unhygienic animal environment.
The most susceptible cows to the disease are those in the first 2 months of lactation and first 3 weeks of dry period, those with more than four lactations, those with sores on teats, those that had prior infection and poorly managed, those with pendulous udders and those with poor teat shape and placement. Infected udders may be swollen, hot/warm, reddened, painful, hardened and later becomes shrunken. There may be total loss in milk yield, discoloration of milk to yellow, green or blood tinged. Milk consistency may change to clots, watery or flaky and may have foul smell and bad taste. Teats may be blocked and the udder surface may have small swelling.
However, most cases of mastitis have no visible changes in milk or udder and therefore go unnoticed. This form of mastitis is known as subclinical and can reduce milk yield by 40%. California mastitis test (CMT) can be done on farm to detect the presence of such mastitis.
How to prevent mastitis
Prevention of mastitis is best reviewed on a whole-farm basis. The working environment at the farm determines how microbes can spread and infect cattle, how cattle become exposed to infection and how working routines and farm staff can be used to reduce mastitis in the herd. The dry period is above all the most important because during this period cows are more prone to infection. But you find that this is also the time when cows are awfully ignored and poorly managed on many dairy farms as they are put out of sight and out of mind.
While cows are grazing in the field ensure that the teats are clean and healthy, and not soiled. Hygienic housing conditions and good working routines help to ensure that the environment discourages accumulation of pathogens. Good handling equipment, materials and techniques avoids teats and udder injuries or soiling and shortens the milking time thereby decreasing potential for mastitis. In summary prevention can be achieved by doing the following:
- Maintain hygienic animal environment such as clean milking parlor, proper drainage of zero grazing unit and proper disposal of waste.
- Avoid sharp objects in the animal environment
- Clip excess hair from the udder to avoid accumulation of dirt
- Disinfect teats before and after milking by teat dipping.
- Use separate towels or cloth for each cow when wiping the teats
- Use good milking techniques i.e. squeezing and not pulling the teats
- Observe good milking speed and ensure complete milking
- Increase the frequency of milking in high yielding animals
- Dry off the cow gradually and administer dry cow therapy 60 days before expected calving date to prevent infection
- Known infected animals should be milked last, starting with the healthy teats
- Newly introduced animals should be milked separately.
- Take milk samples immediately and submit to the nearest veterinary laboratory. The sampling should be done before any treatment is administered.
- Empty the udder every 2-3 hours
- Manage mastitis according to laboratory results and advice from animal health service provider
- Cull animals with lost quarters, recurrent and chronic cases of mastitis.
Use of antibiotics
This is done when the cow has clinical mastitis. The cow is first milked out then the infected teat is cleaned and the tip swabbed with sterilizer and allowed to dry. A plastic tube containing antibiotics is then inserted into the streak canal and the antibiotic is expelled into the milk cistern. The antibiotic fluid is then palpated up into the gland. This process is referred to as intramammary infusion. After this treatment the cow’s milk should be discarded or used to feed calves.
Use of oxytocin
The logic here is to completely remove milk from the infected quarter hence removing the medium in which microbes can multiply. Oxytocin is administered to effect milk let down.
Although many attempts have been made to develop an effective vaccine, the efforts have been curtailed by the large number of microbes that causes mastitis. Some vaccines have been effective against coliform mastitis but overall, the success of vaccines has been minimal.