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Mastitis Case Studies

Cow Management

This resource describes aspects of dairy cow management relative to mastitis.

Dry Cows: Dry cows are cows in their dry period. The dry period is the time between halting of milk removal (milk stasis) and the subsequent calving. Generally, 45 to 50 days is recommended. If less than 40 days, then milk yield in the next lactation will be decreased. The normal procedure to dry off a cow is to withdraw all grain and reduce the water supply several days before the start of the dry period. This drastically reduces the milk production during that time. Then milking is halted about 45 to 50 days before expected date of parturition. Infusion of the udder with antibiotics can help prevent infections that may occur in early involution. After milking is stopped intramammary pressure increases, milk products accumulate in the gland, and further milk secretion is inhibited. Sometimes if the udder becomes extremely congested, it may need to be re-milked. However, this practice stimulates further milk synthesis because intramammary pressure is reduced and pituitary hormones (oxytocin and prolactin) are released. Perhaps more importantly re-milking removes the leukocytes from the udder at a time when many are needed to prevent infection. It usually is unnecessary to re-milk if production is reduced below about 50 lbs per day before milking is stopped. The early dry period (first week or two) is the time of the highest incidence of new intramammary infection (new IMI). The mid-dry period is the time of lowest incidence of new IMI. The peripartum period is also a time of high incidence of IMI.

Nutrients and Mastitis: Deficiencies of the following vitamins and minerals have been shown to be related to increased incidence of clinical or sub-clinical mastitis, increased severity of infection, or elevated somatic cell counts:

  • Selenium - deficient in soils of the Midwest and northeast. Protects mammary tissue from oxidative damage and augments phagocytic function.
  • Vitamin E. Protects mammary tissue from oxidative damage and augments phagocytic function.
  • Less well documented in their relationship to mastitis are: B-Carotene (high in fresh forage, low in stored feed), Vitamin A, Zinc, Copper, Cobalt, and some others.

Culling Cows: The primary reason for culling dairy cows from a herd is due to infertility problems. If a cow does not calve on a regualr basis, she will not produce much milk over time. Culling for mastitis does happen, usually in cases where a cow is chronically infected (often with Staph. aureus). The lose of milk from this particular cow must be weighed against the prospect that she could infect other cows.

Purchasing Cows: The UIUC dairy herd is mostly a closed herd. That is most herd replacements are raised on the farm. However, occassionaly cows are baught from other sources. Many dairy farms, especially large herds, often buy cows. Sometimes producers will buy a large number of cows and bring them into the herd. Few preoducers will quarantine these cows to make sure they do not have diseases that could infect the rest of the herd. this is particularly relevant in the case of contagious mastitis. For example, if a herd does not have any Strep. agalactiae in the herd (only lives in the udder), then the only way that organism could infect the herd would be through buying in infected cows that spread the bacterium to others in the herd. Anytime a previously healthy herd develops an apparent contagious mastitis problem in a relatively short period ot time (a few months), the possibility is good that the organism was introduced to the herd by an outside cow(s).

TMR: Totally Mixed Ration is common method of feeding dairy cattle. TMR are rations that blend all of the diet ingredients formulated to specific nutrient concentrations and mixed to prevent separation. TMR are usually fed ad libitum.

A cow eating a TMR composed of corn silage and other goodies.

DHIA Records: The Dairy Herd Improvement Assoc. provides services to milk producers where they have a milk tester go to the farm monthly and collect a range of information about the cows and the herd. This information is then returned to the producer and it critically useful in making decisions about how individual cows are producing, as well as how the entire herd is doing. Monthly Somatic Cell Counts of cows are important indicators of mastitis problems in individual cows and in the herd as a whole.

Rolling Herd Average: This is an approximation of the average production of milk per cow in a herd over a year's time.

Mastitis Case Studies
Mastitis Resources