Micronutrients and Mastitis

As part of a widespread effort to reduce mastitis and lower somatic cell counts, exciting work is being done in the area of micronutrients and udder health. The nutrients being studied include vitamin E and selenium, copper, zinc and vitamin A.

Copper (Cu)

The primary function of Cu, relative to immunity, is as a component of the enzyme, superoxide dismutase( SOD). Recent studies at the University of Kentucky have shown that heifers fed 20 ppm of supplemental Cu prior to parturition had a lower prevalence of mastitis during lactation than animals fed no supplemental Cu (basal Cu was 8 ppm). Severity of infection was also reduced by Cu supplementation. Ensure the Cu to molybdenum ratio is at least 4:1. For most of Manitoba, 20 ppm of copper in dietary dry matter is more than sufficient. Excessive intake of Cu actually increases oxidative stress and should be avoided.

Zinc (Zn)

Zinc is a component of SOD but marginal Zn deficiency does not reduce SOD activity as greatly as does marginal Cu deficiency. Zinc is also involved in maintenance of skin and keratin. A paper published in the proceedings from the 1994 National Mastitis Council meetings indicates "few controlled studies ...exist and claims for the role of Zn in resistance to mastitis are often subjective and anecdotal". Some studies have shown reduced somatic cell counts when zinc methionine (a chelated form of zinc) was fed to provide 10 to 20 ppm of supplemental Zn. Specific conditions under which zinc methionine improves mammary gland health have not been identified. Available data does not support feeding Zn at levels above the NRC recommendation of 40 ppm as a means of reducing mastitis.

Vitamin A and Beta Carotene

The effect of vitamin A on disease resistance appears to be related to its involvement in maintaining a functional epithelium, its effect on stress and glucocorticoid levels and increasing immune response. Beta carotene is a precursor of vitamin A and is an important fat soluble antioxidant. Effect on mastitis has been variable. Data suggests that vitamin A and beta carotene play a protective role against mastitis and that the effect of beta carotene is likely independent from its role as a vitamin A precursor.
 
Vitamin A fed at rates above the nutrient requirement (70,000 IU/day+) does not greatly influence the incidence of mastitis. Supplementation of beta carotene (200-500 mg/day) during the dry period may improve udder health under certain conditions.

Vitamin E and Selenium (Se)

Vitamin E and selenium (Se) are important components of the cow's immune system. They function as antioxidants. Studies at Ohio State have shown the prevalence and duration of clinical mastitis is reduced when dry cows are fed diets which provide 1000 IU of supplemental vitamin E per day and lactating cows are fed 500 IU of supplemental vitamin E daily. A synergistic response to Se and vitamin E was found. Research at Penn State University found that cows fed diets with 0.3 ppm of supplemental Se recovered faster after being infected with E. coli but that Se did not affect duration of mastitis caused by Staphylococcus aureus. Injecting cows with massive doses of vitamin E (3000 to 6000 IU) one week prior to calving has been shown to improve immune function.
 
Diets should contain 0.3 ppm selenium. Lactating cows should receive 500 - 600 IU vitamin E per day. Dry cows should consume 1000 IU of supplemental vitamin E per day. Mineral premixes do not contain adequate levels of vitamin E. Feeding 15 g of Vitamin E 40,000 will provide 600 IU of vitamin E per day and 25g will provide 1000 IU per day.
 
Source: Nutrition Update Volume 8 No.2, August 1997