As it can be seen the immune system is critically dependent upon proper nutrition suggesting the potential for improving immune function at critical times to prevent infectious disease like mastitis. The current nutrient requirement recommendations for dairy cows do not always account for meeting additional immune cell nutritional needs, thus there is some latitude in modifying diets to potentially improve transition cow immune function. Research from Ohio State University in the 1990s showed increasing vitamin E supplementation above National Research Council (NRC) recommendations greatly decreased mastitis cases as well as severity. This work was incorporated into the 2001 NRC recommendations increasing vitamin E intake from 350 to 1500 International Units/day (IU/d) during the dry period to reduce mastitis risk. Further work by this group showed even higher vitamin E supplementation (4,000 IU/day) had a greater preventive effect. From this work it was determined that cows having blood vitamin E concentrations below 3 micrograms/milliliter (µg/ml) were nearly 9-times at greater risk for mastitis. Dry cows consuming traditional stored forage diets will only maintain a blood vitamin E concentration around 1.5 µg/ml without additional supplementation. Studies not finding protective effects of vitamin E supplementation often did not achieve the desired blood status.
Research from the University of Guelph showed beneficial effects of vitamin A supplementation on preventing mastitis cases in the first 30 days of lactation. It was observed that cows having higher blood concentrations of vitamin A (retinol) were less likely to have mastitis in the first 30 days of lactation. This research did not define a blood concentration threshold but showed as blood concentration increases by 100 µg/ml there was a 60% reduction in mastitis risk.
Research with trace minerals in dry cow diets has been less definitive in showing marked changes in mastitis risk. A survey of cows involved in two Penn State feeding trials showed cows with higher serum iron or lower serum copper concentrations were at greater risk for mastitis. Iron is an essential nutrient for gram negative (coliform mastitis) bacteria. The cow's udder produced compounds such as lactoferrin to bind and prevent bacteria from accessing iron. Copper is important for immune cell function and antioxidant activity to suppress too much inflammation. As much as I am emphasizing more essential nutrients to support immune function, we need to remember all nutrients are potentially toxic and when in excess may have negative effects on the immune response. I am hoping the forthcoming dairy nutrient requirements publication will be addressing immune function as a component to defining nutrient requirements, but don’t hold your breath as there may not be sufficient data to support changes.
So where does this leave us? It comes back to my suggestion that the dry cow diet is the most important one on the farm. We need to properly formulate the dry cow diet to prevent potential disease concerns postcalving, including mastitis. Many dry cow diets are stripped down of supplementation to prevent overfeeding, but the minerals and vitamins remain essential to supplement.
The best approach here is to work collectively with your nutritionist to properly supplement your dry cow diet and use your veterinarian to evaluate the cows' response to supplementation to ensure they are achieving desired concentrations associated with lowered mastitis risk. Remember that just because the supplement is in the diet this does not ensure all cows will achieve the desired effects. There is potential variation in intake, especially in overcrowded feeding systems or during periods of heat stress. Documented variation in mature cow close-up pen intakes is 5-8 lb/day. Your nutritionist needs to account for this variation in intake within your dry cow pens to ensure a greater percent of cows consume adequate nutrients. Also remember there is the potential for antagonistic interactions between nutrients and other dietary compounds that may reduce availability. For example, vitamin A is degraded in the rumen and too a greater extent with more grain or starch in the diet. Recently "precision feeding" has become a desired practice; however, I would advocate that we need precision feeding to achieve precise nutrient outcomes in the cow, not just the diet.
Source : psu.edu