Mastitis costs. On the basis of both his own experience and studies, and an extensive review of recent research, Penn State Professor and Extension Veterinarian Dr. Robert VanSaun stated that one way to significantly reduce mastitis cases is to bump up the levels of several key nutrients in the dairy cow’s diet. VanSaun spoke on “Nutrition and Udder Health” at the recent Mastitis and Milk Quality Conference.
These key nutrients “beef up” the cows’ immune systems, and are particularly important at two points: at drying off and during the period from just before calving through the first several weeks into milk, when cows are more vulnerable to mastitis infections.
The key nutrients include vitamins A and E, selenium and zinc, as well as protein and calcium. Current NRC recommendations, last compiled in 2001, are based on adequate nutrition for milk production, calving, growth and maintenance of body functions. These recommendations, however, don’t take into account what newer research has found: that optimum immune function results from somewhat higher levels of these nutrients, and these higher levels can produce dramatic reductions in mastitis incidence and duration.
VanSaun is quick to point out that although he is a nutritionist veterinarian he does not advocate massive quantities of any single nutrient. “It’s the balance that’s important.”
He also stated, “I’m not going to stand up here and say that nutrition is the sole endpoint of your control of mastitis. Bad management is going to overcome nutrition every time. So will stress. Stress is a key player in mastitis. Stress seems to augment and promote bad nutrition. Overcrowding in the transition barn is going to stress your cows and raise the pathogen load. A bad environment, a wet environment, is going to equal a higher rate of clinical mastitis and infection. But good, balanced nutrition is going to promote the health status of the animal in the process of promoting a good immune response.”
Interestingly, many dairy farmers are not aware that good immune response appears to require higher levels of some nutrients than is currently advocated by the NRC. A lot has been learned since 2001. A committee is currently being formed to revise these recommendations.
VanSaun stated, “If I combine two peer-reviewed studies done at Ohio State where they fed 1,000 IU of vitamin E (double the previous NRC recommendations) to dairy cows during the dry period, they got a very large — a 33 to 34 percent — reduction — in mastitis compared to the controls, and they also saw the clinical duration of mastitis cases shortened.” The cows recovered more quickly.
Those are not the only impressive statistics. For example, researchers again fed cows 1,000 IU of vitamin E per day, but they also measured the cows’ blood levels of vitamin E, “a very simple measure, easily monitored,” explained VanSaun, that is a more accurate measure of vitamin E availability. The cows that had blood levels of less than 3 micrograms per ml. were 9.4 times more likely to have mastitis problems.
A blood level of 3 micrograms per ml. is somewhat challenging to maintain in a dairy cow. “If you’re using an ensiled diet or a hay-based diet for your dry cows, you’re not going to get up to 3, not without some significant level of supplementation,” VanSaun said.
VanSaun believes that 1,000 IU per day of vitamin E is probably minimal.
In some in vitro work, they found that neutrophils, cells in the immune system, were better capable of killing staph aureus, a major cause of chronic mastitis if not treated promptly, when the cow has higher levels of vitamin E and/or selenium, compared to control animals.
A study in Ontario found serum vitamin E was lower in cows that had clinical mastitis within the first 30 days into milk. Those researchers also found an improvement in retained placenta problems with increased vitamin E, along with improved clinical mastitis, but they were unable to quantify the latter. Stunningly, a study looking at vitamin A status found that when the cows’ serum concentration of vitamin A (retinol) was improved, for every 100 nanograms/ml. of improvement, there was an associated 60 percent decrease in clinical mastitis during the first 30 days into milk.
Research from Ohio State, as well as newer research, has showed that when sufficient selenium was provided, there were improvements in mastitis. “We have seen that both inorganic and organic sources of selenium have positive effects on mastitis,” added VanSaun.
What about zinc and mastitis? This has been well studied. “But in the peer-reviewed studies that have been done, nine plus studies said there were positive results with increased zinc, and six plus studies showed no impact, said VanSaun. “There are tremendous testimonials, but in science, testimonials are quite low in the scheme of supporting evidence-based nutrition.”
There were a number of potentially confounding variables that could have resulted in these contradictory results. Clearly, more research needs to be done on zinc. However, positive results were found in the area of reproductive performance with higher levels of zinc.
“Zinc is the single most important trace element. It controls over 220 enzymes in the body. It controls how RNA and DNA are made into proteins that basically control all body functions,” VanSaun continued. “Zinc and vitamin A are actually interrelated, in that zinc is required for what’s called ‘retinol binding protein,’ which is the protein by which vitamin A is transported through the blood.”
If vitamin A is not transported through the blood then your cow has no vitamin A at critical areas of the body, such as the teat epithelium, an important barrier to mastitis pathogen entry. So no matter how good your cow’s vitamin A status is, if that cow is protein deficient or zinc deficient, the vitamin A isn’t going to be doing its job.
Adequate calcium is needed for effective muscle functioning. Without enough of it, you get delayed tightening of the teat sphincter, the only route for pathogens that cause mastitis to enter the body. Low calcium also alters the immune response, and cows with hypocalcemia are a whopping eight to nine times more likely to have mastitis, Ketosis and retained placenta are typically associated with immune dysfunction, and a deficiency of protein will impair lymphocyte function. Adequate protein and vitamin A are also vital to the structure and functioning of the keratin plug, which is another key player in keeping mastitis pathogens out of the mammary gland. The keratin plug, as well as the teat sphincter, are part of that “other tier” of the immune system that presents barriers to the entry of those pathogens. These barriers actually prevent most cases of mastitis, according to VanSaun.
“I’m quite interested in the role of protein here,” continued VanSaun, “so I measured blood albumin, which is the primary blood protein carrier of all our trace minerals and so on. Of cows that had 3 g/dl. or lower of albumin in the blood, two-thirds had disease problems!” Clearly, protein levels matter!
“Cows between 3 and 3.5 g/dl., which is considered normal in most labs, still had 60 percent with disease problems. Only when enough protein was added to the diet and stress factors were minimized would cows reach levels of 3.5 g/dl., where we find two-thirds of these cows being healthy. So albumin is a measure of how we’re meeting the metabolizable protein needs of the girls during this transition from pregnancy into lactation.”
VanSaun also cited an interesting study that came out of the beef industry showing that with very slight deficiencies of nutrients, the first thing to go is the immune response, because the immune system is such a high-maintenance type system.
Since mastitis is the result of a bacterial infection, where the immune system has been either weakened or overwhelmed by mastitis pathogens, a tip-top immune response is what is needed to counter it. In a pinch, you can give injectable minerals, which are more likely to be needed in older, multiparous cows, but, VanSaun commented, “The needles are to prevent critical disasters. Nutrition never comes from the needle. Nutrition comes through the mouth.”
Here is Dr. VanSaun’s nutritional checklist:
• Maintain appropriate protein intake in late pregnancy and early lactation. “I’ve been conservative with my protein at 1100 grams of metabolizable protein during late pregnancy. I have data that we need to be moving to 1200 to 1300 grams.”
• Minimize the severity of negative energy balance. One problem in these early days into milk is that these girls just aren’t eating much, and all the nutrients in the colostrum and milk are coming off their backs. Feed to energy needs, but do not exceed.
• Control potassium, and supplement with adequate calcium and magnesium so the cows can maintain good calcium homeostasis.
• Include adequate trace minerals in the feed, especially selenium, zinc, and copper, although copper status is not well documented in the research relative to mastitis prevention.
• Include adequate to increased vitamins A and E.
• Don’t neglect pathogen reduction and stress reduction.