The Quest to Eradicate Mastitis!

If there is one long lived, rarely defeated dragon in dairying, it is Mastitis. Despite heroic efforts, many a knight in shining armor (aka vets, farmers, researchers) has tried to save fair damsels (aka cows) and lost. Furthermore, the dragon Mastitis has grown ever more powerful and costs the dairy industry $2 billion dollars annually because of treatment costs, discarded milk, lost milk production, vet services, lost premiums and reduced cull values. And the list keeps growing!

When a quest takes place in a movie or fairy tale, there are tests and challenging obstacles to overcome. In the dairy quest for Freedom from Mastitis, there have been countless very real challenges to overcome. Here are five outcomes of some of these battles and forecasts of more to come:

In 1986, compliance with the federal bulk tank somatic cell count (SCC) standard of 750,000cells per milliliter (cell/mL) was instituted.
The limit could be lowered again to 400,000 cell/mL in the near future.
There is the ongoing challenge of being profitable in a market of ever-volatile input and milk prices.
The mounting concern about antibiotic resistance in human medicine is causing antibiotic mastitis therapy to be looked at more critically.
Because the goal is to seek to prevent mastitis infections from happening at all, the quest is changing from defense to complete elimination

From Defense to Elimination

Eliminating mastitis is indeed a quest of very large proportions as explained by Lorraine Sordillo, a mastitis researcher at Michigan State University’s College of Veterinary Medicine, “When I began researching mastitis 30 years ago, we concentrated heavily on epidemiology and microbiology. Now we are placing much greater emphasis on immunology and enhancing the cow’s natural defenses to minimize mastitis infections.”

Sordillo expresses that progress in managing mastitis owes a lot to adherence to the “5-Point Plan for Mastitis Management,” issued decades ago by the National Mastitis Council.

The hallmarks of the 5-Point Plan are (1) teat disinfection; (2) dry-cow antibiotic therapy; (3) use of functionally adequate milking machines; (4) antibiotic therapy for clinical mastitis infections, and (5) culling of chronic cows. Steve Nickerson, University of Georgia Professor of Animal and Dairy Science suggests nine more ways of reducing mastitis prevalence and SCC levels:

herd surveillance and
recordkeeping,
environmental sanitation,
strategic culling,
vaccination,
teat sealants,
herd biosecurity,
dietary supplementation and
mastitis control in bred heifers.

Now the Quest is for Immunity

A quest always has to be larger than life. When you take into account that 137 organisms cause mastitis (Watts 1988), trying to develop vaccines for all of them certainly qualifies as a huge undertaking. Even though that quest is unlikely to be entirely won, Sordillo, nevertheless, has positive expectations about the prospects for mastitis vaccine technology. “The mammary gland is unique in that you can vaccinate it separately, targeting individual cell populations to trigger an immune response,” she said and goes on to explain, “Sub-unit vaccines, which target specific peptides that contribute to disease progression, are the focus of current research.” Sordillo calls for “fresh thinking in development of the adjuvants that serve as the carrier for vaccine delivery.”

In the fight against invasive pathogens, the ultimate goal is to enhance cows’ immune system so that they can ward them off. There are commercially available mastitis vaccines called bacterins. This means that because they help the cow’s immune system recognize the core structure of the target bacteria, they are more effective at helping cows fight new infections rather than preventing them.

Immunity Through Nutrition and Supplementation

Another option is to enhance immunity through nutrition. Today this is Sordillo’s primary area of research. The concept is that immunity is affected by all health events. If there is a challenge in one area – such as uterine infection, metritis or another condition — the immune system is busy healing in the challenged area and, as Sordillo notes, “It lets down its guard in other areas.” The goal is optimal immunity being derived from optimal nutrition. Both Sordillo and Nickerson feel that nutritional supplements have the potential for supporting immunity. “Dietary supplements with trace minerals and vitamins can have immune-modulatory effects on the mammary system.” Nickerson foresees that supplement uses will expand. “We believe supplemental yeast acts as a probiotic, supporting rumen microflora and digestion, particularly in early lactation,” he said.

Using Genomics to Breed for Disease Resistance

Genomics is another area that holds promise, but it is clear that progress in this area could be a long way off. “It is important to recognize that in trying to zero in on mastitis immunity with genomic selection, there is the risk of an adverse impact on other immune channels. This is an evolving area of genetic selection and more data, research and trials are needed to keep the forward momentum. Optimizing host defenses especially during times such as dry-off would have a tremendously positive impact.

The Role of Antibiotics Has Dramatically Changed

Researchers agree antibiotic therapy always will be part of the mastitis offense; many feel that its role will change. “Through regulation and our own proactive efforts, I think we will be seeing increased veterinary involvement, and more emphasis on susceptibility testing in the future,” Sordillo said. “Prophylactic antibiotic use, such as whole-herd dry-cow therapy, probably will not continue as we know it today.”

Immune-stimulating additives explored

The bigger the challenge, the more opportunities there are for exploring new frontiers. Feed additives that can support the immune system are attempting to do that. The goal is to develop the ability of the animal’s body to discern between its own naturally occurring molecules and substances that are foreign. Supplements that can achieve this without risk of toxicity of tissue damage are being developed.

Micronutrient Supplementation

Researchers such as Sordillo and Streicher (2002) target development of micronutrient supplements while keeping main priorities:

increasing effective and sustained immunity
without adding risks of toxicity of tissue damage.

Georgia Trial with 40 Prefresh Heifers

It is informative to review the results of a commercially available additive that was evaluated by researchers at the University of Georgia.

Overview of the Trial: A dietary supplement containing B-complex vitamins and yeast extract was fed daily to 40 prefresh heifers from five months of age until calving. Using a control group of 40 untreated heifers, researchers compared the health and milk production of the two groups.

Summary of the Research Findings:

From 5 to 20 months of age, supplemented heifers had higher systemic levels of the molecule L-selectin, which is a measure of the ability of white blood cells to be mobilized from the blood stream and attack invasive organisms.
After 30 days of feeding the supplement: White blood cells collected from heifers in the treatment group were more active in engulfing two important mastitis-causing bacteria, E. coli, and Staph. Aureus.
At Day 3 of lactation:
Mastitis incidence for the supplemented group was 11%,
Mastitis incidence for the untreated controls was 20%
Three days Post-Freshening:
Somatic cell count (SCC) was 221,000 cells/mL for treated group
Somatic cell count (SCC) was 535,000 cells/mL for control group
Milk production at freshening:
Not significantly different between the two groups,
Production advantage for supplemented heifers as lactation progressed.
By five weeks in milk: Treated group produced 7.0 pounds per day more than untreated controls.

(For further information check these sources: Journal of Animal Science Vol. 90, Suppl. Three/ and Journal of Dairy Science. Vol. 95, Suppl. 2, Abstract 220)

Research Conclusions:

Researchers concluded that `dietary supplementation with immune-supporting additives shows promise in preventing mastitis infections and promoting udder health and milk production. With more research and product development, immune-supporting additives may become a standard recommendation in dairy nutrition.

Nickerson says, “If we can reduce new mastitis infections, and successfully equip the cow to use her own defenses to manage those that do occur, it’s a victory for animal welfare, drug residue risk, milk quality, production and profitability and consumer confidence.”