Thirty years ago in 1970, according to Hoard’s Dairyman data, the US had approximately 12,000,000 total dairy cows, each producing approximately 9,750 pounds of milk annually. In 1999 we had about 9,200,000 cows averaging approximately 17,800 pounds/cow annually. Quite a change!

Out of this period evolved much of the current mastitis control strategy including post milking teat dipping, dry cow therapy for each quarter of every cow, culling chronically infected cows, treating promptly clinical cases and using functionally adequate milking equipment. This program is still valid and heavily used today but will it meet future needs?

Thirty years ago a main concern was contagious mastitis pathogens, especially Strep ag and Staph aureus. The legal maximum for somatic cells was 1,500,000/ml. The strong focus on controlling these contagious bacteria has virtually eliminated Strep ag on most well managed dairies and Staph aureus has been greatly reduced.

Future SCC and Production Levels
At the present time many dairies have mastitis problems associated with infections caused by environmental bacteria present on every dairy farm. We also still have a national SCC standard of 750,000/ml whereas most milk producing regions have lowered their legal limit to 400-500,000/ml. These are issues that will have to be dealt with in the future.

Over the next 20-30 years undoubtedly production/cow will continue to increase approximately 300-400 pounds annually due to improved genetics and management. It may be argued that with increased production/cow will come more problems but this may or may not be the case. Selection for increased milk production likely selects for a host of associated traits; therefore higher production may be coincidental with other improvements that make these production increases possible.

Herd averages greater than 30,000 pounds/cow/year will be common in the future and we have to be prepared for it. Equipment, housing, feeding programs and milking routines will have to be designed to handle such production without causing limitations or breakdowns but will we have mastitis control programs suited for such production levels?

The average herd size will increase in regions of the country where today it may be relatively small. We may like smaller dairies but size generally plays a significant role in being cost efficient. Dairymen in the future are no more likely to be able to command premium prices for their milk than present day dairies. Competing food and beverage industries will force milk to be competitively priced and profit margins will be squeezed. Larger dairies will typically have an advantage due to lower unit costs.

Somatic Cell Counts
The demand for high quality milk will increase due to U.S. consumer demands and international pressure. The current SCC limit of 750,000 eventually will likely be lowered to 400,000. It may occur in steps but future dairymen will have to be prepared to produce milk that is consistently below 400,000 somatic cells /ml.

This level is formidable. There is a great deal of variation associated with somatic cell levels. Any average always has an associated range and for SCC this is large. It is estimated that in order to always be less than the limit of 400,000 cells/ml the average will have to be maintained at about 200,000. This would allow room for a significant short-term spike in cells, for whatever reason, and still result in counts less than 400,000.

Residue Concerns
There will be no relief in terms of pressure to produce and supply residue free milk. Consumers are likely to develop a more demanding attitude about the quality of all food items including milk and milk products. They will demand milk be free of residues of all types, especially antibiotics and other compounds used to treat sick cows. It is not an unreasonable demand and one that we will have to satisfy convincingly in order to garner our share of consumer dollars spent for food and beverages. This demand will force the use of less antibiotics and possibly safer antibiotic type compounds in the future.

An associated issue is the perception that through excessive antibiotic use in animal agriculture we may be creating a situation where more resistant strains of bacteria are developing and they may somehow pose a threat to humans. While this may debatable the damage can be enormous if this perception grows. Perception is a powerful force and the dairy industry needs to develop the perception amongst consumers that it is aware of these concerns and is doing something about it.

Future mastitis control will include much of what we do today plus additional procedures. Relatively less contagious mastitis problems will mean the primary concern will likely be the environmental bacteria. These tend to produce high rates of clinical mastitis which is a serious issue in terms of cost and impact on milk production. With it also come increased use of antibiotics and the associated residue risk. Currently predicting the onset of such problems is limited but maybe in the future new developments will provide help.

Likely in the future new vaccines will come available for other mastitis pathogens and their use will become routine. Other means of increasing the defensive capabilities of the general immune system may also become routine in the future. These tools will not eliminate or diminish the need for current practices because each practice is designed to help control one aspect of the issue. Instead such tools should help fill in some of the voids in protection that may now exist.

We know that with the appropriate measuring and data collection devices that milk conductivity is a reasonable predictor of a clinical mastitis incident. Clinicals are associated with damage to tissues in the gland that separate the blood supply from the milk synthesis and collecting areas. The result is leakage of salts from blood into the milk. Ions like sodium and potassium are electrical conductors and for this reason if they leak into the milk they will increase the conductivity. Generally this may initially be seen a few hours before other clinical symptoms are noted and it may provide an opportunity to intervene earlier and limit the severity of the infection.

Mastitis results from failure in one or more aspects of mastitis protection. It may be due to problems with housing cleanliness, milking procedures, milking time hygiene, dry cow programs, nutrition status of the cow, immune status, prophylactic routines etc.

Present day programs have several areas of weakness where new tools may help. The late dry period is a vulnerable time frame. The dry cow therapy is no longer present, the cow is under severe stress as calving approaches and the nutritional status of the cow may be a problem. Consequently this is a high-risk period for new infections. We will have to do a better job in the future to minimize problems at this time.

In the future with large dairies and hired labor, standard operating procedures will have to be developed for most routine activities to assure that every cow receives the proper procedure as called for when it is called for.