The goal of this application is to provide an introduction to the basic fundamentals of dairy production. Some of the elements to be covered include:

               An overview of the U.S. dairy industry.

               How are dairy cattle raised?

               How is milk produced, and how does it get to market?

               What drugs are available for treating sick cattle?

What can lead to violative drug residues in tissues and milk?

               How are veal calves raised?

               Conducting an inspection of a dairy farm.


The Dairy Industry in the United States

The dairy industry in the United States has changed dramatically since the 1940's, with the number of milking cows dropping from 25 million to 9.2 million, the number of dairy farms dropping from greater than 4 million facilities to approximately 60,000 farms. The U.S. dairy industry is extremely diverse in size and scope, from larger-sized, specialized operations that focus solely on milking cows to small and medium-sized operations that milk cows while farming crop ground for feed and raising all of their replacement animals on farm. The "average" dairy farm has about 150 milking cows. Despite the reduction in both the number of farms and the number of cows, the total milk production has increased from 54 billion kilograms in 1940 to 84 billion kilograms because the milk produced per cow has increased some 5 fold.

               Currently, there are approximately 9.2 million dairy cows located on about 60,000 dairy farms in the United States. This represents 36% fewer farms than were present 10 years ago. The United States Department of Agriculture National Agricultural Statistics Service produced the following figures:


There are dairy farms in all 50 States, however, according to the USDA Economic Research Service, the top 10 producing States in 2011 were:

StateMilk Cows (000's)Milk Production per cow (lbs)
New York61020,807
New Mexico32224,551

As this list indicates, the major milk-producing States are in the West and North. The relative importance of the western regions has grown, while other regions have declined or remained steady. 

While many farms consist of fewer than 100 milking cows, these sized operations contain less than 20% of the total milk cow inventory, as shown in the following charts (also from USDA NASS). Greater than half of all the dairy cows in the United States reside on farms with more than 500 cows.

Total milk production as well as milk production per cow has steadily increased, and cows now produce an average of greater than 21,000 pounds of milk per year (greater than 2,400 gallons, or about 14 times her body weight).



Total per capita consumption of fluid milk has declined slowly because of competition from other beverages and a declining share of children in the population. Since the late 1980s, however, changes in per capita sales of individual types of beverage milk have varied. Per person use of most cream and cultured products has risen steadily for a quarter-century. The University of Wisconsin Dairy Marketing and Risk Management Program reports the following data on fluid milk consumption:

Demand for cheese has been an important force within the U.S. dairy industry. Per capita cheese consumption is double what is was 25 years ago and continues to increase. Rising cheese consumption has been aided by ready availability of a wider variety of cheeses, more away-from-home eating, and greater popularity of ethnic cuisines that employ cheese as a major ingredient.

Per person use of butter has been fairly steady since the early 1970s. However, use of most dry and condensed milks have declined as in-home food preparation has diminished and fresh milk has become cheaper and achieved a longer shelf-life. In commercial food preparation, whey products have replaced some of the former uses of dry and condensed milk products. (Whey is the watery part of milk that separates from curds in the process of making cheese.)

World-wide milk consumption

Total milk consumption (as fluid milk and processed products) per person varies widely from highs in Europe and North America to lows in Asia. However, as various regions of the world become more integrated through travel and migration, these trends are changing. The following table illustrates milk per capita consumption from 2006 data from various countries of the world (data from International Dairy Federation, Bulletin 423/2007).


Liquid Milk (liters)

Cheeses (kg)

Butter (kg)





















Spain (2005)








United Kingdom (2005)




Australia (2005)




Canada (2005)




European Union (25 countries)












New Zealand (2005)




United States












Argentina (2005)












China (2005)





Milk and Milk borne disease

Milk is a significant source of nutrients and dietary elements needed for the maintenance of proper health, especially in children and older citizens. Milk also has the potential to serve as a vehicle of disease transmission and has, in the past, been associated with disease outbreaks of major proportions.Since milk is a good source of nutrients it can also serve as substrate for the growth of microorganisms. Dairy cows and milk on the farm are exposed to many sources of potential contamina­tion. Some of these contami­nants may originate from the animals' water or food source; expo­sure to manure; flies and other insects; contact with diseased animals in the housing or corral areas; injuries to the udder; poor milking practices; improperly functioning milking ma­chines; and contamination during calving or treatment.

 Historically, milk was implicated as a major vehicle of disease.  Two of the most notable milk borne human illnesses were tubercu­losis and brucellosis. Both are bacterial diseases: tuberculosis is caused by Mycobacterium tuberculosis; and brucellosis (Undulant Fever) is caused by Brucella abortus.  Other bacterial milk borne diseases include: salmonello­sis; diph­the­ria; scarlet fever; septic sore throat; and dysentery.  Pasteurization processes were designed and implemented (in the early 1900’s) to eliminate these pathogens from milk. In 1957, more stringent pasteurization require­ments were enacted to eliminate Q fever, (Coxiella burnetii) a febrile rickettsial illness responsible for milk borne outbreaks.

In recent years, the consumption of unpasteurized or contaminated milk and milk products has resulted in human illnesses attributed to: Escherichia coli, Salmonella spp, Listeria monocytogenes, Staphylococcus aureus, Yersinia monocytogenes, and Campylobacter jejuni. There is obvious concern among public health officials regarding the consumption of unpasteurized milk since it is a well established fact that the proper pasteurization of milk would “kill” or inactivate all of the above pathogens.  Additionally, it is critical that milk not be re-contaminated following pasteurization.

The overall incidence of milk borne illness in the United States has been sharply reduced. For example, in 1938, milk borne outbreaks constituted twenty-five percent (25%) of all disease outbreaks due to infected foods and contaminated water. More recent information suggests that milk products are associated with less than one percent (<1%) of such reported outbreaks.This significant reduction in illnesses is a result of greater control and monitoring of the milk supply.  Many groups have contributed to this effort, including State and Federal agencies, dairy and related industries, interested professional groups, educational institutions and the consuming public.

Origin of the Grade "A" Pasteurized Milk Ordinance

In 1856, Massachusetts developed the first milk control laws.  Later New York City adopted dairy farm milk production standards (1901) to improve some of the unsanitary conditions associated with using brewery grain wastes for animal feed. Chicago became the first city to require milk pasteurization in 1908.   The first effort to standardize the milk regulations into a national code began in 1924 when the State of Alabama in conjunction with the United States Public Health Service (PHS) developed the first Federal Milk Code. To assist States and municipalities in initiating and maintaining effective programs for the prevention of milk borne disease, the PHS developed a model regulation known as the Standard Milk Ordinance for voluntary adoption by State and local milk control agencies.

To provide for the uniform interpretation of the Standard Milk Ordinance, an accompanying Code was published in 1927, which provided administrative and technical details as to satisfactory compliance. This Code evolved into the PMO, which incorporates the provisions governing the production, processing, packaging, and sale of Grade “A” milk and milk products. The PMO remains a model code and is written and presented in such a way that States and municipalities can readily adopt this model ordinance for their use. Model ordinances like the PMO are not Federal regulations and PHS/FDA has no direct authority to enforce their provisions. However, when these voluntary milk provisions (the PMO) are adopted by individual States or local authorities into binding ordinances and then enforced, they ensure an effective and uniform regulatory framework for milk control. 

The National Conference on Interstate Milk Shipments (NCIMS)

One problem in controlling the movement and sanitary assur­ance of milk supplies is that milk is often trans­ported between cities and States.  This shipping of milk created concerns between the States which resulted in regulatory inspectors traveling outside their juris­dictions to inspect a milk supply.  This approach often created confusion among the shippers because of occasional non-uniformi­ties in regulations and local interpretations. There existed a definite need for a national uniform program to oversee and govern the shipment of milk products between States. In 1952, a group of States met in St. Louis along with the PHS/FDA and created what is now known as the National Conference on Interstate Milk Shipments (NCIMS). This process was formalized through a Memoranda of Understanding (MOU) signed by PHS/FDA with the NCIMS in 1977.

Initially established to promote uniformity and reciprocity of milk regulations and to facilitate the interstate shipment of Grade “A” milk and milk products, the NCIMS is a voluntary, cooperative program. This cooperative program between the PHS/FDA and the 50 States and Puerto Rico fosters the uniformity of milk regulations and the safety of Grade “A” milk and milk products.

The NCIMS functions to update milk regulations by hosting a biennial conference attended by representatives from Federal and State agencies, the industry and academia. Any stakeholder can submit a proposed change to the PMO.  At the conference, proposed changes are discussed and than voted on by voting delegate(s) from each State. If approved the NCIMS forwards these recommended changes to the PHS/FDA. The PHS/FDA maintains the authority to evaluate specific provisions of the PMO, as recommended through affirmation by the State delegates, and make overriding decisions based on public health and scientific merit about their incorporation into the PMO.

The PHS/FDA maintains the Interstate Milk Shippers List (IMS List). It contains interstate milk shippers that have been certified by the State Milk Sanitation Rating Authorities, or (Certified Rating Officers) as having attained the milk sanitation compliance and enforcement ratings necessary for inclusion on the IMS List.  If a shipper is on this list then all other States will accept milk and milk products from that source. Interstate listed shippers are surveyed at least once every 24 months and the results of these ratings are published in the NCIMS periodical.  All milk shippers listed are also subject to Federal (PHS/FDA) surveys or "check ratings".

The check rating system ensures that the published State rating of a milk shipper on the IMS List is valid and maintained during the interval between State ratings. This Federal spot check is conducted on a group of IMS listed Grade “A” shippers based on a random sampling.  The scope of this Federal oversight system covers all aspects of the dairy industry including dairy farms, receiving and transfer stations, milk processing plants, milk testing laboratories, single service containers, dry milk plants and tank truck cleaning facilities.