Dairy Fundamentals




Holstein (also known as Holstein-Friesian, or Friesian) originated in what is now the Netherlands (northern provinces of North Holland and Friesland).  They are large (mature body weight about 1,500 pounds) with black and white markings (red and white Holsteins also exist, but are less common). Approximately 90% of the dairy cows in the United States are of the Holstein breed.  The 2009 average actual production was 23,151 pounds of milk, 842 pounds of butterfat, and 711 pounds of protein per cow per year. The Holstein Association website can be found at: http://www.holsteinusa.com/


Jersey cattle were originally bred in the Channel island of Jersey. The breed is popular for the high butterfat content of its milk, lower maintenance costs due to its lower mature bodyweight (approximately 1,000 pounds), and genial disposition. This breed makes up slightly more than 5% of the milk cow population in the United States. The official Registered Jersey lactation average in 2011 was 18,633 pounds milk, 889 pounds fat, and 676 pounds protein. The Jersey Association website is: http://www.usjersey.com/

               Other dairy breeds in the United States that are less common include:

Ayrshire cattle originated from the county of Ayr in Scotland, are of medium body size (1,200 pounds mature weight), with red markings.  Seehttp://www.usayrshire.com/ for more.


Guernsey originated on the Isle of Guernsey, in the English Channel. This breed is fawn and white in color, and is particularly known for the unique qualities of their milk, which has a golden color due to a high content of beta carotene. See http://www.usguernsey.com/ for more detail.

Milking Shorthorn cattle originated in the North East of England, and were originally developed as a dual purpose breed, suitable for both dairy and beef production.  These are moderately framed, and are red, red and white, white, or roan in color. The breed website is: http://www.milkingshorthorn.com/

Brown Swiss cattle were developed in the north-eastern part of Switzerland. They are large framed cattle that produce the second largest quantity of milk per year (over 20,000 pounds). Brown Swiss cattle can be grey, dark brown, tan or even almost white in color. Their hooves, muzzle and switch are usually black. http://www.brownswissusa.com/



Life cycle of a Dairy Cow

Following birth, a calf is usually removed from her dam after only a few hours. The newborn calf is fed milk or milk replacer until weaning at about 6 to 8 weeks of age. The calf will then be raised until about 15 months of age. At this time she will be bred, and therefore gives birth for the first time at approximately 24 months of age.  Each lactation lasts 10 to 12 months or longer. Cows are bred while they are producing milk, with the goal of maintaining approximately a yearly calving interval (the average stated in the 2007 National Animal Health Monitoring System report was 13.2 months). At approximately 60 days prior to the expected date of calving, milking is terminated (dry-off) to allow the cow and her mammary gland time to rejuvenate and prepare for the next lactation. Cows average about 2.5 lactations before being removed (culled) from the herd, although many remain productive considerably longer.



In a “typical” diary herd, for every 100 milking cows, there will be:

  • 92 healthy cows
  • 4 that have recently calved
  • 4 with “special needs”. These may be sick, recovering, or lame and are not contributing milk to the bulk tank.

The herd will also have:

  • 16 to 20 dry cows and close-up heifers. These are animals that will calve soon and join the millking herd.
  • 70 to 90 replacement calves and heifers.
During a "typical" day, a milking cow will spend:
  • 6 - 8 hours sleeping
  • 7 - 10 hours ruminating
  • 3 - 5 hours eating (9 - 14 meals)
  • 30 minutes drinking
  • 2 - 3 hours having social interactions like grooming or demonstrating signs of estrus
  • 2 - 3 hours outside pen, either being milked or traveling to and from the milking parlor


Dairy Operation “types”

        The National Animal Health Monitoring System (NAHMS) performed a national survey of dairy producers in 2007. In that study, they found that producers classified themselves into one of the following 4 categories.

        Conventional: On conventional operations, the majority of forage is harvested and delivered to cows. About 64% of dairy operations in the United States fall into this category, containing just over 82% of all dairy cows.

        Grazing: Here, the majority of forage is “harvested” by cows, that is, the cattle spend the majority of their time grazing. This represents 3.1% of dairy operations, with 1.7% of all dairy cows.

        Combination: These operations use both conventional and grazing practices. Over 31% of operations fall into this category, containing almost 15% of all dairy cows.

        Organic: Organic operations meet USDA organic standards. Only 1.7% of operations, with 1.2% of dairy cows, are organic.

Production systems for dairy farms

               Tie Stall barns

                              In this system, cows are milked and fed in their own stalls, either by hand, by using bucket milkers, or using a pipeline system. During good weather, the cows may be turned out into a dirt lot, cement, or pasture area. This is a very labor intensive production method, and milking is difficult (compared to other systems). Therefore, new tie stall barns are relatively uncommon to see.


Free Stall barns

                              In this system, cows freely move from stalls to the feeding area, and milking occurs in a milking parlor. Feeding and cleaning are readliy mechanized, and animals are regularly exercised in that they freely move between resting, feeding, and watering areas.

               Open Lots

                              Here, the cows are housed and fed in pens, rather than covered barns. Again, milking is performed in a dedicated milking parlor. This method works well in climates with low rainfall and relatively constant environmental temperatures.




Cows are milked twice per day on most farms. However, increased milk production can be obtained by milking three or more times per day, and many dairy farms are now doing so. A small minority of dairy farms, primarily those owned by members of religious denominations that do not utilize electricity, still millk cows by hand, rather than with milking equipment. The milk from these operations does not enter the fresh milk market and is utilized only for manufacturing purposes.  Most cows milked in tiestall barns are milked with either a bucket milking system or a pilepline milking system.  To avoid the labor and stooping and bending associated with these system, many types of milking parlors have been developed, where the milker need not bend to be at the level of the cows udder.  A few examples of parlor design include:

Walk-through or step-up parlors

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Herringbone parlors

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Parallel parlors

Rotary parlors

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While the majority of operations in the United States had a tie stall/stanchion milking facility, the majority of cows are on operations that milked in parlors, as shown in the table below (NAHMS, 2007).

Percentage of operations and percentage of cows on these operations by primary milking facility used in 2006:

Facility type

Percent operations

Percent cows*




Tie stall / stanchion






* As a percentage of January 1, 2007, cow inventory.

  Despite a great deal of diversity, milking machines work on the same basic principle: milk is collected from the cow by vacuum.  The following figure from The Babcock Institute for International Dairy Research and Development illustrates the basic components of a milking machine, which include:

1) A vacuum system,

2) Pulsators that alter the vacuum level around the teat so that milking occurs, 

3) Milking units or clusters

4) A milk removal system that transports the milk away from the milking unit to a storage unit.

When a milking machine is used, the double chambered teatcup and the pulsator allow the teats to be subjected alternately to a vacuum (milking phase) and to atmospheric pressure (massage phase). Typically, this pulsation occurs 45 to 65 times per minute.

Regardless of the type of milking system used, a number of steps are recommended to maximize milk qualtiy. The National Mastitis Council has the following checklist of recommended procedures:

        Provide a clean, low stress environment for cows. Clean cows are at lower risk of high bacterial counts in milk and also reduced probability of new intramammary infections. Cows that are frightened or excited before milking may not have a normal milk letdown response, which can lead to reduced milk production and predisposes the cow to a greater rate of infection.

        Check foremilk and udder for mastitis (forestripping). Mastitis can be detected by using the hand to physically examine the udder and milk.

        Waterless teat preparation (Pre-dip).  A sanitizing solution can be applied to the entire length of the teat prior to milking. This solution should remain in contact with the teat for 30 seconds and then be thoroughly wiped off prior to attaching the milking unit.

        Teat wash

       Wash pen. Prior to entering the milking parlor, sprinklers may be used to remove the dirt and manure from the cows udder. Sufficient drip drying time prior to entering the parlor is critical.  

       Hose in the parlor. A common method of preparation in milking parlors is to use a hose (delivering sanitizing solution) to remove debris from teats while the cow is in the parlor to be milked.   

       Single- or multiple- use wet cloth or paper towel. A wash solution in a bucket and individual paper towels to prepare the teats for milking is common in tiestall barns. Sponges and common cloths are more likely to transfer pathogens to uninfected quarters and cows, and are therefore discouraged.

        Teat drying

       Paper towel, cloth, air. Regardless of how the teats are prepared they must be dried, otherwise many organisms are left on the teats. Milking wet teats increases the likelihood of mastitis and reduces milk quality.

        Attach milking units within two minutes after start of stimulation. Milk letdown causes maximum udder pressure approximately one minute after first stimulation and lasts about ten minutes. Most cows milk out in five to ten minutes., therefore attaching the machines within two minutes makes maximum use of the letdown effect.

        Adjust units as necessary for proper alignment.  If the milking units are not placed properly, milk flow may be blocked which increases the amount of milk remaining in the udder at the end of milking. Liner slip, or squaking teat cups, also occur with misaligned milking units. This can result in small droplets of milk being propelled back against the end of the teat, which may contain mastitis-causing organisms, resulting in infections.

        Shut off vacuum before removing unit

       Avoid over-milking. The risk of liner slip and possible new infectgion is greatest when cows are overmilked. Removing the unit while under vacuum can result in liner slip and new infection in one of the other quarters.

        Post-milking teat disinfection. The lower one-third of each teat should be dipped in a commercial teat antiseptic product after every milking to reduce the rate of new infections.

        Backflush systems

       Remove pathogens from milking units immediately after each cow is milked. This will reduce the possibility of transfering pathogens from one cow to the subsequent cows remaining to be milked.


The keys to producing high quality milk include having healty cows (mastitis control, adequate nutrition, good management) in a clean environment. Milking equipment must be clean and functioning properly. Finally, the milk must be cooled rapidly and kept cold until processing.

Grade “A” Pastuerized Milk Ordinance (PMO) Standards for milk

The United States Public Health Service/Food and Drug Administration (USPHS/FDA) with the assistance of Milk Regulatory and Rating Agencies at every level of Federal, State, and Local Government created the Grade “A” PMO, which is the basic standard used in the voluntary Cooperative State-USPHS/FDA Program for the Certification of Interstate Milk Shippers, a program participated in by all fifty (50) States, the District of Columbia and U.S. Trust Territories. The latest revision was in 2011. The chemical, physical, bacteriological and temperature standards for Grade “A” raw milk and milk products for pasteurization, ultra-pasteurization or aseptic processing and packaging are shown in the table below:

 Standards for Grade “A” raw milk and milk products (PMO)


Cooled to 10ºC (50ºF) or less within four (4) hours or less, of the commencement of the first milking, and to 7°C (45ºF) or less within two (2) hours after the completion of milking. Provided, that the blend temperature after the first milking and subsequent milkings does not exceed 10ºC (50ºF).NOTE: Milk sample submitted for testing cooled and maintained at 0ºC (32ºF) to 4.4ºC (40ºF), where sample temperature is >4.4ºC (40ºF), but =7.0ºC (45oF) and less than three (3) hours after collection has not increased in temperature.

Bacterial Limits

Individual producer milk not to exceed 100,000 per mL prior to commingling with other producer milk. Not to exceed 300,000 per mL as commingled milk prior to pasteurization. NOTE: Tested in conjunction with the drug residue/inhibitory substance test.


No positive results on drug residue detection methods.

Somatic Cell Count*

Individual producer milk not to exceed 750,000 per mL.

*Goat milk – 1,500,000 per mL

Dairy operations are licensed by a State Regulatory Agency. These state or local agencies perform twice-yearly inspections of dairy farms to ensure that milk is collected on farm in a manner that promotes disease control, appropriate handling/storage of antibiotics, animal welfare, and food safety.

An example of a blank report is shown here: Dairy Farm Inspection Report - FDA


Raw Milk tests

               Once at the milk processing plant, milk is subjected to a number of tests to determine its quality and acceptability. These include temperature, somatic cell count, standard plate count, lab pasteurized count, coliform count, preliminary incubation count and antibiotic residue testing. Other milk tests that may occur include testing for flavors and odors, freezing point depression (measures for added water), acidity, Brucella ring test, sediment, and fat and protein testing (which is used to determine price).

               The Standard Plate Count (SPC) is a good overall measure of milk quality, however it is difficult to diagnose a problem based on a single test. SPC is a measure of the number of colony-forming units of bacteria in one milliliter of milk. High bacteria counts can come from inside the cow(mastitis), outside the cow (from the udder), inside the equipment (related to poor sanitation), or from growing within the tank (associated with poor cooling). High SPC counts are usually caused by sanitation or cooling problems, such as improper cleaning, film or milk stone build up inside milking equipment, improper sanitizing of equipment, milking dirty cows, excessive use of water in milking preparation, inadequate cooling, or improper sample handling prior to reaching the lab. Rarely is a high SPC caused by mastitis pathogens.



Every dairy must consider that cows produce substantial manure, and therefore considerable investments are required to handle the waste associated with dairy farming. The manure handling system chosen by a producer will depend on state and local regulations as well as farm location, the number of animals, type of animal housing and bedding used, and the type and use of their farmland. The following table presents the composition of typical dairy manure (American Society of Agricultural Engineers, 2003).

Table 3. Fresh manure production per 1,000 pound live animal mass per day*



Standard Deviation

Total manure, lbs



Urine, lbs



Volatile Solids, lbs



Total N



Total P



Total K



* Does not include wastewater and bedding

* Estimates may increase with milk production


The following tables present estimates of daily wastewater produced per cow per day.

Table 4. Wastewater produced per cow per day

# Milking cows

Gallons / cow / day

Cubic feet

0 – 50

5 – 8

0.6 – 1.0

50 – 100

4 – 6

0.5 – 0.8

150 +

2 - 4

0.2 – 0.5


The method of manure handling depends to a large extent on the type of barn/production system employed on the dairy.

Tiestall barns typically collect manure in gutters behind the cows and it is removed from the barn as a solid material by a barn cleaner. Once outside the barn, the barn cleaner places the manure on a storage stack or directly into a manure spreader, which then is used to disperse the material on nearby fields

There are more options available for freestall barns. Some farms use manual scraping where manure is scraped to the end of the barns by a skidsteer or mechanical loader with a scraping attachment. From here, the manure is either stored temporarily in a solid stack or loaded directly into a manure spreader. Other farms use a flush system, where recycled wastewater flushes manure to a storage pit or lagoon. 

Still other farms use automatic alley scrapers, which consist of a hinged V-shaped plough driven by a cable or chain, which is continuously or periodically dragged forward to draw manure to the end of an alley.

The goal of manure / waste storage on a dairy farm includes:

·        Prevent direct discharge of manure or wastewater into surface waters or onto adjacent neighbors’ property.

·        Prevent any nuisance conditions that interfere with normal use and enjoyment of neighbors’ property.

·        Enhance the operational efficiency of the dairy unit.

·        Collect and use dairy manure and wastewater for beneficial purposes such as fertilizer, compost, or bedding.

Common methods of manure / waste storage include slurry manure handling, liquid manure handling, anaerobic lagoons (including digesters for methane burning), and composting. Storage capacity is usually designed for removal and draining twice a year, when convenient for crop production purposes, which will vary greatly depending on crop types and harvest time. The amount of manure that can be applied to any specific area is regulated by the state’s environmental regulatory agency. In some parts of the country, manure application can only be done by people or companies certified or pre-approved by the state agency.