What do dairies look like?
Over the past 60+ years, the dairy industry has seen innovations in milk collection and handling systems, animal nutrition, and genetics. These combined innovations have led to a dramatic increase in the amount of milk that a cow can produce each day. Compared to 1960, the dairy industry produces 3 times as much milk now with just over half as many cows (U.S. Department of Agriculture [USDA] National Ag Statistics Service). Recommended: Common cattle terms and definitions.
In the U.S. most large dairy farms use some type of barn to house and feed cows. Most of these are free stall barns where the cows can move around and choose where to lie down and where along the feed bunk to eat. These barns use a combination of mechanical ventilation (fans) and natural ventilation in the form of curtains that can be lowered (closed) to keep out cold winter winds or raised (opened) in warm weather. Some farms, especially those in warm or arid climates also have open earthen lots-referred to as loafing lots-available to the animals. Some dairies in warm, arid climates do not have barns and house cows exclusively in outdoor lots or corrals. A few large farms graze cows on pastures, but grazing is more common on smaller farms in the U.S. as well as on farms of all sizes outside of the U.S.
Photos 1-6 below show buildings used for housing and milking cows. Of all the different types of animal agriculture farms, dairies probably look the least alike from one area of the country to another; dairies can even vary a lot among different farms in the same area.
Some dairy farms raise their own heifer calves until they are old enough to join the milking herd; others send calves to a farm that specializes in raising heifers. There are numerous ways to house the calves, sometimes individually (Photo 1 below) and sometimes in groups (Photo 2 below). A priority is to keep the calves dry and clean as possible.
One noticeable aspect of dairy farms is the need for feed storage (Photos 3 and 4 below). Most dairies have large piles of hay and silage (plant material preserved by fermenting it). Sometimes feed ingredients are kept in sheds or under plastic to protect them from rain. Dairy cattle require very high quality feed and each cow can eat more than 100 pounds of feed every day!
Dry cows are another group of animals you will often see on a dairy farm. Dry cows are mature cows that are not being milked and are within a few weeks of giving birth. After calving, they will start a new lactation (milking) cycle. Dry cows are usually housed separately from the milking cows (Photo 5 below).
What about the inside?
Dairy cows are milked either two or three times per day, depending on the farm. Photos 1 and 2 below show two kinds of milking parlors. One is a round carousel where the cows step on, have the milker attached, and ride a full circle before stepping off. The other is a herringbone parlor where a group of cows enters all together to be milked and then leaves after milking so another group of cows can enter.
Photos 3, 4, and 5 (below) show where cows spend most of their day. The most common barn type, the free stall, has a feeding area in the center. Outdoor confinement pens put feed lanes along the edge of the corrals. Most farms clean up refused feed and deliver new, fresh feed at least once every day. Water is usually provided in several areas throughout the barn or corrals.
Each side of a free stall barn has one or more rows of bedded stalls which encourage cows to lie down and rest. Aisles separate the feeding area and rows of stalls. Most of the manure is deposited in the aisles.
In warm, arid climates, dairy cows are often housed in outdoor lots (Photos 6 and 7 below). Feed is provided in lanes along the edge of the corrals and water is provided throughout the corrals. Because cows spend most of their time eating, the corrals usually have a concrete apron where the cows stand along the feed lane to prevent this area from getting muddy and to facilitate manure and wasted feed removal. Outdoor confinement areas often include shade structures and raised areas where cows can find dry ground when it rains.
What about the manure?
Dairy cows are big and they eat a lot which means they produce a lot of manure. The amount of manure varies greatly depending on the housing system, washing procedures, and manure collection methods. An example from Clemson University calculates that a 300-cow dairy that collects the manure from the freestall barn and combines it with wash water from the milking parlor will handle more than 8,000 gallons of manure each day.
In free stall barns, manure is removed from the aisles at least once per day and possibly more often using one of three methods: flushing, scraping, or vacuum tanker. See photos 1, 2, and 3 below for examples of each. Similarly, in outdoor corrals, manure is usually removed from the area along the feed lane daily by scraping, flushing or vacuuming.
The collected manure is stored as a slurry or liquid. In a flushing system, water is recycled from the liquid manure or wash water storage structure to flush manure from the aisles.
For farms that use sand bedding, there is usually a step in the manure collection and handling system to separate and reclaim sand to reuse on the farm (see Photos 4 and 5 below).
Some dairies remove manure from the barn and haul it out to fields regularly, sometimes even daily. A study* performed by the University of Wisconsin in 2006 found that 61% of dairies in that state spread manure daily, even in winter. While this number has almost certainly been reduced since 2006, the practice is still common throughout the U.S., especially among smaller dairies.
*Manure Management on Wisconsin Farms http://www.pats.wisc.edu/pubs/31
The slurry manure collected from dairy barns or from the concrete feeding area of open lots can be stored in earthen, steel, or concrete structures. Examples of these manure storage types are shown in Photos 1-4 below.
Are there different ways to manage manure?
Almost all alternative manure treatment systems on dairy farms use solid-liquid separation which, as it sounds, divides the manure into two streams-one that is mostly solid and one that is mostly liquid (Photo 1 below).
The solids can be applied to fields at the dairy, composted (Photo 2 below) and recycled for use as bedding on the farm (Photo 3 below) or sold as a soil amendment for gardens or construction sites. The liquid is stored for application to fields or recycled to flush manure from barns on farms that use flush systems.
Another growing use for dairy manure is anaerobic digestion (Photos 4 and 5 below). The U.S. currently has just under 250 digesters on livestock farms. There are many different types of digesters. Digesters completely enclose the manure to exclude oxygen and encourage methane producing bacteria to be active. The resulting biogas can be used to generate electricity. The leftover manure (effluent) can be used as a crop fertilizer or can undergo solid-liquid separation with the resulting products being used as described above.