Dairy cattle

Calf

Most heifers (female calves) are kept on farm to be raised as replacement heifers, bred to enter the production cycle. Nearly all male calves and any excess female calves are sold on the market, usually at two weeks of age; males fetch a slightly higher price than excess females. Dairy calves sold for meat can be turned into veal, or for one of several types of beef production, depending on available local crops and markets. Such bull calves may be castrated if turnout onto pastures is envisaged, to make them less aggressive. A tiny minority of bull calves, generally descended from elite cows with a proven track record of high lactations, may be put into progeny testing schemes to be considered for a life as a breeding sire.

Most dairy farms separate calves from their mothers within a day of birth to reduce transmission of disease and simplify management of milking cows. Studies have been done allowing calves to remain with their mothers for 1, 4, 7 or 14 days after birth. Cows whose calves were removed longer than one day after birth showed increased searching, sniffing and vocalizations. However, calves allowed to remain with their mothers for longer periods showed weight gains at three times the rate of early removals as well as more searching behavior and better social relationships with other calves.

After separation, some young dairy calves subsist on commercial milk replacer, a feed based on dried milk powder. Milk replacer is an economical alternative to feeding whole milk because it is cheaper, can be bought at varying fat and protein percentages, and is typically less contaminated than whole milk when handled properly. Some farms pasteurize and feed calves milk from the cows in the herd instead of using replacer. A day-old calf consumes around 5 liters of milk per day.

Cattle are social animals; their ancestors tended to live in matriarchal groups of mothers and offspring. The formation of "friendships" between two cows is common and long lasting. Traditionally individual housing systems were used in calf rearing, to reduce the risk of disease spread and provide specific care. However, due to their social behaviour the grouping of offspring may be better for the calves' overall welfare. Social interaction between the calves can have a positive effect on their growth. It has been seen that calves housed in grouped penning were found to eat more feed than those in single pens, suggesting social facilitation of feeding behaviour in the calves. Play behaviour in pre-weaned dairy calves has also been suggested to help build social skills for later in life. It has been seen that those reared in grouped housing are more likely to become the dominant cattle in a new combination of animals. These dominant animals have a priority choice of feed or lying areas and are generally stronger animals. For these reasons, it has become common practice to group or pair calves in their housing. It has become common in Canada to see paired or grouped housing in outdoor hutches or in an indoor pack penning.

Bull

In traditional agriculture for most of human history, herds needed a bull to keep the cows in lactation and to produce calves. Small-time farmers with just a few cows would sometimes arrange bulls to be rented, transferred, or otherwise shared, as it might not make sense to keep and feed a bull for just a few cows. Still, fewer bulls were needed than cows, so excess bulls in the traditional system were still turned into meat, or castrated to become draft animals as oxen.

A bull kept for direct natural herd breeding might service up to 50 or 60 cows during a breeding season. Any more and the sperm count declines, leading to cows "returning to service" (needing to be bred again). It is also considered good practice to rotate such herd bulls when possible, with agents arranging swaps to prevent inbreeding. When bulls are used directly, young bulls are preferred, as older bulls can have their temperament shift unpredictably.

During the 20th century, the popularity of keeping a bull directly on dairy farms rapidly declined in favor of the use of artificial insemination (AI). Bulls are dangerous and a source of injury to farmers and cows. They can damage fences, and farmers risk disaster if their bull becomes infertile or otherwise unfit for service. Additionally, direct use of bulls makes it easier for diseases to spread through a herd, such as the venereal disease Tritrichomonas foetus. The shift was sudden and dramatic. From the 1930s to the 1990s, the vast majority of dairy farms switched to artificial insemination, with bulls only kept as a rare backup for if AI repeatedly failed.

Specialized dairy breeding farms, rather than production farms, are where breeding sire bulls are generally kept in the new system. These facilities possess the specialized setups for safely raising and monitoring bulls. These bulls provide the semen collected for artificial insemination of dairy cows. A single bull can serve far more cows this way than via traditional breeding, providing economies of scale.

Milk production levels

Selective breeding has greatly changed the milk production rates of modern herds. Most dairy cows now produce much more milk than their young could need in a situation in the wild. While a cow in lactation in the 1800s might be able to "dry" if abandoned by humans, a 21st-century dairy cow would suffer a more severe health crisis if milking is neglected for too long.

Dairy cow production levels peak at around 40 to 60 days after calving. Production declines steadily afterwards until milking is stopped at about 10 months. The cow is "dried off" for about sixty days before calving again. Within a 12 to 14-month inter-calving cycle, the milking period is about 305 days or 10 months long. Among many variables, certain breeds produce more milk than others within a range of around 6,800 to 17,000 kg (15,000 to 37,500 lb) of milk per year.

The Holstein Friesian is the main breed of dairy cattle in Australia, and said to have the "world's highest" productivity, at 10,000 litres (2,200 imp gal; 2,600 US gal) of milk per year. The average for a single dairy cow in the US in 2007 was 9,164 kg (20,204 lb) per year, excluding milk consumed by her calves, whereas the same average value for a single cow in Israel was reported in the Philippine press to be 12,240 kg (26,980 lb) in 2009. High production cows are more difficult to breed at a two-year interval. Many farms take the view that 24 or even 36 month cycles are more appropriate for this type of cow.

Dairy cows may continue to be economically productive for many lactation cycles. In theory a longevity of 10 lactations is possible. However, cows are usually culled earlier than this; the average herd life of a Holstein in the United States is fewer than 3 lactations. Cows are culled for the slaughter for a variety of reasons:

• Infertility: failure to conceive and enter a new lactation cycle. Cows are at their most fertile between 60 and 80 days after calving. Cows remaining "open" (not with calf) after this period become increasingly difficult to breed, which may be a sign of poor health. Failure to expel the afterbirth from a previous pregnancy, luteal cysts, or metritis, an infection of the uterus, are common causes of infertility.
• Mastitis: a persistent and potentially fatal mammary gland infection, leading to high somatic cell counts and loss of production. Mastitis is recognized by a reddening and swelling of the infected quarter of the udder and the presence of whitish clots or pus in the milk. Treatment is possible with long-acting antibiotics, but milk from such cows is not marketable until drug residues have left the cow's system, also called the withdrawal period. A farmer may decide it is simpler to cull an aging cow rather than cure her mastitis.
• Lameness: a foot infection or leg problems, which can lead to infertility and loss of milk production. High feed levels of highly digestible carbohydrate cause acidic conditions in the cow's rumen. This leads to laminitis and subsequent lameness, leaving the cow vulnerable to other foot infections and problems which may be exacerbated by standing in feces or water-soaked areas.
• Production: Aging cows generally produce less milk per lactation cycle, while consuming similar amounts of feed and maintenance as younger cows. Once production drops beyond a certain level, it is cheaper to cull the old cow and replace her with younger heifers.

Cow longevity is strongly correlated with production levels. Lower production cows live longer than high production cows, but may be less profitable. Cows no longer wanted for milk production are sent to slaughter. Their meat is of relatively low value, and is generally used for processed meat.

Cow comfort and its effects on milk production

Certain behaviors such as eating, ruminating, and lying down can be related to the health of the cow and cow comfort. These behaviors can also be related to the productivity of the cows. Likewise, stress, disease, and discomfort negatively affect milk productivity. Therefore, it can be said that it is in the best interest of the farmer to increase eating, rumination, and lying down and decrease stress, disease, and discomfort to achieve the maximum productivity possible. Also, estrous behaviors such as mounting can be a sign of cow comfort, because if a cow is lame, nutritionally deficient, or housed in an overcrowded barn, its estrous behaviors are altered.

Feeding behaviors are important for the dairy cow, as feeding is how the cow ingests dry matter. However, the cow must ruminate to fully digest the feed and utilize the nutrients in the feed. Dairy cows with good rumen health are likely to be more profitable than cows with poor rumen health, as a healthy rumen aids in digestion of nutrients. An increase in the time a cow spends ruminating is associated with the increase in health and an increase in milk production. The productivity of dairy cattle is most efficient when the cattle have a full rumen. Also, the standing action while feeding after milking has been suggested to enhance udder health. The delivery of fresh feed while the cattle are away for milking stimulates the cattle to feed upon return, potentially reducing the prevalence of mastitis as the sphincters have time to close while standing. This makes the pattern of feeding directly after being milked an ideal method of increasing the efficiency of the herd.

Cows have a high motivation to lie down. They should lie down for at least five to six hours after every meal to ruminate well. When the lactating dairy cow lies down, blood flow is increased to the mammary gland which in return results in a higher milk yield. When they stand too long, cows become stressed, lose weight, get sore feet, and produce less milk.

To ensure that the dairy cows lie down as much as needed, the stalls must be comfortable. A stall should have a rubber mat and bedding, and be large enough for the cow to lie down and get up comfortably. Signs that the stalls may not be comfortable enough for the cows are the cows are standing, either ruminating or not, instead of lying down, or perching, which is when the cow has its front end in the stall and their back end out of the stall. Dried manure, almond shells, straw, sand, or waterbeds are used for cow bedding.

There are two types of housing systems in dairy production, free style housing and tie stall. Free style housing is where the cow is free to walk around and interact with its environment and other members of the herd. Tie stall housing is when the cow is chained to a stanchion stall with the milking units and feed coming to them.

Artificial light and daylight inlets have an impact on milk production and cow behavior. For cows in lactation a light program of 16 hours light and 8 hours of darkness is recommended, while for non-lactating pregnant cows 8 hours of light and 16 hours of darkness seem to be a better fit.

By-products and processing

Pasteurization is the process of heating milk to a high enough temperature for a short period of time to kill the microbes in the milk and increase keep time and decrease spoilage time. By killing the microbes, decreasing the transmission of infection, and elimination of enzymes the quality of the milk and the shelf life increase. Pasteurization is either completed at 63 °C (145 °F) for thirty minutes or a flash pasteurization is completed for 15 seconds at 72 °C (162 °F). By-products of milk include butterfat, cream, curds, and whey. Butterfat is the main lipid in milk. The cream contains 18–40% butterfat. The industry can be divided into 2 market territories; fluid milk and industrialized milk such as yogurt, cheeses, and ice cream.

Whey protein makes up about 20% of milk's protein composition and is separated from the casein (80% of milk's protein make up) during the process of curdling cheese. This protein is commonly used in protein bars, beverages and concentrated powder, due to its high quality amino acid profile. It contains levels of both essential amino acids as well as branched that are above those of soy, meat, and wheat. "Diafiltered" milk is a process of ultrafiltration of the fluid milk to separate lactose and water from the casein and whey proteins. This process allows for more efficiency in cheese making and gives the potential to produce low-carb dairy products.

Reproduction

Since the 1950s, artificial insemination (AI) is used at most dairy farms; these farms may keep no bull. Artificial insemination uses estrus synchronization to indicate when the cow is going through ovulation and is susceptible to fertilization. Advantages of using AI include its low cost and ease compared to maintaining a bull, ability to select from a large number of bulls, elimination of diseases in the dairy industry, improved genetics and improved animal welfare. Rather than a large bull jumping on a smaller heifer or weaker cow, AI allows the farmer to complete the breeding procedure within 5 minutes with minimum stress placed on the individual female's body.

Dairy cattle are polyestrous, meaning they cycle continuously throughout the year. They tend to be on a 21 day estrus cycle. However for management purposes, some operations use synthetic hormones to synchronize their cows or heifers to have them breed and calve at the ideal times. These hormones are short term and only used when necessary. For example, one common protocol for synchronization involves an injection of GnRH (gonadotrophin releasing hormone). which increases the levels of follicle stimulating hormone and luteinizing hormone in the body. Then, seven days later prostaglandin F2-alpha is injected, followed by another GnRH injection 48 hours later. This protocol causes the animal to ovulate 24 hours later.

Estrus is often called standing heat in cattle and refers to the time in their cycle where the female is receptive towards the male. Estrus behaviour can be detected by an experienced stockman. These behaviours can include standing to be mounted, mounting other cows, restlessness, decreased milk production, and decreased feed intake.

More recently, embryo transfer has been used to enable the multiplication of progeny from elite cows. Such cows are given hormone treatments to produce multiple embryos. These are then 'flushed' from the cow's uterus. 7–12 embryos are consequently removed from these donor cows and transferred into other cows who serve as surrogate mothers. This results in between three and six calves instead of the normal single or (rarely) twins.

As a result of long-term cooperation between USDA and dairy farmers, the United States has since 1992 been the world's largest supplier of dairy bull semen.

Sex-selected semen

A major industry change starting in the 2010s has been the rise of the use of sex-selected semen. A 2025 estimate suggested that based on current trends, the vast majority (>90%) of dairy operations will be using this technique in the near future. In it, semen collected from elite bulls at artificial insemination facilities is filtered for X-chromosome-bearing spermatozoa (generally via flow cytometry). Current techniques result in approximately 90% female calves from cows inseminated with sex-selected semen.

Conventional dairy semen produces roughly equal numbers of male and female dairy calves. Female calves are retained as replacements, while the surplus purebred dairy bull calves have low market value as beef. Crossbreeding with beef breed sires risked a shortage of replacement dairy heifers in the older system. With sex-selected semen, a farm can generate its required replacements from only the highest-producing portion of the herd (around 30-40% usually), and breed the remaining cows with beef sires to produce terminal beef-on-dairy crossbred calves. These hybrid calves command substantially higher prices at the slaughterhouse than purebred dairy bull calves.

Hormone use

Farmers in some countries sometimes administer hormone treatments to dairy cows to increase milk production and reproduction.

About 17% of dairy cows in the United States are injected with Bovine somatotropin, also called recombinant bovine somatotropin (rBST), recombinant bovine growth hormone (rBGH), or artificial growth hormone. The use of this hormone increases milk production by 11%–25%. The U.S. Food and Drug Administration (FDA) has ruled that recombinant bovine somatotropin (rBST), recombinant bovine growth hormone (rBGH) is harmless to people, while the American Cancer Society finds that the use of rBGH can cause adverse health effects in cows. Though the evidence for potential harm to humans is inconclusive and would require more research. The use of rBST is banned in Canada, parts of the European Union, as well as Australia and New Zealand due to possible opposing views and of lack of findings.

In the United States the Pasteurized Milk Ordinance requires a milk sample is taken from every farm and from every load of milk delivered to a processing plant. These samples are then tested for antibiotic and any milk testing positive is discarded and farm identified. Traceback to the dairy is undertaken by the FDA with further consequences including the possibility revocation of ability to sell milk.

Nutrition

Nutrition plays an important role in keeping cattle healthy and strong. Implementing an adequate nutrition program can also improve milk production and reproductive performance. Nutrient requirements may not be the same depending on the animal's age and stage of production. Diets are formulated to meet the dairy cow's energy and amino acid requirements for lactation, growth, and/or reproduction.

Forages, which refer especially to anything grown in the field such as hay, straw, corn silage, or grass silage, are the most common type of feed used. The base of most lactating dairy cattle diets is high quality forage. Cereal grains, as the main contributors of starch to diets, are important in helping to meet the energy needs of dairy cattle. Barley is an excellent source of balanced amounts of protein, energy, and fiber.

Ensuring adequate body fat reserves is essential for cattle to produce milk and also to keep reproductive efficiency. However, if cattle get excessively fat or too thin, they run the risk of developing metabolic problems and may have problems with calving. Scientists have found that a variety of fat supplements can benefit conception rates of lactating dairy cows. Some of these different fats include oleic acids, found in canola oil, animal tallow, and yellow grease; palmitic acid found in granular fats and dry fats; and linolenic acids which are found in cottonseed, safflower, sunflower, and soybean.

Diets may additionally be formulated to strategically reduce methane emissions. Ruminants such as the cow have microbes in their rumen called methanogens which are capable of digesting down plant material so it can be utilized for energy, but also generates methane as a byproduct which is then released into the atmosphere by belching.

Breeds

According to the Purebred Dairy Cattle Association, PDCA, there are 7 major dairy breeds in the United States. These are: Holstein Black/White and Red/White, Brown Swiss, Guernsey, Ayrshire, Jersey, and Milking Shorthorn.

Holstein cows originate from the Netherlands and have distinct black and white or more rarely red and white markings. Holstein cows are the biggest of all dairy breeds. A full mature Holstein cow usually weighs around 700 kilograms (1,500 lb) and is 147 centimetres (58 in) tall at the shoulder. They are known for their outstanding milk production among the main breeds of dairy cattle. An average Holstein cow produces around 10,000 kilograms (23,000 lb) of milk each lactation. Of the 9 million dairy cows in the U.S., approximately 90% of them are of the Holstein descent. The top breed of dairy cow within Canada's national herd category is Holstein, taking up 93% of the dairy cow population, have a production rate of 10,257 kilograms (22,613 lb) of milk per cow that contains 3.9% butter fat and 3.2% protein

Brown Swiss cows are widely accepted as the oldest dairy cattle breed, originally coming from a part of northeastern Switzerland. Some experts think that the modern Brown Swiss skeleton is similar to one found that looks to be from around the year 4000 BC Also, there is evidence that monks started breeding these cows about 1000 years ago.

The Ayrshire breed first originated in the County of Ayr in Scotland. It became regarded as a well established breed in 1812. The different breeds that were crossed to form the Ayrshire are not exactly known. However, there is evidence that several breeds were crossed with the native cattle to create the breed.

Guernsey cows originated just off the coast of France on the small Isle of Guernsey. The breed was first known as a separate breed around 1700. Guernseys are known for their ability to produce very high quality milk from grass. Also, the term "Golden Guernsey" is very common as Guernsey cattle produce rich, yellow milk rather than the standard white milk other cow breeds produce.

The Jersey originates on the island of Jersey in the Channel Islands. Cows usually weigh some 350–400 kg (800–900 lb). The milk is rich and has a yellowish tinge; the fat content may exceed 6%. American Jerseys have been selectively bred for higher milk yield, and are often larger and coarser than the island stock.

Animal welfare

Animal welfare refers to both the physical and mental state of an animal, and how it is coping with its situation. An animal is considered in a good state of welfare if it is able to express its innate behaviour, comfortable, healthy, safe, well nourished, and is not suffering from harmful states such as distress, fear and pain. Good animal welfare requires disease prevention and veterinary treatment, appropriate shelter, management, nutrition, and humane handling. If the animal is slaughtered then it is no longer "good animal welfare". It is the human responsibility of the animals' wellbeing in all husbandry and management practices including humane euthanasia.

Proper animal handling, or stockmanship, is crucial to dairy animals' welfare as well as the safety of their handlers. Improper handling techniques can stress cattle leading to impaired production and health, such as increased slipping injuries. Additionally, the majority of nonfatal worker injuries on a dairy farm are from interactions with cattle. Dairy animals are handled on a daily basis for a wide variety of purposes including health-related management practices and movement from freestalls to the milking parlor. Due to the prevalence of human-animal interactions on dairy farms, researchers, veterinarians, and farmers alike have focused on furthering our understanding of stockmanship and educating agriculture workers. Stockmanship is a complex concept that involves the timing, positioning, speed, direction of movement, and sounds and touch of the handler.

A recent survey of Minnesota dairy farms revealed that 42.6% of workers learned stockmanship techniques from family members, and 29.9% had participated in stockmanship training. However, as the growing U.S. dairy industry increasingly relies on an immigrant workforce, stockmanship training and education resources become more pertinent. Clearly communicating and managing a large culturally diverse workforce brings new challenges such as language barriers and time limitations. Organizations like the Upper Midwest Agriculture Safety and Health Center offer resources such as bilingual training videos, fact sheets, and informational posters for dairy worker training. Additionally the Beef Quality Assurance Program offer seminars, live demonstrations, and online resources for stockmanship training.

For cows to reach high performance in milk yields and reproduction, they must be in great condition and comfortable in the system. Once an individual's welfare is reduced, so does her efficiency and production. This creates more cost and time on the operation, therefore most farmers strive to create a healthy, hygienic, atmosphere for their cattle. As well as provide quality nutrition that keep the cows yield high.

The production of milk requires that the cow be in lactation, which is a result of the cow having given birth to a calf. The cycle of insemination, pregnancy, parturition, and lactation is followed by a "dry" period of about two months before calving, which allows udder tissue to regenerate. A dry period that falls outside this time frames can result in decreased milk production in subsequent lactation. Dairy operations therefore include both the production of milk and the production of calves. Bull calves are either castrated and raised as steers for beef production or used for veal.

The practice of dairy production has been criticized by animal rights proponents. Some of the ethical reasons regarding dairy production cited include how often the dairy cattle are impregnated needed to produce milk, the separation of calves from their mothers to obtain the milk meant for their calves and the fact that dairy cows are considered "spent" and culled at a relatively young age, another reason is that most male calves are of no use to the dairy industry and are sold for beef or veal, as well as environmental concerns regarding any cattle production.