Domestic Cattle

Bos taurus

Summary 5

Cattle—colloquially cows—are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos taurus.

Characteristics 6

Cattle are large quadrupedalungulatemammals with cloven hooves. Most breeds have horns, which can be as large as the Texas Longhorn or small like a scur. Careful genetic selection has allowed polled (hornless) cattle to become widespread.

Cattle are ruminants, meaning their digestive system is highly specialized to allow the use of poorly digestible plants as food. Cattle have one stomach with four compartments, the rumen, reticulum, omasum, and abomasum, with the rumen being the largest compartment.
The reticulum, the smallest compartment, is known as the "honeycomb". The omasum's main function is to absorb water and nutrients from the digestible feed. The omasum is known as the "many plies". The abomasum is like the human stomach; this is why it is known as the "true stomach".

Cattle are known for regurgitating and re-chewing their food, known as cud chewing, like most ruminants. While the animal is feeding, the food is swallowed without being chewed and goes into the rumen for storage until the animal can find a quiet place to continue the digestion process. The food is regurgitated, a mouthful at a time, back up to the mouth, where the food, now called the cud, is chewed by the molars, grinding down the coarse vegetation to small particles. The cud is then swallowed again and further digested by specialized microorganisms in the rumen. These microbes are primarily responsible for decomposing cellulose and other carbohydrates into volatile fatty acids cattle use as their primary metabolic fuel. The microbes inside the rumen also synthesize amino acids from non-protein nitrogenous sources, such as urea and ammonia. As these microbes reproduce in the rumen, older generations die and their cells continue on through the digestive tract. These cells are then partially digested in the small intestines, allowing cattle to gain a high-quality protein source. These features allow cattle to thrive on grasses and other tough vegetation.

The gestation period for a cow is about nine months long. A newborn calf's size can vary among breeds, but a typical calf weighs 25 to 45 kg (55 to 99 lb). Adult size and weight vary significantly among breeds and sex. Steers are generally killed before reaching 750 kg (1,650 lb). Breeding stock may be allowed a longer lifespan, occasionally living as long as 25 years. The oldest recorded cow, Big Bertha, died at the age of 48 in 1993.

On farms it is very common to use artificial insemination (AI), a medically assisted reproduction technique consisting of the artificial deposition of semen in the female's genital tract. It is used in cases where the spermatozoa can not reach the fallopian tubes or simply by choice of the owner of the animal. It consists of transferring, to the uterine cavity, spermatozoa previously collected and processed, with the selection of morphologically more normal and mobile spermatozoa.

A cow's udder contains two pairs of mammary glands, (commonly referred to as teats) creating four "quarters". The front ones are referred to as fore quarters and the rear ones rear quarters.

Synchronization of cattle ovulation to benefit dairy farming may be accomplished via induced ovulation techniques.

Bulls become fertile at about seven months of age. Their fertility is closely related to the size of their testicles, and one simple test of fertility is to measure the circumference of the scrotum: a young bull is likely to be fertile once this reaches 28 centimetres (11 in); that of a fully adult bull may be over 40 centimetres (16 in).

A bull has a fibro-elastic penis. Given the small amount of erectile tissue, there is little enlargement after erection. The penis is quite rigid when non-erect, and becomes even more rigid during erection. Protrusion is not affected much by erection, but more by relaxation of the retractor penis muscle and straightening of the sigmoid flexure.

The weight of adult cattle varies, depending on the breed. Smaller kinds, such as Dexter and Jersey adults, range between 272 to 454 kg (600 to 1,000 lb). Large Continental breeds, such as Charolais, Marchigiana, Belgian Blue and Chianina adults range from 635 to 1,134 kg (1,400 to 2,500 lb). British breeds, such as Hereford, Angus, and Shorthorn, mature at between 454 to 907 kg (1,000 to 2,000 lb), occasionally higher, particularly with Angus and Hereford. Bulls are larger than cows of the same breed by up to a few hundred kilograms. Chianina bulls can weigh up to 1,500 kg (3,300 lb); British bulls, such as Angus and Hereford, can weigh as little as 907 kg (2,000 lb) to as much as 1,361 kg (3,000 lb).

The world record for the heaviest bull was 1,740 kg (3,840 lb), a Chianina named Donetto, when he was exhibited at the Arezzo show in 1955. The heaviest steer was eight-year-old 'Old Ben', a Shorthorn/​Hereford cross weighing in at 2,140 kg (4,720 lb) in 1910.

In the United States, the average weight of beef cattle has steadily increased, especially since the 1970s, requiring the building of new slaughterhouses able to handle larger carcasses. New packing plants in the 1980s stimulated a large increase in cattle weights. Before 1790 beef cattle averaged only 160 kg (350 lb) net; and thereafter weights climbed steadily.

Behavior 6

Under natural conditions, calves stay with their mother until weaning at 8 to 11 months. Heifer and bull calves are equally attached to their mothers in the first few months of life. Cattle are considered to be "hider" type animals,

Beef-calves reared on the range suckle an average of 5.0 times every 24 hours with an average total time of 46 min spent suckling. There is a diurnal rhythm in suckling activity with peaks between 05:00–07:00, 10:00–13:00 and 17:00–21:00.

Studies on the natural weaning of zebu cattle (Bos indicus) have shown that the cow weans her calves over a 2-week period, but after that, she continues to show strong affiliatory behavior with her offspring and preferentially chooses them for grooming and as grazing partners for at least 4–5 years.

Semi-wild Highland cattle heifers first give birth at 2 or 3 years of age, and the timing of birth is synchronized with increases in natural food quality. Average calving interval is 391 days, and calving mortality within the first year of life is 5%.

One study showed that over a 4-year period, dominance relationships within a herd of semi-wild highland cattle were very firm. There were few overt aggressive conflicts and the majority of disputes were settled by agonistic (non-aggressive, competitive) behaviors that involved no physical contact between opponents (e.g. threatening and spontaneous withdrawing). Such agonistic behavior reduces the risk of injury. Dominance status depended on age and sex, with older animals generally being dominant to young ones and males dominant to females. Young bulls gained superior dominance status over adult cows when they reached about 2 years of age.

As with many animal dominance hierarchies, dominance-associated aggressiveness does not correlate with rank position, but is closely related to rank distance between individuals.

Dominance is maintained in several ways. Cattle often engage in mock fights where they test each other's strength in a non-aggressive way. Licking is primarily performed by subordinates and received by dominant animals. Mounting is a playful behavior shown by calves of both sexes and by bulls and sometimes by cows in estrus, however, this is not a dominance related behavior as has been found in other species.

The horns of cattle are "honest signals" used in mate selection. Furthermore, horned cattle attempt to keep greater distances between themselves and have fewer physical interactions than hornless cattle. This leads to more stable social relationships.

In calves, the frequency of agonistic behavior decreases as space allowance increases, but this does not occur for changes in group size. However, in adult cattle, the number of agonistic encounters increases as the group size increases.

When grazing, cattle vary several aspects of their bite, i.e. tongue and jaw movements, depending on characteristics of the plant they are eating. Bite area decreases with the density of the plants but increases with their height. Bite area is determined by the sweep of the tongue; in one study observing 750-kilogram (1,650 lb) steers, bite area reached a maximum of approximately 170 cm2 (30 sq in). Bite depth increases with the height of the plants. By adjusting their behavior, cattle obtain heavier bites in swards that are tall and sparse compared with short, dense swards of equal mass/area. Cattle adjust other aspects of their grazing behavior in relation to the available food; foraging velocity decreases and intake rate increases in areas of abundant palatable forage.

Cattle avoid grazing areas contaminated by the faeces of other cattle more strongly than they avoid areas contaminated by sheep, but they do not avoid pasture contaminated by rabbit faeces.

Sources and Credits

  1. (c) Peter O'Connor aka anemoneprojectors, some rights reserved (CC BY-SA), https://www.flickr.com/photos/anemoneprojectors/9383335082/
  2. (c) Vince Smith, some rights reserved (CC BY), uploaded by Vince Smith
  3. (c) Kim, Hyun-tae, some rights reserved (CC BY), uploaded by Kim, Hyun-tae
  4. (c) Sam McNally, some rights reserved (CC BY-NC), uploaded by Sam McNally
  5. Adapted by Desmon M Dunn from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Bos_taurus
  6. (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Cattle

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