The cattle are domesticated herbivorous mammals that constitute the genus Bos, of the family Bovidae. The cattle are of great importance to humans because of the milk, meat, leather, gelatin, glue, hides and other items of trading they produce. Cattle today are divided into two species: B. indicus, which originated in India and is characterized by a hump at the withers, and B. taurus, which originated in Europe and includes most recent breeds of dairy and beef cattle. The common characteristics of cattle can be provided through classification. They belong to the order Artiodactyla (even-toed, hoofed mammals) and the suborder Ruminantia (decreased number of teeth, with the upper incisors missing and a four-compartmented stomachs). Like others of the family Bovidae, they have paired, hollow, unbranched horns that do not shed. Other Bovidae that are so closely related to true cattle that they can still interbreed include the anoa, bison, gaur, Indian and African buffalo, and yak.
The wild cattle, B. primigenius, of Europe were first domesticated in southeastern Europe about 8500 years ago, which European cattle descended from. The zebu, or Brahman, cattle, B. indicus, were domesticated in southern Asia about the same time. Early records show that cattle were used for sacrifice, draft, milk, meat, and sport. Modern breeds of cattle were formed during the mid-1800s, and most modern breeds were formed in the latter half of that century. The definition of a breed is used to indicate animals that posses distinctive identity in color, size, conformation, and function. Cattle with similar characteristics, however, were present in these areas even before the idea of breeds became dominant. Today about 274 important recognized breeds exist, and new breeds continue to evolve (Encyclopedia Britannica).
The male cattle is first a bull calf and if left intact becomes a bull. If the bull is fixed he becomes a steer and in about two or three years grows to an ox. The female is first a heifer calf, growing into a heifer and becoming a cow. Dairy cattle are those breeds that have been developed primarily to produce milk. The achievements of careful breeding have been outstanding because the individual high-performance cows could produce more than four times the average amount of milk and butterfat. In North America the major breeds of dairy cattle are the Holstein-Friesian, Brown Swiss, Ayrshire, Guernsey, and Jersey. The ancestors of these animals were imported from Europe, where similar cattle exist today. The Holstein-Friesian came from Holland, the Brown Swiss from Switzerland, the Ayrshire from Scotland, the Jersey and Guernsey from England. The major breeds show distinctive characteristics that may be used for identification. The Holstein-Friesian is the largest; a mature cow weighs at least 1500lb (Britannica). It is followed by the Brown Swiss, Ayrshire, and Guernsey. The Jersey is the smallest, with a mature cows weighing 1000lb (Britannica). Breeds also differ in color. The Holstein is black and white, although some may be red and white; the Guernsey is fawn, white markings and a yellow skin; the Jersey may vary from a light gray to a very dark fawn, usually solid in color but sometimes with white spots. The Brown Swiss varies from a very light grayish-brown to dark brown; and the Ayrshire can be red, brown, or mahogany with white. Breeds also differ by volume of milk produced and milk composition. Holstein-Friesians produce the largest volume followed by the Brown Swiss, Ayrshire, Guernsey, and Jersey. Milk in the Jersey contains the highest concentration of fat followed by Guernsey, Brown Swiss, Ayrshire, and the Holstein.
Beef cattle have been bred and selected primarily for the production of meat. Many breeds have been developed or adapted for special conditions. The major breeds of registered beef cattle in North America are Angus, Hereford, Polled Hereford, Charolais, Shorthorn, Santa Gertrudis, Brahman, Brangus, and Red Angus. In recent years, several “exotic” breeds also have been imported. The “exotic” breeds have been used primarily for crossing with the major breeds in North America to increase the size and milking ability of the crossbred offspring for commercial production. The Herefords are characterized by a red coat color and a white face. Polled Herefords have the same characteristics, but they are hornless. Angus are solid black in color and are polled; the Charolais are white or cream colored; and the Shorthorn may be red, white, or roan. The Brahman is usually white in color, with large droopy ears, and a large dewlap. The Santa Gertrudis was developed in Texas from crossbreeding the Brahman and Shorthorn breeds. There are also dual-purpose breeds which are breeds that have been selected for both meat and milk production. They include Milking Shorthorn, Red Dane, Red Polled, and Pinzgauer. Many of the animals classified as either dairy or beef breed, particularly those of continental Europe, could alternatively be classified as dual-purpose breeds.
Cattle are widely distributed throughout the world. The total world cattle population in the late1980s was estimated to be nearly 1.3 billion, with about 31 percent in Asia, 20 percent in South America, 14 percent in Africa, 13 percent in North and Central America, and 10 percent in Europe (Britannica). The leading countries were, in decreasing order India, Brazil, the USSR, the U.S., China, and Argentina. Beef cattle used for breeding in the U.S. are estimated at 34 million (Britannica).
Cattle have been experimental subjects for genetic modification and large-scale cloning. The importance of the genetic modification and large-scale cloning is for agriculture, human medicine, and biotechnology. The researchers divided the fetal fibroblasts which were genetically modified with a marker gene. Then they selected a clonal line, and the cells were fused to enucleated mature oocytes. Three healthy, identical, transgenic calves were generated out of the 28 embryos which were part of the experiment. The importance of the results of the research of cloning cattle is for agriculture, human medicine, and biotechnology. The research indicates fibroblast life-span can be enhanced by nuclear transfer, which could allow to generate as many gene as needed by subjecting the cell line to the successive rounds of nuclear transfer. It is also important that nuclear transfer can improve efficiency of producing transgenic cattle and broaden the range of applications because it allows the targeting DNA inserts to specific sites of genome, which is important for deleting or replacing bovine genes that might interfere with human protein isolation or cause rejection of grafted tissues. Also nuclear transfer can produce one generation of an entire herd of the appropriate sex transgenic cattle, whereas the traditional way would require two generations. Nuclear transfer can save time and cost involved. So as you can see there is a great deal of importance for cattle cloning and nuclear transfer.
Through the process of natural selection you could develop a breed of cattle that very well could be the hardiest to live in their natural environment. If natural conditions caused some to die, the cattle that survived would then breed together and their chances for survival would be greater as each generation passed. For example, if cattle were lived in dry conditions with little water probably a great many would die. However those that survived when breeded together would produce offspring that had a greater chance of survival in the dry conditions. You may develop a breed of cattle that would need very little water to live on. The chances of survival would then probably increase with each generation of cattle. Thus the population of this breed of cattle would greatly increase over time. The reason for this would be that these cattle were better able to adapt to their environment over a period of time through natural selection. You could also support Darwin s theory of natural selection by bringing in cattle that were not used to this type of environment and see if they would be able to survive. The chances are that a great many of these cattle if not all would die. If some did survive, these would be the ones that would start the cycle over again.