Английский учебник

artificial insemination and embryo transfer are frequently used, not only as methods to guarantee that females are bred, but to help improve herd genetics. This may be done by transplanting embryos from stud-quality females, into flock-quality surrogate mothers - freeing up the stud-quality mother to be reimpregnated. This practice vastly increases the number of offspring which may be produced by a small selection of stud-quality parent animals. This in turn improves the ability of the animals to convert feed to meat, milk, or fiber more efficiently and improve the quality of the final product.

There are contrasting views on the ethical aspects of breeding animals in captivity, with one debate being in relation to the merits of allowing animals to live in natural conditions which are reasonably close to those of their wild ancestors, compared to the view that considers natural pressures and stresses upon wild animals from disease, predation, and the like as vindication for captive breeding.

Some techniques of animal husbandry such as factory farming, tail docking, the Geier Hitch and castration, have been attacked by animal welfare groups such as Compassion In World Farming. Some of these practices also are criticized by farmers who use more traditional or organic practices. Genetic engineering is also controversial though it does not necessarily involve suffering. People who believe in animal rights generally oppose all forms of animal husbandry.

Some domesticated species of animals, such as the vechur cow, are rare breeds and are endangered. They are the subject of conservation efforts.

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Text 2. Cattle

Cattle, colloquially referred to as cows, are domesticated ungulates, a member of the subfamily Bovinae of the family Bovidae. They are raised as livestock for meat (called beef and veal), dairy products (milk), leather and as draft animals (pulling carts, plows and the like). In some countries, such as India, they are honored in religious ceremonies and revered. It is estimated that there are 1.3 billion cattle in the world today.

Species of cattle.

Cattle were originally identified by Carolus Linnaeus as three separate species. These were Bos taurus, the European cattle, including similar types from Africa and Asia; Bos indicus, the zebu; and the extinct Bos primigenius, the aurochs. The aurochs is ancestral to both zebu and European cattle. More recently[verification needed] these three have increasingly been grouped as one species, with Bos primigenius taurus, Bos primigenius indicus and Bos primigenius primigenius as the subspecies.

Complicating the matter is the ability of cattle to interbreed with other

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closely related species. Hybrid individuals and even breeds exist, not only between European cattle and zebu but also with yaks (called a dzo), banteng, gaur, and bison ("cattalo"), a cross-genera hybrid. For example, genetic testing of the Dwarf Lulu breed, the only humpless "Bos taurus-type" cattle in Nepal, found them to be a mix of European cattle, zebu and yak.[2] Cattle cannot successfully be bred with water buffalo or African buffalo.

The aurochs originally ranged throughout Europe, North Africa, and much of Asia. In historical times, their range was restricted to Europe, and the last animals were killed by poachers in Masovia, Poland, in 1627. Breeders have attempted to recreate cattle of similar appearance to aurochs by crossing of domesticated cattle breeds, creating the Heck cattle breed. (See also aurochs and zebu articles.)

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Text 3. Biotechnology in livestock

Population growth, income growth and urbanization are fuelling a massive increase in demand for food of animal origin in developing countries - the 'livestock revolution'. In the past, developing countries have coped with the increases in demand mainly by expanding livestock populations. However, declining land areas per agricultural population are now forcing developing countries to intensify livestock production and monogastric animals, i.e. pigs and particularly poultry, are the most important sources of livestock sector growth.

Over the past centuries, biological, chemical and mechanical innovations have provided the basis for livestock sector development by containing the impact of livestock diseases, increasing yields and reducing labour requirements. Today, agricultural biotechnology is a new source of innovations that can potentially reshape agriculture as profoundly as any of the previous fields of technological innovation.

Intensification of livestock production is feared to reduce genetic diversity indirectly by displacing landraces and their inherent diversity as farmers adopt genetically uniform varieties of livestock. Biotechnologies such as cryopreservation of semen and embryos, coupled with artificial insemination and embryo transfer as well as somatic cloning are important actual and potential tools for the preservation of animal biodiversity.

Genetically modified livestock are not likely to play a major role in developing countries in the near future. The larger, short term potential for the application of biotechnologies in the livestock sector of developing countries resides in the use of bio-engineered inputs covering the entire food production chain from animal feed to product processing. In the short to medium term (5 to 10 years), the largest impacts of biotechnology on livestock production in developing countries are likely to stem from increasing the quality of livestock feeds

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through improving nutrient content of forages as well as the digestibility of low quality feeds and through enhanced disease control.

The role of animal diseases as a major constraint to enhanced livestock productivity will substantially increase as animal production intensifies and as livestock densities increase in warmer and more humid ecological zones. Use of DNA biotechnology in animal health through more effective, cheap and robust vaccines combined with enhanced diagnostic tools could contribute significantly to improved animal disease control, thereby stimulating both domestic food production and participation in livestock trade.

Biotechnology also offers considerable potential for improvements in agro-industrial processing, particularly through more environmentally friendly or energy-efficient processes. While most of these technologies are not likely to be accessible to traditional animal agriculture, they will be accessible to a considerable degree to the emerging commercial and industrial sector in many developing countries.

Most of the biotechnology research and development activities (>80%) are conducted by large private companies for commercial exploitation and are designed to meet the requirements of developed markets. They are thus unlikely to be very suitable for the conditions of small-scale farmers in tropical regions of the world and this may lead to increasing inequality of income and wealth within countries (large vs. small farmers) and between countries (developed vs. developing). Given that commercial considerations may not necessarily reflect social concerns and needs, there remains a pivotal role for public-sector research and the involvement of international organizations.

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Text 4. Sheep and Beef Cattle Farming in New Zealand

At June 2002 there were 39.5 million sheep and 4.5 million beef cattle in New Zealand. 10 sheep and 1.1 cattle for every New Zealander. The meat, wool and other products derived from this farming sector are worth around $6.3 billion annually, and account for approximately 22 percent of New Zealand's exports of goods.

Farms.

There are over 13 000 commercial sheep and beef cattle farms in New Zealand, most of which are owned and operated by farming families. Sheep and beef farms are predominantly on hill country in New Zealand. There are a wide range of farm types and systems that vary according to land type, topography, climate, scale and farmer preference. The majority of farms have both sheep and beef cattle, which complement each other in pasture-based grazing systems. Some farms also run deer or have arable crops. This diversification reduces the business risk.

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A representative Central North Island farm is 550 effective hectares, runs 3565 sheep and 402 beef cattle, and is owner-operated with the employment of casual labour and contractors. In the year ended June 2003, it produced for sale 13 900 kg of wool, 2400 lambs, 600 adult sheep and 120 cattle.

All sheep and beef farms are run on low input pasture grazing systems, sometimes supplemented with hay, silage and fodder cropping. This low cost system enables New Zealand farmers to supply high quality pasture-fed meat and wool to world markets at competitive prices.

Meat Processing.

Meat processing is a strongly competitive industry. It includes 18 processor/exporters, six processors who process only for exporters, and 110 companies with export licences. There are a number of other companies that process for the local market only.

Four companies, however, dominate the processing sector, controlling about 80 percent of output the AFFCO Group, Alliance Group Ltd, Primary Producers Co-op Society Ltd (PPCS) and Richmond Ltd. Each of these companies has multiple plants and annual turnovers in the range of $1.2 billion to $1.4 billion. Many of the remaining processors are private companies.

Sheepmeat.

Despite New Zealanders' eating about 12 kg of lamb (plus 12 kg of mutton) per person per year, 87 percent of our lamb production is exported. Annual production is about 402 000 tonnes of lamb and 104 000 tonnes of mutton. This total represents only about 4 percent of world production, butexports account for 47 percent of world exports. New Zealand's sheepmeat industry is very dependent on international meat prices and market access.

Since the mid-1980s, when the sheepmeat industry was heavily subsidised and the processing sector was heavily regulated, the sheep flock has fallen from 70 million to 39 million. The number of lambs slaughtered annually for export has declined from a peak of 39 million to about 25 million. At the same time, however, farm productivity has improved enormously. The national average lambing percentage has increased from 100 percent to 117 percent (that is, 117 lambs from every 100 mated ewes and ewe hoggets), and the average lamb carcass weight has gone up about 30 percent to 16.8 kg. A 57 percent decrease in sheep numbers has led to a 53 percent increase in lamb carcass weights per mated ewe and ewe hogget.

The processing and marketing companies have also responded to the changes in the market place, both in consumer requirements and in the competition from other meats and protein sources. They have progressed from exporting frozen whole carcasses, to further processing into chilled prepacked cuts and boneless products. Sales of chilled meat have continued to grow, and now make up 25 percent of lamb export value. Advances in hygiene, packaging, presentation, handling instructions and distribution have all made lamb a premium product in the higher-priced end of the market. Real returns from lamb meat have

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consequently improved. Beef

Beef exports are still dominated by frozen manufacturing beef exports to North America, but other markets are growing in importance. Asian markets, in particular, are looking for young, tender, grass-fed beef. In September year 2002, New Zealand produced 565 000 tonnes, or 1 percent of the world production of beef. Around 85 percent of this production was exported, representing 7 percent of the world trade in beef.

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Text 5. The slaughtering of sheep, calves and swine in the USA

The slaughtering of sheep, calves and swine with the use of carbon dioxide gas and the handling in connection therewith, in compliance with the provisions contained in this section, are hereby designated and approved as humane methods of slaughtering and handling of such animals under the Act.

(a) Administration of gas, required effect; handling.

(1)The carbon dioxide gas shall be administered in a chamber in accordance with this section so as to produce surgical anesthesia in the animals before they are shackled, hoisted, thrown, cast, or cut. The animals shall be exposed to the carbon dioxide gas in a way that will accomplish the anesthesia quickly and calmly, with a minimum of excitement and discomfort to the animals. In swine, carbon dioxide may be administered to induce death in the animals before they are shackled, hoisted, thrown, cast, or cut.

(2)The driving or conveying of the animals to the carbon dioxide chamber shall be done with a minimum of excitement and discomfort to the animals. Delivery of calm animals to the anesthesia chamber is essential since the induction, or early phase, of anesthesia is less violent with docile animals. Among other things this requires that, in driving animals to the anesthesia chamber, electrical equipment be used as little as possible and with the lowest effective voltage.

(3)On emerging from the carbon dioxide tunnel, the animals shall be in a state of surgical anaesthesia and shall remain in this condition throughout shackling, sticking, and bleeding, except for swine in which death has been induced by the administration of carbon dioxide. Asphyxia or death from any cause shall not be produced in animals before bleeding, except for swine in which death has been induced by the administration of carbon dioxide.

(b) Facilities and procedures.

(1)General requirements for gas chambers and auxiliary equipment; op-

erator.

(i) The carbon dioxide gas shall be administered in a tunnel which is designed to permit the effective exposure of the animal. Two types of tunnels,

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based on the same principle, are in common use for carbon dioxide anesthesia. They are the "U" type tunnel and the "Straight Line" type tunnel, and are based on the principle that carbon dioxide gas has a higher specific gravity than air. The tunnels are open at both ends for entry and exit of animals and have a depressed central section. Anesthetizing, or, in the case of swine, deathinducing, carbon dioxide concentrations are maintained in the central sections of the tunnels. Effective anaesthetization is produced in these central sections. Animals are driven from holding pens through pathways constructed of large-diameter pipe or smooth metal and onto continuous conveyor devices that move the animals through the tunnels. The animals are either compartmentalized on the conveyors by mechanical impellers synchronized with the conveyor or they are otherwise prevented from crowding. While impellers are used to compartmentalize the animals, mechanically or manually operated gates are used to move the animals onto the conveyors. Surgically anaesthetized animals, or killed swine, are moved out of the tunnels by the same continuous conveyors that moved them into and through the carbon dioxide gas.

(ii) Flow of animals into and through the carbon dioxide chamber is dependent on one operator. The operation or stoppage of the conveyor is entirely dependent upon this operator. It is necessary that he be skilled, attentive, and aware of his responsibility. Overdosages and death of animals can be brought about by carelessness of this individual.

(2)Special requirements for gas chamber and auxiliary equipment. The ability of anesthetizing equipment to perform with maximum efficiency is dependent on its proper design and efficient mechanical operation. Pathways, compartments, gas chambers, and all other equipment used must be designed to accommodate properly the species of animals being anesthetized. They shall be free from pain-producing restraining devices. Injury of animals must be prevented by the elimination of sharp projections or exposed wheels or gears. There shall be no unnecessary holes, spaces or openings where feet or legs of animals may be injured. Impellers or other devices designed to mechanically move or drive animals or otherwise keep them in motion or compartmentalized shall be constructed of flexible or well padded rigid material. Power activated gates designed for constant flow of animals to anesthetizing equipment shall be so fabricated that they will not cause injury. All equipment involved in anesthetizing animals shall be maintained in good repair.

(3)Gas. Maintenance of a uniform carbon dioxide concentration and distribution in the anesthesia chamber is a vital aspect of producing surgical anesthesia. This may be assured by reasonably accurate instruments which sample and analyze carbon dioxide gas concentration within the chamber throughout anesthetizing operations. Gas concentration shall be maintained uniform so that the degree of anesthesia in exposed animals will be constant. Carbon dioxide gas supplied to anesthesia chambers may be from controlled reduction of solid carbon dioxide or from a controlled liquid source. In either case the carbon dioxide

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shall be supplied at a rate sufficient to anesthetize adequately and uniformly the number of animals passing through the chamber. Sampling of gas for analysis shall be made from a representative place or places within the chamber and on a continuing basis. Gas concentrations and exposure time shall be graphically recorded throughout each day's operation. Neither carbon dioxide nor atmospheric air used in the anesthesia chambers shall contain noxious or irritating gases. Each day before equipment is used for anesthetizing animals, proper care shall be taken to mix adequately the gas and air within the chamber. All gas producing and control equipment shall be maintained in good repair and all indicators, instruments, and measuring devices must be available for inspection by Program inspectors during anesthetizing operations and at other times.

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Text 6. Silage

Silage is fermented, high-moisture fodder that can be fed to ruminants (cud-chewing animals like cattle and sheep) or used as a biofuel feedstock for anaerobic digesters. It is fermented and stored in a process called ensilage, and usually made from grass crops, including maize or sorghum, using the entire plant, not just the grain. Silage can be made from many other field crops, and other terms (oatlage for oats, haylage for alfalfa) can be used.

It is sometimes a mix of two crops, such as oats and peas. Haylage means ensiled forages, made up of grass, alfalfa and alfalfa/grass mixes. This is used extensively in the Midwest and Northeastern areas of the United States. It is also used widely in Europe for dairy cattle diets.

Baylage is another form of stored forage. In this case hay, alfalfa or grass is cut and baled while still fairly wet. That is, it is too wet to be baled and stored as hay. In this case the dry matter is around 60 to 70%. The bales are wrapped tightly in plastic wrappers. The material then goes through a limited fermentation in which short chain fatty acids are produced which protect and preserve the forage. This method has become popular on smaller farms.

Silage must be made from plant material with a suitable moisture content, about 55% to 70%, depending on the means of storage the degree of compression and the amount of water that will be lost in storage. For corn, harvest begins when the whole-plant moisture is at a suitable level. For pasture-type crops the grass is mowed and allowed to wilt for a day or so until the moisture content drops to a suitable level.

The plant material is collected, chopped into pieces about 1/2" (14 mm) long and packed. In the early days of mechanized agriculture, stalks were cut and collected manually using a knife and horse drawn wagon, and fed into a stationary machine called a "silo filler" that would chop the stalks and blow them up a narrow tube to the top of a tower silo. Current technology uses mechanical

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forage harvesters that collect and chop the plant material, and deposit it in trucks or wagons. These forage harvesters can either be tractor-drawn or self-propelled. Harvesters blow the silage into the wagon via a chute at the rear or side of the machine. Silage may also be emptied into a bagger, which puts the silage into a large plastic bag that is laid out on the ground.

Silage undergoes anaerobic fermentation, which starts about 48 hours after the silo is filled. Traditionally, the fermentation is caused by indigenous microorganisms, but today, some silage is inoculated with specific microorganisms to speed fermentation or improve the resulting silage. The process converts sugars to acids and exhausts any oxygen present in the crop material. The fermentation is essentially complete after about two weeks. Silage inoculants contain one or more strains of lactic acid bacteria, and the most common is Lactobacillus plantarum. Other bacteria used in inoculants include Lactobacillus buchneri, Enterococcus faecium and Pediococcus species.

The fermentation process releases liquid. Silo effluent contains nitric acid (HNO3), which is corrosive. It can also contaminate water courses unless precautions are taken. The high nutrient content can lead to eutrophication (growth of algae blooms).

Silos are hazardous, and people die every year in the process of filling and maintaining them. As well as the risk of injury by machinery or from falls, the fermentation process presents respiratory hazards. Nitrogen dioxide gas is released in the early stages of fermentation, and can kill. Lack of oxygen inside the silo can cause asphyxiation, and molds formed when air is allowed to reach cured silage can cause toxic organic dust syndrome. When filling a silo, fine dust particles in the air can become explosive. The silage itself poses no special danger.

Since silage goes through a fermentation process, energy is used by fermentative bacteria to produce volatile fatty acids (VFA), such as acetate, propionate, lactate, butyrate etc, which preserve the forage. The result is that the silage is lower in energy than the original forage, since the fermentative bacteria use some of the carbohydrates to produce VFA. Thus, the ensiling process preserves forages, but does not improve the quality or the nutrient value.

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Text 7. Maize

Maize usually called corn in some countries, is a cereal grain that was domesticated in Mesoamerica and then spread throughout the American continents. Maize spread to the rest of the world after European contact with the Americas in the late 15th century and early 16th century.

The term maize derives from the Spanish form (maíz) of the indigenous Taino term for the plant, and is the form most commonly heard in the United

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Kingdom. In the United States, Canada and Australia, the usual term is corn, which originally referred to any grain (and still does in Britain), but which now refers exclusively to maize, having been shortened from the form "Indian corn".

Maize is the largest crop in all of the Americas (270 million metric tons annually in the U.S. alone). Hybrid maize is preferred by farmers over conventional varieties for its high grain yield, due to heterosis ("hybrid vigour"). While some maize varieties grow 7 meters (23 ft) tall at certain locations, commercial maize has been bred for a height of 2.5 meters (8 ft). Sweet corn is usually shorter than field-corn varieties.

The stems superficially resemble bamboo canes and the internodes can reach 20-30 centimeters (8-12 in). Maize has a very distinct growth form; the lower leaves being like broad flags, 50-100 centimeters long and 5-10 centimeters wide (2-4 ft by 2-4 in); the stems are erect, conventionally 2-3 meters (7-10 ft) in height, with many nodes, casting off flag-leaves at every node. Under these leaves and close to the stem grow the ears. They grow about 3 centimeters a day.

The ears are female inflorescences, tightly covered over by several layers of leaves, and so closed-in by them to the stem that they do not show themselves easily until the emergence of the pale yellow silks from the leaf whorl at the end of the ear. The silks are elongated stigmas that look like tufts of hair, at first green, and later red or yellow. Plantings for silage are even denser, and achieve an even lower percentage of ears and more plant matter. Certain varieties of maize have been bred to produce many additional developed ears, and these are the source of the "baby corn" that is used as a vegetable in Asian cuisine.

Maize is a facultative long-night plant and flowers in a certain number of growing degree days > 50 F (10 C) in the environment to which it is adapted. The magnitude of the influence that long-nights have on the number of days that must pass before maize flowers is genetically prescribed and regulated by the phytochrome system. Photoperiodicity can be eccentric in tropical cultivars, where in the long days at higher latitudes the plants will grow so tall that they will not have enough time to produce seed before they are killed by frost. These characteristics, however, may prove useful in using tropical maize for Biofuels.

The apex of the stem ends in the tassel, an inflorescence of male flowers. Each silk may become pollinated to produce one kernel of corn. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months) the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking them tender first in boiling water. Modern farming techniques in developed countries usually rely on dense planting, which produces on average only about 0.9 ears per stalk because it stresses the plants.

The kernel of corn has a pericarp of the fruit fused with the seed coat, typical of the grasses. It is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows round a white pithy substance,

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which forms the ear. An ear contains from 200 to 400 kernels, and is from 10-25 centimetres (4-10 inches) in length. They are of various colors: blackish, bluishgray, red, white and yellow. When ground into flour, maize yields more flour, with much less bran, than wheat does. However, it lacks the protein gluten of wheat and therefore makes baked goods with poor rising capability.

A genetic variation that accumulates more sugar and less starch in the ear is consumed as a vegetable and is called sweetcorn.

Immature maize shoots accumulate a powerful antibiotic substance, DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one). DIMBOA is a member of a group of hydroxamic acids (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests including insects, pathogenic fungi and bacteria. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to be attacked by aphids and fungi. DIMBOA is also responsible for the relative resistance of immature maize to the European corn borer (family Crambidae). As maize matures, DIMBOA levels and resistance to the corn borer decline.

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Text 8. Hay

Immature maize shoots accumulate a powerful antibiotic substance, DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one). DIMBOA is a member of a group of hydroxamic acids (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests including insects, pathogenic fungi and bacteria. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to be attacked by aphids and fungi. DIMBOA is also responsible for the relative resistance of immature maize to the European corn borer (family Crambidae). As maize matures, DIMBOA levels and resistance to the corn borer decline.

Good quality hay should be green, not too coarse, and contain plant heads and leaves as well as stems. This is fresh grass/alfalfa hay, newly baled.

Poor quality hay is dry, bleached out and coarse-stemmed. Sometimes, hay stored outdoors will look like this on the outside but still be green inside the bale. A dried, bleached or coarse bale is still edible and provides some nutritional value as it long as it is dry and not moldy, dusty, or rotting.

Commonly used plants for hay include mixtures of grasses such as rye grass (Italian rye grass, Lolium multiflorum), timothy, brome, fescue, coastal bermuda, orchard grass, and other native species, depending on region. Many types of hay may also include legumes, such as alfalfa (lucerne) and clovers (red, white and subterraneum). Pasture flowers are also sometimes a part of the mix, though other than legumes, which ideally are cut pre-bloom, flowers are not necessarily desired, and in some cases may be toxic to animals.

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