Методические указания к контрольным заданиям для студентов агробиологических и агроинженерных направлений заочной формы обучения
Скачать 1.49 Mb.
|
Notes:
ВАРИАНТ №3 BASIC TYPES OF FEEDS Animal feeds are classified into two main groups: concentrates and roughages. The former are high in energy value and are subdivided into following four groups: (a) cereal grains and their by-products (barley, corn (or maize), oats, rye, wheat), (b) high-protein oil meals or cakes (soybean, cottonseed), (c) by-products from processing of sugar beets, and (d) by-products from other industries. Roughages include such feeds (a) pasture grasses, (b) hays, (c) silage, (d) root crops, and (e) straw. Concentrate feeds. a) Cereal grains and their by-products. In the cultural practices of North America and northern Europe, barley, corn, oats, rye, and sorghum are grown mainly as animal feed, however small quantities are processed for human consumption as well. These grains are fed, whole or ground, either singly or mixed with high-protein meals or other by-products, minerals, and vitamins, to form a complete feed for pigs and poultry or an adequate dietary supplement for ruminants and horses. By-products from commercial processing of cereal grains, for instance wheat bran, corn gluten meal1, rice bran or hulls, are used as animal feeds in large quantities. b) High-protein meals. Vegetable seeds such as soybeans, flax-seeds, cottonseeds, sunflower seeds are produced mainly as a source of oil for human food and industrial uses. After these seeds are processed to remove the oil, the residues, which may contain from 5 per cent to less than 1 per cent of fat and 20 to 50 per cent of protein, are used as animal feeds. The latter are valuable supplements to roughages or cereal grains and other low-protein feeds because they provide the protein needed for efficient growth of production. c) By-products of sugar beets. From the sugar-beet industry come beet tops, which are used on the farm either fresh or ensiled, and dried beet pulp and beet molasses, which are produced in the sugar factory. These are all palatable, high-quality sources of carbohydrates. In some European countries, fodder beets and some other roots are grown as animal feed. d) Other by-product feeds. By-products of brewing industry (yeast), dairy industry (dried skim milk or whey or buttermilk) and fish industry (fish meal) contain 50 per cent or more of high-quality protein and such mineral elements as calcium and phosphorus so they are well-known as useful animal feeds. Roughages. a) Pasture. Various pasture grasses (timothy, Sudan grass) and legumes (clovers, soybeans, sorghum), both native and cultivated, are the most important single source of feed for cattle, horses, sheep, and goats. During the growing season they supply most of the feed for these animals at a cost lower than other feeds that must be harvested, processed, and transported. Hundreds of different grasses, legumes, bushes, and trees are acceptable as feeds for grazing animals. The nutritive value of the cultivated varieties has been studied, but information is incomplete for many naturally growing plants. b) Hay. It is produced by drying different mature grasses (such as timothy and Sudan grass) or legumes (alfalfa, clover) when they contain the maximum quantity of digestible protein and carbohydrates but before the seeds develop. The moisture content must be reduced to 22 per cent or less to prevent moulding, heating, and spoilage during storage. Legume hays are high in protein, while the grasses are lower in protein but vary greatly with the stage of maturity and level of nitrogen fertiliza tion which have been applied to the crop. Hay is usually fed to animals when sufficient fresh pasture grass is unavailable. c) Silage. Silage is usually made from immature plants of corn, sorghums, grasses, legumes in a storage container to exclude the air and allow fermentation to develop acetic and other acids, which preserve the moist feed. Storage may be in upright tower silos or in trenches in the ground. Best quality silage results when the forage is ensiled with a moisture content of 50 to 65 per cent. Ensiled forage can be stored for a longer period of time with lower loss of nutrients than dry hay. The nutritive value of silage depends upon the type of forage ensiled and how properly it has been made. d) Root crops. Nowadays such root crops as mangels, rutabagas, cassava and sometimes potatoes are used less extensively as animal feed than in the past, for economic reasons. Roots are lower in dry-matter content than are most of the other feeds listed. They are relatively low in protein also and provide mostly energy. e) Straw and hulls. Quantities of straws that remain after wheat, oats, barley, and rice crops are harvested and used as feed for cattle and other ruminants. The straws are low in protein and very high in fibre. Moreover, digestibility of straws is low. Straw is useful in maintaining mature animals during periods of shortage of other feeds, but it is too low in quality in order to be satisfactory for long periods without adding supplements. Corn stalks, cottonseed hulls, and rice hulls can also be used as sources of fibre in ruminant rations. Rice hulls are lower in value, while the others are similar to straw. Notes: 1. corn gluten meal – кукурузная глютеновая мука 2. hull – пленка (зерна), лузга 3. flaxseed – льняное семя 4. sunflower seed – семя подсолнечника 5. residue – остаток 6. ensiled – засилованный 7. beet molasses – свеклосахарная меласса 8.brewing industry (yeast) – пивоваренная промышленность (дрожжи) 9. dried skim milk/whey/buttermilk – обезжиренное сухое молоко/сухая сыворотка/сухая пахта 10. mature – зрелый, созревший 11. to mould – плесневеть 12. mangels/rutabagas/cassava – кормовая свёкла/ брюква/ маниока 13. digestibility – усвояемость ВАРИАНТ №4 ANIMAL ETHOLOGY Ethology is the scientific study of the behaviour of animals in their natural habitat. It is mainly a 20th-century phenomenon and is a branch of zoology as only animals have nervous systems and they have abilities for perception, coordination, orientation, learning, and memory. Many naturalists have studied aspects of animal behaviour through the centuries, among the early ethologists were Herbert Spencer and Charles Darwin. However, the modern ethology as a discrete discipline was established by biologists Konrad Lorenz (Austria) and Nikolaas Tinbergen (the Netherlands) in the 1920s. In 1973 they and zoologist Karl von Frisch (Austria) were jointly awarded the Nobel Prize in Physiology or Medicine for their work in developing ethology. Their emphasis was on field observations of animals under natural conditions. Tinbergen concentrated on the importance of both instinctive and learned behaviour to animal survival. He is especially well known for his long-term observations of sea gulls, which led to important generalisations on courtship and mating behaviour. Among his more important works are Social Behaviour in Animals (1953), and Animal Behaviour (1965), The Study of Instinct (1951). About 1910 Frisch proved that fish could distinguish colour and brightness differences and he later discovered that auditory acuity and sound-distinguishing ability in fish is superior to that in humans. However, Frisch is best known for his studies of bees. His research was devoted to communication among bees, so-called "dance language", and added greatly to the knowledge of the chemical and visual sensors of insects. In 1919 he demonstrated that they can be trained to distinguish between various tastes and odours. Also, he found that bees communicate the distance and direction of a food supply to other members of the colony by rhythmic movements or dances. In 1949 Frisch established that bees, through their perception of polarized light, use the sun as a compass. Study of the honey bee's navigational system has revealed much about the mechanisms used by higher animals. The most important discovery of Lorenz concerned the early learning of young nidifugous birds, a process which he described in 1935 and called imprinting. Lorenz observed that at a certain critical stage soon after hatching, the young chickens, ducklings and goslings learn to follow real or foster mothers. Lorenz discovered that this following response could be transferred to an arbitrary stimulus if the eggs were incubated artificially and the stimulus was presented for the few days after hatching. The concept of imprinting has been widely adopted in developmental psychology. The study of animal behaviour now includes many different topics, ranging from animal behaviour during the reproductive period to communication between animals. Many different hypotheses have been proposed in order to explain the variety of behavioural patterns which are found in animals. Modern ethology concentrates on the systematic observation, recording, and analysis of how animals function, with special attention to physiological, ecological, and evolutionary aspects. Nowadays, the ethologist is more interested in the behavioural process than in a particular animal group and often studies one type of behaviour, for instance, aggression, in a number of animal species. It has been found that an organism's actions may be classified as either instinctive or learned behaviour. The former include the actions that are not influenced by the animal's previous experience, such as common reflexes. The latter comprise the actions that are depended on earlier experiences, for example, problem solving. Ethologists put emphasis on the complex interaction of environment and genetically determined responses, especially during early development. Thus, evolution based on the general mechanisms, which are described by ethology, has generated a nearly endless list of behavioural wonders by which animals have almost perfectly adapted to their world. Notes: 1. sea gull – чайка 2. courtship – ухаживание 3. auditory acuity – острота слуха 4. nidifugous bird – выводковая птица 5. imprinting – запечатление, импринтинг (термин в этологии) 6. to hatch (out) – вылупляться (из яйца) 7. arbitrary stimulus – зд. произвольный раздражитель ВАРИАНТ №5 ANIMAL FEEDS Animal feeds include any feedstuff which is grown or developed for livestock and poultry. The main aim of a farmer is to provide animals with as highly nutritional diets as possible in order to maintain them healthy and ensure the quality of such final animal products as meat, milk, or eggs. Even today the problem of feeds is still a subject of study for agricultural scientists. Proteins, carbohydrates, fats, minerals and vitamins are known as the basic nutrients that animals require for growth, reproduction, and good health, but the amount of these substances varies greatly with the type of feed. The first effort to evaluate feeds for animals on a comparative basis was made by Albrecht Thaer (1752-1828), in Germany, who developed "hay values" as measures of nutritive value of feeds. Tables of the value of feeds and of the requirements of animals were first drawn up in Germany; later they were used in other countries as well. Present-day knowledge represents an expansion and further improve ment of these early efforts. The usual chemical analyses of feeds provide information on the total amount of dry matter, protein, fat, fibre, and ash4 contained in the feed. Energy value, mineral elements, and vitamins are also determined; these values are included in complete tables of feed composition. The better methods for chemical analyses of feeds are developed, the more reliable data are obtained for calculating feeding rations for animals. Animal feeds are classified according to: 1) the origin, that is, plant or animal origin of feeds; 2) the chemical composition, such as high-protein, high-fibre, high-moisture etc; 3) the nutritional value, as concentrates and bulky feeds. Generally, animal feeds may be classified into two large groups: concentrates and roughages. The former are higher in energy value than the latter and are subdivided into the following types: 1) cereal grains such as wheat, corn (maize), oats, rye, barley and their by-products which remain after grain has been processed for human use, 2) high-protein oil meals or cakes from soybeans, sorghum, 3) by-products from processing of sugar beets, 4) animal and fish by-products. Roughages include such feeds as: 1) green roughages (clover, timothy, other pasture grasses and legumes), 2) dry roughages or fodder (hays, straws); 3) silage, 4) root crops. Green forage grasses, silage and roots comprise a group of succulent feeds which are high in moisture. Concentrates are valuable in feeding all classes of animals as they have a high food value relative to volume, that is, they are rich in both protein and carbohydrates as well, they contain a number of microelements, minerals and vitamins. Roughages are bulky feeds with high-fibre content which is poorly digestible. Thus, they are fed in large quantities to cattle and sheep but they are not suitable for feeding pigs. Succulents are known as palatable feeds but contain a lot of water and have a laxative effect. The younger the grass is, the higher it is in vitamins and minerals, so farmers start grazing cattle and sheep as early in spring as possible. The quality of silage and its nutritive value is greatly affected by a number of factors such as the type of a forage crop, the plant age and storage conditions. Roots are low in protein but high in carbohydrates and moisture, so they are often used as supplements to hay and straw in order to provide complete rations for cattle and sheep. Feeds vary not only in the amount of nutrients but in costs from season to season. Thus, it is important for a farmer to select feed ingredients for complete rations as economically as possible. Nowadays large-scale commercial livestock companies as well as small-scale producers widely use special computer programmes for selecting feed mixtures that will satisfy the nutrient requirements of a specific type of animal at a particular stage of development. The more palatable and nutritious rations are provided for animals on the basis of the lower-cost feeds, the higher profits a farmer can get. |
Похожие:
 |  | Деловой иностранный язык. Методические указания по выполнению контрольных работ для студентов 2 курса заочной формы обучения, обучающихся... | |
| «27» июня 2007 г., и в соответствии с рабочими учебными планами специальности 030501 – Юриспруденция, утвержденными Ректором спбгиэу... | | Учебная практика проводится на 2-м курсе для студентов очной формы обучения и студентов бакалавров, на 1-м курсе для студентов очно-заочной... |
| Методические указания предназначены для студентов заочной формы обучения по специальности Техническое обслуживание и ремонт автомобильного... | | Методические указания предназначены для студентов, бакалавров и магистрантов очной и заочной формы обучения всех направлений и профилей... |
| Методические указания предназначены для студентов, бакалавров и магистрантов очной и заочной формы обучения всех направлений и профилей... | | Уголовно-процессуальные акты [Текст]: методические указания по выполнению контрольных работ для студентов заочной формы обучения... |
| ПМ. 01 Ведение расчетных операций, мдк. 01. 01 Организация безналичных расчетов, уп. Пм. 01 [Текст]: методические указания по выполнению... | | Методические указания по практике для студентов специальности «автомобильные дороги», дневной и заочной формы обучения / Составители:... |