Заглавная страница Избранные статьи Случайная статья Познавательные статьи Новые добавления Обратная связь КАТЕГОРИИ: АрхеологияБиология Генетика География Информатика История Логика Маркетинг Математика Менеджмент Механика Педагогика Религия Социология Технологии Физика Философия Финансы Химия Экология ТОП 10 на сайте Приготовление дезинфицирующих растворов различной концентрацииТехника нижней прямой подачи мяча. Франко-прусская война (причины и последствия) Организация работы процедурного кабинета Смысловое и механическое запоминание, их место и роль в усвоении знаний Коммуникативные барьеры и пути их преодоления Обработка изделий медицинского назначения многократного применения Образцы текста публицистического стиля Четыре типа изменения баланса Задачи с ответами для Всероссийской олимпиады по праву Мы поможем в написании ваших работ! ЗНАЕТЕ ЛИ ВЫ?
Влияние общества на человека
Приготовление дезинфицирующих растворов различной концентрации Практические работы по географии для 6 класса Организация работы процедурного кабинета Изменения в неживой природе осенью Уборка процедурного кабинета Сольфеджио. Все правила по сольфеджио Балочные системы. Определение реакций опор и моментов защемления |
Task 12 Read the text using your dictionary. Give Russian equivalents to the following words and phrases.
Avian influenza; high morbidity/mortality rate; characteristic lesions; subcutaneous haemorrhages; oedema; prov- entriculus; susceptible to something; the causative agent; mechanical means of transfer of infection; the onset of signs; field outbreaks; inappetence; suffocation; blood-tingled mucus; the acute phase; excitation. AVIAN INFLUENZA Avian influenza (Fowl Plague) in chickens is characterised by a high morbidity and mortality rate with respiratory and nervous signs. The characteristic lesions include subcutaneous haemorrhages, cyanosis of the head region, oedema of various parts of the body, and haemorrhages in the pro- ventriculus. Incidence. Avian influenza virus, associated with highly fatal disease, has been isolated in a number of countries. Less pathogenic types are frequently associated with respiratory disease in turkeys. Infection is probably widespread in wild bird populations. Susceptibility. Influenza virus naturally infects ducks, however, chickens, turkeys, geese, quail, and a wide variety of wild birds are susceptible to the infection. Cause. The causative agent is a virus which belongs to the influenza group of viruses. There are a number of serotypes isolated from avian species which differ widely in their pathogenicity. The virus is readily destroyed in the poultry environment. Transmission. 1. Contact spread readily occurs among pen mates. 2. Aerosol spread of the virus has been reported to occur between flocks. 3. The possibility of vertical transmission should always be considered, especially with less pathogenic types. 4. Mechanical means of transfer of infection include people, equipment, and artificial insemination. Clinical signs. In susceptible chickens following an incubation period of 2-4 days the signs of the disease may appear suddenly. The course of the disease is usually short and the virus spreads rapidly within a flock. Following the onset of signs, birds may only live a few hours. In field outbreaks morbidity may be 100 per cent and mortality may vary from 50 per cent to 100 per cent. The flock is generally depressed. Individual birds have ruffled feathers, inappetence and drop in egg production. The eyelids may be closed and the conjunctiva is red and swollen. Characteristically oedema and cyanosis develop around the head region involving the comb, wattles and the area surrounding the eyes. The oedema may extend down the neck and breast. Oedema of the glottis may occur causing difficulty in breathing resulting in suffocation. When respiratory signs are present a grey to blood-tinged mucus exudes from the nostrils. There may be haemorrhages in the mouth. In most outbreaks varying degrees of diarrhea may be observed. Affected birds usually die within 2 days of the onset of signs. Birds surviving the acute phase of the disease develop nervous signs including excitation, convulsions, or circling movements and ataxia. Task 13. Read the text and do the assignments that follow it. THE PREVENTION OF DISEASE There is no factor that will prevent disease coming on to or spreading within a farm. Disease usually occurs because a number of factors are working against the animal, for example the weather, its nutrition or the number of stock in one building. All livestock units should formulate a comprehensive policy to prevent disease. All new stock should be inspected to ensure they are healthy. Some general signs of health are applicable to most animals: bright alert eyes, clean tail, groomed coat, even breathing, no sign of discharge from the nose, no coughing and healthy appetite. All new stock must be vaccinated against any known on-farm diseases. The environment in which the animal lives probably has the greatest influence on the continuing good health of the animal. The more intensive the livestock system, the more attention must be paid to hygiene. The animal’s own dung is a constant source of infection, so one of the animal’s major requirements is a clean lying area. Many livestock buildings and pens require regular cleaning and disinfection. The spread of and the severity of a disease can be reduced by the use of drugs. The best examples of these are antibiotics, insecticides and wormers. Regular visits from the veterinary surgeon can go a long way in preventing disease. Regular visits every three or four months, when the veterinary surgeon and the stockperson can get together to look at and talk about the health of the unit, can help build up a health profile of the farm. This information can be useful when trying to identify or locate the cause of a problem. Task 14. Answer the questions: 1) Why is it important to work out a comprehensive pro gramme to prevent disease? 2) What are some general signs of healthy animals? 3) Why is hygiene so important in intensive livestock systems? 4) Is it necessary to use drugs to prevent diseases? 5) How often should the veterinary surgeon visit the farm?
|
||||
Последнее изменение этой страницы: 2017-02-17; просмотров: 635; Нарушение авторского права страницы; Мы поможем в написании вашей работы! infopedia.su Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав. Обратная связь - 18.221.165.246 (0.004 с.) |