12th Class

Poultry includes the birds like chicken (hen), ducks, geese and turkey. Poultry farming deals with the rearing of them for their eggs and meat. Fowls are widely distributed as domesticated animal since time immemorial, but in the present century, it has become an important small scale industry due to modern need for palatable and nutritive food which it provides in the form of eggs as well as adult animal. An egg laying poultry bird is called hen (layers) and the poultry birds groomed for obtaining meat are called chicken or broilers. India and the neighbouring countries, like Burma, Sri Lanka are the original home of the red jungle fowl (Gallus gallus). It seems that Aseel or Malay fowl were carried to Europe through the Middle East about 2,000 years ago and have given rise to the present-day European breeds. Poultry farming v/s livestock rearing : Poultry birds are easy to more...

Sericulture is the breeding and management of silk worms for the production of silk. It has been practiced in India since second era or century B.C. The silk which is produced by silk worm is of a valuable natural protein fibre. Silk worms are the larvae of silk moths. The rearing of silk worm for the production of silk is known as sericulture. History of silk : Historical account of use of silk and rearing of silk worm eggs, larvae and cocoons are available from china. It was Lotzu the empress kwang-Ti who for the first time discovered the silk thread and its source the silk worm cocoon. The technique of sericulture was kept as a secret by the chines people. In about 550 B.C. The sericulture technique was diffused to European countries. The available mythological literature deals with facts rearing the use of silk in ancient India. By about more...

There are many breeds of sheep (ovis aries) and goats (Capra hircus) in our country. Today sheep are raised in all parts of the world. Sheep provide us with wool, skin and mutton and goats provide us with milk, meat, skin and hair. The fine soft wool called pashmina is the underfur of Kashmir and Tibet goats. A sheep lives for about 13 years. Feeding of sheep and goats : Sheep feed on green tender grass or weeds or other herbage. Goats feed on a variety of trees by browsing on the buds and foraging on a variety of plants. Oil cakes and mineral mixture are also fed to keep sheep in good condition. Breeding of sheep and Goats : To improve the quality of a sheep, cross-breeding experiments are usually done. For this purpose, a good quality wool yielding or mutton producing sheep is chosen and cross breed with more...

Yak (Poephagus grunniens) is found in Tibet, Ladakh, Lahaul, Spiti, Garhwal and Sikkim. It gives meat, hide and wool. Yak is also used for tilling land. The transport of people and goods in these regions would be impossible without this animal.

Biopesticides are living organisms of their products used for killing pests of interfering with their biological processes. Bioherbicides : Biological control of weeds involves (1) Utilization of insects which would feed selectively on weeds and (2) use of certain microorganisms which produce diseases in weeds and eliminate them. Much of the work using insects for biological control has been done in North America. In India and Australia, the overgrown of cacti was checked by the introduction of cochineal insect (Cactoblastis cactorum). The first bioherbicide was mycoherbicide, based on the fungus Phytophthora palmivora, and was developed in 1981. Bioinsecticides : Bioinsecticides include : (1) Pathogens, parasites and predators (2) Sterilization strategy (3) Insect hormones (4) Natural insecticides Aphids have been controlled by the use of ladybugs or praying mantis. Screw-worm was eradicated by releasing sterile males (sterilized by irradiation) at the time of mating to compete with natural fertile population. Introduction more...

Integrated pest management is the selection, integration and implementation of pest control based on predicted economic, ecological and sociological consequences. IPM is based on the assumption that no single safe pest control. Method will be successful. IPM, therefore, seeks to use a variety of biological, physical and chemical methods integrated into a cohesive scheme designed to provide long-term protection. Biological methods include using natural predators of pests, using resistant varieties, crop rotation, intercropping, etc. Mechanical methods include manual destruction of eggs of pests, removing weeds, etc. Use of chemical pesticides is carefully timed.

The spore-forming bacteria have been particularly useful in controlling certain pests. Bacillus popilliae is used for the control of Japanese beetle. The bacterium Bacillus thuringenesis produces protein toxins. One of these, thurioside, is active against different groups of insects. Sporeine was the first bioinsecticide developed on commercial scale in Germany. Sporeine kills insects by inhibiting ion transport in the midgut. Genes for some of these toxins have been isolated and transferred to host through recombinant DNA technology (transgenic plants). Transgenic plants of tomato showing resistance to horn worm larvae have been obtained.

There are a number of chemicals which can kill or destroy these pests. These chemicals are called as pesticides (cides means to kill). Pesticides are sprayed over crops, human dwellings etc. Few familiar pesticides are baygon spray, finit (flit), DDT, BHC which are widely used in houses to kill mosquitoes, flies, ants, cockroaches etc. During the Second World War, two synthetic pesticides i.e. DDT (dichloro diphenyl trichloroethane) and \[2-4\text{ }D\](2, 4 dichlorophenoxy acetic acid) were mainly used. Types of pesticides : Pesticides are of several types depending upon the types of pests killed or controlled. Thus they may be: (1) Fungicides : Destroy fungal pathogens. Inorganic fungicides include Bordeaux mixture, Burgandy Mixtue, sulphur, mercuric chloride, etc. Organic fungicides are dithane \[S-21,\] dithane \[M-22,\] dithane \[Z-78\](all carbamates), oxanthiins (e.g., vitavax), mercury compounds (e.g., agrosan, tillex), benzimidiazole derivatives (e.g., benlate). (2) Weedicides/Herbicides : They kill weeds in agriculture/horticulture and unwanted plants. Depending more...

Due to harmful effects of pesticides on organisms, some alternative methods of pest control are being used and biological pest control is one of the suitable methods, i.e., use of other organisms to kill the pests constitutes biological pest control and such organisms are called biopesticides. Bioherbicides/Biological control of weeds          Bioherbicides are organisms or their extracts which destroy weeds without harming useful plants. The first bioherbicide is devine, which is a mycoherbicide, based on fungus Phytophthora palmivora. It is being used since 1981 to control Morrenia odorata (milkweed vines) in Citrus orchards. Similarly Collego is another mycoherbi­cide from conidia Colletotrichum gloeosporioides fungus. Bioinsecticides : They are living organisms or their products which are able to kill or repel specific insects. (1) Use of parasites, predators and pathogens : e.g., control of aphids by use of praying mantis or lady bug, i.e., Mantis. Bacillus thuringiensis : One of the most widely more...

Communicable Diseases.        (i) Meaning : The diseases which are caused by pathogens (viruses and living organisms) and readily spread from the infected to the healthy persons are called communicable or infectious diseases. A German physician, Robert Koch, listed the following four conditions to establish that a specific pathogen causes a particular disease –          (a) The suspected pathogen should be invariably present in the animals suffering from the disease and should not be found in healthy individuals.          (b) The pathogens isolated from the diseased animal should be grown in a pure culture.          (c) When this culture is inoculated into a healthy host, the latter should develop the disease and show its characteristic symptoms.          (d) The pathogen should be recoverable from the experimental host, and it should be the same as the original one.          Kotch’s postulates proposed for animal diseases, hold good for human diseases also. more...