DOMESTICATION AND IMPROVEMENT OF ANIMALSFlame Institute

Honey mainly consist of monosaccharides

Both the chambers contain about 7 rectangular wooden frames called comb frames arranged vertically. The vertical frames are filled with comb foundation sheet. These sheets are made of wax and contain hexagonal imprints. They are detachable. They are available in the market.

Honey extraction : Honey is stored in combs of super frames. It is extracted from the comb by a simple machine called honey extractor. It has a drum containing a rack inside to hold the super frames. It is made to rotate by a set of two-gear wheels, operated by a handle.

The super frames are removed from the hive. The caps of the comb cells are cut off by a double edged knife. Then the frames are fixed in the rack and the rack is made to rotate by operating the handle. The honey is forced out into the drum from the comb cells. From the drum the honey is collected in vessels through an exit present in the drum.

Location of Apiary : The hives should be set, in places where there are plenty of flowering plants. The place should be neat and clean and free from any obnoxious smell. There should be clean drinking water near by because each bee colony requires two glasses of water per day for their survival

Protection

(1) Honey bees should be protected from garden lizard and snakes.

(2) Black ants steal honey. So water should be placed at the base of the stand.

(3) Wasps kill honey bees. So protection should be provided against wasps.

(4) Wax-moth damages the combs. So the combs must be ” protected from wax-moths.

Formation of honey : Honey is a viscous sugary fluid formed from the nectar within the stomach of the honey bee. The bees visit flower, suck the nectar, store it in the stomach and return to the hive. In the stomach the nectar is processed. It is regurgitated and swallowed repeatedly for about 240 times. Then the processed nectar is deposited in the comb cells. This processed nectar is called unripe honey or green honey. It contains about 80% water. The unripe honey is converted into ripe honey by evaporation. The ripe honey contains less than 20% water. When the honey becomes ripe, the cells are capped or closed. The honey in the unsealed cell is unripe.

Chemical composition : Honey contains nearly 80 different substances of important to human beings. The important chemical are as follows

(1) Levulose – 38.9%

(2) Dextrose – 21.28%

(3) Maltose & other sugars – 8.81 %

(4) Enzymes & pigments – 2.21%

(5) Ash – 1.0%

(6) Water – 17.20%

(7) Vitamins – A, B, B₂, B₃, B₆, C, E, and K

(8) Minerals – Ca, Na, K, Mg, Fe, P, S etc

Value of Honey : Honey is a valuable food and medicine. Its uses are summarised below:

(1) As it has high content of sugar it is used as a sweetener. Until last century before the discovery of sugar throughout most of human history honey was the only available sweetener.

(2) Honey has a high calorific value. One kilogram of honey has 3350 calories while 1 litre of milk contains only 310 calories.

(3) Many athletes drink honey before games and between events in order to restore the energy used up.

(4) Doctors prescribe honey for old people and children who need to build up their strength quickly.

(5) Honey is used to heal wounds.

(6) It is used to cause free urination.

(7) It is used as a means of easing the belly.

(8) It is a good tonic for ulcer.

(9) It facilitates digestion and improves appetite.

(10) It prevents a running nose. It is a sure remedy for cold and cough.

(11) Honey is used as medicines for children to treat complaints of the liver.

Bee wax : Bee wax is secreted by the abdominal gland of bees. It is used for the construction of comb. It is an yellowish solid insoluble in water. It is used for the preparation of paints, varnishes, candles, models, etc. It is used as a ground substance for the preparation of ointments, creams etc. It has many industrial uses. It is used extensively in engineering industries, railways, textiles, leather industries etc.

Bee venom : Bee venom is secreted by the poison-glands of stings. Bee venom is a curative toxin in humans. It is transparent and it has a bitter burning taste. It is acidic in nature. It contains formic acid, histamine, tryptophan, sulphur, many proteins, volatile oils, enzymes like hyaluronidase and phospholipase and magnesium phosphate. Clinically it has the following uses :

(1) It is an active remedy for rheumatism.

(2) It is used to treat certain eye diseases like keratoconjunctivitis (inflammation of cornea), iris (inflammation of iris), iridocytis (inflammation of iris and ciliary body).

(3) It is used to cure skin diseases like tuberculosis of the skin.

(4) The cholesterol level in blood falls by the treatment of bee venom.

(5) Bee venom controls blood pressure.

Communication and Dance of honey bee : Ernst Spytzner (1788) explained for the first time that honey bees communicate with each other by means of definite movements of their body, now called bee dance. Later on Prof Karl von Frisch (1946 – 1969) studied and decoded the language of the dance of honey bee and he was awarded Nobel Prize for his work. He explained that scout bee performs 2 types of dance :

(1) Round dance : Round dance is performed when a newly discovered food source is close (less than 75 meters) to the hive. There is no indication of direction of the new source in this dance; the smell of flower brought back by the scout bees tells the foragers the kind of flowers for which to search.

(2) Tail wagging dance : It is performed for long distance (more than 100 meters) sources of food. It is also called shuffle dance. By this dance the scout bee conveys the direction of new source with reference to the position of the sun. In the tail wagging dance scout bee swiftly and repeatedly moves along a straight line and then makes two semicircles along the side of this line. If during this dance tail wagging is directly vertically upwards it indicates that the source is present towards the sun. If tail wagging is vertically downwards it indicates that the source is present opposite to the sun. If tail wagging is in oblique direction, it indicates that the source is located at an angle to the position of the sun.

Bee keeping industry : Before1953 attention to bee–keeping was paid only by state governments but in the same year, all India Khadi and Village Industries Commission (KVIC) started to pay attention to it and it was controlled by Union Government itself. Due to the functioning of the central organisation, bee–keeping industry was spread in South India in some northern states also. Now-a-days bee-keeping industry is nation wide and is a good source of cottage industry.

Lac Culture

Lac is the resinous secretion produced by lac insect as protective covering around its body. It belongs to genera Laccifera or Tachardia. Lacifera lacca is the common Indian lac insect. It lives on the trees of fig family namely kikar, ber (Zizyphus mauritiana), babul (Acacia nilotica), dhak or palas (Butea monisperma), kusum (schleichera oleosa), Katha or khair (Acacia catechu), peepal (Ficus religiosa) and gular (Ficus glomerata).

Lac insect feeds upon the sap of its host plant like any other sap sucking insect. It is found in India and Philipine islands.

Male and female chambers : The adult male and female insects live on the tree twigs enclosed in thick capsules or chambers separately. The male chamber are elongated and cigar- shaped. Each male chamber has a branchial aperture in its anterior part.

The female chamber is smaller and rounded. It has a branchial aperture in its anterior part and a tubercular or anal opening in the posterior part.

Male and female lac insects : The female is more degenerated. It has a bag -like body with a small reduced antenna. The eyes legs and wings are lost during metamorphosis. The male lac insect is red in colour. It has an incipient head with antennae and eyes. The thorax has three pairs of legs and abdomen carries genital sheath, penis and a pair of long caudal setae, one on either side of genital sheath.

The wings may be present or absent. Because of the absence of mouth parts, the insect is incapable of feeding.

Life-cycle : The male lac insect crawls out of its chamber by pushing open the operculum reaches the female chamber and fertilizes the female through the anal or tubercular opening of female shell. The male dies soon after copulation. The female secretes more resin forming a large sized chamber. Thus the secretion by females mainly contributes to lac.

Oviposition takes place into a space inside the female chamber made by the contraction of the body of female. This space is called incubating chamber. Each female lays 200-300 eggs. The eggs hatch into red coloured larvae. These crawl out of the female’s incubating chamber. The mass emergence of larvae is called swarming.

Each larva is boat-shaped in appearance and is about 1/2 mm in length. Its head bears paired antennae and the ocelli. The mouth parts are of piercing and Sucking type with maxillae and mandibles together forming the sucking tube or proboscis. Its thorax is three segmented and each thoracic segment carries a pair of walking legs. The abdomen bears a pair of long caudal setae.

Attachment of larvae to new shoots : The larvae on emergence craw1 on the twigs of any one of the host trees mentioned earlier and settle down on the undersurface of new shoots. These prefer young succulent shoots. These force their proboscis through the bark and insert it into the phloem tissue and start feeding. Here these metamorphose into the adult insects and by secreting lac enclose themselves into the chambers.

Secretion of Lac : The secretion forms a shining layer over their bodies in the beginning but hardens and becomes opaque later on. The secretion is produced by the cutaneous glands of the skin and is deposited around three openings the two branchial apertures at the anterior end and anal opening at the posterior end. The secretion is in the form of waxy filaments which have a woolly white appearance. On coming in contact with air, these join to from a continuous covering.

Composition of lac : Lac is a complex substance having large amount of resins, together with sugar, water and other alkaline substances. The percentages of various constituents are as given below

(1) Resin – 68 to 90 %

(2) Dye – 2 to 10 %

(3) Wax – 6 %

(4) Albuminous matter – 5 to 10 %

(5) Mineral matter – 3 to 7 % and

(6) Water – 3 %

Lac Cultivation : In order to obtain lac, lac insects are cultured and the technique of lac production is known as the lac culture. It involves proper care and regular pruning of the host plants, propagation of insects, and collection and processing of lac, For the purpose of propagation the older branches containing crusts are tied with new branches and this method is called oculation. When new crusts are formed, the old twigs are removed (approximately 20-30 cm long) and this is known as harvesting.

Extraction of Lac : The largest yield of lac and dye are obtained by harvesting the infested twigs while females are still living. The harvesting is done twice a year in June and November. The encrused twigs are pruned and lac scrapped from them. This is known as stick lac. It is grounded and sieved. The resulting granular lac is called seed lac, and the fine particles the dust lack. The seed lac is washed, melted spread out in a thin layer and dried thus forming the shellac of commerce. The dust lac is used for making toys, shellac is used in the preparation of varnishes, paints and polishes; in making gramophone records and in filling ornaments like bangles and bracelets. It is used as insulating material.

Damages Caused to Lac Crop

(1) Lac crops is reported to be damaged by squirrels, rats, and monkeys.

(2) Certain insects also attack lac insect.

(3) Parasites : Eight species of chalcidoids live as parasites in the body of lac insects. These deposit their eggs into the body of insects through their anal opening.

(4) Predators : Eublemma amabilis and Holcocerea pulverea are the two lepdoteran predators that damage about 35% of the lac cells. Their females lay eggs on or near the encrustation. The larvae that hatch out bore through the lac deposit and feed on lac insects.

Precautions to be Taken During Lac Culture

(1) Lac intended to be used as brood should be cut at or near the swarming period, never more than one week before.

(2) Lac to be used as brood must be healthy and resistant to the parasite and predator’s attack.

(3) Lac used as brood should be removed after a maximum period of 3 weeks from the date of swarming.

(4) All brood lac after use and the lac cut from the tree should be scrapped from the sticks to destroy larvae and pupae of predators of parasites.

(5) Lac should not be stored after cutting. It should be treated as soon as possible.

(6) Fumigation and water immersion immediately after cutting are also helpful in the disinfection of Lac by insects.

Economic importance of Lac : Lac is used in the preparation of sealing wax (shellac), paints, varnish, the manufacture of photographic materials, electrical goods. Lac is also used in the preparation of bracelets, buttons, toys and in filling hollow gold ornaments. Lac is also utilized in confectionery trade and in artificial leather and pottery. Gramophone industry used to consume 30-40% of the annual production in the preparation of records.

Cultivation of Lac in India : India has monopoly in the production of lac. It is about 75% of the world’s total output. Approximately 40 lakh ponds of lac is produced. Bihar M.P. and west Bengal are major lac producing states in India. Thailand is major competitor of India as it shares 25% of the total exports. India exports about 1,80,400 kg. of lac The use of lac is being gradually replaced by plastic.

Poultry

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 raise, can be acclimatised to a wide range of climatic conditions, have short life span and are prolific breeders and thus poultry farming is advantageous over livestock rearing. Hens have an average yield of 60 eggs per year, but high yielding varieties can produce more than 240 eggs in a year.

Poultry contributes about Rs. 7,500 crores to the gross national product (GNP) of India. India ranks fifth in the world’s egg production. Egg is one such food commodity which cannot be adulterated. The average per capita consumption is about 32 eggs and 600 grams of poultry meat a year. At present poultry is estimated to provide employment to about seven lakh families.

Raising of poultry

(1) Fowl house : Fowls can be reared in the hills of India without houses, but in the plains, well- ventilated and illuminated, dry houses are essential. A house of 1.8 x 1.5 x 1.5 m has sufficient accommodation for six fowls. An open shed or verandah must be attached to this house as run to the fowls for exercise. The fowl house may be either of wood or brick and the roof is made up of corrugated iron sheets, thatch or wood. The house and shed should be cleaned daily. Fowls of different ages are kept in separate houses. In regions with moderate climate, they are kept in cages (coops).

(2) Feed : The quality and balanced quantity of food material are the back-bones of poultry. The feed given to poultry birds should contain all the essential nutrients like carbohydrates, fats, proteins, minerals and vitamins. The feed usually consists of mashed cereals like bajra, wheat, maize, jowar, ragi, rice bran and oil cakes. The fish meal’ prepared from the wastes of fish processing industry and meat meal’ prepared from the wastes of meat processing industry is also used to feed poultry birds.

(3) Breeds of fowls : The whole poultry industry is centred round the fowls so the selection of good breed of birds for particular area is essential. The selection of fowl breed should be based on the object with which fowls are kept. Some important indigenous breeds of domestic fowl (desi hens) include Aseel, karaknath, Basara, Chittagong, Ghagus, Brahma and Cochin. Desi hens are hardy (strong) and possess natural immunity against common diseases, but they are small, slow growing, and lay small- sized and less number of eggs. The average egg production of a desi hen is about 60 eggs per annum, which is very poor. Keeping this fact in mind , a large number of poultry birds have been imported, breed and acclimatised to local conditions. Some of these are excellent egg layers while others are good meat producing birds. Some of the high egg-yielding exotic breeds of hens which have been successfully acclimatised in India include white Leghorn, Rhode Island Red, Black Minorca, Plymouth Rock, Light Sussex and New Hampshire. White Leghorn is one of the most popular egg breeds all over the world. The local varieties of hen (desi hens) have been cross breed with the high-yielding varieties of exotic breeds to obtain new breeds which combine the good characteristics of both the breeds. The new improved breeds (hybrid breeds) of poultry birds grow fast, take less feed, lay more bigger-sized eggs, and are more resistant to diseases. ILS – 82, B – 77 HH – 260 are some important improved, high yielding breeds developed in India by cross breeding. The ILS-82 and B – 77 breeds lay about 200 eggs, whereas HH – 260 breeds lay more than 260 eggs per annum.

(4) Diseases of poultry : The poultry keeper should always be careful against the diseases. Some important diseases of poultry birds are fowl pox, ranikhet (viral), fowl cholera, salmonellosis, diarrhoea, coryza (bacterial) and aspergillosis (fungal) However, the most common disease amongst fowls is Ranikhet disease, caused by a virus. The disease affects the fowls of all ages. Mortality is very high about 98 to 100 per cent. But, with better management, proper housing and nutrition and timely vaccination of the chicks, the disease can be controlled very effectively.

Other poultry birds : Besides domestic fowl, other birds like ducks, turkeys, etc are also raised. Ducks comprise about 6 per cent of the total poultry population in India. They are more abundant in the southern and eastern parts of India. Muscori, pekin, Aylesbury, Campbell, Indian Runner and Syhlet meta are some important breeds ducks. Narfold, British white, Broad Breasted Bronze and Beltsville small white are some important breeds of turkeys in India.

Poultry development in India : Poultry is one of the important components of the farmer’s economy as it provides additional income and job opportunities to a large number of rural population in the shortest possible time. Central poultry breeding farms at Bombay, Bhubaneswar, Hessarghatta and Chandigarh engaged in scientific poultry breeding programme developed high egg producing hybrids and fast growing broiler breeds. Central Duck Breeding Farm at Hessarghatta is catering to requirements of high egg producing khaki campbell breeding stock duckling. The poultry industry has grown rapidly in India in the last twenty years from a backyard farming activity to a modern and highly scientific industry. As a result of government’s efforts, during the seventh plan period, egg and broiler production registered a compound growth rate of 7.3 percent and 18 per cent respectively. The egg production is estimated to be about 26.1 billion in 1994-95.

Fisheries

Fishes are a valuable and easily accessible source of food, rich in protein, highly nutritious and easily digestible. By the aquatic animals, they are abundantly available from sea, rivers, lakes, ponds and marshes.

Aquaculture is the production of useful aquatic plants and animals such as fishes, prawns, shrimps, lobsters, crabs, molluscs by the proper utilization of small and large bodies of water. Pisciculture is the production and breeding of fishes by man in ponds.

India has abundant marine and inland fish resources. It has a cost line extending to 4667 Km long and a continental shelf of 2,59,00 square Km offering good scope for fish production. The fish production has increased many folds since India got independence. During 1990-91 the annual fish production of our country has been 38.22 lakh tons. The per capita consumption of fish in India is estimated at 1.51 Kg/year. India is at present the 6^th foremost seafood producing nations in the world.

History : From pre-historic period, fishes have used as protein rich diet for human beings. The popularity of fishes has been mentioned in our religious books like Ramayana and Mahabharata also.

In west Bengal, Bihar and orissa, the fish industry is about 1,500 years old. In Bengal every family traditionally has atleast one pond for fishes.

Table : 10.3-8 Cultivable fish species

S.No.	Zoological name	Common Name	Areas of availability
	Fresh water fishes
1.	Catla catla	Catla	All over India common in Krishna and Godavari rivers
2.	Labeo rohita	Rohu	North, East and South India
3.	Labeo calbasu	Calbasu	North and South India
4.	Cirhinus mrigala	Mrigal	North and South India
5.	Mystus singhala	Singhara	All over India
6.	Heteropneustes fossilaris	Singhi	All over India
7.	Wallago attu	Malli	North, east and South India
8.	Clarius batrachus	Fresh water shark magur	All over India
	Brackish water fishes
1.	Chanos chanos	Milk fish	A.P.coast
2.	Mugil cephalus	Grey mullet	East coast
3.	Laters calcorifer	Perch	East coast
4.	Marine fishes
(i)	Sardinella longiceps	Oil sardine	West and south coasts
(ii)	Harpodon heherius	Bombay duck	Maharastra coast
(iii)	Hilsa ilisha	Hilsa/ Indian shed	Coastal India
(iv)	Stromateus sinensis	Pomfret	Indo pacific coast
(v)	Anguilla anguilla	Eel	Coastal India
(vi)	Aluitheronema	Salmon	East and west coast
(vii)	Cyano-glossus semifas- ciatus	Flat fish	East coast of India

Culture method : The success in fish culture and the high production of table – size fish through carp culture depends largely on the designing and construction of ponds. The basic principles involved in designing and construction of carp culture ponds are of very specialized nature and vary form region to region depending upon several factors like topography, soil types, water supply etc. The requirements with regard to the designing and construction of fish farm are entirely different from those attributed to agriculture and animal husbandry farms.

Types of Ponds Ponds for carp culture may be broadly classified into three types : (1) the nursery ponds, (2) the rearing ponds and (3) the stocking ponds. The ponds which are small and shallow are used for raising fry from spawn (4-5 mm to 25-30 mm) may be termed as Nursery ponds or Nurseries. Ponds used for rearing fry upto fingerling stage (50 mm and above) are known as Rearing ponds. The rearing ponds are slightly larger but not proportionately deep and are used for rearing fry upto fingerling (50 mm & above) stage. While ponds which are used for stocking fry/fingerlings to obtain table-size fish may be called as stocking ponds. The stocking ponds are still larger and deeper (0.2 to 2.0 ha in size and 2 m to 2.5 m in depth).

Species Composition and Species Densities : Rearing of dietetically compatible species is one of the fundamental principles in fish culture. The divergent feeding habits of the Indian major carps and of the exotic Chinese carps are therefore taken advantage of in mixed culture. This divergence of feeding habits develop, as stated earlier, from advance fry stage and yet limited over- lapping in feeding habits is but to be expected. In view of this, trials were made with two, three. Four and six species compositions, within which variation in species densities or ratios were also attempted. Some of the combinations tried were as follows :

Silver carp + Grass carp :: 1:1

Catla + Rohu + mrigal :: 2:4:4

Silver carp + grass carp

+ common carp :: 4:3:3

Catla + Rohu + Mrigal

+ common carp :: 3:4:1:2

Catla + Rohu + mrigal

+ Grass carp :: 8:3:1:4

Silver Carp + grass carp + common

Carp + Rohu :: 2.4:1.2:2:2.4

Catla + Rohu + Mrigal + Silver

Carp + Common Carp :: 2.4:4.8:1.0:2.4:2.4

Types of Breeding

(1) Natural Breeding Habits : Major carps are essentially river fishes. They normally do not breed in confined waters Major carps breed in rivers throughout monsoon month’s i.e. June to August. Major carps exhibit local migration in monsoon months. After travelling some distance against current in flowing waters, they enter shallow marginal inundated waters, where they breed. These fishes do not exhibit any parental care. Ova are small, numerous and fertilization is external. Females lay eggs and the males sprinkle its milt over the eggs which are fertilized by inter-mixing of water, Milt or seminal fluid milky white non-sticky and non-granular. Milt consists of innumerable microscopic structures called spermatozoa. These spermatozoa have small head. During the period of their existance, they are extremely active inhabiting a constant jerking motion.

There is sexual dimorphism in major carps. Females are generally larger than males Following factors are important which influence spawning of major carps.

Optimum temperature seem to be essential for breeding but major carp have known to breed over a wide range of temperature between 4⁰C – 40⁰ C. Some have suggested that excessive dissolved oxygen is essential but carps have bred in water where the dissolved oxygen was actually reduced due to mixture of pollutants after the floods. pH from 7.5 to 8.3 are recorded to be suitable for spawning. Turbidity do not seem to be essential for breeding of major carps. Fish spawning induced by lightening and thunder is also doubtful. Cloudy day, however, seemed favourable for breeding of carps. Endocrine and sex stimulating hormone of pituitary gland and series of subsequent physiological changes are important for spawning

(2) Bundh Breeding of Indian Major Carps : Indian major carps i.e. catla catla, Labeo rohita and Cirhinus mrigala do not naturally breed in confined waters though they attain sexual maturity in these environments. Their natural breeding takes place in rivers, certain reservoirs and in artificially constructed bundh type tanks where. Favourable conditions stimulate than for spawning Bundhs breeding contribute a lot to induce breeding of major carp fish.

The bundhs are of two types viz., Wet bundh and dry bundh.

(i) Dry Bundh : A dry bundh is a shallow depression enclosed by earthen walls, (locally known as bundh) on three sides and an extensive catchment area on the fourth. Bundhs get flooded during the south-west monsoon, but remain completely dry for a considerable period during the remaining part of the year.

The topography of the land has a great role to play in the location and distribution of the dry bundhs. In bankura district of west Bengal, most of the dry bundhs, are fed with water from storage tanks, constructed in the upland area.

(ii) Wet Bundh : The wet bundh is a perennial pond located on the slope of a vast catchment area of undulating terrain, with proper embankments having an inlet facing towards the upland and an outlet towards the opposite lower ends. During summer, the deeper portion of the pond retains water containing breeders. The remaining portion is dry and is used for agriculture.

(3) Induced breeding : One of the dependable source of quality seed supply is by inducing major carps to breed in ponds by the use of pituitary hormone injections. Pituitary extract for inducing fish to breed is used extensively in many countries. Use of fish pituitary extracts for stimulating spawning of Indian Major carp is met with considerable success in recent years. The cost of seed production by induced breeding is very low as compared to the collection made from natural resources.

Hormone Injection : Major carps do not breed in ponds due to the fact that the environmental factors which are responsible for spawning in natural habitats are absent in confined waters. Sex stimulating hormones of the pituitary gland play an important role in the maturation of gonads and spawning in fishes.

The pituitary extract can be kept effectively and utilized successfully in inducing spawing of major carps through injection.

The method of injection of pituitary extract are following types.

(1) Intramuscular (2) Intra paritonial (3) Intracranial

Economic importance of fishes

(1) Oils : Fish oils are employed in leather industry for chamoising.

Fish body oils are also employed in the manufacture of candles, lubricants, cutting oils etc. Liver oil is a valuable source of vitamin A and Liver oils are of medicinal use.

(2) Fish protein : It is used for edible and industrial purposes.

(3) Fish Meal : It is prepared from the wastes of fish oil or canning industry or from the whole fish of non-oil type. Wastes of cod industry are known as “White fish meal”. The chemical composition of fish meal is.

(i) Proteins = 55 to 70 %

(ii) Minerals = 10 to 20 %

(iii) Moisture = 6 to 12 %

(iv) Calcium = 5.36 %

(v) Phospholipids = 3.42 %

(vi) Iodine = Traces

(vii) Vitamines = A, D and K

Fish meal is also used as major food of domestic animals like pigs, poultry, cattle, etc. It contains easily digestible proteins, calcium and phosphorus.

(4) Fish glue : It is a product mainly of tail regions of fishes such as cod, Haddock, pollack, Hake etc.

(5) Ising glass :It is a high grade collagen produced from the air bladder or swim bladder of certain fish viz., cat fishes and carps. The air bladder or swim bladder is firstly washed to remove the blood and other extra matter and then outer layer is scrapped off. The scrapped bladder is used for the preparation of purse, honey comb, book and ribbon.

(6) Fish fins : The fins of large sized sharks are used for the preparation of soups and further washed into sea water, dusted with wood ashes and lime and finally sun dried to get the cured shining product.

(7) Fish flour : It is highly nutritive food human beings, and prepared commercially by solvent extraction process. It is easily digested by the infants of 3 to 4 months also and is eaten in the form of biscuits, bread cakes, sweets and soup. It has particular odour so it has to be treated chemically to remove the bad smell.

(8) Fish fertilizer : The wastes obtained during the preparation of fish meal is widely used as manure for coffee, tea and tobacco plantation.

Pearl Culture

History of Pearl Industry : For the first time the idea of pearl industry was evoked in Japan which was carried out in the Bay of Japan located at South coast of Hansoo. But in Japan, pearl culturists feel difficulty due to unfavourable climatic conditions. Kokichi Mikimoto (1858-1954) is referred to be the father of pearl industry. Pearl is a concretion formed by molluscs. It consists of nacre or mother of pearl. It is characterised by iridescence and translucence.

Pearls is produced by the marine molluscs such as pearl oyster and mussel.

Types of pearls : Pearls are of seven types. They are the following –

(1) Lingha pearl : This is the best quality pearl obtained from marine oysters.

(2) Seed pearls : The small pearls are called seed pearls.

(3) Baroque pearls : These are spherical pearls formed inside the body.

(4) Blister pearls : These are pearls attached to the shell. They are half-spherical in shape.

(5) Oriental pearls : These are true pearls with a great lustre, beauty and a smooth surface.

(6) Natural pearls : These are the pearls obtained from pearl oysters of deep oceans.

(7) Cultured pearls : These are the pearls obtained from cultivated species of pearl oysters.

Composition of pearl : Pearl comprises of water, organic matter, calcium carbonate and the residue.

(1) Water 2 – 4 %

(2) Organic matter 3.5 – 5.9 %

(3) Calcium carbonate 90 %

(4) Residue 0.1 – 0.8 %

The pearl is formed of nacre. The nacre is formed of two substances namely a calcium carbonate which is in the form of argonite or calcite and an albuminoid substance called conchiolin/colchitin

Pearl-producing animals : Pearls are produced by bivalve molluscs. There are marine as well as fresh water animals.

(1) Pinctada vulgaris

(2) Pinctada fucata

(3) Pinctada chemnitzi

(4) Pinctada margaritifera

(5) Pinctada anomioides

(6) Pinctada atropurputea

(7) Haliotis

(8) Mytilus

(9) Placuna blacenta

(10) Placuna maxima

(11) Unio margaritifera

Cultivable species : Pearls are intensively produced by cultivating pearl oysters. The most important molluscs cultivated for pearls are Pinctada vulgaris.

Biology of pearl oysters : Pearl oysters are sedentary animals. They are attached to rocks. They have two valves. One valve is cemented to the rocks and the other free. They spawn twice in a year. The eggs are hatched into free swimming larvae. The larvae sink to the bottom of the water and develop into young oysters called spats. They grow to their maximum size in four or five years.

Pearl formation : The pearl oysters produce pearl as an adaptation against outside materials. When a foreign material such as a sand, grain or a parasite happens to enter the body it adheres with the mantle. The mantle epithelium at once grows over the material in the form of a sac and encloses it. This mantle epithelium starts secreting concentric layers of nacre around the foreign material. The completed structure is called pearl.

Culture of pearls : The culture of pearls is a complex but sensitive process. It involves the following steps.

(1) Collection of oysters : Oysters for pearl culture are obtained by three methods. They are as follows :

(i) Pearl oysters are collected from the bottom of the sea.

(ii) Spats (young oysters) are collected by placing cages in spat-falling areas of the sea.

(iii) In the laboratory eggs of pearl oysters are fertilized and young once are obtained.

(2) Preparation of graft tissue : The piece of tissue which is inserted into the oyster is called graft tissue It is cut off from the mantle of another oyster. The graft must be in the form of a square of 2 ´ 2 mm in size.

(3) Preparation of nucleus : The nucleus is a foreign material which is inserted into the oyster. It is in the form of 2 mm in diameter. It is prepared from the shell of molluscs

(4) Implantation : The oyster is placed on a table. The foot is exposed. A small incision is made on the foot. On this incision the graft tissue is placed. The nucleus is placed on the tissue. Then the oyster is released in cages. The entire operation should be completed in 30 minutes.

(5) Rearing of oysters : The operated oyster are placed in cages and the cages are suspended from rafts in the sea. This type of culturing oysters is called raft culture.

(6) Harvesting : Pearls attain their maximum in three years. After three years, the oysters are removed from cages and the pearl is taken out. Chemically pearl is made up of CaCO₃ and conchiolin.

Quality of pearl : The pearls obtained are of variable shaped and sizes. They may be white, or cream red or pink red in colour. The spherical pearls of rainbow colour are rarely found. The best quality of pearl is known as ‘lingha pearls’ and obtained from marine oysters.