Animal husbandry and plant breeding are two major aspects of increasing production of food.Besides these, new techniques such as embryo transfer technology and tissue culture are also of great importance to increase food production.
Animal breeding aims at increasing the yield of animals and improving the desirable qualities of the produce. Two methods of animal breeding are: inbreeding and outbreeding, based mainly on breeding work with cattle.
1. Inbreeding: It refers to the mating of more closely related individuals within the same breed for 4-6 generations. Inbreeding increases homozygosity, so it is necessary for evolving a pure line in any animal. Continued inbreeding causes inbreeding depression.
2. Outbreeding: It is the breeding of unrelated animals which may be of following three types:
- Outcrossing: Mating between unrelated members of the same breed which have no common ancestors on either sides of their pedigree up to 4-6 generations.
- Cross breeding: Breeding superior males of one breed with superior females of another breed. It allows the desirable qualities of two different breed to be combined Ex: Hisardale is a new breed of sheep in Punjab by crossing Bikaneri ewes and Marino rams.
- Interspecific hybridisation: Mating between memebers of two different species produces interspecific hybrids.
Controlled Breeding Experiment
Controlled breeding experiments are carried out using artificial insemination and MOET. Artificial insemination involves inseminating native cows with the semen of superior bulls of exotic or indigenous breeds. Artificial insemination helps to overcome several problems of natural mating such as comparatively lesser amount of semen is required, cows at distant places can also be fertilized, etc.
MOET(Multiple Ovulation Embryo Transfer Technology)
It is an another method used in artificial breeding. In it a cow is administered hormones, with FSH like activity, to induce follicular maturation and super ovulation i.e., instead of one egg(produce normally) 6-8 eggs are produced.
The super ovulated animal is either mated with an elite bull or artificially inseminated. The fertilized eggs at 8-32 cell stage, are recovered non-surgically and transferred to surrogate mothers. The genetic mother is available for another round of super ovulation.
Dairy Farm Management
- Refers to management of animals for obtaining milk and other products for human consumption. It deals with processes and systems that increases yield and improve quality of milk. Dairy animals include cow, buffalo, goat, etc.
- The best known breeds of Indian buffaloes are the Murrah(Punjab, Haryana, U.P), Jaffar Abadi(Gujarat),etc.
- Important breeds of sheep are Deccani and Nellore breeds(for mutton), Rampur-Bushari(long coarse wool), Lohi(good quality wool, also milk), Bhakarwal(undercoat for shwals), and Nali(superior carpet wool).
- Common breeds of goats are Malabari(Kerala), Berari(Maharashtra), Marwari(Rajasthan), Beetal(Punjab).
- Exotic breeds of goats are Alpine(Alps), Toggenberg and Saanen.
Poultry Farm Management
- Poultry is rearing of domesticated fowls and pigeons, etc
- Poultry birds exclusively grown for meat are called broilers, layers are for egg production, cockerels are young male fowls and roosters are mature male fowls.
Some commonly used of fowls are as follows:
- Indigenous breeds: Chittagong, Aseel, Bursa, Danki, etc
- American breed: Plymouth, Rock, Wyandotte, Rhode Island red, new Hampshire.
- Asiatic breeds: Brahma, Langshan, Cochin.
- English Breeds: Sussex, Orpington, etc.
- Mediterranean Breeds: Leghorn, Minorca, Ancona, Spanish, etc.
Care and management of honey bees is called as Apiculture. Important species of honey bees are Apis dorsata(rock bee), Apis indica(Indian bee), Apis florea(Little bee), and Apis mellifera(European bee). All of them occur in nature as wild insects.
However, because of their high economic importance, the honey bees, especially A.mellifera is domesticated and cultured.
Sericulture is the breeding and management of silk worms for the production of silk at commercial level. Perbine caused by parasitic protozoan Nosema bombyscis, Grasserie(virus), Muscaradine(fungus), Flacharie(virus) are some disease of silk worm.
Fishery is an industry devoted to the catching , processing or selling of fish, shellfish or other aquatic animals for food. Aquaculture is rearing and management of useful aquatic plants and animals like fish, oysters, mussels, prawns, etc. Pisciculture is rearing, catching and management of fish. There are two main types of fisheries:
- Inland or fresh water fisheries: pertain to two types of waters- fresh water and brackish water. Important fresh water edible fishes of India are: Labeo rhoita(rohu), Labeo calbasu(calbusa), Catla, etc.
- Marine fisheries: deal with the fishery aspects of the sea water or ocean. Some of the important marine fishes are- Hisla(Hisla), Aluitheronema(salmon), etc.
Blue revolution: Is concerned with fish production in India.
Plant breeding is the genetic improvement of the crop in order to create desired varieties of plant types that are better suited for cultivation, give better yields and are disease resistant. Various steps required for developing new varieties are:
- Collection of germplasm: The entire collection having all diverse alleles for all genes in a given crop is called germplasm collection. A good germplasm collection is essential for a successful breeding programme.
- Evaluation and selection of parents: The germplasm is evaluated so as to identify plants with desirable combination of characters. The selected plants are multiplied and used in the process of hybridisation.
- Cross hybridisation among the selected parents: Cross hybridisation of two parents to produce hybrids that genetically combine the desired characters in one plant.
- Selection and testing of superior recombinants: This step yields progeny plants that are superior to both of the parents.
- Testing, release and commercialisation of new cultivars: The material is evaluated in comparison to the best available local crop cultivar- a check or reference cultivar.
Examples of some improved varieties:
- Wheat: Kalyan sona, Sonalika, Sharbati sonora, etc.
- Rice: Jaya and Ratna.
- Sugarcane: Saccharum barberi, Saccharum officinarum
Plant breeding for disease resistance:
A wide range of fungal, bacterial and viral pathogens, affect the yield of cultivated crop species, especially in tropical climates. In this situation, breeding and development of cultivars resistant to disease, enhance food production.
Some microbe resistant crop varieties developed by breeding:
Plant breeding for resistance to insect-pests:
Insects and pests infections are two major causes for large destruction of crop plants. Insect resistance in host crop plants may be due to morphological, biochemical or physiological characters. Plants with resistance are developed by plant breeding methods.
Some insect pest resistant crop varieties developed by breeding are:
Plant breeding for improved food quality:
Breeding of crops with high levels of vitamins and minerals or higher protein and healthier fats are called biofortification and is the most practical aspect to improve the health of the plant. Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improvement in: protein content and quality, oil content and quality, vitamins and micronutrients and mineral content. Maize hybrids that had twice the amount of the amino acids-lysine and tryptophan and wheat variety with high protein content Atlas 66 were developed. IARI(Indian Agricultural Research Institute), New Delhi, has also developed many vegetable crops that are rich in minerals and vitamins.
Single cell protein(SCP)
- One of the alternate source of proteins for animal and human nutrition is single cell protein. The cells from micro-organisms such as bacteria, yeasts, filamentous algae, etc. are treated in various ways, used as food and referred to as single cell protein.
- Microbes like Spirulina can be grown on waste water from potato processing plants(containing starch), straw, animal manure, and even sewage to produce food rich in proteins, minerals, fat, carbohydrates and vitamins.
Some common used microbes as SCP producers:
- Cyanobacteria: Spirulina
- Bacteria: Methylophillus methylotrphus
- Yeasts: Canadida utilis
- Filamentous fungi: Fusarium graminearum
Plant Tissue Culture
- Plant tissue culture is the technique of maintaining and growing plant cells, tissue or organs in vitro aseptically on artificial medium in suitable containers under controlled environmental conditions. The part which is cultured is called explant.
- Embryoids are nonzygotic or somatic embryo-like structure which are produced by in vitro culture and have the ability to form full fledged plants.
- Cellular totipotency is the ability of a somatic cell/explant to produce the complete organism. The explants are treated with specific anti-microbial chemicals to make free from microbes. Culture media containing inorganic salts, certain vitamins, sucrose and the desired growth regulators is provided, that is required for the desired growth and development of the explants.
- Hormones used in plant tissue culture are auxin, cytokinins, gibberellins, ABA, polyamines. Three conditions for in vitro culture
- Producing thousands of plants through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e. they are soma clones. Many important food plants like tomato, banana, apple, etc. have been produced on commercial scale using this method.
- Steps in micropropagation include initiation of culture from an explant on a suitable nutrient medium, shoot formation from the explant, rooting of in vitro developed shoots, hardening of plantlets and transplantation to fields.
- Depending upon the type of explant, tissue culture is called shoot tip culture, multiple shoot culture, anther/haploid culture, embryo culture, embryoid culture, etc.
Protoplast culture and Somatic hybridization
- When a hybrid is produced by fusion of somatic cells of two varieties or species, it is known as somatic hybrid and the process is called somatic hybridization.
- First, the cell wall of the plant cells are removed then the protoplasts of the two plants are brought in contact and made to fuse by means of electrofusion or chemicals like polyethylene glycol(PEG) and sodium nitrate. The fused protoplasts soon develop their own walls and then they are called somatic hybrid cells.
- Successful somatic hybrids have also been obtained from different species of Brassica, Petunia, and Solanum.
- Pomato is somatic hybrid between potato and tomato that belong to two different genera.
- Protoplasts culture has opened up avenues for development of hybrids of even asexulally reproducing plants. Somatic> hybrids may be used for the production of useful allopolyploids.
Applications of plant tissue culture
The various applications of plant tissue culture are:
- The use of plant cells to regenerate useful products i.e. , a plantlets which is used for various purposes.
- Plantlets are used for rapid clonal propagation.
- Transgenes can be introduced into individual plant cells. The plantlets can be regenerated from these cells which give rise to the highly valuable transgenic plants.
- For induction of mutations as genetic manipulations can be carried out more rapidly when plant cells are in protoplast state. New genes can be introduced(Ex: male sterility, herbicide resistance).
- For raising stress resistant plants.