Strategies for Enhancement in Food ProductionNEET Zoology · Class 12 · NCERT Chapter 9

Introduction

The human population keeps growing. More people means more food is needed. The traditional ways of farming cannot keep up on their own, so scientists and breeders have developed new strategies to produce more food from the same land and water.

Two major revolutions changed food production in the twentieth century. The Green Revolution (1960s) used high-yielding semi-dwarf wheat and rice varieties to multiply grain output. The Blue Revolution focused on fish and aquatic production. This chapter covers the biology behind both, plus newer techniques like tissue culture and single cell protein.

You can expect 1 NEET question from this chapter. The most tested areas are: MOET, the Hisardale breed, Apis indica, the steps of plant breeding, Atlas 66 wheat, lysine-rich maize, Spirulina, and tissue culture terms (totipotency, callus, somaclone).

Animal Husbandry

Animal husbandry is the science and practice of managing farm animals: feeding them, housing them, breeding them and controlling disease. It includes dairy animals, poultry, bees, fish and more.

About 70 percent of the world's livestock is found in India and China. India has a large population of cattle, buffalo, goats, sheep and poultry. Milk, eggs, meat, wool and honey are major products.

Management of Farms and Farm Animals

Dairy Farm Management

Dairy farming produces milk and milk products. The key management practices are:

• Selection of good breeds: choose breeds with high milk yield and resistance to local diseases (e.g. Sahiwal cow for India).
• Proper feeding: balanced diet of roughage and concentrates. Nutrition directly affects milk quality and yield.
• Hygiene and cleanliness: clean sheds, clean udders before milking, clean milking equipment. This prevents bacterial contamination of milk.
• Regular veterinary care: routine health checks, vaccinations and quick treatment of any disease. A vet visit schedule keeps the herd healthy.

Poultry Farm Management

Poultry farming produces eggs and meat. Poultry birds include chicken, ducks, turkey and geese. The most important birds commercially are chickens, particularly egg-laying breeds (layers) and meat breeds (broilers).

• Disease-free and hygienic conditions:poultry diseases (e.g. Ranikhet disease, fowl pox, Marek's disease) spread rapidly in crowded conditions. Regular vaccination and clean housing are essential.
• Controlled environment: temperature, light cycles and ventilation are managed to maximise egg production and meat quality.
• Breeding objectives: select for high egg production per year, good feed conversion ratio (weight gained per kg of feed eaten) and disease resistance.

Animal Breeding

The goal of animal breeding is to increase the yield of useful products (milk, meat, eggs, wool) and to improve the overall quality of the breed. Two broad strategies are used: inbreeding and outbreeding.

Inbreeding

Inbreeding is mating of closely related animals within the same breed for 4 to 6 generations. It requires identifying superior males and superior females in the population, then mating them together.

• Advantage: exposes harmful recessive genes, allowing breeders to eliminate them from the herd. Produces a homozygous (pure-breeding) line that passes its traits reliably to offspring.
• Disadvantage: prolonged inbreeding causes inbreeding depression: reduced fertility, low immunity and declining productivity. The fix is outbreeding.

Outbreeding

Outbreeding is mating between unrelated animals. There are three types:

• Out-crossing: mating animals of the same breed but with no common ancestors for at least 4 to 6 generations. Best for overcoming inbreeding depression.
• Cross-breeding: mating superior males of one breed with superior females of another breed. Combines the good traits of both breeds. Classic NEET example: Hisardale sheep, developed in Punjab by crossing Bikaneri ewes (female) with Marino rams (male). The result has the hardiness of Bikaneri plus the fine wool quality of Marino.
• Interspecific hybridisation: mating animals from two different species. The classic example is the mule (male donkey x female horse). The mule is strong and has a long working life but is almost always sterile.

Artificial Insemination

In artificial insemination, semen is collected from a superior bull, stored (sometimes frozen), and used to inseminate many females. Benefits:

• One bull can sire thousands of calves per year instead of a few dozen.
• Semen can be transported across long distances or used after the bull dies.
• Reduces transmission of sexually transmitted diseases between animals.

MOET (Multiple Ovulation Embryo Transfer)

MOET multiplies the genetic contribution of a superior female:

1. A superior cow is given gonadotropins (FSH) to cause super-ovulation: typically 6 to 8 eggs released instead of 1.
2. She is mated naturally or by artificial insemination with a superior bull.
3. The fertilised embryos (at 8 to 32 cell stage) are flushed out non-surgically from the uterus.
4. Each embryo is transferred into a surrogate mother to complete development.

Result: one elite female produces many offspring per year. MOET is used in cattle, sheep, horses and many other livestock species.

Apiculture (Bee-Keeping)

Apiculture is the maintenance of hives of honeybees for the commercial production of honey and beeswax. The Indian honeybee Apis indica is the most common species used by Indian beekeepers. (The Italian bee Apis mellifera is also used because it is gentler and produces more honey.)

• Honey is a high-value food product; beeswax is used in cosmetics, polish and pharmaceuticals.
• Pollination benefit: bees are the most important pollinators of many food crops (fruit trees, oilseeds, vegetables). Keeping hives near orchards and fields increases crop yield significantly.
• The pasturage (area where bees collect nectar) determines the quantity and quality of honey. Bees should be kept near flowering plants.

Fisheries

A fishery is an industry that deals with catching, processing and selling of fish and other aquatic animals. Fisheries are important for food security and employment.

• Inland fisheries: freshwater fish from rivers, ponds, lakes and canals. Common cultured species: Catla, Rohu, Mrigal, Common carp.
• Marine fisheries: sea fish caught from the ocean. Common species: Hilsa, Sardines, Mackerel, Pomfret.
• Aquaculture: farming aquatic organisms (fish, prawns, oysters, seaweeds) in controlled conditions.
• Pisciculture: farming specifically of fish. India has one of the largest freshwater aquaculture programmes in the world.

Plant Breeding

Plant breeding is the science of changing the traits of plants to produce new varieties with desired features: higher yield, better quality, resistance to disease, pests or drought, and so on.

Classical plant breeding depends on the genetic variation that already exists in the gene pool. Modern biotechnology-based approaches extend what classical breeding can do.

Classical Steps in Plant Breeding

1. Collection of variability (germplasm collection): gather as many varieties as possible from all over the world, including wild relatives of the crop. This material is stored in a gene bank (germplasm collection).
2. Evaluation and selection of parents: screen all collected material for the desired traits (yield, disease resistance, nutritional quality, etc.). Select the best plants as parents.
3. Cross hybridisation among selected parents: artificially cross-pollinate the selected parents to combine their best traits in one plant. This is where the new genetic combinations are created.
4. Selection and testing of superior recombinants: grow out the hybrids over several generations. Identify individual plants that have the desired combination of traits and perform better than both parents. Self-pollinate repeatedly to fix the traits.
5. Testing, release and commercialisation: test the new variety in multiple locations over several years. Farmers try it on their fields. If the variety performs well consistently, it is officially released as a new cultivar and seed is made available.

Plant Breeding for Disease Resistance

Diseases caused by fungi, bacteria and viruses can destroy a large fraction of a crop. Breeding for disease resistance avoids the need for expensive and environmentally harmful pesticides.

• Resistance genes are found in wild relatives of the crop or in landraces.
• NEET example: semi-dwarf high-yielding wheat varieties resistant to wheat rust (Puccinia), developed by Norman Borlaug during the Green Revolution.
• Himgiri wheat: resistant to hill bunt and leaf and stripe rust.

Plant Breeding for Pest (Insect) Resistance

Insects and pests reduce yield. Resistance can be incorporated by breeding for physical or chemical traits that deter pests:

• Morphological traits: solid stems (reduce stem borer attack), hairy leaves (reduce aphid and jassid attack), rough leaf surface.
• Chemical traits: high aspartate and low nitrogen in maize reduces fall armyworm damage; high nectar content in sorghum reduces shoot fly attack.

Biofortification

Biofortification is plant breeding that improves the nutritional quality of a crop: higher vitamins, more minerals, more protein, or better amino acid profile. The goal is to fight nutritional deficiency diseases in populations that depend on a single staple crop.

• Atlas 66 (wheat): a variety with unusually high protein content. Used as a donor parent to improve protein levels in commercial wheat.
• Maize hybrids: developed with twice the normal amount of lysine and tryptophan (both essential amino acids that normal maize is deficient in).
• Iron-rich rice, vitamin A-rich crops (e.g. Golden Rice): examples of modern biofortification using genetic engineering beyond classical breeding.

Single Cell Protein (SCP)

Single cell protein is dried biomass of microorganisms grown in large fermenters and used as a protein supplement in food or animal feed.

• Spirulina (a cyanobacterium, blue-green alga): protein content about 60 to 70% of dry weight. Can be grown on waste water from potato processing or starchy effluents. Used as a human protein supplement and animal feed.
• Methylophilus methylotrophus: a bacterium that uses methanol as its carbon and energy source. Can produce 25 tonnes of protein per acre per year. Developed commercially (Pruteen) for animal feed.
• Why SCP? It reduces the pressure on conventional protein sources (fish meal, soya), uses very little land, and can be produced from industrial waste. It also reduces pollution.

Tissue Culture and Micropropagation

Plant tissue culture uses the property of totipotency: the ability of a single plant cell to express its entire genome and grow into a complete organism.

The basic process:

1. Take a small piece of plant tissue called an explant (can be a leaf piece, stem segment, root tip, or even a single cell).
2. Place the explant on a sterile nutrient medium containing sugars, mineral salts and plant growth hormones.
3. The explant divides and forms an undifferentiated mass of cells called a callus.
4. Transfer the callus to a medium with a different hormone ratio. Shoots and roots form. Each regenerated plantlet is a somaclone (genetically identical to the parent).
5. Transfer the plantlet to soil. This rapid multiplication technique is called micropropagation.

Somatic hybridisation: Remove the cell walls from two different plant cells using cellulase and pectinase enzymes to get protoplasts (naked cells). Fuse the protoplasts electrically or chemically. Grow the fused cell on nutrient medium. The resulting hybrid plant has the combined genome of both parents. Classic NEET example: Pomato, made by fusing protoplasts of potato and tomato.

• Applications of tissue culture: production of disease-free plants (virus- free potato from meristem culture), rapid multiplication of rare or elite varieties, production of haploid plants via anther culture, conservation of endangered plant species.

Worked NEET Problems

Summary Cheat Sheet

• Green Revolution: high-yielding semi-dwarf wheat and rice varieties; Norman Borlaug; rust resistance.
• Blue Revolution: increase in fish and aquatic production.
• Animal husbandry: ~70% of world livestock in India and China.
• Dairy management: good breed, balanced feeding, cleanliness, regular vet visits.
• Poultry birds: chicken, duck, turkey, goose.
• Inbreeding: mating of closely related animals; exposes recessives; can cause inbreeding depression.
• Out-crossing: same breed, no common ancestor for 4 to 6 generations; reverses inbreeding depression.
• Cross-breeding: two different breeds of the same species. Hisardale = Bikaneri ewe x Marino ram.
• Interspecific hybridisation: two different species. Mule = male donkey x female horse (sterile).
• Artificial insemination: one superior bull sires thousands per year; semen can be frozen and transported.
• MOET: gonadotropins cause super-ovulation (6 to 8 eggs); embryos flushed and transferred to surrogates.
• Apiculture: Apis indica (Indian honeybee); products: honey + beeswax; benefit: crop pollination.
• Inland fish: Catla, Rohu, Mrigal. Marine fish: Hilsa, Sardines, Mackerel, Pomfret.
• Plant breeding steps (5): germplasm collection → parent selection → cross hybridisation → selection of superior recombinants → testing and release.
• Biofortification: Atlas 66 = high protein wheat. Maize hybrids = 2x lysine and tryptophan.
• Single cell protein: Spirulina (cyanobacterium, grown on waste water, 60 to 70% protein). Methylophilus methylotrophus (bacterium, uses methanol).
• Totipotency: ability of a single plant cell to grow into a whole plant; basis of tissue culture.
• Tissue culture sequence: explant → callus → plantlet (somaclone) = micropropagation.
• Somatic hybridisation: protoplast fusion of two different plant species. Pomato = potato + tomato protoplasts fused.

Next: use the interactive learning widgets to explore animal breeding methods, walk through the five steps of plant breeding, and compare all food production methods, or work through the 15+ NEET PYQs with full solutions. To time yourself, take the free 10-question mock test. You may also want to read our notes on the related chapter Microbes in Human Welfare, which covers how microorganisms are used in food and industry.