Strategies for Enhancement in Food Production Biology Notes - Animal Husbandry, Plant Breeding, Biofortification, SCP and Tissue Culture

I. Animal Husbandry

• It is the scientific agricultural practice of breeding and raising livestock.
• It deals with the care and breeding of livestock (buffaloes, cows, pigs, horses, cattle, sheep, camels, goats, etc.), poultry farming, and fisheries.
• More than 70% of the world livestock population is in India and China. However, their contribution to world farm produce is only 25%, indicating low productivity per unit. New technologies should be applied to improve quality and productivity.

Management of Farms & Farm Animals

1. Dairy Farm Management (Dairying)

• It is the management of animals for increasing yield and quality of milk and its products.
• Milk yield depends on the quality of breeds in the farm.
• It is important to select good breeds having high yielding potential and resistance to diseases.
• Ways for the yield potential:
  • Look after the cattle (housing well, give adequate water, and maintain disease-free).
  • Feeding of cattle in a scientific manner – emphasis on the quality and quantity of fodder.
  • Stringent cleanliness and hygiene of cattle and handlers while milking, storage, and transport of the milk.
• Nowadays, these processes have been mechanized, reducing the chance of direct contact of the produce with the handler.
• To ensure these stringent measures:
  • Regular inspections to identify and rectify problems.
  • Regular visits by a veterinary doctor.

2. Poultry Farm Management

• Poultry is the domesticated birds used for food or eggs (e.g., chicken, ducks, turkey, and geese).
• Components of poultry farm management:
  • Selection of disease-free and suitable breeds.
  • Proper and safe farm conditions.
  • Proper feed and water.
  • Hygiene and health care.

Animal Breeding

• A breed is a group of organisms related by descent and similar in general appearance, features, size, etc.
• Breeding is the modification of an organism’s genotype to make it more useful to humans (e.g., Jersey (improved cattle breed), Leghorn (improved chicken breed)).
• Animal breeding aims at increasing the yield of animals and improving the desirable qualities of the produce.
• Breeding is of two types: Inbreeding and Out-breeding.

a. Inbreeding

It is the mating of more closely related individuals within the same breed for 4-6 generations. The strategy is as follows:

• Identify and mate superior males and females of the same breed.
• Evaluate the progeny obtained and identify superior males and females among them for further mating.
• In cattle, a superior female produces more milk per lactation. A superior male (bull) gives rise to superior progeny.

Advantages of Inbreeding

• It increases homozygosity to evolve a pure line animal.
• It exposes harmful recessive genes that are eliminated by selection.
• It helps in the accumulation of superior genes and elimination of less desirable genes, increasing the productivity of the inbred population.

Continued inbreeding, especially close inbreeding, may reduce fertility and productivity, known as inbreeding depression. To solve this, selected animals should be mated with unrelated superior animals of the same breed.

b. Out-breeding

It is the breeding of unrelated animals, including out-crossing, cross-breeding, and interspecific hybridization.

i) Out-crossing

• It is the mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4-6 generations.
• The offspring of such a mating is known as an out-cross.
• It is the best method for animals with low milk productivity or growth rate in beef cattle.
• It helps to overcome inbreeding depression.

ii) Cross-breeding

• It is the mating of superior males of one breed with superior females of another breed.
• The desirable qualities of two different breeds are combined.
• The progeny hybrid animals may be used for commercial production or subjected to inbreeding and selection to develop new stable superior breeds.
• Example: Hisardale (sheep) developed in Punjab by crossing Bikaneri ewes and Merino rams.

iii) Interspecific Hybridization

• It is the mating of males and females of two different species.
• In some cases, the progeny may combine desirable features of both parents and may be of considerable economic value (e.g., Mule from male ass × female horse).

Controlled Breeding Experiments

1. Artificial Insemination

• The semen collected from a male parent is injected into the reproductive tract of a selected female by the breeder.
• Semen is used immediately or frozen and used later. Frozen semen can also be transported.
• The success rate of crossing mature males and females is low, even with artificial insemination.

2. Multiple Ovulation Embryo Transfer Technology (MOET)

• It is a programme for herd improvement, improving the chances of successful hybrid production.
• A cow is administered hormones such as FSH to induce follicular maturation and super ovulation (production of 6-8 eggs per cycle instead of one).
• The animal is either mated with an elite bull or artificially inseminated. Fertilized eggs at the 8–32 cell stage are recovered non-surgically and transferred to surrogate mothers.
• MOET has been demonstrated for cattle, sheep, rabbits, buffaloes, mares, etc.
• High milk-yielding breeds of females and high-quality (lean meat with less lipid) meat-yielding bulls have been bred successfully to increase herd size in a short time.

Bee-keeping (Apiculture)

• It is the maintenance of hives of honeybees to produce honey and beeswax.
• The most common species that can be reared is Apis indica.
• Honey is a food of high nutritive and medicinal value.
• Beeswax is used in the preparation of cosmetics, polishes, etc.
• Apiculture can be practiced in areas with bee pastures of wild shrubs, fruit orchards, and cultivated crops.
• Important points for successful bee-keeping:
  • Knowledge of the nature and habits of bees.
  • Selection of a suitable location for keeping beehives.
  • Catching and hiving of swarms (groups of bees).
  • Management of beehives during different seasons.
  • Handling and collection of honey and beeswax.
• Bees are pollinators of crop species such as sunflower, Brassica, apple, and pear.
• Keeping beehives in crop fields during the flowering period increases pollination, improving crop and honey yield.

Fisheries

• Fishery is an industry of catching, processing, or selling fish, shellfish, or other aquatic animals (prawns, crabs, lobsters, edible oysters, etc.).
• Fish Types:
  • Freshwater fishes: Catla, Rohu, common carp, etc.
  • Marine fishes: Hilsa, sardines, mackerel, pomfrets, etc.
• Fisheries provide income and employment to millions of fishermen and farmers.
• Aquaculture (farming of aquatic organisms) and pisciculture (farming of fishes) are techniques to increase the production of aquatic plants and animals.
• Blue Revolution: The development and flourishing of the fishery industry.

Plant Breeding

Plant breeding is the manipulation of plant species to create desired plant types suitable for better cultivation, higher yields, and disease resistance.

• Green Revolution: The development and flourishing of agriculture, heavily dependent on plant breeding.
• Classical Plant Breeding: Involves hybridization of pure lines and artificial selection to produce desirable traits.
• Modern plant breeding uses molecular genetic tools.

Desirable Traits for Plant Breeding

• Increased crop yield and quality.
• Increased tolerance to environmental stresses (salinity, extreme temperatures, drought).
• Increased resistance to insect pests and pathogens.

Steps of Plant Breeding

1. Collection of Genetic Variability

• In wild relatives of many crops, pre-existing genetic variability is available.
• Collection and preservation of wild varieties, species, and relatives of cultivated species is a prerequisite for effective exploitation of natural genes.
• The entire collection of plants/seeds having all the alleles for all genes in a given crop is called germplasm collection.

2. Evaluation and Selection of Parents

• The germplasm is evaluated to identify plants with desirable characters.
• Selected plants are multiplied and used for hybridization.
• Pure lines are created wherever desirable and possible.

3. Cross Hybridization of Selected Parents

• Desired characters are genetically combined from two different parents to produce hybrid plants.
• Example: High protein quality of one parent is combined with disease resistance from another parent.
• Limitations:
  • Very time-consuming and tedious process.
  • Hybrids may not combine the desirable characters; usually only hundreds to a thousand crosses show the desired combination.

4. Selection and Testing of Superior Recombinants

• Crucial to the success of the breeding objective, requiring careful scientific evaluation of the progeny.
• Yields plants that are superior to both parents.
• These are self-pollinated for several generations until they reach a state of uniformity (homozygosity) so that the characters will not segregate in the progeny.

5. Testing, Release, and Commercialization

• Newly selected lines are evaluated for yield and other agronomic traits of quality, disease resistance, etc.
• Tested in research fields under ideal fertilizer application, irrigation, and crop management practices.
• Evaluated in farmers’ fields for at least three growing seasons across multiple agro-climatic zones, compared to the best available local crop cultivar.

Crop Improvement Examples

Wheat and Rice

• In India, food production increased through high-yielding varieties of wheat and rice in the mid-1960s (Green Revolution).
• Wheat production increased from 11 million tons (1960) to 75 million tons (2000).
• Rice production increased from 35 million tons to 89.5 million tons.
• Nobel laureate Norman E. Borlaug (International Centre for Wheat & Maize Improvement, Mexico) developed semi-dwarf wheat.
• In 1963, high-yielding and disease-resistant wheat varieties like Sonalika and Kalyan Sona were introduced in India.
• Semi-dwarf rice varieties were derived from IR-8 (International Rice Research Institute, Philippines) and Taichung Native-1 (Taiwan). Later, better-yielding varieties Jaya and Ratna were developed in India.

Sugarcane

• Saccharum barberi (grown in North India, poor sugar content and yield) was crossed with Saccharum officinarum (tropical canes in South India, thicker stems, higher sugar content but poor growth in North India).
• Resulted in a hybrid sugarcane with high yield, thick stems, high sugar, and ability to grow in North India.

Millets

• Hybrid maize, jowar, and bajra developed in India, including high-yielding varieties resistant to water stress.

Plant Breeding for Disease Resistance

• Plant diseases cause crop losses up to 20-30% or even total.
• Disease-resistant cultivars enhance food production and reduce the use of fungicides and bactericides.
• Resistance is the genetic ability to prevent pathogens from causing disease.

Types of Plant Diseases

• Fungal: Rusts (e.g., brown rust of wheat, red rot of sugarcane, late blight of potato).
• Bacterial: Black rot of crucifers.
• Viral: Tobacco mosaic, turnip mosaic.

Methods of Breeding for Disease Resistance

1. Conventional Breeding

The steps include:

1. Screening germplasm for resistance sources.
2. Hybridization of selected parents.
3. Selection and evaluation of the hybrids.
4. Testing and release of new varieties.

Examples of Crop Varieties Bred by Conventional Method

• Conventional breeding is constrained by the limited availability of disease resistance genes.
• Inducing mutations and screening for resistance help identify desirable genes, which can be multiplied directly or used in breeding.
• Other methods include selection amongst somaclonal variants and genetic engineering.

2. Mutation Breeding

• Mutation (sudden genetic change) can create new desirable characters not found in the parental type.
• Mutation breeding uses chemicals or radiation (e.g., gamma rays) to produce plants with desirable characters, which are selected and multiplied or used in breeding.
• Example: In mung bean, resistance to yellow mosaic virus and powdery mildew was induced by mutations.
• Resistant genes from wild species introduced into high-yielding varieties (e.g., resistance to yellow mosaic virus in Abelmoschus esculentus resulted in Parbhani Kranti).
• Resistance genes can be transferred by sexual hybridization between the target and source plant.

Plant Breeding for Developing Resistance to Insect Pests

• Morphological, biochemical, or physiological characteristics provide insect resistance in host crop plants, e.g.:
  • Hairy leaves: Resistance to jassids in cotton and cereal leaf beetle in wheat.
  • Solid stems in wheat: Non-preference by the stem sawfly.
  • Smooth-leaved and nectar-less cotton varieties: Do not attract bollworms.
  • High aspartic acid, low nitrogen, and sugar content in maize: Resistance to maize stem borers.
• Sources of resistance genes include cultivated varieties, germplasm collections, or wild relatives.

Examples of Crop Varieties Bred for Insect Pest Resistance

Plant Breeding for Improved Food Quality

• Over 840 million people lack adequate food, and 3 billion suffer from micronutrient, protein, and vitamin deficiencies (hidden hunger).
• Biofortification: Breeding crops with higher nutrient levels to improve public health.

Objectives of Breeding for Improved Nutritional Quality

• Improve protein content and quality.
• Improve oil content and quality.
• Improve vitamin content.
• Improve micronutrient and mineral content.

Examples of Hybrids with Improved Nutritional Quality

• Maize hybrids: Twice the amount of amino acids (lysine and tryptophan) compared to existing hybrids.
• Wheat: Variety Atlas 66 with high protein content.
• Iron-fortified rice: Contains over five times as much iron as common varieties.
• Vitamin and mineral-rich vegetables (released by Indian Agricultural Research Institute, New Delhi):
  • Vitamin A-enriched carrots, spinach, pumpkin.
  • Vitamin C-enriched bitter gourd, bathua, mustard, tomato.
  • Iron and calcium-enriched spinach, bathua.
  • Protein-enriched beans (broad, lablab, French, garden peas).

Single Cell Protein (SCP)

• It is the protein derived from single-celled organisms.
• It is an alternate source of proteins for animal and human nutrition. Examples: Spirulina (a blue-green alga), Methylophilus methylotrophus (a bacterium).
• Spirulina is rich in protein, minerals, fats, carbohydrates, and vitamins. It is grown on materials like wastewater from potato processing plants, straw, molasses, animal manure, and sewage, which also reduces environmental pollution.
• A 250 kg cow produces only 200 g of protein per day, whereas 250 g of Methylophilus methylotrophus produces 25 tonnes of protein due to its high rate of biomass production and growth.

Tissue Culture

• A technique of growing plant cells, tissues, or organs in a sterile culture medium under controlled aseptic conditions.
• The ability to generate a whole plant from any cell or explant is called totipotency. An explant is any part of a plant grown in a test tube under sterile nutrient media.
• The nutrient medium must provide a carbon source (e.g., sucrose), inorganic salts, vitamins, amino acids, and growth regulators like auxins and cytokinins.
• The method of producing thousands of plants in a short time through tissue culture is called micropropagation.
• These plants are genetically identical to the original plant, i.e., they are somaclones.
• Examples include tomato, banana, and apple.
• Tissue culture is used to recover healthy plants from diseased plants. The meristem (virus-free) from an infected plant is removed and grown in vitro to obtain virus-free plants. Examples include meristems of banana, sugarcane, and potato.
• Somatic hybridization: The fusion of protoplasts from two different plant varieties with desirable characteristics to produce hybrid protoplasts, which can be grown into a new plant called somatic hybrids. Protoplasts are isolated after digesting the cell walls of plant cells.

Example: Protoplast of tomato + protoplast of potato → pomato. This hybrid plant has characteristics of both tomato and potato but lacks all desired characteristics for commercial utilization.