Animal Husbandry

With the world population continuously increasing, enhancing food production is a major challenge. Biological principles, particularly in animal husbandry and plant breeding, play a vital role in improving food yield and quality. Newer technologies like embryo transfer and tissue culture further contribute to this enhancement.

Animal husbandry is the agricultural practice focused on breeding and raising livestock. It's a combination of scientific principles and practical skills, essential for farmers. It involves the care and breeding of animals useful to humans, such as buffaloes, cows, pigs, horses, cattle, sheep, camels, and goats.

Animal husbandry also includes poultry farming (domesticated birds for food/eggs) and fisheries (rearing, catching, processing, selling fish, shellfish, and other aquatic animals).

For centuries, humans have utilised animals for products like milk, eggs, meat, wool, silk, and honey.

Although India and China together hold over 70% of the world's livestock population, their contribution to world farm produce is only 25%, indicating low productivity per animal. Therefore, applying scientific management and newer technologies is crucial to increase productivity and quality in animal farming.

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Management Of Farms And Farm Animals

Implementing a professional approach to traditional farm management practices can significantly boost food production. This involves optimising systems for various types of animal farms.

Dairy Farm Management

Dairying focuses on managing animals to produce milk and milk products for human consumption. Animals commonly found in a dairy include cows and buffaloes, providing products like milk, cheese, yogurt, butter, etc.

Effective dairy farm management involves processes to increase milk yield and improve milk quality. Key aspects include:

• Selection of good breeds: Choosing high-yielding breeds suitable for the local climate and resistant to diseases is paramount.
• Proper care: Animals need adequate housing, sufficient water, and must be kept disease-free.
• Scientific feeding: Providing good quality and quantity of fodder is essential for maximising yield potential.
• Hygiene: Maintaining stringent cleanliness and hygiene of both the animals and the handlers is critical during milking, storage, and transport to prevent contamination. Modern practices increasingly involve mechanisation to reduce direct contact.
• Record keeping and inspection: Regular inspections and maintaining records help identify and address problems promptly.
• Veterinary care: Regular visits by a veterinary doctor are necessary for animal health management.

Poultry Farm Management

Poultry farming involves raising domesticated birds (fowl) like chickens, ducks, turkeys, and geese for food (meat) and eggs.

Important components of poultry farm management mirror those in dairy farming:

• Selection of disease-free and suitable breeds: Choosing birds with desirable traits for egg laying or meat production.
• Proper and safe farm conditions: Providing adequate space, ventilation, and protection from environmental stress and predators.
• Proper feed and water: Ensuring a balanced diet formulated for the birds' age and purpose (laying hens or broilers).
• Hygiene and health care: Maintaining strict cleanliness in sheds, feed, and water to prevent disease outbreaks. Regular health monitoring and vaccination are important.

Outbreaks of diseases like 'bird flu' (avian influenza) highlight the importance of strict biosecurity measures in poultry farms to prevent the spread of infections.

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Animal Breeding

Animal breeding is a critical aspect of animal husbandry aimed at improving animal productivity (yield) and the desirable qualities of animal products. Desirable traits can include increased milk production, faster growth rate, lean meat, disease resistance, etc.

A breed is defined as a group of animals related by descent and sharing similar characteristics in appearance, size, shape, and other features.

Animal breeding methods are broadly classified into:

1. Inbreeding: Mating of more closely related individuals within the same breed for 4-6 generations.
2. Outbreeding: Breeding between unrelated animals.

Inbreeding

Strategy: Identify superior males and females within a breed and mate them. Evaluate the progeny and select superior offspring for further inbreeding. Superior females (e.g., high milk-producing cows) and superior males (e.g., bulls producing superior progeny) are key to this process.

• Inbreeding increases homozygosity, helping to develop purelines (genetically uniform strains) in animals, similar to Mendel's purelines in plants.
• It helps in the accumulation of superior genes and the elimination of undesirable recessive genes by exposing them in homozygous state, allowing for selection against them.
• However, continued close inbreeding can lead to inbreeding depression, resulting in reduced fertility and productivity.

To overcome inbreeding depression, selected inbred animals are mated with unrelated superior animals of the same breed (an outcross). This usually helps restore vigour, fertility, and yield.

Out-breeding

Out-breeding involves mating unrelated animals. There are three types:

1. Out-crossing: Mating of individuals within the same breed but with no common ancestors for 4-6 generations. The offspring is called an out-cross. This method is useful for improving productivity in animals that are below average. A single outcross can often alleviate inbreeding depression.
2. Cross-breeding: Mating superior males of one breed with superior females of another breed. This aims to combine desirable traits from two different breeds. The hybrid progeny can be used directly for commercial production or further bred and selected to develop new stable breeds. Example: Hisardale, a new breed of sheep developed by crossing Bikaneri ewes and Marino rams.
3. Inter-specific hybridisation: Mating of male and female animals belonging to two different, but related, species. The hybrid offspring may possess desirable traits from both parents and can have economic value. Example: Mule, produced by crossing a male donkey and a female horse.

Artificial Insemination (AI): Controlled breeding experiments often utilise AI. Semen from a selected male is collected and injected into the reproductive tract of a selected female. Semen can be used fresh or frozen for later use or transport. AI helps overcome limitations of natural mating, such as physical differences, unwillingness to mate, or geographical separation of superior parents.

Multiple Ovulation Embryo Transfer Technology (MOET): A programme used for herd improvement to increase the success rate of producing hybrids and rapidly multiply desired individuals.

• A cow is administered hormones (with FSH-like activity) to induce super ovulation, causing it to produce 6-8 eggs per cycle instead of one.
• The animal is either naturally mated with an elite bull or artificially inseminated.
• Fertilised eggs (embryos at 8-32 cell stage) are non-surgically recovered.
• These embryos are transferred into surrogate mothers (recipient cows).
• The genetic mother can then be used for another round of super ovulation.

This technology has been applied in cattle, sheep, rabbits, buffaloes, and horses, enabling the rapid multiplication of high-yielding females and high-quality meat-producing males.

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Bee-Keeping

Bee-keeping (Apiculture) is the practice of maintaining colonies of honeybees (in hives) for producing honey and beeswax. It is an ancient practice and a thriving cottage industry.

• Honey is a highly nutritious food and is used in traditional medicine.
• Beeswax is used in cosmetics and polishes.

Increased demand for honey has led to large-scale apiculture, making it an income-generating industry.

Bee-keeping requires sufficient bee pastures (flowers/plants for nectar and pollen) and specific knowledge. Key factors for successful bee-keeping:

• Knowledge of bee biology, nature, and habits.
• Choosing a suitable location for hives.
• Handling bee swarms (groups of bees leaving the hive).
• Managing beehives throughout different seasons.
• Collecting honey and beeswax.

Bees are important pollinators for many crops (sunflower, Brassica, apple, pear). Placing beehives in crop fields during flowering increases pollination efficiency, benefiting both crop yield and honey yield.

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Fisheries

Fishery is an industry related to catching, processing, and selling fish, shellfish, and other aquatic animals. A significant portion of the global population relies on fish and aquatic products for food.

Common freshwater fishes consumed in India include Catla, Rohu, and Common carp. Marine fishes consumed include Hilsa, Sardines, Mackerel, and Pomfrets.

Fisheries contribute significantly to the Indian economy, providing income and employment to millions, especially in coastal areas.

To meet increasing demand, production techniques have been improved through:

• Aquaculture: The cultivation of aquatic organisms (plants and animals) in controlled conditions.
• Pisciculture: Specifically, the rearing of fish in ponds or enclosures. Pisciculture is a subset of aquaculture focused only on fish.

These practices have led to a 'Blue Revolution', analogous to the 'Green Revolution' in agriculture, increasing the production of aquatic food resources and generating income.

Plant Breeding

Traditional farming methods have limitations in meeting the food demand of a growing population. While better management and increased cultivation area help, plant breeding has been crucial in significantly increasing crop yields and improving crop quality.

The 'Green Revolution' in India, starting in the mid-1960s, dramatically increased food production (particularly wheat and rice) and made the country self-sufficient. This was largely dependent on plant breeding techniques used to develop high-yielding and disease-resistant varieties.

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What Is Plant Breeding?

Plant breeding is the deliberate manipulation of plant species to create new varieties with desired characteristics, making them better suited for cultivation, giving higher yields, and being resistant to diseases and pests.

Conventional plant breeding has been practiced since ancient times. Modern plant breeding incorporates advancements in genetics, molecular biology, and tissue culture alongside traditional methods (crossing and selection).

Desirable traits targeted in plant breeding include:

• Increased crop yield.
• Improved quality (e.g., protein content, oil quality).
• Increased tolerance to environmental stresses (drought, salinity, heat, cold).
• Resistance to pathogens (fungi, bacteria, viruses).
• Increased tolerance to insect pests.

Plant breeding programmes are systematic processes, involving several key steps:

1. Collection of Variability (Germplasm Collection): Genetic variability is the essential starting point. This involves collecting and preserving diverse wild varieties, species, and relatives of cultivated crops. The entire collection containing all alleles for all genes in a crop is called the germplasm collection.
2. Evaluation and Selection of Parents: The germplasm is evaluated to identify plants with desired traits. Selected plants are multiplied, and purelines (homozygous lines) are developed if needed. These plants are chosen as parents for hybridisation.
3. Cross Hybridisation among the Selected Parents: Plants with complementary desirable traits are cross-pollinated to create hybrids that combine these traits genetically. This is a meticulous process involving emasculation and pollination (as described in Chapter 2). Only a small percentage of crosses result in desirable combinations.
4. Selection and Testing of Superior Recombinants: Progeny from hybridisation are screened for plants that possess the desired combination of traits. Superior plants are selected and self-pollinated for several generations to achieve homozygosity and stability of the desired traits (making them true-breeding).
5. Testing, Release, and Commercialisation of New Cultivars: The selected lines are tested for yield, quality, disease resistance, and other agronomic traits in research fields under optimal conditions. Promising lines are then tested in farmers' fields across multiple locations representing different agroclimatic zones for at least three growing seasons. Performance is compared to existing best local varieties (check cultivars). If proven superior, the new variety is released for commercial cultivation.

Plant breeding has significantly contributed to India's agricultural success, leading to the Green Revolution and self-sufficiency in food grains.

Examples of successful plant breeding efforts in India:

• Wheat and Rice: Development of semi-dwarf, high-yielding, and disease-resistant varieties. Norman E. Borlaug developed semi-dwarf wheat varieties. In India, varieties like Sonalika and Kalyan Sona were introduced. Semi-dwarf rice varieties (IR-8, Taichung Native-1) led to Indian varieties like Jaya and Ratna. This significantly increased wheat and rice production between 1960-2000.
• Sugarcane: Hybridisation of the high-yielding, high-sugar tropical cane (Saccharum officinarum) with the native North Indian cane (Saccharum barberi) to produce varieties suitable for North India with high yield, thick stems, and high sugar content.
• Millets: Development of high-yielding, water-stress resistant hybrid varieties of maize, jowar, and bajra.

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Plant Breeding For Disease Resistance

Plant diseases caused by fungi, bacteria, and viruses lead to significant crop losses, especially in tropical climates. Breeding for disease resistance is a key strategy to enhance food production and reduce the reliance on chemical fungicides and bacteriocides.

Resistance in a plant is its genetic ability to prevent a pathogen from causing disease. Understanding the pathogen and its transmission is important for breeding resistant varieties.

Examples of crop diseases:

• Fungal: Brown rust of wheat, red rot of sugarcane, late blight of potato.
• Bacterial: Black rot of crucifers.
• Viral: Tobacco mosaic, turnip mosaic.

Methods for breeding disease resistance:

• Conventional Breeding: Involves hybridisation and selection, similar to breeding for other traits. Steps: screening germplasm for resistance sources, crossing selected resistant parents with desirable varieties, selecting resistant hybrids, and testing/releasing new resistant varieties.

Table of some disease-resistant crop varieties developed by hybridisation and selection:

Crop	Variety	Resistance to diseases
Wheat	Himgiri	Leaf and stripe rust, hill bunt
Brassica (Karan rai)	Pusa swarnim	White rust
Cauliflower	Pusa Shubhra, Pusa Snowball K-1	Black rot and Curl blight black rot
Cowpea	Pusa Komal	Bacterial blight
Chilli	Pusa Sadabahar	Chilly mosaic virus, Tobacco mosaic virus and Leaf curl

• Mutation Breeding: When conventional methods are limited by available resistance genes, mutations can be artificially induced using chemicals or radiation (mutagens). Mutated plants are screened for desirable traits, including disease resistance. Plants with induced resistance can be directly multiplied or used in breeding programs. Example: Resistance to yellow mosaic virus and powdery mildew was induced by mutations in mung bean.
• Genetic Engineering: Transferring resistance genes from unrelated species or even other organisms into crop plants (transgenic plants).
• Selection amongst Somaclonal Variants: Variants produced during tissue culture (somaclones) can sometimes show desirable traits like disease resistance.

Genes for resistance are often found in wild relatives of cultivated species. Transferring these genes to high-yielding cultivated varieties is done through sexual hybridisation, followed by selection. Example: Resistance to yellow mosaic virus in bhindi (okra) was transferred from a wild species to create the variety Parbhani kranti.

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Plant Breeding For Developing Resistance To Insect Pests

Insect and pest infestations cause significant damage to crops, leading to substantial yield losses. Breeding crop plants for resistance to insect pests is another important strategy for enhancing food production.

Insect resistance in host plants can be due to various characteristics:

• Morphological characteristics: Hairy leaves (resistance to jassids in cotton, cereal leaf beetle in wheat), solid stems (non-preference by stem sawfly in wheat), smooth leaves and nectar-less varieties (do not attract bollworms in cotton).
• Biochemical characteristics: High aspartic acid content, low nitrogen and sugar content in maize (resistance to maize stem borers).
• Physiological characteristics.

Breeding for insect pest resistance follows the same steps as breeding for other traits (hybridisation, selection, testing). Resistance genes can be sourced from cultivated varieties, germplasm collections, or wild relatives.

Table of some insect pest resistant crop varieties developed by hybridisation and selection:

Crop	Variety	Insect Pests
Brassica (rapeseed mustard)	Pusa Gaurav	Aphids
Flat bean	Pusa Sem 2, Pusa Sem 3	Jassids, aphids and fruit borer
Okra (Bhindi)	Pusa Sawani, Pusa A-4	Shoot and Fruit borer

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Plant Breeding For Improved Food Quality

Malnutrition and 'hidden hunger' (micronutrient deficiencies) affect billions globally, even those with sufficient calorie intake. Improving the nutritional content of crops is crucial for public health.

Biofortification is the process of breeding crops with higher levels of vitamins, minerals, protein, or healthier fats.

Objectives of breeding for improved nutritional quality:

• Increasing protein content and improving protein quality (amino acid balance).
• Increasing oil content and improving oil quality (fatty acid profile).
• Increasing vitamin content (e.g., Vitamin A, C).
• Increasing micronutrient and mineral content (e.g., iron, calcium, zinc, iodine).

Examples of biofortification achievements:

• Development of maize hybrids with twice the amount of amino acids (lysine and tryptophan).
• Wheat variety Atlas 66, with high protein content, used to improve other wheat varieties.
• Development of iron-fortified rice varieties with significantly higher iron content.
• Release of nutrient-rich vegetable varieties by IARI, New Delhi: Vitamin A enriched carrots, spinach, pumpkin; Vitamin C enriched bitter gourd, bathua, mustard, tomato; Iron and calcium enriched spinach and bathua; Protein enriched beans.

Single Cell Proteins (SCP)

Conventional agriculture alone may not be able to meet the future food demands, especially with increasing population and a shift towards meat-heavy diets (which require more grain production). Single Cell Protein (SCP) offers an alternative protein source.

Single Cell Protein (SCP) refers to edible unicellular or multicellular microbial biomass used as a source of protein for human or animal nutrition.

Microbes can be grown on an industrial scale to produce large quantities of protein. Examples:

• Spirulina (blue-green algae): Can be grown on inexpensive substrates like wastewater from potato processing plants, straw, molasses, animal manure, or sewage. Provides a source of protein, minerals, fats, carbohydrates, and vitamins. Its cultivation also helps in reducing environmental pollution.
• Certain bacteria like Methylophilus methylotrophus can produce large amounts of protein due to their high growth rate and biomass production.

The acceptance of edible mushrooms as food suggests that microscopic fungi and other microbes grown for SCP could also become acceptable as a food source.

Tissue Culture

As traditional plant breeding can be slow and limited, tissue culture techniques were developed to provide faster and more efficient methods for plant propagation and improvement.

Tissue culture involves growing plant parts (explant) or cells in a test tube or culture vessel under sterile conditions, using a special nutrient medium.

The key principle behind tissue culture is totipotency: the capacity of any plant cell or explant to develop into a whole plant.

The nutrient medium must contain essential components like a carbon source (sucrose), inorganic salts, vitamins, amino acids, and plant growth regulators (auxins, cytokinins) to support cell growth and regeneration.

Micropropagation: This is the method of producing thousands of plants from a small piece of tissue or explant through tissue culture in a relatively short period. Plants produced this way are genetically identical to the original parent plant and are called somaclones.

Micropropagation is used for commercial production of many food plants like tomato, banana, and apple.

Another important application is producing virus-free plants from infected plants. Even if a plant is infected with a virus, the meristematic tissues (apical and axillary meristems) are often virus-free. Meristems can be excised and grown in vitro using tissue culture to regenerate virus-free plants (meristem culture). This has been successful for banana, sugarcane, and potato.

Scientists can also isolate single cells from plants and remove their cell walls using enzymes to obtain naked protoplasts (cells surrounded only by the plasma membrane).

Somatic hybridisation: Protoplasts from two different plant varieties (each with a desirable trait) can be fused together to create hybrid protoplasts. These hybrid protoplasts can then be grown in culture to regenerate new plants called somatic hybrids.

Example: Fusion of tomato protoplast and potato protoplast resulted in a somatic hybrid called pomato. Although achieved, pomato did not possess the commercially desirable combination of traits from both parents.

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