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Feeding standards are vital guidelines that specify the necessary nutrient amounts for animals’ growth, health, and production. These standards have evolved since the nineteenth century and are classified into three types: comparative, digestible nutrient, and production value. They provide daily nutrient requirements or percentages of the diet, depending on the feeding method. Precise feeding uses daily requirements, while ad libitum feeding employs percentages.
A. Comparative type
1. Hay standard: In 1810, German scientist Thaer revolutionized the practice of animal feeding by introducing a standard for comparing different types of feed. This standard used meadow hay as the reference unit and considered it equivalent to 91 lbs. of clover hay, 200 lbs. of potatoes, or 625 lbs. of mangels. This allowed for a more accurate measurement and comparison of feed options, aiding farmers in their feeding decisions. Prior to this, feeding practices relied on practical experience due to limited knowledge of feed composition and animal needs. However, with Thaer’s new standard, farmers were able to make more informed choices when it came to providing proper nutrition for their animals. This marked an important advancement in the field of animal husbandry and laid the foundation for further research and understanding in the years to come.
2. Scandinavian “feed unit” standard: In 1884, Professor Fjord introduced the Scandinavian feeding standard, which focuses on the feed unit. One pound of common grains like corn, barley, or wheat is considered one unit, with other foods valued relative to this. The standard recommends one feed unit per 150 lbs. of body weight, with an additional unit for every three pounds of milk produced.

Nutrition plays a significant role in any livestock development program, and the expression of genetic potential for production depends on the adequate supply of nutrients. For profitable livestock production, it is essential to feed livestock nutritionally balanced diets with minimum cost and wastage, as feed cost accounts for more than half of the cost of livestock produce. Providing a balanced diet to animals can reduce feed costs, minimize nutrient wastage, and improve feed efficiency, thereby positively impacting the environment by reducing nutrient excretion.
The demand for animal products such as milk, meat, and eggs is constantly increasing to meet the needs of the growing human population. Better awareness of health and rapid urbanization, with a higher preference for quality animal products, has further fueled this demand. Human food is incomplete in terms of optimum nutrition without animal products like meat, milk, and eggs. To maximize the production of animal products according to their genetic potential, animals must be fed a balanced ration scientifically formulated to provide all essential nutrients.
Balanced feeding involves feeding livestock according to their requirements to achieve growth and production in line with their genetic potential. Understanding the nutrient requirements and the relative value of feeds as a source of these nutrients is the foundation of scientific feeding. Effective measures to achieve a balanced diet include accurate feed formulation based on the nutritional value of each feed ingredient, precise quantification, proper blending of different feedstuffs, optimal use of mineral mixtures, salt, feed additives, and the application of improved feed processing techniques tailored to the relevant species of livestock.

Dry matter intake (DMI) is crucial for animal performance, especially in cattle. It ensures that animals receive the necessary nutrients and energy for metabolic functions. Cattle have complex digestive systems with unique metabolic functions. Variations in feed intake are essential throughout the growth cycle to maintain a balance in response to metabolic and environmental challenges.
Limitations in feed intake can lead to nutrient deficiencies, impacting growth rates and overall profitability. Feed stress can also result in health issues and digestive disturbances.
Importance of Predicting Dry Matter Intake (DMI) in Cattle Using NRC Guidelines
Predicting Dry Matter Intake (DMI) in cattle is crucial for managing livestock health, productivity, and economic efficiency. The National Research Council (NRC) offers guidelines to estimate DMI, aiding producers in optimizing feeding strategies. Here’s why predicting DMI is essential:
1. Optimizing Nutrient Intake
• Meeting Nutritional Needs: Accurate DMI prediction ensures cattle receive sufficient energy, protein, vitamins, and minerals for maintenance, growth, lactation, or reproduction.
• Avoiding Deficiencies: Inadequate feed can result in poor health, reduced production, and reproductive issues.
• Preventing Overfeeding: Excessive intake can lead to health problems like acidosis, obesity, or metabolic disorders.
2. Improving Productivity

Assessment of nutrient requirements for ruminants is essential in order to maintain good health and optimal production levels in these animals. Ruminants have a unique digestive system that allows them to digest plant-based feed, such as grass and hay, through a process called fermentation. This process produces volatile fatty acids which are then absorbed by the animal and serve as their main source of energy. Therefore, it is important to ensure that the diet provided to ruminants contains enough nutrients to support both their metabolic needs as well as their production demands. This assessment includes factors such as age, weight, stage of lactation or pregnancy, level of activity, and environmental conditions. In addition, the quality and quantity of available forage should also be considered when determining the nutrient requirements of ruminants. Proper assessment can help prevent deficiencies or excesses of certain nutrients which can lead to health issues and decreased productivity in these animals. Ultimately, by accurately assessing the nutrient requirements for ruminants, producers can develop appropriate feeding programs that promote overall well-being and performance in their herds.

Providing balanced nutrition to different groups of dairy cows with varying production levels is a significant challenge for commercial dairy farmers. The production performance of dairy cows is directly influenced by the type of feed provided. Ensuring balanced nutrition is crucial to optimize productivity in milk production and reproduction while minimizing feed costs. Dairy cow rations should consist of high-quality forages, a balanced mix of grains and protein sources, essential minerals, vitamins, and other feed supplements. Proper feeding practices are essential to prevent under or overfeeding and ensure that cows receive the right amount and combination of feed ingredients.
Formulating well-balanced rations that meet the nutrient requirements of cows results in optimal feed digestion and utilization. Transitioning from traditional feeding systems to a total mixed ration (TMR) feeding system is recommended for efficient and profitable feeding of dairy cows. TMR feeding systems have been widely adopted in developed countries due to their effectiveness. Each mouthful of TMR provides a complete and balanced ration for the cows, reducing feed selection by the animals and promoting synchronization of carbohydrate and protein availability in the rumen, leading to lower rumen acidity.
TMR feeding systems offer benefits such as labor savings, the ability to feed various types of feeds, and ensuring a nutritionally balanced ration at all times. While TMR may pose challenges in meeting individual nutrient requirements for each cow, larger dairy farms with multiple groups of cows can effectively manage this issue. By providing a nutritionally balanced ration consistently, TMR feeding systems help cows consume energy close to their requirements while maintaining the physical characteristics of roughage necessary for proper rumen function, ultimately leading to optimal production and economic efficiency.

Imbalance between feed availability, feed ingredient prices, and livestock product prices, such as milk, meat, and eggs, leads to poor animal performance, low growth rates, reduced reproductive efficiency, and high morbidity and mortality rates. This issue is particularly severe in South Asian countries like Pakistan, Nepal, India, and Bangladesh, where there is a widespread lack of sufficient high-quality feed. To address this challenge, it is essential to develop technologies for utilizing non-conventional feeds and fibrous agricultural residues more effectively.
The large number of livestock in these countries is both an asset and a liability. Many of the less productive animals are owned by impoverished individuals who have no alternative livelihood options and cannot reduce their livestock numbers. Therefore, efforts must be made to enhance production by optimizing the use of available feed resources, minimizing losses from diseases and parasites, implementing better management practices, and focusing on genetic improvement. The primary feed resources in these regions are crop residues, such as rice and wheat straws, sorghum and maize stovers, and sugar cane bagasse. These materials are typically low in protein and high in fiber, with energy content in a lignified form.
India, with 17.5% of the global population and 20% of the world’s cattle population, faces challenges due to limited land availability for agriculture. The country’s animal population grows at a rate of 0.66% annually, while the human population increases rapidly at 1.6%. With only 4% of cultivable land allocated to farm feed production, there is intense competition between human and animal populations for food and fodder resources. India currently experiences a deficit of 44% in concentrate feed ingredients, 10.5% in dry crop residues, and 35.6% in green fodder, exacerbating the shrinking farmland due to urbanization.
Traditional feed in India consists of crop residues or straw from grains like jowar, bajra, ragi, wheat, and barley, either whole or ground. These materials can be fed alone or in combination with fresh fodder. The limited availability of land for fodder crops necessitates the exploration of non-traditional or

The term “chelate” comes from the Greek word “chel,” meaning “claw,” indicating that the element is tightly held or clawed by the ligand. The term was coined by Morgan and Drew in 1920, defining it as a chemical compound in the form of a heterocyclic ring with a metal ion attached by coordinate bonds to at least two non-metal ions, known as chelation. A chelate is a type of mineral complex, which is a mixture of a mineral and an organic compound like a protein or polysaccharide. Chelation refers to the bond formed between a metal ion (mineral) and a ligand (protein or amino acid chelating agent). Chelates are created by reacting a mineral salt with an enzymatically prepared mixture of amino acids and small peptides under controlled conditions. The ligand binds the metal at multiple points, forming a ring structure with the mineral, resulting in a chelate.
In animal feed, chelated minerals, such as iron, manganese, cobalt, copper, and zinc, are commonly used to enhance bioavailability and support metabolic functions. These trace elements are transitional elements on the Periodic Table, forming stable complexes or chelates due to their ability to form coordinate covalent bonds.
The primary goal of chelates is to improve mineral absorption in animals during periods of high nutritional demand, such as pregnancy, lactation, weaning, and environmental or disease stress. Chelates have been studied for their effects on immunity, reproductive performance, and overall herd health. To maximize mineral absorption, chelated compounds should be stable in the rumen.
Chelates are stable, electrically neutral complexes that protect trace minerals from chemical reactions during digestion, ensuring their availability to the animal. Chelated minerals are used to increase bioavailability and uptake, reaching the plasma intact and separating at the site of action. They can replace a portion of inorganic minerals in animal diets and are suitable for all species. Soluble chelated trace minerals are designed for use in drinking water supplies.

Ruminants possess the remarkable ability to efficiently utilize non-protein nitrogen (NPN) substances as substitutes for protein, thanks to the presence of microbes in their rumen. These substances contain essential amino acids, which are crucial for the proper growth and development of animals. The microbes in the rumen play a significant role in synthesizing these essential amino acids from NPN sources, making them readily absorbable by the ruminant’s digestive system. In fact, research has demonstrated that rumen bacteria prefer utilizing amides, amino acids, and ammonium salts for energy production and growth, rather than proteins. This utilization of NPN substances is essential for meeting the protein requirements of ruminants and ensuring their overall health and productivity. Consequently, incorporating NPN-rich feeds into ruminant diets can be a cost-effective alternative to traditional protein sources.
Definition: Non-protein-nitrogenous (NPN) substances refer to feedstuffs that contain nitrogen in a form other than proteins or peptides. In fresh herbages, up to 30% of the total nitrogen content may consist of NPN substances.

The profitability of dairy animals depends on milk yield and reproductive efficiency. High-yielding cows require more nutrients to support increased milk production. However, early lactating cows and buffaloes often face a Negative Energy Balance (NEB) due to inadequate energy intake, which hampers their performance. To enhance productivity, it is essential to minimize the extent and duration of NEB. One effective approach is the use of bypass nutrients, which safeguard essential dietary components like fat and protein from rumen fermentation, enabling better digestion and absorption in the lower digestive tract. Additionally, protected starch, chelated minerals, and vitamins can also boost animal performance.
“Bypass Nutrients” are nutrients that undergo minimal fermentation in the rumen, allowing them to remain intact for digestion and absorption in the lower gastrointestinal tract. These slowly degradable nutrients provide a steady nutrient supply to rumen microbes, unlike easily soluble nutrients that lead to sudden spikes in nutrient availability.
Rationale behind the protection of dietary nutrients
The potential benefits of delivering nutrients directly to the intestine in a form available for direct absorption and utilization by the animals are:
1. Prevention of energy losses associated with the degradation and fermentation of nutrients in the rumen, thus sparing available energy for productive purposes.
2. Ensuring that particular nutrients will be available to the host animal in their original form.
3. Taste masking of unpalatable substances.
4. Preventing interactions among nutrients and their oxidation during storage.

India is one of the top ten countries most affected by disasters, as defined by the Disaster Management Act of 2005. Natural disasters, such as floods, droughts, and earthquakes, often lead to food and water shortages. Man-made disasters, like industrial accidents and pollution, can further worsen conditions for animals. Ensuring animal welfare during disasters is essential for family survival, as livestock provide food security. Developing a comprehensive animal care plan is vital to safeguard animals during and after natural disasters.
During natural disasters, the primary objective should be to prevent animals from starving by diverting feed from lactating animals whenever possible. Implementing restricted feeding is crucial, even if it results in weight loss and reduced milk yield in lactating animals. Utilizing various measures such as conserved fodders, cost-effective hydroponic systems, unconventional feed resources, and nutrient blocks can help prevent livestock mortality and morbidity during emergencies.
Natural calamities often lead to significant livestock losses, highlighting the importance of feed security for animals during and after disasters. Developing feeding strategies to sustain animals in the face of natural calamities is crucial.
Feeding strategies during feed shortages aim to maintain animals at a minimum body weight for survival, prioritize feeding productive stock, and understand critical weight losses for different species. Critical body weight varies by species, breed, and age, with cattle at risk if weight loss exceeds 20%. Understanding these factors is essential for effective feed resource allocation during emergencies.
Developing countries face feed shortages exacerbated by natural disasters, creating a gap between feed demand and supply. Hydro-meteorological disasters pose challenges in transporting feed, leading to increased costs. In such situations, ensuring animal survival through rationed feeding is crucial. Booster feed can aid in their recovery once conditions improve

Feed is a significant expense in raising small ruminants, accounting for 60% or more of total production costs. Nutrition is crucial for flock reproduction, milk production, and lamb and kid growth. Late gestation and lactation are critical periods for ewe and doe nutrition, with lactation having the highest nutritional demands. Nutrition levels determine the growth rate of lambs and kids, particularly protein requirements. Animals on inadequate diets are more prone to diseases and fail to reach their full genetic potential.
Small ruminants require energy, protein, vitamins, minerals, fiber, and water for optimal health. Energy is often the most limiting nutrient, while protein is the most costly. Imbalances in vitamins and minerals can affect animal performance and health. Fiber is essential for a healthy rumen environment and digestion. Water, though inexpensive, is often overlooked.
Feed intake percentage varies based on the animal’s size, with smaller animals needing a higher intake proportionally. Maintenance requirements increase with activity levels, environmental conditions, and life stages such as pregnancy, lactation, and growth. Sheep and goats can meet their nutritional needs with various feed sources as long as requirements are met. Feeding programs should consider animal needs, feed availability, and nutrient costs.
Comparative Feeding Behaviour and Digestive Physiology in Goats and Sheep
1. Goats excel in utilizing cell wall-rich and nitrogen-poor forages compared to sheep and cattle.
2. Goats have a longer retention time of feed in the digestive tract, higher cellulolytic bacteria concentration in the rumen, and efficient blood urea recycling.
3. In harsh conditions, goats consume less water and more dry matter than sheep.

Metabolic disorders in cattle, such as Milk Fever, Ketosis, Fat Cow Syndrome, and Hypomagnesaemia, affect dairy cows post-calving, disrupting blood metabolites and health. Triggers include diet changes, calving stress, and mineral deficiencies. Untreated, these disorders can lead to mild discomfort or severe complications.
Metabolic diseases are most prevalent in high-producing dairy cows due to the breeding and feeding practices aimed at maximizing milk yield. The period from calving to peak lactation is particularly susceptible to these conditions due to the high turnover of fluids and organic materials. The transition period, defined as 3 weeks before and after calving, is crucial for managing nutrient requirements and preventing metabolic disorders.
As milk production per cow has increased over the years, the complexity of nutrition and management for high-producing cows has also risen. The shift from forage-based to concentrate-rich diets at calving challenges rumen adaptation and can lead to negative energy balance. Balancing milk yield and reproduction becomes a critical aspect of dairy farming success.
Given the interconnected nature of these disorders, herd health management strategies are essential for prevention. Regular monitoring and understanding of metabolic diseases are vital for the successful operation of a dairy farm.
Milk Fever
Milk fever, also known as parturient paresis or hypocalcaemia, is a prevalent metabolic disorder in high-producing dairy animals worldwide. This condition primarily affects dairy cows close to calving and is caused by a low level of calcium in the blood (hypocalcaemia). It is a result of dietary errors and can lead to decreased productivity and economic losses for farmers. Milk fever is a significant concern for dairy industry professionals as it can significantly affect milk production, reproduction, and overall herd health.

Background
Blood collection from cows and other animals is a routine procedure often performed for diagnostic, research, or health-monitoring purposes. Diagnostic testing, such as hematology, biochemistry, hormone assay, infectious disease testing, and animal pregnancy diagnosis, can be done using blood. Blood samples are required for genetic testing (DNA fingerprinting or parentage determination), pharmacokinetic studies, and immunological studies. Another use of blood collection is monitoring animal health.
It is essential to consider that proper techniques of blood sample collection should be followed. Avoid introducing infection to the animal during blood collection. Remember the animal welfare to minimize distress and discomfort to the animal during blood collection.
Materials Required
• Sterile syringe or vacutainer (usually 16-18 G needle)
• Blood collection tubes (BD Science K2 EDTA Vacutainer(R) PLUS 6 mL) for whole blood, serum tubes for serum collection, or other specific tubes depending on the test (Figure 1).
• Antiseptic solution (e.g., alcohol or iodine)
• Restraint (head gate or halter)
• Gloves

Background
Milk is known as a whole food for human consumption. It is the first food of the newly born human mammals. Milk contains almost all the nutrients required for the patients, the elderly, pregnant mother and new born baby. There is no doubt that milk plays a significant role in human development. We can prepare many physical forms of milk like cheese, yogurt, ghee, and milk powder. The calcium content is higher in buffalo than in cows. Buffaloes are the second largest source of milk and produce 15 % milk. Higher biological value proteins, fat, soluble vitamins, fatty acids, amino acids, water-soluble vitamins, and calcium are all present in milk. The main antioxidant components of milk and milk products are sulfur, phosphate, zinc, and amino acids like cysteine (necessary to produce collagen).
Milk somatic cells are normal cells found in milk in small amounts (epithelial cells), some of which are leukocytes (white blood cells). When mastitis is infected or injured, leukocyte production rises. Milk with a low SC level produces superior milk products that last longer. Better milk management, better cleanliness, and correct nutrition all contribute to a decrease in milk SC, which indicates poor milk production hygiene and a cause of mastitis. Milk somatic cells are made up of both immunological and milk-producing cells. In terms of defense, somatic cells are the second line. During the routine process of milking, these cells are secreted in milk. Somatic cell count is a good tool for evaluating farm cleanliness in bulk milk and is utilized worldwide as an indication of udder health in individual milk. The most prevalent condition affecting dairy buffalo production and their health and well-being is mastitis. The somatic cell count consists of immune cells (75%), such as neutrophils, macrophages, lymphocytes, erythrocytes, and epithelial cells (25%). Investigators have made different attempts to exploit milk somatic cells as a potential non-invasive sample to diagnose early pregnancy udder health in bovines.

Background
Fine needle aspiration (FNA) is a minimally invasive diagnostic procedure used to obtain cells from a mass or lesion for examination under a microscope. It’s a valuable tool in diagnosing tumors in canines (Figure 5) and other species of animals, including humans.
Advantages of FNA
• Minimal invasiveness to the animals. Thus, no sedation of animals is required.
• Rapid results - Results are obtained faster as cell processing is not required.
• Cost-effective
• Risk-free
• FNA can be performed under image guidance, such as ultrasound, CT, and MRI, for precise identification of the location of cells inside the tissue.
• May be able to differentiate between benign and malignant tumors
• Can assess tumor grade
• FNA helps monitor treatment response. FNA is helpful as it can help pre-plan the treatment of the dogs. If the tumor is malignant, then the treatment can be given immediately, and if it is benign, then the treatment can be postponed.

Background
Urine collection is a fundamental procedure in veterinary medicine, providing valuable insights into an animal’s health status. Urine analysis can detect urinary tract infections, kidney function, and metabolic disorders. Several methods can be employed for urine collection in dogs, each with its advantages and limitations. Always collect urine in clean, sterile and leakproof containers.
Procedures of Urine Collection In Animals
1. Free catch or voided urine: Collecting urine as the animal voids naturally. This procedure is non-invasive and easy to perform. However,
the collection of voided urine may not be free from contaminants. Contamination risk from external genitalia and dilution or concentration variation in urine composition is common.
2. Catheterization: Inserting a catheter into the urethra to obtain a sample, often used in larger animals or when free catch is not possible. It provides a sterile sample that is suitable for bacterial culture and cytology. However, catheterization is an invasive procedure with the potential for trauma and discomfort to the animals.
3. Cystocentesis: Inserting a needle directly into the bladder through the abdominal wall to collect a sterile sample. Like catheterization, cystocentesis provides a sterile sample, ideal for bacterial culture and cytology.

Background
As a non-invasive and relatively stress-free method, saliva holds great potential as a diagnostic sample. It has already been utilized in diagnostic tests for rabies and other diseases in dogs. Saliva secretion is the secretion of salivary glands that maintains homeostasis in the oral cavity, protects against pathogens, and helps digest food. It contains inorganic substances, cells (blood and epithelial cells) and microorganisms. Saliva also contains immunoglobulins, enzymes, hormones, and cytokines derived from serum and bronchial secretions. The saliva of dog is being used to detect rabies virus (Kasempimolporn et al., 2000), parvo virus (Kocaturk et al., 2021), cancer and measure stress levels. Obtaining saliva rapidly, painlessly, and uncomplicatedly can be an easy tool for disease screening.
For the identification of serval prognostic biomarkers for various physiological and pathological conductions, saliva proteomics can be very helpful. In humans, saliva contains more than 3000 proteins (Kawas et al., 2012). Several diseases like oral carcinoma, AIDS, hepatitis B, cystic fibrosis, and other diseases like diabetes mellitus. Differential expression of dog saliva proteins compared to human saliva revealed 2532 proteins. Proteins related to apoptosis and adhesion were predominant in the oral proteome of dogs, in addition to proteins related to regeneration and healing processes such as FGF and EGF (Sanguansermsri, et al., 2018).

Background
Peripheral blood mononuclear cells (PBMCs) are a crucial immune system component. Isolating them from whole blood allows for an in-depth study of immune responses, disease mechanisms, and the development of noveltherapies. Lymphocytes, monocytes, and other different  white blood cells (WBCs) possessing circular nuclei make up the cells of PBMCs. These cells can be directly obtained from whole blood using different separating methods. PBMCs can be utilized for multiple purposes, from drug assessment to expression analysis to parentage determination.
• Toxicity assessment of novel compounds: Interaction of drugs with PBMCs can help assess the safety of compounds and set appropriate doses for safe consumption.
• Comparative analysis: In vitro assessment of diseased vs. healthy PBMCs can provide insights into affected biochemical pathways. The effects of foreign chemical compounds can also be assayed to drive future studies.
• Personalized medication: Studying PBMCs can help develop a genetic immune profile, leading to more specificity and effectiveness in personalized medicines.
• Occupational disorders: Diseases developed due to the overexposure of certain toxic compounds can also be determined by testing PBMCs in peripheral blood.

Background
Peripheral Blood Mononuclear Cell (PBMC) smears are a valuable diagnostic tool in veterinary medicine, offering insights into various animal diseases. By isolating and examining PBMCs— comprising lymphocytes and monocytes, veterinarians can detect hematologic abnormalities, immune responses, and the presence of infectious agents or neoplastic cells.
This method is particularly useful in diagnosing viral, bacterial, and parasitic infections, as well as immune-mediated disorders and certain cancers. PBMC smears provide a quick and cost- effective way to assess animal health, aiding disease diagnosis, monitoring, and treatment planning. Following is the utility of PBMC smear in animal disease diagnosis;
1. Identification of abnormalities in WBC morphology
2. Identification of abnormalities in the number of cells like leukosis leukopenia.
3. Certain viral infections, such as canine distemper or feline leukemia virus (FeLV), can cause characteristic changes in PBMCs that are detectable on a smear.
4. Detection of blood parasites like Babesia and Ehrlichia. These parasites are detected using a blood smear; isolation of PBMC from whole blood is not required.
5. Certain types of cancers, like leukemia or lymphoma, can be identified through changes in PBMCs. Abnormal proliferation of lymphocytes or the presence of blast cells can suggest hematologic malignancies.

Background
Immunocytochemistry is the immunostaining of a specific cell or its components in a cell smear. It is a technique to visualize a specific protein or an antigen in cells based on an antigen- antibody interaction (Figure 10). The site of antibody-antigen binding can be visualized by color development (enzymechromogen system) or fluorescence. The macrophages can be visualized in the smear of peripheral blood mononuclear cells by immunocytochemistry using antibodies against macrophages. We need to use a light or fluorescent microscope to detect color or fluorescence, respectively.

Background
Milk somatic cells are a diverse population of cells found in milk, including epithelial cells, leukocytes (white blood cells), and macrophages. Isolating these cells from milk provides valuable insights into mammary gland health, mastitis detection, and milk quality assessment.
Several methods can be employed for milk somatic cell isolation. Among the others, centrifugation is the most common method of cell separation. Filtration, immunomagnetic separation and flow cytometry are the other methods of isolating specific cell populations.
In bovines, isolating milk somatic cells is useful in milk quality assessment, mastitis detection, and mammary gland biology research. An increased milk somatic cell count level, particularly neutrophil, indicates mammary gland inflammation. Healthy and mastitis glands can be diagnosed by analyzing the differential counting of milk somatic cells.

Background
Staining of milk somatic cells is the oldest method of enumerating cell types in milk by direct microscopic examination. Various stains, namely propidium iodide, methylene blue and hematoxylin-eosin stains, are used.
The total milk cell (TMC) pellet obtained above was resuspended gently in 500 μl of PBS 1X (Sigma, MA, USA). Place 20 μl of cell suspension on a clean glass slide (BioGenex, CA, USA) and let it dry at room temperature.
Materials and reagents required
1. Positively-charged glass slides
2. Glass coverslips
3. Hot plate
4. Fixatives – Methanol or ethanol
5. Hematoxyline and Eosin stain
6. Phosphate-buffered saline (PBS)
7. Distill water
8. Ethanol for dehydration
9. Xylene
10. Mounting medium (like DBX)

Background
Immunostaining is a technique used to visualize specific proteins or antigens within cells. In milk somatic cells, immunostaining is employed to identify and quantify various cell types, study their functional characteristics, and diagnose diseases. Immunostaining can be used to identify and characterize different cell types based on the expression of specific surface markers. For example, CD45 is a leukocyte marker, while cytokeratins are markers for epithelial cells. In addition to the research on mammary gland biology, immunostaining is a valuable tool for studying the biology of the mammary gland. It can be used to investigate the expression of genes involved in milk production, cell differentiation, disease processes and even pregnancy detection. For example, galectin-3-binding protein (LGALS3BP) is a gene with elevated expression in the PBMCs of early pregnant buffaloes (Sharma et al., 2023). In this chapter, we have investigated the protein expression of LGALS3BP in milk somatic cells to determine if immunopositive cells are present in milk. Apart from this, stem cells in milk can be identified using markers like CD133, CD73, CD44,and other cell surface markers (Coni et al., 2023).

Background
During a fine needle aspiration biopsy (FNAB), a small amount of mammary tissue fluid is removed using a fine needle by applying suction, and cells present therein are identified in a thin smear. FNAB has been the most sensitive, quick, and precise tool for the differential diagnosis of malignancy. However, further research is required into the possibility of malignancy in dogs based on cytological evidence and candidate gene expression analysis. This is a noninvasive cancer detection technique and is often used in clinics.
Materials and Reagents Required
1. Fixative- cold acetone, ethanol, or aldehyde-based fixative (10% neutral buffered formalin/ NBF or paraformaldehyde).
2. Ethanol – 70%, 90% and 100%
3. Washing buffer (phosphate buffer saline)- PBS
4. Clean glass slides – preferably positively charged
5. 22-gauge needle fitted with 2 ml syringe
Procedures
Prepare for a dog having a mammary tumor
• Clean the site of the mammary tumor with alcohol and allow it to dry.
• Keep slides ready, clean, and dry.

Background
Staining is a crucial step in the microscopic examination of fine needle aspirates (FNAs) from canine mammary tumors. It enhances the visibility of cellular structures, making it easier to diagnose the tumor type. The cryopreservation of unfixed, air-dried smears of FNA can safely be used for staining up to 33 months, including immunostaining for epithelial and mesenchymal cell markers like cytokeratin and vimentin (Furusawa et al., 2023).
Common Staining Techniques
1. Romanowsky Stains: Romanowsky stains are a group of related stains, Dimitri Romanowsky in 1891. It used a mixture of Eosin (an acidic dye) and methylene blue (a basic dye). The original method has since been modified to include additional derivatives of methylene blue, such as azure B, leading to more distinct staining effects (Marshall, 1986). It is widely used in hematology, cytology, and microbiology for staining blood smears, bone marrow smears, and other cell types. These stains are significant for identifying and differentiating cellular components like nuclei, cytoplasm, and intracellular structures in various types of cells.
• May-Grunwald-Giemsa stain: A modification of the Romanowsky stain, combined with Giemsa for its ability to differentiate between cell types and structures. It stains nuclei blue and cytoplasm pink. Giemsa stain utilizes the azure dye to stain the azurophilic cellular components purple.

Background
Leishman stain (named after W. B. Leishman, a British surgeon) is one of the Romanowsky- type stains. It is a differential stain used to stain the different components of the cells variably. The Leishman stain is one of the best for routine blood staining and can be used for FNAC smear staining. It stains the peripheral blood smear when examining blood film under the microscope (Figure 20).
Leishman stain combines Azure B (blue) and Eosin Y (orange) dyes. Azure B has an affinity for DNA and acidic groups in cell nuclei, while Eosin Y has an affinity to basic groupings in cytoplasm. The staining results show crisp blue nuclei while the cytoplasm takes a purple hue.
Procedure for Leishman Staining
Sample Preparation
• Obtain a thin blood smear or FNAC sample.
• Air-dry the smear thoroughly.
• Flood the slide with methanol for 3-5 minutes for fixation
• Air dry the smear.

Materials and Reagents Required
1. Fixative- cold acetone or methanol
2. Ethanol – 70%, 90% and 100% for rehydration and dehydration
3. Xylene for clearing
4. Washing buffer (phosphate buffer saline)- PBS
5. Hydrogen peroxide – for endogenous peroxidase blocking
6. Normal horse serum or any other serum: 2.5% horse serum or any other serum can be used to block non-specific epitopes.
7. Ki67 mouse primary antibody
8. Secondary antiboy kit - Impress Excel kit (Cat no. MP-7601; Vector Laboratories, NY, USA) or a similar kit from other vendors like Biogenex (Figure 22; left panel).
9. Peroxide substrate kit—Immpact NovaRed (cat no. SK-4850; Vector Laboratories, NY, USA) for developing a red color signal (Figure 22; right panel).

Background
Cells are the basic unit of life. The morphology of cells describes their structural framework. It refers to the morphological features of the cell(s). It comprehends the various shapes and sizes in which cells function. Thus, the shape and size of the cell and the number of cells indicate their functional status. Hematological diagnostics requires the proper assessment and valid classification of cells for final diagnosis and prognosis. Clinicians, patients, and diagnosticians are all concerned with achieving a definitive specific diagnosis employing a single investigative test. The utilization of different cytological examinations from different organs gives adequate indicative data that leads to treatment outcomes.
What is ImageJ?
ImageJ is a public-domain image processing and analysis software that is Java-based and developed by the National Institutes of Health. The software is used to process and analyze scientific images.
The key features of ImageJ are 1) the versatility of working with various image formats, 2) extensibility with several plugins, 3) multidimensional data handling capability, and 4) vibrant community, making ImageJ a unique software for image processing and analysis. It can run as an online applet or be downloaded and used as an app.

The cell number of a particular cell type in a total cell population might indicate the physiological or pathological status of the cell smear/FNAC/tissue. ImageJ is a powerful open- source software extensively used for image assessment, including cell counting. In this chapter, the steps to count cells using ImageJ has been discussed. There are two ways to count the cells in a research image using ImageJ.
A. Manual Counting
Use the “Cell Counter” plugin or simply use the multipoint tool in ImageJ. Open it, select the cell type you want to count, and click on each cell in the image to tally them. Double-click on the multipoint tool. A separate window will open named point tool. One can select the type of marking, color and size of making (Figure 30). Keep clicking on the cell type to be counted. It will record the number of cells counted. If one wants to count the second cell type in the same image, change the counter number and select the size, color and type of click point.

Measuring cell size, diameter, length, distance between cells, area, etc, are important indicators of the identification of cell types and the physiological or pathological state of cells and tissues. ImageJ is a useful program that allows researchers and scientists to work with microscopy images for cytomorphological detailing.
The steps to measure cell size are:
A. Open Your Image in ImageJ: First, open the image containing the cells you want to measure.
B. Set the Scale (Optional): If your image has a known scale (e.g., if you used a microscope with a calibrated scale bar), you can set it inImageJ. This step ensures accurate measurements.
Go to Analyze > Set Scale. Enter the known distance (in pixels) and the corresponding physical distance (e.g., micrometers). Click OK.
C. Choose the Measurement Tool: ImageJ provides several measurement tools. The most common ones for cell size are: Area Measurement: Use the Polygon Selection Tool to outline the cell, and then go to Analyze > Measure.
D. Length Measurement: Use the Straight-Line Selection Tool to measure the length of cell projections (e.g., neurites or filopodia).
E. Record Measurements: After selecting the appropriate tool, click and drag to measure the cell area or length. Press’ t’ to record the measurement. Repeat for multiple cells if needed.
F. View Results: The measured values will appear in the Results window. You can access the results by going to Analyze > Measure or by opening the Results window directly.

Abstract
Transgenic organisms are defined as being introduced artificially with a transgene and incorporated stably into their genomes. There are various aquatic organisms in which the trans-genesis process has been applied like fish, crustaceans, molluscs, etc. Presently scientists can transfer a particular gene for a desirable and beneficial trait from one organism to another with more precision and in less time than traditional breeding. To date, over thirty-five species have been genetically engineered in laboratories. The transgenic fish are efficient feed converters. Salmon is the first transgenic fish that was used as food. Various techniques are involved in aquatransgenesis. They include – microinjection, electroporation, particle gun bombardment, liposome-mediated gene transfer and so on (setac. onlinelibrary.wiley.com). Through all these techniques a fish is genetically transformed so that it has desirable and beneficial trait. Numerous significant biotechnological uses for fish transgenesis are anticipated to be beneficial across a wide range of industries. The majority of genetically engineered fish serve purposes in fundamental studies of genetics and development. Various research teams have been creating genetically modified zebrafis to identify aquatic pollution. The lab that created GloFish initially aimed for them to alter their colour in response to pollutants, acting as environmental indicators. Transgenic fish have an improved growth rate than their nontransgenic counterparts. Moreover, they are disease-resistant and can be used as models for performing various scientific experiments in the field of environmental toxicology and biotechnology. All these beneficial traits are making transgenic fish more valuable in the biotechnological field. To fully realize the potential of transgenic fish technology in aquaculture, certain ethical and ecological issues must be scientifically resolved.
Keywords: Aqua-transgenesis, Genetically modified organisms, Microinjection, Biotechnological potential

Introduction
Aquaculture, the farming of aquatic life like fish and shellfish, has become essential for global food supply. It helps meet the rising demand for seafood, supports countless livelihoods, and promotes sustainable development. As wild fish populations dwindle due to overfishing and environmental damage, aquaculture provides a sustainable way to ensure food security and economic growth. Monosex culture, the practice of raising only one sex of a species, is particularly useful for fish like tilapia and prawns, where one sex grows faster and more efficiently. By focusing on single-sex populations, aquaculture can boost production, simplify management, and increase overall yield. Monosex culture is important because it can improve profits while protecting the environment
Historical Development of Monosex Practices
The development of the monosex culture began in the mid-20th century when scientists started to investigate ways to control the sex ratios of fish populations. Early methods focused on selective breeding to improve traits like growth rate and size. Over time, advancements in genetic manipulation and hormonal treatments have revolutionized the field, allowing for more precise control over sex determination. Hormonal treatments like 17 alpha methyltestosterone for sex reversal in tilapia during the 1970s, significantly improved production efficiency. The development of genetic technologies, such as chromosome manipulation and CRISPR, has further propelled monosex culture into mainstream aquaculture practices. Today, monosex culture is recognized as a cornerstone of sustainable aquaculture, with ongoing research aimed at refining techniques and addressing ethical considerations associated with genetic interventions.

Introduction
Sexual development in animals is considered one of the most complex research areas. This complexity arises from the underlying genetic structures that determine gender. Additionally, sexual development is viewed as one of the most intricate traits that have evolved, making it essential to studying evolution and population genetics (Schartl et al., 2018). According to evolution, fish have a link between invertebrates and higher-stacked vertebrates. According to Smith & Wootton, (2016), Kang et al. (2017), nearly all known mechanisms of sex determination observed in vertebrates have been identified in fish. As a result, finding the fish sex determination genes and their role in fish biology has excellent significance for the purely biological science of sex determination in animals. The energy from food is consumed into growth before fish become sexually mature. Since there is a range of ages for sexual maturity among different fish species, this explains the bilateral sexual growth differences in the species. The common carp (Cyprinus carpio) and the half-smooth tongue sole (Cynoglossus semilaevis) are two species that show a pattern in which females mature later than males, leading to larger females.
Sex-determining genes and their action mechanisms are crucial for guiding sex control breeding strategies in animals like the Nile tilapia (Oreochromis niloticus) and yellow catfish (Pelteobagrus fulvidraco), where males are categorized as more advanced than females Shao and Chen 2012; Chen et al., 2013; Long et al.., 2015; Mei and Gui. 2020). However, over ten years ago, the most evolved animals were the primary research subjects on the genes that determine sex and the mechanisms by which they work. According to Sinclair et al., SRY, also known as Sinclair, is the first human sex-determining gene found on the Y chromosome. in mice) and subsequently turned out to be a gene that determines maleness.

Introduction
Infectious diseases in aquaculture are becoming increasingly important to address to support the growth and sustainability of the industry. This is especially true as many view farmed seafood production as a key solution for feeding the world’s growing population and reducing poverty in numerous countries (FAO, 2016). It is essential to establish biosecurity programs that effectively prevent, manage, and eliminate diseases within aquaculture operations. Biosecurity plays a critical role in safeguarding agriculture and aquaculture operations from the devastating effects of disease outbreaks. These programs are critical to safeguarding the health of aquatic species, protecting ecosystems, and ensuring the sustainability of the industry. At first, implementing biosecurity measures in aquaculture may seem like a simple concept. The well-known saying “prevention is better than cure” is especially relevant to aquaculture diseases, given the significant economic consequences of disease outbreaks. Effective biosecurity practices can help prevent these costly issues from arising. Biosecurity is a comprehensive and coordinated strategy that includes policies and regulations designed to assess and manage risks across various sectors, such as food safety, animal health, and plant health, while also addressing related environmental risks. Biosecurity measures focus on preventive practices such as quarantine, hygiene protocols, and environmental management.

Introduction
Chromosome manipulation, the targeted alteration of chromosome quantity and combination, represents a cornerstone of genetic enhancement in aquaculture. Initially rooted in early twentieth-century studies focused on fundamental biology—particularly in amphibian models—this field has significantly expanded to enhance desirable traits through methods like polyploidy and uniparental inheritance (Arai, 2001; Benfey, 1999; Benfey, 2011; Cherfas, 1975; Devlin & Nagahama, 2002; Felip et al., 2001; Guo et al., 2009; Hulata, 2001; Komen & Thorgaard, 2007; Nagy, et al., 1979; Nagy, et al., 1978; Neyfakh, 1956; Ojima & Makino 1978). Over time, researchers worldwide have meticulously refined these techniques, transforming chromosome manipulation into a powerful tool for developing aquaculture strains with improved performance traits. By the late 20th century, aquaculture research began leveraging chromosomal modifications in finfish and aquatic invertebrates to achieve increased growth rates, disease resistance, and enhanced survival, with such techniques becoming extensively applied in commercial aquaculture operations (Pandian & Koteeswaran, 1998; Piferrer et al., 2009; Purdom, 1972). Over the past 30 years, a wide body of research has focused on optimizing treatment conditions specific to each target species, yielding robust evaluations of various aquaculture performance metrics. These metrics, including survival, growth, reproductive maturation, and disease resistance, have proven essential in assessing the effectiveness of polyploid and uniparental (gynogenetic and androgenetic) progeny (Purdom, 1976; Refstie et al., 1977; Romashov et al., 1960; Romashov & Belyaeva 1964; Stanley 1976; Stanley, 1976; T. J. Pandian, 2011; Devlin & Nagahama 2002; Guo, et al., 2009; Hulata, 2001; Komen & Thorgaard, 2007). As aquaculture has grown into the fastest-expanding sector of animal food production globally, the demand for sustainably produced, high-quality protein continues to rise. This surge in demand is driven, in part, by the decline of global fisheries due to overfishing, pollution, and habitat degradation. Consequently, the aquaculture industry faces the challenge of increasing output sustainably, necessitating the development of improved fish strains that support the resilience and efficiency of farmed stocks. To meet these demands, a range of genetic modification methods has been employed, aiming to produce fish with desirable traits such as rapid growth, superior meat quality, and enhanced resistance to disease (Xu et al., 2015). Chromosome manipulation has thus emerged as a critical tool, facilitating precise genetic interventions to enhance farmed species’ overall performance and adaptability.

Introduction
As global demand for seafood and high-protein foods grows, aquaculture has become a vital, fast-growing sector in food production. Fish farming supports food security, livelihoods, and nutrition worldwide but faces challenges like disease outbreaks, low growth rates, inefficient feed conversion, and limited genetic diversity. To address these issues, genetic improvement has become a key focus, enhancing farmed species’ resilience, productivity, and sustainability. Traditional breeding methods have driven genetic advancements, yet modern biotechnologies, particularly gene editing, now offer transformative potential (Gjedrem et al., 2012). Gene editing enables precise DNA modifications, enhancing desired traits without adding foreign genes. CRISPR-Cas9 TALENs (Transcription Activator-Like Effector Nucleases) and ZFNs (Zinc Finger Nucleases) are vital tools. Among these, CRISPR-Cas9 has gained particular prominence due to its simplicity, affordability, and high specificity (Doudna & Charpentier, 2014). In aquaculture, gene editing can increase disease resistance, accelerate growth rates, and improve feed conversion efficiency— each vital for production efficiency and environmental sustainability (Yáñez et al., 2020). Despite its promise, gene editing in aquaculture faces technical, ethical, and regulatory challenges. Issues such as off-target effects, public acceptance, regulatory diversity, and animal welfare concerns impact the adoption of gene-edited fish in food production (Van Eenennaam & Young, 2017). This chapter explores gene editing’s transformative role in aquaculture, assessing strategies to enhance disease resistance, growth, feed efficiency, and regulatory and ethical considerations. By understanding gene editing’s current landscape, stakeholders can evaluate its potential to support sustainable aquaculture and food security worldwide.

Introduction
Aquaculture is the farming of aquatic organisms, which includes fish, mollusks, crustaceans, and aquatic plants. Over the past forty years, aquaculture has played a significant role in increasing the global supply of fish for human consumption, leading to a marked rise in worldwide fish production. Nearly half (49.3%) of the world’s food fish are currently farmed for aquaculture (FAO, 2023). The proportion of inland fisheries and aquaculture in India’s overall fish production has increased from 46% in the 1980s to over 85% in recent years, resulting in the country with the second-largest aquaculture production. Fishing is a thriving industry with a wide range of resources and enormous potential in India. It is also a highly significant economic activity. Aquaculture may be the solution to ensuring global food security because fish can produce significantly more biomass per unit surface area than terrestrial animals. Aquaculture has a significant impact on world food security and is also considered a potential factor for the pollution of vast marine resources. The application of eco-friendly aquaculture methods can help the aquaculture industry thrive sustainably by reducing its negative effects on the environment. In the twenty-first century, biotechnology is becoming a crucial technology for long-term sustainability management and protection (Cantor, 2000).

Introduction
Aquaculture has emerged as the fastest-growing sector in global agriculture. The total fish production worldwide includes both wild catches and aquaculture outputs. In recent years, fish production has consistently risen, reaching around 130.9 million tons, which accounts for 52% of the fish available for human consumption (FAO, 2024). Molecular breeding in fisheries and aquaculture utilizes cutting-edge genetic technologies to enhance favourable traits in aquatic species. This approach encompasses the application of molecular markers, genome-wide association studies (GWAS), and gene editing techniques to improve attributes such as growth rates, disease resistance, and resilience to environmental stressors. For example, marker-assisted selection (MAS) facilitates the identification and selection of superior broodstock by leveraging genetic markers associated with advantageous traits.

Introduction
Teleost fish, the largest group of vertebrates, comprise about 30,000 species on Earth, while shellfish include over a million species (Nelson, 2006). About 400 of them have been cultivated, according to Gjedrem and Robinson (2014). One of the most environmentally friendly ways that people may get protein is through fish farming. Over the past few decades, aquaculture has grown rapidly among all agricultural sectors. Fish aquaculture, however, is confronted with several significant obstacles. Most cultivated species have not undergone genetic modification through breeding and are still in their natural state. Although there are a few species-specific feeds, most farmed species do not have tailored diets. Pathogens such as bacteria, parasites, and viruses lead to various fish diseases, resulting in significant financial losses in aquaculture (Meyer and Schnick 1989). Diseases caused aquaculture to lose billions of dollars annually in revenue worldwide. Aquaculture has had
significant issues due to aquatic toxicants (Dunier and Siwicki 1993), which has led to environmental problems in the aquaculture sector (Cao et al., 2007). Innovative solutions and technology are needed to address these issues to make aquaculture advantageous and sustainable.

Introduction
Molecular systematics is a branch of systematics that uses molecular data, particularly DNA sequences, to understand the evolutionary relationships among organisms. It utilizes nucleic acid and amino acid sequence compositions to analyse the taxonomy, phylogeny, and biogeography of biological organisms. It offers a superior alternative to morphological systematics, which relies on physical traits. This approach has significant applications in taxonomic studies, disease diagnosis, biodiversity conservation, and industrial purposes. The integration of molecular biology and bioinformatics has significantly advanced the capabilities of molecular systematics, making it a powerful tool in both microbiological research and public health.

Introduction
Aquaculture is rapidly outpacing all other sectors in agricultural development. The study of fish genetics gained traction in the 20th century, driven by advancements in the understanding of Inheritance and reproduction. During the 1960s, selective breeding programmes aimed at enhancing genetic qualities became more common (Gjedrem and Baranski, 2009). Currently, more than 60 fish and shellfish species are going through selective breeding (Gjedrem and Baranski, 2009). Despite this, many critical traits like resistance to disease, efficiency of feed conversion, fatty acid composition and quality of meat are challenging to assess in breeding prospects but significantly impact the yield and profitability of several aquaculture species. Genetic mapping refers to the process of creating a genetic map (Van Ooijen and Jansen, 2013). Making genetic linkage maps is still essential for carrying out genetic and genomic research and many aquaculture species have had such maps developed. Developments in genotyping and sequencing technologies have made it the creation of higher-density, high-resolution (HR) genetic linkage maps. However, there are now important tasks in linkage analysis due to the usage of a large number of molecular markers. High-density linkage maps are valuable tools for studying genomic biology and evolutionary genetics because they serve as the foundation for QTL (quantitative trait loci) mapping. They facilitate the quantification of recombination rates, linkage disequilibrium levels, and chromosomal rearrangements across chromosomes, between sexes, and among different populations. The development of marker-Assisted Selection (MAS) has gained significant consideration and has significantly accelerated genetic breeding efforts in numerous cultured aquatic organism (Li, 2019; Yu, 2019). Quantitative trait loci (QTL) linked to economically important variables are frequently mapped using genetic linkage maps, which are an invaluable tool for examining genomic regions. (Huang, 2020; Wan 2017; Zhou, 2021). Growth rate, flesh quality, and disease resistance are only a few of the important features that are regulated by several genes or loci. The use of genetic maps in QTL (quantitative trait loci) mapping is essential for determining the locations of genes linked to these traits. (Huang, 2020; Li, 2019; Wan, 2017; Wang, 2018). The mapping of trait-related quantitative trait loci has been greatly improved by recent developments in high-throughput next generation sequencing techniques (You, 2020). Research in this field has greatly advanced through the use of a variety of techniques, including restriction site-associated DNA sequencing (RAD-seq), genotyping-by-sequencing, specific-locus amplified fragment sequencing, and genome-wide association studies (GWAS). Of these, RAD-seq is thought to be an appropriate, robust, and economical approach that has demonstrated 172 Aquaculture Genetics: Breeding, Conservation, and Sustainable Production efficacy in detecting genotypes and single nucleotide polymorphisms (SNPs) (Andrews, 2016). Linkage mapping in aquaculture is a valuable tool that has revolutionized selective breeding. By revealing the genetic foundations of key traits, it allows for more efficient and sustainable aquaculture practices. The integration of linkage mapping with other genomic technologies is expected to enhance productivity, improve disease management, and ensure the long term sustainable growth of aquaculture industries worldwide.

Introduction
The method of selective breeding involves selecting particular breeding prospects to accumulate beneficial alleles and increase the prevalence of desired traits in a population. Characteristics, including growth, disease resistance, reproduction, development, and coloration, are frequently addressed in aquaculture (Maluwa, 2022). Selective breeding, whereby people are picked to have offspring with desired traits, is the foundation of genetic improvement initiatives in all organisms. This is a type of directed evolution in which the breeder determines fitness instead of the organism’s innate capacity for survival and procreation. Darwin’s theory of natural selection was affected by selective breeding, which existed before the mechanics of heredity were discovered. Darwin agreed that deliberate human selection used excellent outcomes (Hill, 2017). By choosing better parents, a species’ desirable features can be improved. Common carp (Cyprinus carpio) were first cultivated in ponds in China 4,000–5,000 years ago, marking the beginning of fish farming. Environmental effects, growing competition for water, and increased demand due to population development and declining wild fish sources are some of the issues aquaculture faces as it grows. Controlled mating and lineage monitoring were two early breeding techniques that resulted in severe inbreeding and decreased output. Mendel’s plant experiments established the groundwork for quantitative and contemporary genetics when they were made public in
1900 (Gjedrem and Baranski, 2010). Mendel’s experiments were confirmed in 1900, marking the beginning of selective breeding for plant production. Fifteen years later, Farm animals were treated using the same methods (Hagedoorn, 1950). Genetically modified stocks are used for most plant and farm animal production. Genetic advancement in aquaculture is still sluggish, though. Although the first aquaculture family-based breeding program began in 1975, by 2010, only 8.2% of aquaculture production was based on genetically modified stocks (Neira, 2010; Rye et al. 2010).

Introduction
In the twenty-first century, the importance of the fisheries and aquaculture sectors to global food security and nutrition has become more and more evident. The global population is anticipated that there will be roughly 10 billion people (by 2050) on the planet, which will lead to an increase in food demand. Over the past few decades, the aquaculture sector acted as the most promising food-producing sector (FAO, 2022). According to reports, the aquaculture sector in India has suffered significant harm from the recurrent occurrence of infectious diseases with bacterial, viral and parasitic pathogens, which has hindered sustainable development. Reports have surfaced regarding the emergence and reappearance of diseases in aquaculture (Bondad-Reantaso et al., 2005). Over the past twenty years, there has been a major increase in the occurrence of pathogens and disease emergence and reemergence. In addition, it has become clear that diseases transcend the boundaries of land and water when they first appear or reappear. This means that the transfer of germs and the dissemination of diseases are closely associated with fish movement, particularly with live fish intended for aquaculture or ornamental seafood sector. Therefore, biosecurity measures are essential for safeguarding our food supply, the environment, and both human and animal populations from the introduction and spread of various diseases (Austin et al., 2022; Austin, 2023).

Introduction
Fisheries and aquaculture are crucial for global food security, providing a significant portion of the world’s animal protein supply. With the rapid growth of the human population and the overfishing of natural fish stocks, it is more important than ever to increase aquaculture production sustainably. Advances in molecular cytogenetics are crucial for promoting sustainable growth and innovation in fisheries and aquaculture. These advancements offer deeper insights into the genetic factors that govern key traits like growth, reproduction, and environmental resilience, enabling aquaculture to address global food demands while safeguarding biodiversity and maintaining genetic
integrity. The integration of these techniques in fisheries and aquaculture has led to significant advancements in the genetic improvement of cultured species, disease management, and biodiversity conservation in recent years. Moreover, these scientific advancements offer innovative methods for effective disease control and the preservation of aquatic biodiversity, all of which contribute to aquaculture’s long-term viability and growth. Over the past two decades, fish karyotype studies have been combined with genome sequencing, revealing more remarkable genome plasticity and variability in fish compared to other vertebrates. Comparative fish genome analysis evaluates divergence rates and explores sex-determination genes and gene family evolution in teleosts. ,Currently, over 80 fish species have their genomes annotated in the Ensembl database (https: //www.ensembl.org/index.html, accessed on 6 April 2021), and around 150 are assembled to the chromosome level in the NCBI database (https://www.ncbi.nlm.nih.gov/genome/). However, the quality of many assembled genomes has been criticized for not meeting reference genome standards. Fish genome sequencing is expected to grow significantly by 2028 due to initiatives such as the Earth BioGenome Project. This chapter will explore the chronological development of cytogenetic techniques used in aquaculture and fisheries, emphasizing their role in improving quality, ensuring disease resistance, and promoting environmentally sustainable practices.

Introduction
By 2050, experts anticipate the world’s population will surpass 9 billion, resulting in a 70 percent increase in the need for food, feed, and fiber. This increase will coincide with significant lifestyle and consumption shifts primarily driven by urbanization. A notable decline in the consumption of grains and pulses is anticipated, while there will be a marked increase in the intake of vegetables, fruits, meat, dairy, and fish. With its long-standing contribution to human nutrition, aquaculture is key in supplying high-quality proteins (Nash 2010; Gui et al., 2018). As the population grows, resource scarcity and environmental degradation become increasingly urgent. The necessity for land resources to meet societal demands has turned attention toward oceans as a critical frontier for human survival. Fish, in particular, are emerging as an important source of high-quality protein for the human food (Baiden et al., 2007). Over the last few decades, aquaculture has developed into the very fastest developing in the agricultural sector. In 2020, fisheries production surpassed 60 percent of what was recorded in the 1990s, driven
by an unprecedented aquaculture output of 122.6 million metric tons (MT (FAO 2022). Given this context, aquaculture and fisheries are expected to be pivotal in ensuring global nutritional security (Subasinghe, 2017). Fish provide around 20% of the world’s animal protein, serving as a healthy option for wealthier populations due to their high polyunsaturated fatty acid (PUFA) content. Simultaneously, small indigenous fish species are vital for the nutrition of lower socioeconomic groups, offering essential proteins, oils, vitamins, and minerals (Mohanty et al., 2010). Worldwide, the fishing and aquaculture industries play a crucial role in enhancing nutrition and sustaining economies. These sectors provide vital nutrients to approximately 3 billion individuals and constitute more than half of the animal protein consumed by 400 million people in economically disadvantaged areas. Fisheries and aquaculture play a crucial role in the livelihoods of over 500 million individuals in developing nations. The growth of aquaculture has been particularly noteworthy, with an annual growth rate of 7%, and fish products account for over 37 percent of the global food trade by volume. As wild fish stocks continue to decline, the cultivation of aquatic species, such as fish, crustaceans, mollusks, and aquatic plants, has become a cornerstone of the global seafood supply. As concerns rise over future food shortages and increasing prices, Fish farming and other forms of aquaculture serve as dependable sources of vital nutrients and protein, playing a significant role in enhancing global food availability and supporting efforts to combat malnutrition worldwide. Furthermore, the sector fosters promoting rural development by creating employment opportunities and enhancing local economic initiatives .In response to the rising demand for aquatic products, significant increases in aquaculture production will be necessary. Biotechnology offers a range of tools to facilitate the sustainable growth of aquaculture, fisheries, and the broader food sector. With the growing public demand for seafood and the degradation of marine habitats, researchers are increasingly focused on biotechnological solutions to enhance marine food production. This positions aquaculture as a rapidly evolving field of research (Melamed et al., 2002). Through biotechnology, researchers can identify and merge genetic characteristics in aquatic organisms to enhance their productivity and quality. Current research emphasizes identifying genes that enhance natural growth

Meteorology is the scientific study of the atmosphere. It focuses on the physical processes and phenomena that occur within the Earth’s atmosphere, including weather and climate. Meteorologists study these processes to understand, explain, and ultimately forecast the Earth’s weather.
Think of the atmosphere as a vast and dynamic fluid that surrounds our planet (Fig. 1.1). Meteorology seeks to understand:
• Composition of the atmosphere: What gases and particles make up the air we breathe?
• Structure of the atmosphere: How is the atmosphere layered (e.g., troposphere, stratosphere)?
• Atmospheric motion: Why does the wind blow? What drives air currents?
• Energy balance: How does the Earth receive and redistribute energy from the sun?
• Formation of weather phenomena: How do clouds, rain, snow, storms, and other weather events develop?

Earth’s atmosphere is a dynamic and complex system that plays a crucial role in supporting life as we know it. This chapter explores into the fascinating world of this gaseous envelope that surrounds our planet, exploring its composition, structure, and the processes that drive both our daily weather and long-term climate. It includes:
• Composition and Structure: It will begin by examining the unique blend of gases that make up the atmosphere, including nitrogen, oxygen, argon, and trace amounts of others. It will also be explored how the atmosphere is structured into distinct layers (troposphere, stratosphere, mesosphere, thermosphere, and exosphere), each with its own characteristics and role.
• Weather: Weather refers to the short-term conditions of the atmosphere at a specific time and place. We’ll discuss the key elements of weather, such as temperature, pressure, humidity, wind, and precipitation, and how they interact to create the ever-changing weather patterns we experience.
• Climate: In contrast to weather, climate describes the long-term average of atmospheric conditions in a particular region. We’ll investigate the factors that influence climate, including latitude, altitude, proximity to oceans, and atmospheric circulation patterns. We’ll also explore the different climate zones found across the globe.
• Interconnectedness: A key focus of this chapter understands how weather and climate are interconnected. Daily weather patterns are influenced by the same fundamental atmospheric processes that shape long-term climate. For example, the way the sun’s energy interacts with the atmosphere drives both daily temperature variations and global climate patterns.

Imagine the air around us. Even though we can’t see it, air has weight. Atmospheric pressure is essentially the force exerted by the weight of the air molecules above a particular point on the Earth’s surface.
Think of it like this: Imagine you’re at the bottom of a swimming pool. The water above presses you down, and you feel that pressure. Similarly, the atmosphere, a giant ocean of air, has layers of air molecules, and their weight presses down on everything below, including us.
• Atmospheric pressure is defined as the force per unit area exerted by the weight of the air column extending from the surface of the earth to the top of the atmosphere above that area (Fig. 3.1).

The process through which heat energy is transferred from a body at higher temperature to a body at lower temperature without any material medium between the two bodies is x called radiation. The outer surface of the the Sun is at higher temperature compared to the surface of the earth. Solar radiation is the electromagnetic energy emitted by the Sun. It is the primary source of energy for the Earth’s climate system, driving atmospheric and oceanic circulation, influencing weather patterns, and sustaining life through photosynthesis.2 This energy  travelsthrough space as electromagnetic waves, encompassing a broad spectrum of wavelengths, from high-energy gamma rays and X-rays to ultraviolet, visible, infrared, and radio waves. The portion of this spectrum that reaches the Earth’s surface is crucial for a multitude of processes, making the study of solar radiation fundamental to understanding our planet’s environment. This introduction will lay the groundwork for exploring the characteristics, distribution, and interaction of solar radiation with the Earth’s atmosphere and surface.
4.1. Wave Length of Radiation
The wavelength of radiation refers to the distance between two consecutive peaks or troughs of a wave. It’s a measure of the length of one complete cycle of the wave (Fig. 4.1).

Light is a form of electromagnetic radiation that is visible to the human eye. It is a crucial aspect of our daily lives, and its importance extends beyond just visibility (Fig. 5.1). Light plays a vital role in various fields, including agriculture, energy, health, and more.
5.1. Properties of Light
• Wavelength: Light consists of different wavelengths, which determine its color. The visible spectrum of light includes colors ranging from approximately 380 nanometers (violet) to 780 nanometers (red).
• Intensity: Light intensity affects its brightness and energy. Higher intensity light is more energetic and can have a greater impact on various processes.
• Direction: Light travels in straight lines and can be directed or focused. This property is essential for applications like lasers, optics, and solar concentrators.