eChapters

Introduction
1.1. Definition and Significance of Natural Products
Natural products are chemical compounds or substances derived from living organisms in nature. These diverse sources, including plants, animals, fungi, and microorganisms, produce a wide range of chemical structures and functions. The significance of natural products lies in their diverse biological activities and potential applications in therapeutics, agriculture, and various industries. Natural products have been used for centuries in traditional medicine and continue to serve as the foundation for many modern pharmaceuticals, providing templates for the development of synthetic analogues and novel drugs. Their complexity and unique structural features often translate into high biological activity, making them valuable in the discovery of new therapeutic agents. Furthermore, natural products are generally perceived as safer and more environmentally friendly compared to synthetic chemicals, contributing to their appeal in numerous applications.
1.2. Historical Perspective on the Use of Natural Products
The use of natural substances has a long history, with evidence of their application in ancient civilizations such as Egypt, China, India, and Greece. Traditional medical systems, including Ayurveda, Traditional Chinese Medicine, and Indigenous practices, have utilized plants, animals, and minerals to treat various ailments. These early practices laid the foundation for the systematic investigation of natural products and their medicinal potential. One of the earliest documented uses of natural products in medicine is the Ebers Papyrus, an ancient Egyptian text from around 1550 BCE (Packard, 1931). Similarly, ancient Indian texts, such as the Charaka Samhita and the Sushruta Samhita, describe the use of plant-based medicines in Ayurvedic tradition. The scientific investigation of natural products gained momentum in the 19th century, with the isolation of pure compounds, including morphine, quinine, and penicillin.
1.3. Current Trends and Applications
Natural products are invaluable in various industries, serving as a rich source of bioactive compounds for drug development, sustainable agriculture, and functional food products. Many modern medicines, such as the anticancer drug paclitaxel and the antimalarial artemisinin, are derived from natural sources. These naturally-derived compounds often possess unique structures and mechanisms of action that are difficult to replicate synthetically.

Introduction 
Before 1800, it was believed that organic compounds could only be synthesized by living organisms, not possible in the laboratory. Friedrich Wohler successfully synthesized the first organic compound urea in the laboratory. Recently, synthetic organic chemistry has been a well-established science to construct derivative or new compounds, which have been utilized in the fields of medicine, food, clothing, nutrition, polymers, plastic, highly durable materials, and high energy fuels, that are beneficial to humans, and society. To achieve faster organic transformations, many advancements have been made, as a result, catalysts have been taken into account, which provides an alternate faster path for the reaction by lowering the activation energy. The catalysts play a very crucial role in achieving organic transformations more efficiently, affordably, and with higher yields in less time. Additionally, the catalyst which is environment-friendly and easily recoverable after completion of the process, would be beneficial in both economic and ecological ways (Trost, 1991). The utilization of nanoparticles as catalysts in organic transformations is more advantageous over conventional catalysts because of lower catalyst loadings, and high performance of the reaction in heterogenous phase. The large surface area of nanoparticles is responsible for high reactivity towards organic transformations. Till now, many nano-dimension metals like gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) efficiently utilized to catalyze organic transformations (Muskan et al., 2022). The ever-growing demand for productive and sustainable catalytic systems has driven the utilization of transition metal nanoparticles as catalysts in organic conversions (Pathak et al., 2024). Among these, copper-based nanoparticles have shown great potential as catalysts due to their large surface area and variable oxidation states, which enable them to function as both oxidizing and reducing agents, effectively replacing traditional palladium catalysts (Pathak et al., 2024). Copper-based nanoparticles having specific physicochemical properties, varying in size, porosity, surface/volume ratio, and shape can also be synthesized through different physical, chemical, and biogenic methodologies. Most physical and chemical methods are considered toxic, have huge energy demands, and have high-temperature demands. In contrast, biogenic methods are simple and non-toxic. The biogenic procedure can be done by using microbes, fungi, algae, plants, extracts, etc. This chapter provides insights into various aspects of the biogenic synthesis of copper-based nanoparticles using plants and multiple catalytic applications in recent organic transformations.

1. Introduction
Hydrogenation plays a vital role in the transformation of organic compounds, making it essential for synthesizing fine chemicals and pharmaceuticals. This process is widely utilized in both laboratories and for industrial applications (Andersson et al., 2008). Typically, two approaches are used for hydrogenation: traditional one involves direct hydrogenation using pressurized hydrogen gas, and the other relies on transfer hydrogenation (TH), which involves addition of hydrogen into a molecule from a non-H2 sources (Johnstone et al., 1985). The use of high-pressure hydrogen gas, however, demands significant investment in infrastructure, making it less economically feasible for developing a sustainable hydrogenation industry. In contrast, TH has gained increasing attention due to its sustainability, particularly when employing hydrogen donors derived from biomass, such as alcohols and organic acids, which are abundant, cost-effective, and easy to handle instead of using non-renewable H2 gas for reduction of CO2 (Becattini et al., 2021) (Figure 1).
2. Historical Background and Classification
The hydrogen transfer process has a rich history spanning over a century. In 1903, Knoevenagel first demonstrated that palladium black effectively promoted the disproportionation of dimethyl 1,4-dihydroterephthalate into dimethyl terephthalate and cis-hexahydroterephthalate, in which hydrogen transfer was occurred between identical molecules (identical donor and acceptor) (Knoevenagel et al., 1905). This pioneering work established the foundation for hydrogen transfer reactions. Braude and Linstead later categorized these reactions into three distinct types (Braude et al., 1954):

Introduction 
Schiff base ligands (also called azomethines) were first revealed by German chemist Hugo Schiff in 1864. They are synthesized through a straightforward condensation reaction between an amine and a carbonyl compound (aldehyde or ketone). This reaction forms a characteristic imine group (>C=N-) while eliminating a water molecule as a byproduct. Schiff bases are highly versatile and serve as ligands for various transition metals, forming complexes with applications in catalysis, material science, and medicinal chemistry. Their ease of synthesis, tunable structure, and ability to stabilize metal centers make them valuable in both academic research and industrial processes (Cozzi, 2004). They can form stable complexes with almost all metal ions, offering various coordination geometries. Their flexibility makes them valuable in catalysis, medicinal chemistry, and materials science, with wide applications across these fields. Schiff base metal complexes exhibit exceptional catalytic performance in various high-temperature reactions (>100 °C), even under humid conditions. These complexes are widely employed in catalytic processes, such as oxidation, reduction, carbon-carbon bond formation, polymerization, and asymmetric synthesis (Zoubi et al., 2016). Recently, interest in olefin polymerization has increased due to their ability to catalyze the formation of commercially significant branched and linear polyethylenes. Their versatility, structural tunability, and high stability make them ideal for such applications, offering pathways to develop advanced materials with tailored properties for industrial and commercial use. Schiff base complexes thus remain central to modern catalysis research. These complexes have shown great potential in producing polymers with tailored properties, making them highly valuable in industrial applications. Schiff base complexes have gained attention for their catalytic roles, particularly in the reduction of ketones to alcohols and the alkylation of allylic substrates. These complexes, typically coordinating with metal ions, facilitate crucial organic transformations by stabilizing intermediates, offering an efficient and selective route for various chemical reactions. Schiff base complexes enable controlled ring-opening polymerization of cycloalkenes at low temperatures, offering precise molecular weight regulation without side reactions. In contrast, traditional catalysts like tungsten, molybdenum, or ruthenium with alkylating agents require high temperatures and lack molecular weight control, making Schiff bases more efficient for polymerization. The oxidation of hydrocarbons catalyzed by Schiff base complexes has garnered significant academic and industrial interest. These metal complexes are studied for their ability to facilitate efficient and selective oxidation reactions, offering insight into their catalytic activity and potential applications in chemical processes and industrial oxidation technologies. The ring-opening of large cycloalkanes is challenging due to their stability, but Schiff base complexes of cobalt(II) and chromium(III) effectively catalyze these reactions. These complexes enhance metal center reactivity and stabilize intermediates, enabling efficient cleavage of cyclic structures and expanding possibilities for catalytic transformations in synthetic and industrial chemistry. These complexes not only facilitate the process but also exhibit important enantioselectivity, creating them valuable catalysts in asymmetric synthesis and fine chemical production. Chiral Schiff base complexes have emerged as versatile and efficient catalysts in various organic transformations, particularly in asymmetric synthesis. Schiff bases derived from salen and binaphthyl frameworks are effective in Michael addition reactions, offering high enantioselectivity and catalytic efficiency. While transition metal complexes

1. Introduction
Palladium (Pd), which has the atomic number 46, was discovered in 1803 by the English chemist William Hyde Wollaston. It is a well-known transition metal recognized for its versatile catalytic properties in chemical reactions, material sciences, and various industries. The palladium-catalyzed coupling reactions extend beyond the formation of biaryls. Many carbon–carbon, carbon–nitrogen, and carbon–oxygen bond-forming reactions in organic chemistry are facilitated by palladium salts and catalytic systems derived from palladium. Some notable organic reactions that involve palladium include the Mizoroki-Heck reaction, (Biffis et al., 2018, Koranne et al., 2023, Lee et al., 2021) Suzuki-Miyaura coupling, (Zhang et al., 2023) Negishi reaction, (Haas et al., 2016). Stille coupling, (Cordovilla et al., 2015). Sonogashira coupling, (Chinchilla & Najera, 2007) Tsuji-Trost reactions, (Kvasovs et al., 2023). and Wacker catalytic processes. (Zhang et al., 2023) In this chapter, we will focus on the applications of palladium and its salts in C-N bond-forming reactions.
2. Palladium (Pd)-Catalyzed C–N Bond Formation
Besides copper, palladium metal is considered as the most widely used metal in organic synthesis. The discovery of cross-coupling reactions catalyzed by palladium(0) complexes in the 1970s was a highly important achievement that substantially changed the strategy of organic chemistry. Best applications of the palladium salts are in enantiolective and new C-N bond forming reactions. Stephen L. Buchwald and John F. Hartwig opened up the catalytic scope of palladium in newer methodologies on C–N bond forming reactions during 1990s, (Ruiz- Castillo & Buchwald, 2016) and henceforth, new methodologies of carbocycles, heterocycles, and simple organic compounds have been created in large scales (Rayadurgam et al., 2021). The mechanisms of palladium-catalyzed C-N cross-coupling reactions are critically discussed in numerous high-quality research journals with different theoretical and experimentally proven methods (Beletskaya & Averin, 2021). However, the most acceptable mechanistic pathway to reaction products in these Pd-catalyzed reactions involving palladium is illustrated in Scheme 1. The process begins with the formation of a palladium complex through the reaction of an aryl halide (which can be aliphatic, heteroaryl, or functionalized alkenes/alkynes), a palladium salt, and amino nucleophiles. In the presence of a suitable base, the loosely bonded halide or any leaving groups are eliminated, leading to the formation of a palladium (IV) complex. This complex then undergoes reductive elimination, resulting in stable aminated aryl, heteroaryl, alkyl, or functionalized alkenes/ alkynes. Additionally, a more generalized reaction mechanism is presented in a circular pathway format, highlighting the bonding approaches, rearrangements, intermediate formations, and the final release of target compounds, as depicted in Scheme 1. The involvement of higher valence organo-palladium complexes in such catalytic transformations have been well established (Hickman & Sanford, 2012).

1. Introduction
With commercial uses ranging from the production of high-quality substances to the manufacture of pharmaceuticals, hydrogenation is an essential step in the formation of organic compounds (Cerveny et al., 1986). There are two main approaches to hydrogenation: direct hydrogenation, which employs pressurized hydrogen gas, and transfer hydrogenation (TH). A versatile and effective approach for producing a large variety of hydrogenated molecules, the TH method entails adding H2 to molecules via an origin other than H2 gas. This approach is increasingly preferred over direct hydrogenation and has recently attracted considerable interest in hydrogenation research. The benefits of the TH method include (i) the elimination of potentially dangerous pressurized hydrogen gas and the complexity of experimental setups, (ii) the accessibility, cost-effectiveness, and ease of use of hydrogen donors, (iii) the potential to recycle the main byproduct, and (iv) the availability and stability of the catalysts employed (Brieger et al., 1974).
1.1. The Historical Context, Core Principles, and Groundbreaking Research on TH (transfer hydrogenation)
With a history spanning more than a century, the TH reaction has a rich past. In order to enable hydrogen transfer between equivalent donor and acceptor units, Knoevenagel showed in 1903 that palladium black could efficiently aid in the disproportionation of dimethyl 1,4-dihydro terephthalate into dimethyl terephthalate and cis-hexahydroterephthalate. Three primary types of hydrogen transfer reactions were distinguished by Braude and Linstead: (i) the hydrogen movement within a single molecule; (ii) hydrogen disproportionation, which entails transfer among identical donor and acceptor units; and (iii) TH-dehydrogenation, which takes place between distinct donor and acceptor units. Of them, THdehydrogenation— often just called TH—is the most well-known and often applied sector. Meerwein-Ponndorf-Verley (MPV) reductions, early transition metal-catalyzed reactions, organocatalytic processes, enzyme-catalyzed reactions, heat techniques, and base-catalyzed reactions are among the types of TH reactions that are classified according to the type of catalyst used. The historical context, important research, and underlying ideas of each category will be covered in detail in this section.In 1925, Meerwein et al. independently reported the significant MPV reduction, which were the first TH process involving carbonyl groups. After earning his Ph.D. under Richard Anschütz in Bonn, where he was appointed a professor in 1914, Hans Meerwein (1879–1965) moved to Königsberg in 1922 and then to Marburg. His name is associated with a number of processes and reagents,

Introduction
Metal-catalyzed C–N cross-coupling reactions are powerful synthetic methods for producing both simple and complex organic compounds, including natural products. These methodologies typically involve shorter reaction times and can achieve good to excellent yields with a broad range of reactions, exhibiting high regioselectivity in certain cases. The coupling of carbon and nitrogen to create organic compounds that contain nitrogen, such as urea and amides, is one of the most fundamental chemical reactions and plays a crucial role in human civilization. C–N coupling reactions have significant importance in industry, starting with the production of ammonia (NH3) through the Haber–Bosch process. Molecules containing C–N bonds are prevalent in a variety of organic materials, natural products, pharmaceutical compounds, and agricultural chemicals. This wide applicability makes them crucial chemicals, leading synthetic organic chemists to continuously seek out novel synthetic methods. In recent years, numerous synthetic strategies involving either transition metals or metal-free enzymes and biocatalysts have emerged. Additionally, new technologies, such as electroreduction, have been employed in these C–N coupling processes (Bariwal & Van der Eycken, 2013, Li et al., 2022, Yin et al., 2024, Rahman et al., 2022).
Common copper salts/complexes, and diamino ligands
Copper is commonly found coordinated by two, three, or four ligands, resulting in linear, trigonal planar, or tetrahedral geometries. Well-known and inexpensive copper halides, such as copper (II) glycinate, copper (II) acetylacetonate (particularly CuI), copper acetates, copper oxide, copper sulfate, and copper triflate salts, are widely used as catalytic systems in C–N bond-forming reactions. Additionally, other complexes such as Cu di-isopropyl salicylate (CuDIPS), copper phthalocyanine, and copper aspirinates have also been employed in these reactions. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions are well-established methods for forming triazoles via C–N bonds in one pot. These reactions often involve domino click chemistry and green approach methodologies, leading to the synthesis of biologically important triazoles. Copper salts in combination with diamine ligands are widely used in C–N bond-forming reactions through cross-coupling strategies. Some notable examples of such diamino compounds that can coordinate with copper are illustrated in Figure 1.

Introduction 
Over the past few decades, magnetic nanoparticles (MNPs) have been showing great importance in the field of organic synthetic reactions, catalysis, sensors, biomedicines, environment rehabilitation, etc. (Gawande, M. B. et al., 2013; Del Rio, M. et al., 2022). Numerous research teams have recognized the significance of solid support materials for the creation of environmentally acceptable nano catalysts with high catalytic activity in light of the infinite advantages of MNPs (Sharma, R. K. et al., 2016; Gawande, M. B. et al., 2013; Deng, J. et al., 2011; Nasrollahzadeh, M. et al., 2015; Hudson, R. et al., 2014; Payra, S. et al., 2017; Chng, L. L. et al., 2013; Parandhaman, T. et al., 2017; Zhang, F. et al., 2014; Pourjavadi, A. et al., 2012). Heterogeneous catalysts in organic chemistry are solid catalysts that, while remaining in a distinct phase (usually solid) from the reactants (generally liquids or gasses), promote chemical reactions without being consumed in the process. These catalysts, which have multiple benefits such as ease of separation, recyclability, and selective reactivity, are essential in a variety of industrial processes and laboratory reactions (Lattuada, M. et al., 2007; Jiang, K. et al., 2011). The standard formula for ferrite nanoparticles is MFe2O4, where M is usually divalent metal ion like copper (Cu), zinc (Zn), or nickel (Ni), and iron (Fe) is the common metal (Kazemi, M. et al., 2018). These nanoparticles work very well as heterogeneous catalysts in a variety of chemical reactions because of their special magnetic and electrical characteristics.Because of its special qualities as a catalyst in a variety of processes, copper ferrite (CuFeO4), a mixed-metal oxide, has drawn interest in organic chemistry (Kharisov, B. I. et al., 2019; Zhu, J. et al., 2014; Vannucci, A. K. et al., 2012). It is a spinel-type ferrite that can catalyse a variety of organic transformations because it combines iron and copper in a stable, highly active structure. With benefits including high stability, reusability, and low toxicity, these catalysts are frequently employed in processes like oxidation, coupling, and reduction (Taghavi Fardood, S. et al., 2018). The Figure 1 represents schematic diagram of a reaction where the ferrite nanoparticles as catalyst have been recovered with the aid of an external magnet after the formation of reaction product.

Introduction 
Natural product scaffolds and heterocyclic ring-based organic compounds are crucial for developing bioactive substances and therapeutic drugs, serving as essential structural units for bioactive molecules and pharmacophores. Numerous experts have worked hard to design and develop organic synthesis, which could make it easier to obtain these crucial organic chemicals. Due to the multistep reactions involving several hazardous chemicals, conventional organic synthesis is neither commercially feasible nor environmentally benign. To overcome these issues, improvisation or developing a new synthetic approach with a superior atom and step economic procedure is always desirable. The biggest challenge in organic synthesis is functionalizing a carbon-hydrogen (C-H) bond in a molecule. This is generally achieved through radical intermediates and catalysis by enzymes or transition metals. The transition metal-catalyzed process is the most popular due to its high chemoselectivity, site-selectivity, and efficiency (Yamaguchi et al., 2012). Inert C-H bonds can be directly functionalized, offering appealing synthetic strategies that enhance both atom and step economy and provide an overall efficiency of multistep synthetic sequences, leading to a sustainable and greener approach. These optimizations provide atom and step-economical methods for synthesizing structurally complicated organic molecules with broad substrate scope and good to exceptional product yields (Ackermann, 2011; Gensch et al., 2016). Direct conversion from the substrate to the desired organic compound without pre-functionalization is attractive and cost-effective. However, it can be quite challenging to selectively functionalize particular C-H bonds due to the inertness of those C-H bonds having similar electronic and bonding properties and the ubiquity of C-H bonds in organic molecules (Sambiagio et al., 2018). Two main techniques have been explored to obtain selectivity in C-H bond functionalization (Brückl et al., 2012). The first is based only on the natural reactivity pattern of an organic molecule. This strategy is highly successful for some heterocycles with at least one specific reactive site due to the presence of heteroatoms. However, it produces inadequate selectivity for most aliphatic and aromatic hydrocarbons. The latter is to direct further functionalization at a particular site using directing groups already present in the molecule (Kuhl et al., 2012). The development of directing groups that effectively control the regioselectivity of C-H functionalization has lately transformed this field, enabling the incorporation of desired groups in unfunctionalized sites (Docherty et al., 2023; Labinger & Bercaw, 2002). Employing directing groups, various functional groups are added to a molecule using this method. Directing groups are crucial for breaking a C-H bond in a transition metal catalysis reaction, where the metal center in the active catalyst complex is usually coordinated with the substrate through a weak interaction with the nearby C-H bond. This interaction is typically not selective; thus, the metal centre may activate numerous C-H bonds on the substrate. However, when a directing group is incorporated into a substrate, the metal center can interact more strongly and regioselectively with a specific region on the substrate as directed by the directing group. This causes selective cleavage

Introduction
India has vast animal genetic resources with a wide variety of indigenous farm animals including cattle. The cattle breeds have evolved over generations to adapt to the agro-climatic and socio-economic needs of the people. Domestic animal diversity is defined as the spectrum of genetic differences within each breed and across all breeds within each domestic animal species, together with the species differences; all of which are available for the sustainable intensification of food and agriculture production . The domestic animal diversity has evolved over millions of years through the processes of natural selection forming and stabilizing each of the species used in food and agriculture. Over the more recent millennia the interaction between environmental and human selection has led to the development of genetically distinct breeds. Selection processes, directed by both humans and the environment, together with the random sampling processes causing genetic populations to drift over generations, have accelerated the development of the diversity within species leading to the creation of distinct genetic differences amongst breeds.
India is the seventh largest country in the world and it is recognized as one of the 12-mega biodiversity centres of the world. It is well marked off from the rest of Asia by mountains and the sea, which gives the country a distinct geographical entity. Due to diverse agro-ecological regions and topographic conditions, India has rich repository of both flora and fauna. India has vast animal genetic resources with a wide variety of indigenous farm animals. Indigenous animal breeds are now 53 for cattle, 20 for buffalo, 39 for goat, 45 for sheep, 8 for horses & ponies, 9 for camel, 14 for pig, 3 for donkey, 3 for dog, 1 for yak, 20 for chicken, 3 for duck, and 1 for geese, besides many other non-descript and mixed populations. Livestock husbandry is an age-old important occupation for Indian farmers. The unique and rich animal biodiversity is extensively referred to in Indian scriptures.

Understanding Immunogenetics
The study of genetic basis of the immune response is known as immunogenetics. The term was introduced with the discovery of ABO blood groups and were first demonstrated through the existence of “natural” antibodies i.e., isoantibodies. The broad field of immunogenetics include study of normal immunological pathways as well as identification of genetic variations that result in immune defects, which may facilitate detection of new therapeutic targets for immune diseases. Hence, understanding and subsequent manipulation of host immune response (immunomodulation) is the most precise and effective tool to reduce disease incidences and nullify the limitations associated with antibiotic treatment or vaccination. Therefore, breeding for disease resistance has gained considerable attention from researchers in the recent past.
Immune Response Genes
Often it was observed that individuals respond differently to same infectious agent. A possible explanation may be the genetic variability between them. Indeed, many studies have looked for associations between genes involved in immunity and disease outcome and it has been found that certain immune response (Ir) genes play the crucial role. This concept was discovered in the mid-1960s and this discovery introduced an apparently new level of antigen recognition whose diversity and specificity had to be explained in addition to those of familiar immunoglobulins. Hence immune response (Ir) genes were defined as antigenspecific genes that control the ability of an animal to raise an immune response, either humoral or cellular to a particular antigen .

Reproduction is the backbone of animal production and productivity is the key to development. Reproductive inefficiency is one of the most important causes of economic losses in animal industries and it is realized throughout the world. Despite the remarkable advancement that has been made in the field of reproductive physiology in recent years, infertility due to low conception rate and high embryonic mortality rate remains a major problem. To meet future needs and to be able to sustain agricultural production, agricultural research and its applications need to use all emerging technologies one of which is modern reproductive biotechnologies.5 Thus, various assisted-reproductive techniques have been developed and refined to obtain a large number of offspring from genetically superior animals or obtain offspring from infertile (or sub-fertile) animals in addition to disease control. Reproductive biotechnologies intend to be used routinely to shorten generational intervals and to propagate genetic material among breeding animal populations. To achieve this goal, reproductive technologies have been developed in generations over the years, namely artificial insemination (AI), embryo transfer (ET), manipulation of fertilization in vitro (IVF), cloning and transgenesis. These, together with sperm separation techniques, including that of selection of spermatozoa for chromosomal sex (commonly named sex-sorting) all face today a strong wave of increasing commercialization.9 Hence, this review paper highlighted the reproductive biotechnology options and their roles in the improvement of livestock production.
Roles of Reproductive Biotechnology in Animal Production
Biotechnology is defined as a technique that uses living organisms to make or modify and improve products. The emergence and development of reproductive technologies have been driven by the economic gain offered by the potential increase in the number of offspring from genetically superior animals or simply to safeguard the genetic pool of infertile or sub-fertile animals. In other words, reproductive technologies were developed to offer possibilities for wider use of superior germplasm.In recent times, there has been increasing challenges for

Animal husbandry programmes have been run through the State schemes. Each State has to evolve its own breeding policy deciding on choice of breed, cross breeding strategy, optional mixture of animals of different breeds required, breeding goals in terms of expected genetic progress to be achieved, specific breeding programmes and the control measures that should be adopted to achieve the desired genetic gains in the population.
General parameters in the breeding policy formulated by various States are
• Indigenous milch breeds such as Shaiwal, Red Sindhi and Gir, should be selectively developed for dairy traits in their native tracts.
• Indigenous dualpurpose breeds such as Hariana, Tharparkar, Rathi, Kankrej, Gaolao, Ongole Deoni etc. should be developed selectively in their native tracts for dairy and draft traits.
• Indigenous draft breeds like Kangayam, Hallikar, Khillari, Amrit Mahal etc. should be developed selectively for draft traits in their native tract.
• Non-descript cattle will be bred with exotic semen to produce cross breed with Holstein Friesian or jersey and maintaing 50% exotic impenitence. In some States Red Sindhi, Tharparkar and Hariana have also been used upgrading non-descript cattle.
• Development of indigenous breeds
• To develop indigenous breeds Government of India has initiated three schemes namely National Project for Cattle and Buffalo Breeding, Central Herd registration scheme, Central Cattle Breeding Farms.
• Central Herd Registration Scheme
• For identification and location of superior germplasms of cattle and buffaloes, propagation of superior genetic stock, regulating sale and purchase, help in formation of breeders societies and to meet requirement of indigenous bulls in the different parts of the country. Government of India

The global demand for high producer animals is rising, and cattle producers are looking for ways to improve productivity and efficiency. One method for developing cattle with enhanced traits is crossbreeding – combining the desirable qualities of two or more cattle breeds into one animal.
Crossbreeding allows cattle producers to take advantage of breed differences and heterosis while managing unwanted traits.
Implementing an effective breeding strategy can help cattle producers select for optimum performance in their herd.
Benefits of Crossbreeding Cattle
Crossbreeding offers commercial beef producers several advantages compared to using only straight-breed animals. Some key benefits include:
1. Heterosis – Crossbred animals exhibit hybrid vigour or heterosis, which is the increased performance for traits like growth rate, fertility, and longevity compared to purebred animals.
The heterosis effect results from the increase in heterozygosity or genetic diversity from combining divergent breeds. Heterosis levels are highest in first-cross animals (the initial cross between two pure breeds.
2. Complementarity – An additional advantage of crossbreeding is combining the strengths of two or more breeds to produce an animal with the ideal blend of traits.
For example, crossing a breed known for high intramuscular fat and marbling, like Angus, with a lean breed that excels in meat yield and growth, like Charolais, can result in an animal with both good marbling and leanness.
3. Breed Complementation – Crossbred animals also benefit from breed complementation. This occurs when the strengths in one breed offset or complement the weaknesses in the other breed. For example, British maternal breeds tend to be lower in milk production but exhibit excellent maternal behaviour

Closed Nucleus Breeding Scheme (CNBS)
In the CNBS the germplasm flows in only one direction. That is from the nucleus to the cooperating herds or flocks. In the traditional pyramid there is only one way of flow of genes with in the pyramid, downwards from top to bottom. This means that the only some of cumulative genetic progress in commercial production is improvement that occurs at the top of the pyramid. If the nucleus tier makes no genetic improvement then no improvement will be noticed in the root of the tiers. However even if the nucleus tier thus make improvement progress is not seen immediately at lower levels in the pyramid. It takes time for the genetic progress in one tier to be transmitted to the next tier. The resultant difference in performance between any two adjacent tiers is called IMPROVEMENT LAG.
It is usually expressed in terms of no. of years of genetic improvement that are represented by the difference in performance between adjacent tiers. There are two factors that affect the size of the improvement. Age structure in the lower tiers. Source and merit of dams used in the lower tiers, e.g. Lag can be reduced by keeping the sires and dams in lower tiers for shorter periods of time before replacing them with younger stock. Lag can be reduced by transferring females downwards tiers. Even greater reduction result if some nucleus parent can be transferred directly to commercial tier. Only downward flow of genes from nucleus to lower tiers. No gene flow into nucleus tier, e.g. Most traditional breed of livestock modern pig and poultry breeding programme have CNBS structure.

There is urgent need to increase the production in order to meet the demand for the exploding population. This could be achieved by applying various modern methodologies in selection and breeding of livestock. Increasing the productivity through genetic improvement requires adequate identification and intensive selection of genetically superior sires. About 93 per cent of the total herd improvement comes from breeding of young bulls from tested sires and only six per cent from selection of dams.
With the advances in artificial insemination and cryopreservation of semen, a sire has a potential of serving 3/4th million cows and producing 1/4th million progenies.
Thus, selection of bulls is of great importance in dairy herd improvement.
For maximising the genetic gain by sire selection, it is essential that the method of estimating breeding values of sires should be unbiased and efficient. The breeding value refers to the average genetic effect of the genes passed on by the individual to its offspring and is estimated to know whether the individual is genetically superior to other individuals or not for the trait concerned.

The sheep population in India is estimated to be about 65.07 million ranking second in the world (Anonymous, 2019). There are 42 descript breeds of sheep distributed in various agro climatic zones of the country (Anonymous, 2017). It is well-known that the sheep rearing provides nutritional security and insurance to the farmer at the time of crisis due to crop failure. Therefore, sheep is seen as, “finance elevator” by the countryside poor farmer (Sharif et al., 2011). Two major sources of income; meat and wool make sheep industry a very profitable enterprise. In addition, a rich source of nitrogen, phosphorus and potash present in the droppings of sheep improves the soil fertility. Indian sub-continent isa rich source of diverse ovine germ plasm.
The native breeds of sheep of from India are well adapted to geo-physical and agro-climatic conditions. Most of the breeds of sheep in India have evolved through natural selection. Most of the breeds have generally been named after their place of origin and on the basis of prominent characters. This vast ovine biodiversity in India is being eroded rapidly and more than 50% of sheep breeds are currently under threat.
Sheep biodiversity in India is characterized by high degree of endemism and variations in agro-climatic conditions of the different regions have led to the development of various breeds/strains. Selecting for breeding animals with superior EBV in growth rate, meat, milk, or wool production, or with other desirable traits has revolutionized livestock production through out the world.
Breeding means, the manner in which selected males and females are mated. The breeders identify and select desirable qualities in animals for future mating and discard less desirable qualities. For the improvement of livestock (farm animals) selection and breeding must be practiced simultaneously. Continuous selective breeding leads to homozygosity in a population resulting in loss of variability. If all the individuals are alike, the breeder cannot make progress in future. Hence, there is a need to create variability in population. This can be achieved by breeding. Therefore, selection and breeding go hand in hand for the improvement of livestock.

It is imperative that the country should develop strategic planning so that available resources in different agro ecological zones of the country to exploited judiciously and utilize sustainably for further enhancing the productivity of cattle and buffaloes. Therefore, agroclimatic region and animal production system-based breeding policy strategies with a focus on large scale implementations of improved animal genetics and breeding innovations by development organizations with active participation of farmers/breeders are discussed here. Before developing sustainable breeding strategies for improving the productivity performance of a particular breed/genetic group of animal population in a given agro-climatic region, it is necessary to have a comprehensive details of population size of breed along with analysis of existing activities such as farmer/breeder’s perceptions and socio-economic levels, agriculture and livestock production systems, available feed and fodder resources, animal genetic resources, their production potentials and utilization pattern, breeding organizations, infrastructure and development facilities . The Quinquennial All India Livestock Census contains information on the herd/flock structure, sex, age, etc. and it does not reflect the factual situation about the status of breeds in terms of their population. Hence, the actual population of each breed and their geographical distribution is not clearly known. The correct picture about these breeds would be available only when breed-wise census of the livestock is carried out and status and performance of breeds are surveyed in their natural habitat and the same has been initiated in the recent survey . In the back ground of the collected and collated information on all above aspects, following region specific animal breeding strategies can be planned for conservation and genetic improvement of bovine genetic resources under different animal production systems.
Genetic Improvement of Non-Descript Zebu Cattle by Crossbreeding
The most rapid and effective approach to genetically improve the largest chunk of non-descript zebu cattle population is through crossbreeding with exotic dairy cattle breeds particularly in milk shed areas around peri-urban and industrial towns

Combining Ability Estimation
Crosses made in a definite fashion are a prerequisite for combining ability estimation. Estimated by half-sib (GCA) and full-sib (SCA) mating. Various steps like parent selection for crosses, performing crosses, their evaluation, and interpretation are involved while estimating of combining ability. For analysis of crosses, biometrical techniques like diallel analysis, partial diallel, and Line x tester analysis are used. If GCA variance is higher than SCA variance the importance of AGA & parent selection will be effective for the improvement of such traits. If SCA variance is higher than GCA variance there is importance of NAGA( dominance & epistasis) & Heterosis breeding may be rewarding. If GCA=SCA variance then AGA & NAGA are equally important in the expression of character, In this situation reciprocal recurrent selection may be adopted for population improvement.
Selection for GCA
General combining ability (GCA) is the average value of the inbred line based on its behavior in crosses with other lines. The mean performance of the line is expressed as deviation from the mean of all crosses.GCA is owing to the activity of genes which are largely additive in their effects as well as additive × additive interactions.

Definition: Heterosis is defined as the percent increase in the performance of outbred animals over the average of their parents.
The mean superiority of hybrids over the average of their parental lines is called heterosis. Heterosis or hybrid vigor is the increased vigor of the offspring over that of the parents when unrelated individuals are mated. Hybrid vigor includes greater viability, faster growth rate, greater milk production and greater wool production in domestic animals. The amount by which the hybrids exceed the mean performance of better parent is called heterobeltiosis or Euheterosis. The term heterosis was coined by G.H. Shull (1914). Heterosis or hybrid vigour is synonym to each other. However, the heterosis is a phenomena exhibited by an individual or a group of individuals due to heterozygosity of genes. Heterosis in quantitative terms can also be defined as the non-additive gene action. While “hybrid vigour” is the resultant of heterosis phenomena expressed phenotypically by an increase in vigour, size, production, reproduction, survival rate, growth, and economic returns etc. the heterosis is a measure of extent magnitude of out breeding.
In livestock, hybrids may be produced by crossing between two species/breeds/ lines/strains. Technically, heterosis may be positive or negative. However, the desirability of a trait is more important than the sign of heterosis. In some cases, the negative heterosis could be a desirable one (e.g. age at first lay, age at first calving, calving interval, back fat thickness etc.). The amount of heterosis obtained usually depends upon the extent of heterozygosity attained by the hybrids, which in turn is based on the diversity of sire and dam lines crossed. It also depends upon the degree of dominance, over dominance and/ or for which the heterosis is exhibited. Thus, the main causes of heterosis are directional dominance, over dominance and epistasis.