eChapters

Introduction

India is primarily an agriculture-based country, with the livestock sector being a vital component of its agricultural landscape. The meat sector plays a crucial role in providing livelihoods and jobs to rural and village populations. Slaughtering food animals not only yields meat but also generates valuable byproducts that can significantly benefit society. Typically, only one-third of an animal’s weight is meat; the remaining two-thirds consist of byproducts and waste, which must be effectively processed and utilized. Efficient utilization of these byproducts directly impacts both the economy and environmental pollution. The yield of animal byproducts can range from 50% to 60% of an animal’s live weight. According to statistics from the Department of Animal Husbandry and Dairying (DAHD, 2019), India saw the slaughter of 11.92 million buffalo, 3.05 million cattle, 50.86 million sheep, 97.19 million goats, 10.73 million pigs, and over 2.81 million poultry birds in 2018-19, resulting in the production of 8.11 million tonnes of meat.

Introduction

As per 20th Livestock Census, 2019 goat population in the country was 148.8 million, the second largest species in terms of number after cattle. Uttar Pradesh, one of India’s largest states in terms of population and agricultural activity, boasts a substantial goat population of 14.48 million, which accounts for approximately 9.73% of the country’s total goat population. Goats indeed play a crucial role in many agrarian economies worldwide, including India. In regions where crop and dairy farming may not be as economically viable, goats provide a valuable source of income and sustenance for small and marginal farmers as well as landless laborers. Goats, specifically Capra hircus, possess unique qualities that make them valuable assets in meeting this growing demand for animal protein (Rout et al. 2018). The livestock market has been experiencing significant growth, with global trade presenting vast opportunities for livestock farmers to increase their income. One notable trend over the past decade has been the increasing preference for animal protein consumption worldwide. This shift in dietary habits has led to a surge in demand for meat products, particularly in developing countries where access to protein-rich foods may be limited. The adaptability, diversity, and versatility of goats make them an invaluable resource for agriculture and livelihoods in both developed and developing nations, contributing to food security and economic sustainability in many regions (Mazhangaraet al. 2019).

Introduction

Podocytes are highly specialized cells with a complex structure that plays an important role in kidney physiology. The characteristic feature of these cells is that its cell body has foot processes which interdigitates with the foot processes of another podocytes leaving filtration slits in between them. These filtration slits are bridged by the slit diaphragm which is an extracellular structure. These cells are located on the outer surface of glomerular basement membrane (GBM) and thereby they check the protein loss. The cell body of these cells contain nucleus, golgi apparatus, smooth and rough endoplasmic reticulum, lysosome and mitochondria. Their main function is in establishing the selective permeability of the glomerular f iltration barrier. Several molecules, including nephrin, CD2AP, FAT, ZO-1, P-cadherin, Podocin, and Neph 1-3 have all been shown to be associated with the slit diaphragm (SD) protein complex, and some of these molecules are critical for its integrity. In cases of chronic disease podocytes gets loosen and they separate from the surface of glomerular basement membrane (GBM). Podocyte injury frequently leads to reorganization of the slit diaphragm and reorganization of the foot process structure. Disturbances of podocyte architecture results in retraction of its foot processes which leads to proteinuria. This may be thelater progress into acquired glomerular diseases. The approach to regenerate podocyte and develop a mechanism of podocyte specific drug delivery system by understanding the molecular mechanism of podocyte function appears a promising area for treatment of proteinuric kidney diseases in future.

Introduction

It is estimated that zoonotic infections account for around 60% of infectious diseases and 70% of newly developing infections in humans. The major zoonotic illnesses that have outbreaks documented between 2009 and 2023 have been divided into two categories: endemic and emergent (IDSP). Zoonoses that are either newly discovered in a population or that have been known to exist in the past but are rapidly expanding in frequency or geographic range are referred to be emerging zoonotic diseases.A variety of underlying causative variables contribute to the genesis of zoonotic illnesses, which pose a worldwide risk to the health of both humans and animals. They reduce food availability, impede agricultural output, and contribute in unnecessary trade embargos. Livestock is crucial to the livelihoods of impoverished farmers, consumers, and traders in India. Close relationships between human population groups and animals, the consumption of unpasteurized milk and dairy products, the intensification of animal production andincreased trade in animals and animal products, the high number of stray animals, illegal slaughter, and improper waste disposal are major risk factors in the introduction and sustenance of zoonotic infections. These outbreaks are continuously increasing. More and more such episodes of new zoonoses such as Nipah virus disease, Crimean Congo Hemorrhagic Fever (CCHF), Kyasanoor Forest Disease (KFD), Dengue, Chikungunya, Japanese encephalitis, and Zika virus disease have been reported between 2014 and 2023 as compared to the period between2009and 2013.

Introduction

To maintain optimum reproductive status early diagnosis of reproductive problems is important. Various advance diagnostic techniques are available for diagnosis of reproductive problems. Some of them are still in early stages of development or some though available; are not widely used due to various constrains.The various diagnostic techniques used in animal reproduction are ultrasonography, Doppler ultrasonography, endoscopy, laparoscopy, hormonal assays, vaginal cytology, x ray etc.

Accurate history and Thorough examination of reproductive tract

Accurate history is a powerful tool of enormous clinical value. Behavioral problems due to pain or psychological factors can also be ruled out on the basis of adequate history of the patient. Tentative differential diagnosis can be made by taking history of previous breedings.Through digital and vaginiscopic exanimation of reproductive tract helps to rule out anatomical abnormalities, which may interfere with natural mating. It also helps in diagnosis of fertile phase of oestrus cycle. In cases of refusal to mate due to anatomical problems like septum, narrow passage or due to behavioral problems AI can be performed. Vaginoscopic examination aids vaginal cytology in deciding right time of natural service or insemination in proper breeding management or abnormal oestrus cycle.

Introduction

The peripartum period, spanning from 3 weeks pre-calving to 3 weeks post calving, is a critical phase in a cow’s life. During this time, cows are susceptible to various diseases that can significantly impact their health, productivity and reproductive performance. Changes in metabolism and lack of optimum immunity have been closely associated with most of the transition period diseases. Hormonal changes in the early lactation results in drain in energy and nutrients rendering the animal in some degree of negative energy balance. Increased lipid mobilization in transition period has its role in fatty liver and ketosis directly.Metabolic stress in peripartum cows refers to the physiological changes that occur around calving, affecting energy and nutrient balance.

Introduction

Status of Tuberculosis : Tuberculosis is a complex and multispecies disease since the origin of human civilization. Evidence of tuberculosis (TB) exists in 3000 years old Egyptian mummies and about 17,000 year old fossilized bison (Fareed et al., 2024). Now, every year, 10 million people fall ill with tuberculosis. Out of 10 million people currently with new active TB, 1,40,000 (range, 69,800–235,000) are estimated to be new cases of zTB (1.4%) of which an approximately 11,400 (8.1%, range 4,470-21,600) died (WHO, 2020).Despite being a preventable and curable disease, 1.5 million people die from TB each year – making it the world’s top infectious killer (WHO, 2023). Disease is still in an increasing scenario as evident that in 2018, an estimated 10 million people fell ill with TB and 1.5 million died of the disease whereas in 2021 there were an estimated 10.6 million new cases of TB and 1.6 million TB deaths (Ayalew et al., 2023). COVID-19 has further increased the projection of TB and increased the expected case number. As it is predicted that between 2020-2050, 31.8 million will have died of TB, More than half million cases of TB annually are classified as drug resistant, as a result, TB is becoming more difficult to diagnose and treat.

Introduction

In poultry, the intestine is home to trillions of microorganisms, with bacterial concentrations reaching up to 10¹² bacteria per gram of digesta. In a healthy digestive system, this microbial community is highly diverse and metabolically active, supporting crucial functions in digestion, immune defense, and overall health. The gastrointestinal tract (GIT) of a newly hatched chick begins as a sterile environment but quickly develops a complex microbiota as the bird matures. The composition of gut microbiota is highly variable, shaped by environmental factors, diet, the genetic makeup of the host, and other influences. This dynamic microbiome plays a pivotal role in nutrient absorption, disease resistance, and growth efficiency, making it a central focus in poultry health management and productivity enhancement.The health and productivity of poultry are fundamentally influenced by the gut microbiome, which shapes digestion, immunity, and growth potential. Microbial diversity variesacross several poultry species, including broilers raised intensively, native chickens in free-range conditions, and unique species such as Guinea fowl, Kadaknath, and red jungle fowl. Using advanced metagenomicsanalysis of microbial diversity, structure, and function, highlighting the implications of microbiota composition on poultry health and productivity possible. The gut microbiota is increasingly recognized as a major determinant of health and productivity in poultry. It not only influences nutrient absorption and metabolism but also plays a critical role in immune response and pathogen resistance. Intensive farming practices have altered gut microbial ecosystems in commercial broilers, often reducing diversity compared to native breeds and heritage species raised in field conditions.

Introduction

Climate change specifies long-term shifts in weather patterns, which are measured over decades to millions of years. In modern times, it predominantly concerns the increase in Earth’s average temperature due to human activities, particularly the burning of fossil fuels10. The rise in greenhouse gases such as carbon dioxide, methane, and nitrous oxide traps heat in the atmosphere, leading to global warming. In connection with animal health, climate change affects the ecosystems in which animals live, influencing the availability of water and food, the spread of diseases, and the physiological stress animals endure due to temperature extremes. Domestic animals, mostly livestock, are vulnerable to heat stress and reduced productivity, whereas wildlife faces altered habitats and increased exposure to pathogens. The connection between climate change and animal health is intricate, as changes in temperature, humidity, and weather patterns create new challenges for both domestic and wild species.

Introduction

In modern poultry farming, the need for alternatives to probiotics is increasing due to concerns about the stability, viability, and potential side effects of using live microbes. Postbiotics have emerged as promising substitutes, offering similar health benefits without the risks. Postbiotics are non-viable microbial metabolitewhich exhibit benefits like promoting gut health, boosting immunity, and preventinfections, which are crucial for sustainable poultry production. Postbiotics enhance gut health by modulating immune responses, improve the microbialenvironment,and inhibit pathogenic growth. Furthermore, their incorporation can reduce theneed for antibiotics in poultry farming, contributingto a decrease in antimicrobial resistance. With the growing global population and increasing demand for animal protein, postbiotics offer sustainable solutions. The review concludes that postbiotics could revolutionize poultry farming, aligning with global efforts toward food security and the achievement of the United Nations Sustainable Development Goals, particularly Goal 2 i.e. Zero Hunger. Future research should focus on optimizing these additives for large-scale commercial use.This paper highlights the concepts of postbiotics, their mechanisms of action, current research advances, beneficial effects in poultry farming, and future prospects.

Introduction

The classic bone tissue engineering paradigm highlights several key players: biocompatible scaffold that closely mimics the natural bone extracellular matrix niche, osteogenic cells to lay down the bone tissue matrix, morphogenic signals that help to direct the cells to the phenotypically desirable type, and sufficient vascularization to meet the growing tissue nutrient supply and clearance needs. The biomaterials are critical components in the bone-tissue engineering strategies, including polymers, ceramics, or their combinations applied in various forms, such as membranes and three-dimensional (3D) scaffolds. These materials typically mimic the extracellular matrix of bone tissue during the tissue regeneration process, providing mechanical support and a suitable environment for cell attachment, proliferation, and differentiation

Introduction

Parvoviruses are nonenveloped, single-stranded DNA viruses belonging to the genus Protoparvovirus, member of the Parvoviridae family, that has been included within the species Carnivore protoparvovirus 1, together with Feline panleukopenia virus (FPV), Mink enteritis virus (MEV) and Raccoon parvovirus (RPV), according to the International Committee on Taxonomy of Viruses (Tijssenet al 2011). Two distinct parvoviruses are known to infect dogs—the pathogenic CPV 2 and CPV-1 or the minute virus of canine (MVC). CPV-2, the causative agent of acute hemorrhagic enteritis and myocarditis in dogs, is one of the most important pathogenic viruses with high morbidity (100%) and frequent mortality up to 10% in adult dogs and 91% in pups. CPV-2 is the etiologic agent of a contagious disease, mainly characterized by clinical gastroenteritis signs in younger dogs. This virus that causes the disease “parvo”, first emerged among dogs in Europe around 1976. By 1978 the virus had spread unchecked, causing a worldwide epidemic of myocarditis and inflammation in the intestines (gastroenteritis) and could infect domestic dogs, spreading in the global dog population within 2 years. This original type, was rapidly replaced by two antigenic variants, types 2a and 2b (Parrish et al 1985, 1991), and in 2000 a third type CPV-2c was detected (Buonavogliaet al 2001). Canine parvovirus (CPV) is responsible for acute gastroenteritis in pups, with a high rate of mortality (Carmichael and Binn, 1981). We now know the virus is not limited to dogs, but is capable of causing infections in wild canines such as coyotes and wolves, and other wild animals, including foxes, raccoons and skunks. Since its emergence in 1978, it was and remains a common and important cause of morbidity and mortality in young dogs.

Introduction

The preservation of animal specimens for museums is a critical practice in natural history, enabling education, research, and conservation awareness. Traditionally, specimens are often sourced from zoological facilities or specific conservation programs. However, the innovative use of fallen animals—animals that have died of natural causes or accidents—presents a sustainable and ethical method of specimen preparation. India has large livestock population. As per 20th livestock census in the country, livestock sector of India comprised of 303 million bovines (Cattle, Buffalo, Mithun and Yak), 74.26 million sheep, 148.88 million goats, 9.06 million pigs and about 851.81 million poultry. Each year large number of livestock is lost due to natural disaster such as flood, cyclones, draughts avalanches, landslides, snowstorm and forest fire. Approximately 55% of its buffalo, 38% of its cattle, 41% of its goats and 47% of its pigs are vulnerable to floods which regularly destroy farmlands. On the other hand, 44% of country’s livestock are affected by draught. Cyclones also causes huge loss to the livestock as well as to the wildlife. According to Down to Earth magazine and Centre for Science and Environment approximately 92519 livestock were killed in India in 2023 due to extreme weather including cyclones.

Introduction

“Invest in Women: Accelerate Progress” -the theme of the International Women’s Day 2024 celebrated by the United Nations and multiple organizations across the world highlighted the need of review of different works and efforts in bringing gender equality in various development departmentsincluding agriculture and allied sectors. This reflects the importance being given to the efforts towards gender equality at the highest level.

Agrifood systems are a major employer of women globally and constitute a more important source of livelihood for women than for men in many countries. Empowering women and closing gender gaps in agrifood systems thus, enhances the well-being of women and their households, reducing hunger, boosting incomes and strengthening resilience.Increasing women’s empowerment is essential for women’s well-being and has a positive impact on agricultural production, food security, diets and child nutrition. Also,the gender-transformative approaches to change restrictive social norms are cost effective and have high returns, but morework is needed on developing pathways to implement gender-transformative approaches.

Introduction

Emerging and reemerging infectiousdiseases are defined as the diseases of which the incidence has shown an increasing trend in the recent past or threatening to increase in the near future. Emerging infectious disease (EID) are caused by apathogen previously unknown to cause disease orre-emerging pathogens, which have previously causeddisease but now reveal increased infectivity orextended transmission ranges that improve their ability to cause disease in human populations. Today, whole world is facing a concerning rise in emerging infectious diseases and the majority of EID have been observed in the past decades.Multiple recent EID outbreaks e.g. the 2003 SARS and the 2012 MERS outbreaks, the 2009 swine flu pandemic,the 2013–2016 Ebolavirus epidemic, the 2014chikungunya outbreak in the Western Hemisphere,the 2015 Zika and the 2019 SARS Cov 2 virus epidemic have exhibited significantmorbidity and mortality and large geographicranges. These outbreakshave indicated the potential for evenmore severe outcomes in future outbreaks. Severaladditional pathogens are also considered capable ofproducing EID outbreaks, these include Escherichia coliO157:H7, hantavirus, dengue virus and West Nilevirus, while malaria, tuberculosis (TB), cholera, andinfluenza are often considered reemerging diseases with the potential for new outbreaks.Many newly emerging diseases in humans are actually long-standing zoonosesof animal host species that appeared inhuman populations following a climatic or environmental change. The complex interplay between climate change, ecosystems, and human activities have created conditions that favour the emergence and spread of infectious diseases posing significant challenges to public health. Although, improved sanitation, increased access to health care, and advances in preventive and clinical medicine have reduced the mortality and morbidity rates of several infectious diseases.

Introduction

The gut microbiota is the complex and dynamic community of microorganisms that includes various bacteria, fungi and other microorganisms, proliferate and lead a symbiotic/mutual relationship with the host system. These microorganisms protect the host against pathogens by unique mechanisms, helps to maintain shape and strengthen the intestinal epithelium and boost immune response. Diverse bacterial metabolites can immigrate the host bloodstream and other parts of the body via various channels in humans and animals, such as gut-microbiota-brain, gut microbiota-skin, gut-vagina, gut liver, gut-bones etc. However, many aspects of modern lifestyle would alter the gut microbiota and lead to numerous diseases including inflammatory bowel disease, diabetes mellitus, obesity, and metabolic syndrome. Probiotics and other beneficial microbes exert many beneficial effects on their hosts by modulating the gut microbiota. While the term probiotic is reserved only for well-characterised strains with clinically proven health benefits, other beneficial microorganisms include, organisms responsible for the fermentation of foods viz. yogurt, kefir, kombucha, kimchi and many others that have been shown to have distinct health benefits. Interestingly, major group of these beneficial organisms belong to lactic acid bacteria.

Introduction

Lactic acid bacteria (LAB) are characterized as Gram-positive cocci or rods, non-aerobic but aerotolerant, able to ferment carbohydrates for production of energy and lactic acid. Lactic acid bacteria includes different major genera: Lactococcus, Enterococcus, Lactosphaera, euconostoc, Melissococcus, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus and Weissella. Other genera are Aerococcus, Microbacterium, Propionibacterium and Bifidobacterium. Through carbohydrate fermentation along with lactic acid, various organic acids are produced due to which there is a fall in pH level and creates unfavorable environment or inhibits growth of some undesired microorganisms. The low pH makes organic acids lipo -soluble, allowing them to invade into cytoplasm of pathogens by rupturing cell membrane. LAB are generally regarded as safe (GRAS), and have a significant role in the preservation of foods and fermented products. Under controlled conditions they can be used as natural competitive microbiota or as specific starter cultures. Antagonistic substance like bacteriocins are produced from lactic acid bacteria that inhibits the activity and growth of other bacteria and these bacteriocins are active against various pathogens in minimum concentration. These are antimicrobial peptides modified by post -translational mechanisms and exported to the extracellular medium. Till date about 239 bacteriocin producing LAB genome and 789 putative bacteriocin producing genes cluster are stored in the public databases. Many gram positive and gram negative bacteria in the environment produce bacteriocins.

Introduction

Let food be thy medicine and medicine be thy food- the age-old quote by Hippocrates, is certainly the tenet of today. Microbial cultures have been used for millenniums in food and alcoholic fermentations and in the past century have undergone scientific scrutiny for their ability to prevent and cure a variety of diseases. Later it became popular in improving human and farm animal nutritive values and recently in aquaculture also. The growing interest in the understanding the role of food in human health has moved from its primary role as a source of energy to the subtle action of biologically active food components on human health. Henceforth functional foods or nutraceuticals are of great demand in present time. The growing scientific evidence suggests that the food supplements containing beneficial bacteria can provide an array of benefits to the host. Now a day’s probiotic fermented foods are in great demand due to the awareness of beneficial aspects of probiotics among people. Several industries focused on the improvement of conventional fermented foods scientifically in order to fetch good market for their products. Particularly, animal feed companies and researchers have been looking for alternative products and strategies that can help to maintain animal gut health in order to prevent or reduce the prevalence of pathogens in the food chain. After understanding the mechanism and beneficial aspects of probiotics in detail at molecular level in earlier chapters, now it is relevant to discuss the applied part of probiotics. In this chapter, commercial importance of probiotics and probiotics derived products at industrial level are emphasized.

Diversity of gut microbial community

The human microbiota (the collection of microbes that live on and inside us) consists of about 100 trillion microbial cells that outnumber our ‘‘human’’ cells 10 to 1, and that provide a wide range of metabolic functions that we lack. It has been estimated that they encode 100-fold more unique genes than our own genome. Furthermore, the gut microbes contribute to energy harvest from food, and changes of gut microbiome may be associated with bowel diseases or obesity. To understand and exploit the impact of the gut microbes on human health and well-being it is necessary to decipher the content, diversity and functioning of the microbial gut community. If we consider ourselves as superior organisms encompassing these microbial symbionts, by far the majority of genes in the system are microbial. In this sense, completing the human genome also requires the characterization of the microbiome (the collection of genes in the microbiota).

Methods of counting viable and non-viable bacteria in gut

Before the advent of genome sequencing and genome-wide analysis method, our knowledge of molecular characteristics of diverse gut microbial population was extremely limited. To obtain an estimate of cultivability, microbial ecologists generally compare microscopic counts with total viable counts. The total viable count made on a nonselective agar based medium estimates the number of colony forming units (cfu) per gram of sample. The finding that total viable counts are typically lower than total microscopic counts was thought to be due to the number of dead cells. Indeed, dead bacteria in feces may constitute up to one third of the total bacterial community. However, recent nucleic acid based studies indicated that a majority of bacteria in a variety of ecosystems are different from those described in culture.

Introduction

It became clear from the discussions of previous chapters that probiotics perform metabolic functions such as fermenting indigestible dietary residues and endogenous mucus, production of vitamins, and absorption of minerals. They also play key role in intestinal epithelial cell proliferation and differentiation, and the homeostasis of the immune system. Further, probiotics are also known to involve in modifying gut pH, antagonizing pathogens through the production of antimicrobial compounds, competing with pathogens for recept or sites as well as for available nutrients and growth factors, stimulating immunomodulatory cells of the host, and produce a wide range of enzymes such as lactase, amylase, lipase, protease, phytase and so on. The molecular mechanisms of probiotics are largely unknown and opens avenue for research in probiotics. Moreover, current research in probiotics and health consciousness in the public lead to an increased interest towards probiotics from the public, researchers, governmental organizations (such as the WHO/FAO) and medicine and food companies. In this chapter, application of probiotics in treating various diseases and disorders are discussed.

Introduction

Cell surface components such as adhesins, polysaccharides, and proteins play major roles in the adherence of probiotic bacteria to the intestinal epithelium, interactions that might lead to pathogen exclusion and immunomodulation of host cells. Probiotic bacteria have the ability to produce exocellular polymers called Exopolysachcharides (EPSs). These exocellular polymers present in the surface of many lactic acid bacteria, including Lactobacilli.The adhesive properties of lactobacilli are directly linked to their surface properties which are influenced by the structure and composition of their cell wall. The cell envelope of lactobacilli, bacteria, is composed of the bilipidic plasma membrane with embedded proteins encompassed by the cell wall. The bacterial cell wall consists of a thick multilayered sacculus made of peptidoglycan (PG) with teichoic acids (wall teichoic acids (WTA) and/or lipoteichoic acids (LTA)), exopolysaccharides (EPS), proteinaceous filaments called pili, and proteins that are anchored to the cell wall through different mechanisms (Figure 1).

Some species of lactobacilli possess an additional paracrystalline layer of proteins surrounding the PG layer, referred to as the S layer. These macromolecules together may play crucial roles in determining species and strain-specific characteristics of lactobacilli by influencing host-microbe interactions and microbial adaptations to the changing host environment. Several studies implicate that cell surface components, either individually or collectively, involve in host-microbe interactions. Lactobacilli beneficially affect the host in many ways by producing abundant variety of EPSs through the activity of extracellular glycosyl transferases. Approximately 30 species of lactobacilli are described as EPS producers. Among them, the best known are L. casei, L. acidophilus, L.brevis, L. curvatus, L. delbrueckii bulgaricus, L. helveticus, L. rhamnosus, L. plantarum, L. johnsonii, etc.

Introduction

Preceding chapters discuss the essentials of probiotics, their role in maintaining gut health in combination with prebiotics and significance of systematic classification of probiotic isolates. Further, to draw an idea how probiotics function in the gut, it is essential to know the interaction of probiotics with other microorganisms in the gastrointestinal milieu - the site of their probiotic action. Knowledge in the ecology of probiotic microorganisms in host environment such as gut gives an ideal picture of their functioning manner and the factors (both host and microbial) responsible for it.

Study of microbial ecology in the gastrointestinal tract is very difficult since gut harbors highly diversified microflora that varies not only at species level but also at individual level. The diversity of gut microflora in two healthy individuals of same species may exhibit variations in their composition and it may be influenced by geodemographic factors also. In this regard, the present chapter deals with the study of ecology of Lactobacillus- most commonly used probiotic bacteria in the gastrointestinal tract which in turn helps in framing selection criteria for screening of potential probiotics.

Recent studies on interaction between human and gut microflora discussed that co-evolution between microorganisms and their host have contributed for the development of a very complex microbial diversity in the gut. Highly diversified microflora in the human gut is a consequence of natural selection at two levels, top-down and bottom-up selection pressure. Hierarchy theory expounds that higher levels compel lower levels for possible organizational solutions i. e. organisms at the higher levels govern the structure or population dynamics of an ecosystem while on contrary lower levels control the structure of ecology when bottom-up level is the selection pressure. In case of interaction between human and gut microflora, being host human is at higher level in the hierarchy for selection and as mentioned above, top down selection pressure is driven by higher levels; host selects the beneficial microorganisms for functional redundancy leading to the development of a microbial community with divergent microbial divisions. Chances for lateral gene transfer also thought to influence the selection process and there by structure of the microbial community. On the other hand, competition among the members of host selected microbiota exert bottom up selection pressure resulting in the development of highly specialized genomes with functionally prominent set of genes. Natural selection at host level obviously favors functionally constant microbial communities which benefits the host with functional redundancy encoded in their genomes. Mean while bottom-up cell-level selection pressure aspire to favor niche specialization to avoid competition between the members of microbial community. In order to be a part of specialized niche, to become more potent microorganisms adapt a particular set of abiotic and biotic factors within the habitat by acquiring new sets of genes essential for their survival and thus escape the competition from decrepit microbial species.

Introduction

From earlier chapters, it is evident that Lactobacilli and Bifidobacteria are the two important genera that have potent applications in food microbiology and human nutrition due to their role in food and feed production, preservation and also due to probiotic potentialities. Most of the bacterial species are still unknown indicating that the identification and classification of bacteria is a hard task since the beginning of microbiology and consequently our knowledge about bacterial ecology is very low. Mean while the expectations about novel bacterial products are high. Therefore, bacterial identification has become a growing field of interest in microbiology. Since, Lactobacilli and Bifidobacteria genera include a large number of species and strains exhibiting important properties in an applied context, chiefly in the area of probiotics as food and therapeutics, an updated list of species belonging to these two genera, their phylogenetic relationships and other relevant taxonomic information are of great significance. The classification and identification of a probiotic isolate at strain level point out its typical habitat and origin. Moreover, the species, or genus name, may also indicates the strain’s safety and technical applicability for its use in probiotic products. Taxonomy helps to place a newly identified organism in a relevant group and enables the scientific communication. Further it facilitates the construction of databases that can be used for rapid identification of organisms at laboratory level easily. Thus, taxonomy of Lactobacilli and Bifidobacteria helps to study these organisms scientifically and allows characterizing and arranging them in an orderly manner which promote the scientific community to explore the benefits from those organisms for the betterment of mankind.

Introduction

Probiotics, prebiotics and synbiotics are interrelated terms. Probiotic is discussed in detail in previous chapter. In this chapter, prebiotics and its effect on gut along with probiotics are emphasized. Prebiotics can be defined as non digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system in ways claimed to be beneficial to health. They were f irst identified and named by Marcel Roberfroid in 1995. He defined prebiotic as a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health. Further, FAO defined prebiotic as “a non-viable food component that confers a health benefit on the host associated with modulation of the microbiota.”Whereas the term synbiotics refers to a product that contains both probiotics and prebiotics in the form of synergism. A synbiotic has been defined as “a mixture of prebiotics and probiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract, by selectively stimulating the growth and activating the metabolism of one or a limited number of health promoting bacteria, and thus improving host welfare”. As described above, the combined use of prebiotics and probiotics is often described as synbiotic, but the United Nations Food & Agriculture Organization (FAO) recommends that the term “synbiotic” be used only if the net health benefit is synergistic.

The term probiotic means “for life” and it is currently used to refer bacteria that are associated with beneficial effects for humans and animals. The credit for first observation made on the positive role of some selected bacteria was attributed to Eli Metchnikoff, the Russian born Nobel Prize recipient, worked at the Pasteur Institute in the beginning of the last century. Metchnikoff suggested that - “the dependence of the intestinal microbes on the food makes it possible to adopt measures to modify the microflora in our bodies and to replace the harmful microbes by useful microbes”. Interim Henry Tissier, a French paediatrician, observed that children with diarrhea in their stools had a low number of bacteria which are characterized by a peculiar Y shaped morphology. On the contrary, these “bifid” bacteria were abundant in healthy children. Based on these observations, Tissier suggested that “bifid” bacteria could be administered to patients with diarrhoea to help restore a healthy gut microflora. These two scientists were the first to give scientific intimation for the use of probiotics when even the term probiotics was not coined. Later in 1965, the term probiotics is coined by Lilly and Stillwell to describe substances produced by one microorganism, that stimulate the growth of another. Subsequently, Parker defined probiotics as organisms and substances that contribute to intestinal balance. Further, Fuller (1989) improved the Parker’s definition of probiotics as “live microbial feed supplements which beneficially affect the host animal by improving its intestinal microbial balance”. Havenaar and Huis in’t Veld (1992) extended the probiotic definition with the description: “A viable mono or mixed culture of microorganisms which, applied to animal or man, beneficially affects the host by improving the properties of the indigenous microflora”. At the end of the millennium, Salminen and his coworkers (1999) proposed the following definition: “probiotics are microbial cell preparations or components of microbial cells that have a beneficial effect on the health & well- being of host”. Whereas FAO/WHO (2001) defined probiotics as “living bacteria that, when administered in adequate amounts, confer a health benefit on the host”. This definition for probiotics is widely accepted.

Introduction

Colorimetry is a scientific technique widely used across various fields to quantify the concentration of substances based on their color intensity. Colorimetry is a branch of analytical chemistry that focuses on measuring the absorbance or transmission of light by colored solutions. It utilizes the principles of optics and spectroscopy to determine the concentration of a substance in a solution based on its color intensity. This technique relies on the Beer-Lambert law, which states that the absorbance of light by a solution is directly proportional to its concentration and path length.

Principles of Colorimetry

The fundamental principle of colorimetry lies in the interaction of light with matter. When light passes through or is reflected off a substance, certain wavelengths are absorbed, while others are transmitted or reflected. The color we perceive is due to the wavelengths of light that are reflected back to our eyes. In colorimetry, a photometric measurement is made using a colorimeter or spectrophotometer, which quantifies the intensity of light absorbed or transmitted by a sample.

Introduction

Biochemistry is branch of life science which deals with the study of chemical reactions occurring in the living cells and organisms. The term biochemistry was first introduced by German chemist Carl Neuberg in 1903. Since biochemistry is associated with the biological reactions and energy changes associated with these reactions or transformations within the living cell, biochemistry may thus be treated as a discipline in which biological phenomenon are analysed in terms of chemistry. The branch of biochemistry for the same reason has been variously named as “Biological Chemistry” or “Chemical Biology”. Modern biochemistry has two branches descriptive and dynamic biochemistry. Descriptive biochemistry deals with qualitative and quantitative characterization of the various chemical components of cell and the dynamic biochemistry deals with the elucidation of the nature and the mechanism of reactions involving these chemical cell components.

Qualitative analysis of biological sample deals with the examination of the organic or inorganic cell associated components in order to determine its composition. It denotes the presence of various biomolecules, elements or groups of elements that are present in the sampling population. It is possible to determine whether a particular component is present or absent in a sample by performing a qualitative analysis of the sample. Qualitative analysis is the identification of elements, species and/or compounds present in a sample.

Introduction

Urinalysis, the examination of normal and abnormal components of urine, is one of the most important aspect of clinical pathology that aids in accurate and timely diagnosis in veterinary practice. Urine is considered as one of the most accessible bio-fluid that can be collected using non- invasive techniques in adequate quantities. It includes the evaluation of colour, odour, turbidity, volume, pH, specific gravity, protein and glucose content, ketone bodies, blood, erythrocytes, leukocytes, epithelial cells, casts, crystal, micro-organisms, etc. Urinalysis gives us valuable information regarding the several important attributes of renal function. For example, specific gravity of urine gives valuable insights over the potential of the Henle’s loop to dilute urine and the distal convoluted tubules to concentrate urine after ruling out the extra-renal factors affecting the urine specific gravity. It is highly useful to evaluate the different types of urogenital diseases and it also provides significant information regarding several systemic disorders. It is comparatively quicker to perform and is relatively a low-cost test that could be easily done in most clinical setups.

Introduction

Biological fluids refer to any liquid substances found within living organisms that play essential roles in physiological functions. These fluids can include blood, urine, cerebrospinal fluid, saliva, digestive juices, rumen fluid, peritoneal fluid, pleural fluid, pericardial fluid, synovial fluid, amniotic fluid, milk etc.

Collection of biological fluids refers to the process of gathering various types of bodily f luids from animals for scientific study or medical purposes. This collection often involves techniques like blood draws, urine collection, cerebrospinal fluid sampling, saliva collection, etc., depending on the specific fluid and the research or diagnostic needs. These f luids are valuable for understanding the health, metabolism, genetics, and other aspects of animal biology. Collecting and analyzing these biological fluids is crucial for understanding health and disease processes, diagnosing illnesses, monitoring treatment effectiveness, and advancing medical and scientific research.

Introduction

Immunology deals with the body defence system consisting of various cells and biomolecules that prevents entry of foreign infectious and toxic agents by different mechanisms. The mammalian immune system operates in two ways like innate or non specific immunity and adaptive or acquired or specific immunity. Innate part constitutes the physical (skin, hair, tears and mucous secretions) containing enzymes that prevents primarily entry of pathogen. It is the first line of defence action, very fast but not adequate. Adaptive form constitutes defensive cells and secreted immunoglobulins. It takes time to develop effectively, especially when the body sees the organism for the first time. Immunoglobulins (Ig) or antibodies are a group of proteins produced from B lymphocytes and plasma cells in response to the presence of any foreign substances. They are 5 basic types like M, A, G, E and D each with specific function. The system can produce antibody molecules, directed to about 1 million different kinds of antigens. All immunoglobulins have a similar basic structure.

Introduction

Diagnostic biochemistry, is a branch of laboratory medicine that focuses on the analysis of bodily fluids to diagnose and monitor diseases. This field plays a crucial role in understanding the biochemical mechanisms underlying various conditions, enabling accurate diagnosis, prognosis, and management. The biological samples for diagnosis include blood, urine, cerebrospinal fluid, pleural fluid and tissues.

Factors Affecting Serum Enzyme Activity or Protein Level

1. Organ Mass and Enzyme Tissue Concentration:

• Higher enzyme concentrations in organs can lead to greater increases in serum enzyme activity during disease. For instance, the liver’s large mass contributes to potential increases in serum ALT activity.

2. Cell Location

• The proximity of cellular enzymes to the blood, urine, or other fluids determines the fluid in which an enzyme’s activity will increase upon cell injury. For example, renal tubular gamma-glutamyltransferase (GGT) is released into urine, not blood, following injury.

Introduction

Most glands of the body deliver their secretions by means of ducts. These are called exocrine glands. There are few glands that produce chemical substance that they directly secrete into the blood stream for transmission to various target tissues. These are ductless or endocrine glands. The secretions of endocrine glands are called as hormones. Therefore, it is a chemical substance which is produced in one part of the body, enters the circulation and is carried to distant target organs and tissues to modify their structures and functions. Hormones are stimulating substances and act as body catalysts. The hormones catalyze and control diverse metabolic processes. Despite their varying actions and different specificity’s depending on the target organ, the hormones have several characteristics in common with enzymes. They act as body catalysts resembling enzymes in some aspect. They are required only in small quantities. They are not used up during the reaction. They differ from enzymes because they are produced in an organ other than that in which they ultimately perform their action. The major hormone secreting glands are as follows— Pituitary, Thyroid, Parathyroid, Adrenal, Pancreas, Ovaries and Testes. The hormones are classified into following main classes according to the chemical structures:

Introduction

Water is the most abundant compound in the body, and most of life’s essential processes take place in this aqueous environment. Although there is substantial variation, the total body water (TBW) of most domestic animals is approximately 60% of body weight (0.60 l/kg).Electrolytes are substances that exist as positive or negative charged particles in aqueous solution. The positively charged particles are “cations,” and the negatively charged particles are “anions”. The osmotic properties of a solute in solution are related to the number of particles in solution and not to its weight or its charge. One osmole of a non-dissociable substance is equal to its molecular weight in grams. One osmole of any substance that dissociates in solution into two or more particles is equal to the molecular weight in grams divided by the number of particles into which each molecule dissociates. Osmolarity is defined as the number of osmoles per l of final solution, whereas osmolality is the number of osmoles per kilogram of water. Although the expressions are similar, osmolality more correctly describes the osmotic properties as measured in the clinical laboratory.

Biotechnology is being harnessed in various aspects of the livestock industry to hasten breed development for improved animal health and welfare, enhanced reproduction, and improved nutritional quality and safety of animal-derived foods. Various biotechnology methods are used in improving the breeding stock of animals. These include artificial insemination (AI), embryo transfer (ET), in-vitro fertilization (IVF), sexing of semen and embryos, micromanipulation of oocytes/ embryos, transgenesis, somatic cell nuclear transfer and the emerging technology on genomics and marker-assisted selection (MAS). Artificial Insemination: One of the earliest perfected technology is artificial insemination (AI) where new breeds of animals are produced through the introduction of the male sperm from one superior male to the female reproductive tract without mating. AI reduces transmission of venereal disease, lessens the need of farms to maintain breeding males, facilitates more accurate recording of pedigrees, and minimizes the cost of introducing improved genetics. Various technologies have evolved that led to the efficient use of AI in developing desired livestock, including the methods of freezing semen or cryopreservation and sperm sexing.

Introduction

Cell culture is a technique that involves the isolation and in vitro maintenance of cells isolated from tissues or whole organs derived from animals, microbes or plants. This technique has immeasurable role in the field of biology. The scientific progress in biology, microbiology and biotechnology in recent years can be credited on the development of cell culture technology. With the development of cell culture the isolation of viruses has become less cumbersome, the assessment of the efficacy and toxicity of new drugs has been easier, new vaccines are being developed and there has been development in biotechnology assisted reproductive technology.

In general, animal cells have more complex nutritional requirements and usually need more stringent conditions for growth and maintenance. For the growth of the cell in vitro specific mediums are required by the cells. Previously natural mediums like plasma ,serums were used but with the advent of synthetic media the specific needs of different cell types can be catered with. Cell culture is governed by a provided set of protocols requiring a sterile pure culture of cells, various nutrients for its growth, sterile cell culture hood, appropriate aseptic techniques and the utilisation of suitable conditions for optimal viable growth of cells.

Introduction

Biochemical techniques are fundamental tools that allow scientists to investigate the molecular intricacies of biological systems, including DNA, RNA, and proteins. These techniques are essential for understanding cellular processes, genetic functions, and disease mechanisms. By employing biochemical methods, researchers can dissect complex biological systems at the molecular, cellular, and genomic levels, paving the way for advances in basic biology and therapeutic interventions.

Introduction

In a historic landmark, Genentech, a young Californian Company pioneering in gene splicing (which includes recDNA technology, genetic engineering, gene transplantation, gene cloning), saw its stock price skyrocket form $35 to a staggering $89 within just 20 minutes of the New York Stock Exchange’s opening bell on October 15, 1980. This was marked as the fastest stock price growth ever witnessed on that exchange. The company’s success was attributed to the ground-breaking work it had been involved in producing human insulin through genetic engineering that offered a revolutionary alternative for diabetics allergic to the then traditional insulin of porcine origin. Genentech’s pioneering work in gene splicing has its roots in the early 1970s. In 1972, Stanley Cohen and Herbert Boyer were credited with creating the first recombinant DNA molecule. Their experiments demonstrated the ability to create recombinant DNA molecules that could be introduced into bacteria like E? coli, offering a foundation for future advancements in genetic engineering.

Introduction

Nucleic acids, primarily DNA and RNA, are essential for the storage and expression of genetic information. Under physiological conditions, the amino and oxo tautomers of purines and pyrimidines predominate. Adenine a., guanine (G), cytosine c., thymine (T), and uracil (U) are the main building blocks of nucleic acids. Other building blocks include 5-methylcytosine, 5-hydroxymethylcytosine, pseudouridine, and N-methylated heterocycles. A -glycosidic bond connects D-ribose or 2-deoxy-D-ribose to the N-1 of a pyrimidine or the N-9 of a purine, with the syn conformers being the most common.

Nucleotides are the monomeric units of nucleic acids that contain a phosphate group attached to the sugar’s 3’ or 5’ hydroxyl. Extra phosphate groups form nucleoside diphosphates and triphosphates. These have high group transfer potential and help make covalent bonds. Cyclic phosphodiesters cAMP and cGMP act as second messengers. 3′ 5′ phosphodiester bonds link nucleotides to form polynucleotides, which have a directional 5′ and 3′ end. Four bases—A, G, C, and T—compose DNA, and hydrogen bonds (A to T, G to C) hold them together to form a double helix. Human DNA consists of approximately 3 billion base pairs organized into 23 chromosomes, encoding around 25,000 protein-coding genes and various non-coding RNAs (ncRNAs).

Introduction

Robert Brown discovered the nucleus in some plant cells in 1831. After analyzing tissues from a range of animals and plants, T. Schwann (1839) declared, “All living organisms are composed of cells.”

The fundamental elements of Prokaryotic and Eukaryotic cells

The simplest cells, called prokaryotic cells, have a straightforward structural arrangement. There is only one membrane system in it. They contain rickettsia, spirochete, mycoplasma, virus, blue-green algae, and bacteriablue-green algae, or cyanobacteria are the largest and most intricate prokaryotes, where higher plant photosynthesis occurs and have changed throughout time.

Prokaryotic cells

Prokaryotic cells range in size from 1 to 10 µm. They take place in a range of formats. A bacterial cell is made up of three basic parts:

I. External layer: It is composed of the inner cell or plasma membrane, middle cell wall and outer slimy capsule.

a. Cell membrane: The thin, flexible membrane of the cell, composed of proteins and lipids, regulates the flow of chemicals throughout the cell. It carries respiratory enzymes for reactions that release energy. Respiratory enzymes are found in mesosomes, which are folded regions of the plasma membrane that are compared to the mitochondria in eukaryotic cells. Similarly, the pigments and enzyme molecules found in photosynthetic cells are linked to the in-folds of the plasma membrane known as photosynthetic lamella, which is responsible for absorbing light and converting it into chemical energy.

b. The cell wall: It is the non-living, semi-rigid layer that encloses the cell membrane, with a thickness that varies from 1.5 to 100 µm. It is chemically made up of peptidoglycans. Certain bacteria, such as mycoplasma, don’t have cell walls.

Introduction

Human and animal body comprises of various tissues that are the functional unit of organ functioning and coordination. The tissues are further consisting of well differentiated cells that makes the tissue to behave in a special way for a particular purpose. The animal tissues are divided into epithelial, connective, muscular and nervous tissues. Epithelial tissues form the protective covering and inner lining of the body and organs. Connective tissues develop from the mesodermal cells of the embryo. they support and bind other tissues in the body. The muscular tissue develops from the mesoderm of the embryo and meant for movement and locomotion. Nervous tissue makes up the peripheral and the central nervous system and is responsible for initiation and transmission the nerve impulse. The tissues are biochemically composed of water, lipid, protein, ash, and carbohydrate along with other mineral and vitamins that are needed for its basic functioning. The extracellular matrix (ECM) forms a major component of connective tissue that forms layer and surrounds the cells or tissues meant for protection, signalling and communication. The protein component of ECM basically includes collagen, elastin, keratins, fibrillin, fibronectin, laminin and proteoglycans. Collagen is the major protein component of connective tissue that provides tensile strength, shape and fixes the organ in its position. Collagen is not homogenous rather consists of around 19 different types of proteins. There are around 30 variants of protein found in collagen. collagens type I and type II are respectively found in skin and bone. Collagen is triple helical polymer of highly elongated fibrils consisting of around 1000 amino acids majority of which consists of glycine along with proline and hydroxyproline. The forces like hydrogen bonds, covalent bonds, electrostatic, hydrophobic, and van der Waals are responsible for stabilizing the structure of collagen.

Introduction

Biochemistry of blood is extremely complex. It plays vital role in maintaining homeostasis with in the body. Blood is a specialized connective tissue which is a fluid that circulates all through the body in cardio vascular system. Blood consists of 55 per cent of plasma and 45 per cent of cellular components.

Plasma: A straw coloured liquid component of blood. Understanding the chemical basis of plasma is very crucial for diagnosis and treating various conditions. The compositional breakdown of plasma can be put forth as 90-92 % of water that acts as transport medium for the remaining 8-10 % of the solutes. Solutes further can be classified as electrolytes (salts), proteins, Lipids, other nutrients and waste products.

Plasma electrolytes: These are the minerals found in the blood that are electrically charged. Their role is very crucial in lot of physiological activities like

• Maintaining the balance of fluids interior and exterior to the cells.

• Carries electrical signals all through the body

• Helps in contraction of muscles

• Regulates blood pressure

Introduction

Energy metabolism is the complex process by which living organisms convert nutrients into energy for survival, growth, and reproduction. It involves a series of interconnected biochemical reactions that occur within cells.

Key Components of Energy Metabolism

• Catabolism: The breakdown of complex molecules (carbohydrates, proteins, and fats) into simpler ones, releasing energy.

• Anabolism: The synthesis of complex molecules from simpler ones, requiring energy input.

• ATP: The primary energy currency of cells, used to power various cellular processes.

• Enzymes: Catalysts that facilitate metabolic reactions.

Introduction

According to the body needs, minerals may be divided into 2 groups like macrominerals and microminerals. Macrominerals are required in amounts greater than 100 mg/day. They include 6 elements like calcium, phosphorus, magnesium, sodium, potassium and chloride. Whereas microminerals are also known as trace elements and are required in amounts less than 100 mg/day. They include 10 elements like chromium, cobalt, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, zinc and silicon. Some minerals are always required since small amounts of inorganic salts are always excreted Fruits, vegetables and cereals are the chief sources of the mineral elements in the diet. Milk products supply the majority of the calcium and phosphorus in the diet.

Milk and milk products are the richest source of calcium along with beans, leafy vegetables and egg yolk. It is absorbed from upper small intestine. Absorption of calcium is active process and requires calcium binding protein present in the intestinal mucosal cells. The absorption is regulated by vitamin D, parathyroid hormone, high protein diet, pH, high dietary lactate and citrate are the factors that promotes calcium absorption. Whereas high dietary phosphate, alkalinity and impaired fat absorption are the factors that inhibits calcium absorption. Of the total body calcium, 99 % present in bones and teeth in the form of hydroxyapatite and 1 % is present in body fluids and other tissues. Calcium in bones acts as a reservoir, which helps to stabilize calcium ions in plasma and extracellular f luid Parathyroid hormone and active vitamin D stimulate osteoblasts while estrogen hormone inhibits osteoclasts.

Introduction

Vitamins are the organic derived accessory food factors apart from carbohydrate, lipid and proteins meant for specific biological functions, optimum growth and health of an organism. These factors are are required in minute amount in the diet for proper functioning of biological enzymes. The term accessory factors were given by Hopkins to the essential nutrients present in the natural foods. Funk (1913) coined the term vitamine to the active principal present in rice polishings. Vitamins are classified into two categories like fat soluble A and water-soluble b Vitamins A, D, E, K are fat soluble whereas Vitamins B and C are water soluble. The B group of vitamins include vitamin B1, B2, B6, biotin folic acid, B12 etcall the fat-soluble vitamins are isoprenoid in nature consisting of repeating isoprenoid units. And meant for diversified functions. The water-soluble vitamins are heterogenous group of compounds generally not stored in the body and readily excreted in urine. These are mostly act as coenzymes for the vital biological enzymes deficiency of which reflects in the form of various deceases.

Vitamin A, include retinoid group of compounds like retinol, retinal and retinoic acid Retinol is a primary alcohol containing β-ionone ring with isoprenoid units, double bonds and hydroxyl group. Naturally it exists as ester of long chain fatty acids. Retinal is the aldehyde form whereas Retinoic acid is the acid form. Carotene is provitamin A normally found in plant origin foods that in the intestine gives rise to two moles of retinal by enzyme carotene 15-15-dioxygenase. Diet contains retinol esters and p-carotene. Retinol esters are hydrolyzed into fatty acids and retinol that absorbed into intestinal mucosal cells. p-carotene Is absorbed and converted into retinal by p-carotene dioxygenase. Retinal then converted into retinol. In the intestinal mucosal cells, retinol re-esterifies with fatty acid to form retinol ester.

Introduction

Lipids (dietary or body reserve) serves as the major source of energy for the body at the time of carbohydrate depletion. Triacyl glycerol (TG) forms the major part of lipids alongwith phospholipids, cholesterol and fat-soluble vitamins. The different forms of lipids are utilised by the body for generation of energy in the form of ATP. In addition, it serves as the source of essential fattyacids and vitamins for different metabolic purpose.

Dietary triacylglycerols (TG) are digested by lipase group of enzymes (lingual, gastric, pancreatic and intestinal) secreted by the digestive tract into free fatty acids and 2-monoacylglycerols. The 2-monoacylglycerols are either absorbed as such or hydrolysed into glycerol and fatty acids which are then absorbed independently. The glycerol and fatty acids are distributed to different tissues through circulation and utilised in the following ways

i. Storage in fat cells of adipose tissue in the form of triacylglycerols.

ii. Oxidised in peripheral tissues for production of energy.

iii. converted to glucose in hepatic cells in the process of gluconeogenesis.

iv. Synthesis of other derived compounds like steroids and eicosanoids in gonadal and other tissues

v. Synthesis of phospholipids and cholesteryl esters.

Introduction

Protein metabolism is a complex and multifaceted process that plays a crucial role in the overall health and function of living organisms. At the most fundamental level, protein metabolism involves the synthesis, breakdown, and utilization of proteins, which are essential macromolecules that serve a wide range of structural, functional, and regulatory roles within the body.

The process of protein synthesis, or translation, begins with the transcription of genetic information stored in DNA into messenger RNA (mRNA) molecules. These mRNA molecules then serve as templates for the assembly of specific sequences of amino acids into polypeptide chains, which ultimately fold into the three-dimensional structures of functional proteins. This highly regulated process is essential for the production of the diverse array of proteins required for cellular processes, tissue repair, immune function, and numerous other physiological activities. In contrast, protein degradation, or catabolism, refers to the breakdown of proteins into their constituent amino acids. This process is mediated by various proteolytic enzymes, such as endopeptidases, exopeptidases, and dipeptidases, which cleave the peptide bonds that hold the amino acid residues together Protein degradation serves important functions, such as the recycling of amino acids for energy production or the synthesis of new proteins, the removal of damaged or misfolded proteins, and the regulation of cellular signaling pathways.

Introduction

Carbohydrates, the aldehyde/ ketone derivatives of the higher polyhydric alcohols, or compounds that yield these derivatives on hydrolysis, constitute of mainly four groups viz. monosaccharides, disaccharides, oligosaccharides and polysaccharides. Energy comes mostly from carbohydrates, and products of their degradation are also used for the synthesis of other substances including fatty acids, cholesterol, amino acids etc They are also components of compound lipids, conjugated proteins, and some of their derivatives can even function as medications (e.g., cardiac glycosides, etc). Disorders such as glycogen storage disorders (GSDs) and galactosemia can be brought on by an inherited lack of certain enzymes in the metabolic pathways of various carbohydrates. Diabetes mellitus is characterized by disruption of the metabolism of glucose.

In ruminants, the end products of digestion are largely volatile fatty acids viz. acetic acid, propionic acid and butyric acid and some monosaccharides. As they pass through the ruminal epithelium, they undergo different degrees of metabolism. The fate of volatile fatty acids are as follows: Acetate as precursor to Acetyl CoA (TCA cycle; fat synthesis); Propionate as precursor to glucose (glycolysis; milk lactose) and Butyrate as precursor to Acetyl CoA (TCA cycle). All the digested and absorbed monosaccharides and volatile fatty acids enter into the liver, where two mechanisms operate such as withdrawal of carbohydrates from blood (e.g. glycogenesis; glycolysis etc) and release of glucose by liver to blood (e.g. glycogenolysis; gluconeogenesis etc). In case of monogastrics, the processes of digestion/ fermentation of carbohydrates especially occur in the small intestine. The fate of absorbed glucose and metabolic conversions in the animal body mainly comprise of storage as glycogen in liver and muscle (small amount); oxidation of glucose for providing energy (via Glycolysis pathway; other alternative pathways such as Hexose Monophosphate Pathway (HMP)/ HMP Shunt and Uronic acid pathway etc) and fat synthesis as well as storage in the form of fat in adipose tissue.

Introduction

Energy is the major source required to maintain the structure and function of all living cells. This energy is derived from oxidation of carbohydrates, lipids and proteins that is taken in the form of diet. The energy liberated from the process of oxidation is generally captured in the form of ATP, which is known as energy currency of the living cells. Each gram of carbohydrate and protein gives about 4 Kcal on oxidation, while each gram of fat gives about 9 Kcal. Oxidation means addition of oxygen or removal of hydrogen from a compound or removal of electron from an ion or atom increasing its positive charge. Reduction means removal of oxygen or addition of hydrogen to a compound or addition of electron to an ion or atom decreasing its positive charge. Commonly the oxidation reactions are conjugated with reduction reactions and known as redox reactions. Redox reactions are often associated with release of energy. The redox chain constitutes chain of different compounds of increasing redox potentials between hydrogen and oxygen. The living cells depend on redox reactions for their energy requirements. The reactions start by removal of H2 from the substrate, which is then transferred to different components of redox chain, then finally to oxygen to form water. Components of redox chains have a redox potential higher than hydrogen and lower than oxygen.

Introduction

All enzymes are proteins, except a tiny subset of catalytic RNA molecules. Most of the classical metabolic enzymes are named by adding the suffix -ase to the name of their substrates or to a descriptive term for the reactions they catalyze. For example, urease has urea as a substrate. Alcohol dehydrogenase catalyzes the removal of hydrogen from alcohols (i.e., the oxidation of alcohols). A committee of the International Union of Biochemistry and Molecular Biology (IUBMB maintains a classification scheme that categorizes enzymes according to the general class of organic chemical reaction that is catalyzed The six classes are Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, and Ligases.

The integrity of their natural protein structure is necessary for their catalytic activity. Catalytic activity is typically lost when an enzyme denatures or dissociates into its constituent subunits. An enzyme’s catalytic activity is always eliminated when it is disassembled into its constituent amino acids. Thus, the catalytic activity of protein enzymes depends on their primary, secondary, tertiary, and quaternary structures. Aside from their amino acid residues, certain enzymes don’t need any other chemical groups to function. Others need a cofactor, which is an extra chemical element. Cofactors can be complex organic or metalloorganic molecules called coenzymes, or they can be one or more inorganic ions like Fe2+, Mg2+, Mn2+, or Zn2+.

Introduction

A pentose sugar, one or more phosphate groups, and a nitrogenous base (purine or pyrimidine) make up a nucleotide. Phosphodiester bonds, which connect the 5’-hydroxyl group of one pentose to the 3’-hydroxyl group of the next, bind nucleic acids together as polymers of nucleotides. RNA and DNA are the two different forms of nucleic acids. RNA nucleotides contain ribose, while uracil and cytosine are typical pyrimidine bases. Thymine and cytosine are common pyrimidine bases, and DNA contains 2’-deoxyribose in its nucleotides. In both RNA and DNA, adenine and guanine are the main purines. There is ample evidence to suggest that genetic information is encoded in DNA The Avery MacLeod-McCarty experiment, in particular, demonstrated how DNA obtained from one bacterial strain may infiltrate and change the cells of another strain, giving it some of the genes from the donor. The Hershey-Chase experiment demonstrated that a bacterial virus’s DNA contains the genetic instructions needed for the virus to replicate in a host cell, but not its protein coat. Watson and Crick proposed that native DNA is made up of two antiparallel chains arranged in a right-handed double helical configuration based on a compilation of numerous published data points. A-T and G-C, two complementary base pairs, are created by hydrogen bonds inside the helix. 10.5 base pairs are stacked per turn, perpendicular to the double helix’s long axis, at a distance of 3.4 Å. There are various structural configurations for DNA A- and Z-DNA are two variants of the Watson-Crick form or B-DNA The DNA molecule bends as a result of certain sequence-dependent structural differences.