Raju Kushwaha*, Vinod Kumar, Muneendra Kumar, Mokshata Gupta, Dhapse Sanket Rajkumar
Department of Animal Nutrition, College of Veterinary Science and Animal husbandry,
DUVASU, Mathura-281001
Email: rajuvet15@gmail.com
Nutrition of animal interacts with their immune system. Major nutrients like energy protein and fat and micronutrients like vitamins and minerals are play a vital role in evoking animal immune response. The relation ship between nutrition and disease resistance is complex. But it is well documented that the micronutrients play important role in animal immunity. Minerals like zinc, copper chromium, iron, cobalt, selenium and manganese and vitamins (antioxidant) like Vitamin E, Carotenoids (beta carotene) and vitamin A, vitamin C are having significant role in animal immune status. Some vitamins and minerals the amount required for optimal growth response is greater than the amount required for growth and reproduction. Cattle can have sufficient vitamin and minerals intake for adequate growth and reproductive performance but not have optimal immune response.
Stress associate with weaning and transportation has a negative effect the immune system. This stress typically occurs when the animal is exposed to a variety of infectious agents as a result of marketing /transporting/ management procedures. Nutrition can interact with these two primary factors mostly likely us a result of infectious agents. Preweaning nutritional deficiencies or through decreases feed intake associated with stress. Decreased feed intake/ nutrient has further depressed the immune function and potentially increases susceptibility to infection. Nutrients derived from dietary proteins, carbohydrate and fats as well as micronutrients, vitamins and minerals interact with immune cells systematically in the circulating blood, regional lymph nodes and specialized immune system of gastrointestinal tract.
Immunology
Immunity refers to reactions by an animal’s body to foreign substances such as microbes and various macromolecules, independent of a physiological or pathological result of reaction. Immunity is generally classified as either innate immunity (natural) or acquired (specific). Innate immunity includes physical /chemical barriers, the complement system, phagocytes such as macrophages, neutrophils, and natural killer cells and macrophages derived cytokines such as alpha and beta interferon’s and tumor necrosis factor. Acquired immunity, which is induces by natural exposure or vaccination, includes antibiotics, lymphocytes and lymphocyte-derived cytokines such as interleukin-2 interleukin–4 and transforming growth factor. Acquired immunity if further divided into either Humoral or cell mediated immunity. Humoral immunity is mediated by B-lymphocytes, which respond to antigens to become antibody producing cells and memory cells and provide defense against intracellular microbial infection. In cell-mediated immunity, the T lymphocytes and associated cytokines provide defense against intracellular pathogens and tumor cells. Humoral immune response can be measured by estimating the antibody production by zinc turbidity method.
Zinc
Zinc is an essential trace element for the immune system. The innate as well as specific parts of immune system are influenced by Zn. Zinc is component of numerous enzymes like Superoxide dismutase (SOD), RNA polymerase, DNA polymerase, Thymidine kinase and Ribonuclease. Zinc deficiency results in atrophy of the thymus and increase leukocyte count with reduced number of lymphocytes. Immature neutrophils are elevated in zinc deficient animals. Zinc is important in activation of B cells and NK cells. Zinc is essential co factor for the thymic hormone thymulin. Thymulin is secreted by thymic epithelial cells and induces differentiation in immature T cells. Zinc influences host defense mechanism via: phagocytic activity, cell mediated immunity and humoral immunity. Zinc enhances the phagocytic activity of macrophages and neutrophils. Phagocytic cell consume large quantities of oxygen during the so-called respiratory burst, which accompanies the ingestion and killing of microorganisms and production of H2O2 and O–2 radicals in response to challenge by foreign particles. The protection of neutrophils against the damaging effects of super oxide radicals is probably the function of the cytosolic cu-zn containing super oxide dismutase.
Copper
Copper is a component of Superoxide diamutase enzyme. Through this enzyme activity, copper enhances the phagocytic process of neutrophils and macrophages. ceruloplamin a copper containing protein. Around 90% the circulatory copper present in form. The concentration of ceruloplasmin higher in inflammatory site due to increased blood supply. The copper present in the ceruloplamin used by neutrophils and macrophages used for their phagocytosis process. Copper deficient animals exhibit severe symptoms of immune dysfunctions. These include: Decreased functions of T cells, decreased NK cell cytotoxicity and distorted lymphocyte population. Copper deficient animal show decrease in antibody cell response with increased susceptibility to infection. Copper deficiency appears to alter the plasma membrane thus altering immune response to infection.
Chromium
Chromium so important to health maintenance particularly during stress. Cr seems to be an essential trace element because it is a component of Glucose Tolerance Factor that potentiates the action of insulin. GTF is organo metallic compound consist of trivalent chromium ions bound to several molecules of niacin, and amino acids. GTF facilitate interaction between insulin and insulin receptor in target tissue. Supplemental chromium enhances the immune response of stressed calves. Stress result in elevated blood concentration of cortisol, which is known to depress immune function. Periparturient and early lactation dairy cows are under great physical and metabolic stress. Under these conditions Cr supplementation enhances immune responses. Chromium supplementation enhances both Humoral and cell mediated immune response under stress.
Iron and Cobalt
Iron important for heam synthesis. It exerts immune role via catalyze enzyme which converts hydrogen peroxide to water in anti oxidant system. Impaired cell mediate immune response was observed in iron deficient animals. Primarily affect antibody formation associated with B cells. In pigs, iron deficiency prone to more disease susceptibility. Cobalt deficiency affects neutrophil function. Its deficiency affects resistance to parasitic functions. Higher faecal egg counts are observed in Co deficient lambs after natural infection with gastrointestinal nematodes.
Vitamins (antioxidant)
Antioxidant function as to remove harmful free radicals produced through normal cellular activity, there by maintaining structural integrity of immune cells. Major free radicals found in biological system are super oxide, hydrogen peroxide, hydroxyl radical and fatty acid radicals. Free radicals are highly reactive compounds because they are missing an electron. Free radicals can react with nucleic acids causing mutation, they can react with enzymes and render them in active and they can react with fatty acids in membranes causing membrane instability. Free radicals can eventually kill cells and damage tissue. Reactive oxygen metabolites are unavoidable products of normal metabolism process and are not ways harmful. Super oxide and hydrogen peroxide are involved physiologically in the chemistry of several enzymes and are used by phagocytic cells to kill bacteria. In balance between production to ROM and their safe disposal however can initiate oxidative chain reactions and lipid per oxidation. Natural antioxidant includes vitamin E, vitamin A carotenoids (beta carotene) and vitamin C. Beta carotene potent direct acting anti oxidants where as vitamin A is less active anti oxidant but its role in disease registance was well documented as maintaining the epithelial integrity of immune cells. In general minerals do not act directly act antioxidant but are critical components of the antioxidant enzymes.
Vitamin E and Selenium
Primary function of vitamin E as an anti oxidant. Its supplementation enhances the neutrophil function. Both vitamin E and Se are important in cellular antioxidant system. High dietary vitamin E reduces the requirement for selenium. The principle biochemical role of selenium is through enzyme ie. Glutathione peroxidase. Glutathione perxoidase is an important part of cellular antioxidant system. Selenium supplementation also improves neutrophil function. Neutrophils from cows supplemented with 0.3 ppm of supplemental selenium killed mastitis pathogen more effectively than non-supplemented group. Vitamin E and Se influences the function of immune cells especially mammary gland. Vitamin E and the selenium containing enzyme glutathione peroxidase are important in the function on PMN. When pathogen invades the mammary gland they trigger an influx of PMN and other white cells. These cells engulf and destroy bacteria and other harmful organism. If vit E and Se are not in adequate supply, the total no. of PMN and the life span of these cells will be greatly reduced.
Vitamin A and beta-carotene
Carotenoids are red and yellow pigments serve as precursor (beta carotene) to vitamin A. Beta-carotene is an efficient quencher of singlet oxygen and can function as antioxidant. Vitamin A cannot quench singlet oxygen and has less antioxidant activity then other antioxidant. But vitamin A prevents epithelial keratinization and maintains the cellular integrity of lymphoid organs, which is important for combating disease stress. Beta carotene increases lymphocyte cytotoxic activity, stimulate production of various cytokines, enhances phagocytic activity of neutrophils and macrophages and increase activity of natural killer cells. It enhances both cellular and humoral immunity. Beta-carotene enhances peroxidase activity in macrophages and myelo peroxidase activity of neutrophils.
Conclusion
Micronutrients effectively modulate the animal immune response. Zinc and copper enhance both cell mediated and Humoral immune response. Chromium evokes animal immune status especially in stress condition. Vitamins i.e. antioxidants prevent the tissue against the free radicals generated in normal cellular metabolism. Vitamin E and Se particularly important for mammary gland immunity. Beta-carotene act as potent antioxidant and prevent the tissue damage caused by free radicals. Thus, the possibility if dietary nutrient manipulation for optimization of immune response with out compromising the genetic potential of animals for growth and production appears to be feasible and thus will economically benefit the livestock farmers and the sector as whole.