Interrelationship of feeding with immunity and parasitic infection: a review

Authors overlook the recent findings in the field of the complex interrelationship among nutrition, immune status and parasitic infestation. After summarizing the general characteristics of the active immune system, they describe the first period of the systemic immune response, the acute phase reaction. The cause of drastical decrease in serum zinc concentration is redistribution into the liver and lymphocyte metallothioneins. Immune deficiency correlates only indirectly with the nutrition. Ingestion of feed mycotoxins (e.g. T-2 toxin) and peroxides causes lymphocytes depletion in the lymphoid organs. Events of immunological stress are a special form of homeorrhetic control. Lack of energy and protein hardly damages the humoral immunity. Undernutrition fundamentally affects the cell-mediated immune response and the complement production. In animals, the lack of calcium, magnesium, iron, zinc, copper, iodine and selenium has been associated with signs of immunodeficiency. The concentrations of trace elements required for healthy animals are often below what is required for animals experiencing an immunological challenge. Zinc has both specific and aspecific role in the immune defence mechanism. Zinc regulates the maturation and function of immune cells, among others by protecting developing lymphocytes from apoptosis. As part of the zinc-finger proteins, may influence DNA transcription. The thymus synthesizes a 9-amino acid peptide hormone, the thymulin, which is activated after having bound zinc. Selenium has a vitamin E-independent immunostimulant effect in the marginally supplied animals. Active form of vitamin D3 regulates transcription at cell level, acts as an immunomodulator and promotes phagocytosis. Lack of essential fatty acids in the diet of experimental animals caused atrophy of lymphoid organs and the reduction both the T-cell mediated and the independent immune response. Practical application of the new immunological findings is the segregated early weaning (SEW). Feed allergy results either in immediate hypersensitivity reaction within 1 to 2 hours or a T cell-mediated delayed hypersensitivity reaction within days. Under a certain number of worms ("threshold value") the host organism did not show detectable changes. Parasitic infection changes the body and skeletal composition: the water content increases, that of protein and fat drop; the calcium and phosphorus concentration of bones decreases. Helminths, developing in the animal, may cause serious local lesions; anaemia and the change of plasma proteins. Worms' toxins stimulate the production of gastrointestinal hormones, causing reduction in voluntary feed intake. Rabbits with biliary coccidiosis significantly decreased voluntary feed intake and the digestibility of the fats. The extent of infection and the oocyte excretion of Eimeria maxima in growing chickens showed a strong negative correlation with the plasma carotenoid level and strong positive correlation with the blood nitrogen oxide and γ-interferon concentration.