Immunomodulatory Effects of Natural Feed Additives for Meat Chickens

Abstract

Broiler chickens are increasingly kept in large numbers in intensive housing conditions that are stressful, potentially depleting the immune system. With the prohibition of the use of antibiotics in poultry feed spreading worldwide, it is necessary to consider the role of natural feed additives and antibiotic alternatives to stimulate the chickens’ immune systems. We review the literature to describe phytogenic feed additives that have immunomodulatory benefits in broilers. We initially review the major active ingredients from plants, particularly flavonoids, resveratrol and humic acid, and then describe the major herbs, spices, and other plants and their byproducts that have immunomodulatory effects. The research reviewed demonstrates the effectiveness of many natural feed additives in improving the avian immune system and therefore broiler health. However, some, and perhaps all, additives have the potential to reduce immunocompetence if given in excessive amounts. Sometimes additives are more effective when given in combination. There is an urgent need to determine tolerance levels and optimum doses for additives deemed most suitable to replace antibiotics in the diet of broiler chickens. Effective replacement is most likely with readily available additives, such as olive oil byproducts, olive leaves and alfalfa. It is concluded that effective replacement of antibiotic function with plant-derived additives will be possible, but that further research is necessary to determine optimum doses.

The effects of herbal plant extract on the growth performance, blood parameters, nutrient digestibility and carcase quality of rabbits: A meta-analysis

“…Furthermore, the suppressive effect of natural herbs on the immune response was closely associated with a reduction in the production of pro-inflammatory cytokines [ 41 ]. Nevertheless, studies in ruminants and poultry revealed that herbs could develop the immune-modulatory system [ 42 , 43 ]. Their use in feed additives could therefore be beneficial in to supporting animal health.…”

Evaluation of the Antimicrobial Activity of a Formulation Containing Ascorbic Acid and Eudragit FS 30D Microparticles for the Controlled Release of a Curcumin–Boric Acid Solid Dispersion in Turkey Poults Infected with Salmonella enteritidis: A Therapeutic Model

“…Despite the fact that a large number of feed additives have been studied and evaluated as a replacement for the use of antibiotics, most of them are relatively effective and economically feasible, as well as variable in terms of the effects they produce [20]. In this context, one of the strategies that have been considered in order to solve the problems of effectiveness of feed additives is the use of combinations of two or more of them in the same treatment [21][22][23][24].…”

Farm Animal Welfare—From the Farmers’ Perspective

“…Replacing antibiotics in the diet of chickens with feed additives that stimulate the birds’ immune system is also possible. Flavonoids and other active ingredients that do this are plentiful in a range of herbs and spices [ 59 ]. Some of the most promising supplements are olive oil byproducts, olive leaves, and alfalfa, but the optimum doses for most of the supplements have not yet been reliably determined.…”