Phytogenic and Phytochemical as Alternative Feed Additives for Animal Production

For centuries, plant-based ingredients extracted from herbs, spices, and medicinal flora have been used to enhance feed quality, flavor, and preservation, as well as in traditional healing medicine. As our understanding of their functional mechanisms grows, new opportunities arise for their application in the treatment of metabolic disorders and as feed supplements to promote positive physiological responses in various animal species. These naturally derived products are environmentally friendly and safe for living organisms, offering a wide range of beneficial properties, including antimicrobial, antioxidant, antiallergic, anticancer, antimutagenic, liver-protective, and immunomodulatory effects. Following the European Union's prohibition on antibiotic use as growth promoters in food-producing animals in 2006, researchers have turned their attention to natural alternatives, such as phytogenic substances, also referred to as phytobiotics or botanicals. These compounds have been demonstrated to boost animal productivity, encourage feed consumption, enhance nutrient absorption, and support optimal intestinal health. Promising feed additives include medicinal plants, such as milk thistle seeds, turmeric, rosemary leaves, and thyme. Additionally, bee pollen and propolis, which have both plant and animal origins, have been explored as substitutes for antibiotics and coccidiostats in animal nutrition, and have shown potential as growth enhancers and immune boosters. This book provides a comprehensive overview of the most commonly used natural substances as alternatives to growth-promoting antibiotics and details their mechanisms of action and effects in animals. The aim is to update the current knowledge and promote further research to identify additional beneficial natural molecules that can help reduce the negative impacts of antibiotics on animals, humans, and the environment.

Phytogenic substances derived from plant organs are bioactive compounds widely used to enhance health, food safety and shelf-life. These substances exhibit diverse biological activities, supporting animal and human health by promoting antioxidant defenses and enhancing immune function. They can mitigate the production of oxygen-containing reactive species (ROS) generated by environmental stressors, inhibit enzymes implicated in cellular damage, enhance mitochondrial function, and improve energy biosynthesis and availability. Incorporating phytogenic additives into livestock diets is a safe, effective, and economically viable strategy for mitigating the adverse effects of conventional feed additives on animal and human health. Reducing antibiotic use in livestock production is critical and can be achieved by integrating phytogenic substances, herbs, spices, medicinal plants, probiotics, prebiotics, synbiotics, and postbiotics along with implementing robust biosecurity measures. This chapter emphasizes the role of phytogenic products as growth promoters in livestock production, and their potential applications in enhancing food safety and security. The subtherapeutic use of antibacterial drugs has significantly enhanced meat, egg, and milk production over the centuries. However, the use of antimicrobial agents promotes the selection of resistant microbes that can proliferate rapidly and become dominant within microbial populations, potentially compromising the effectiveness of treatment for microbial infections in humans.

The modern animal industry faces a persistent challenge: meeting growing consumer demand for high-quality, low-cost food while maintaining stringent standards of sanitation, health, and welfare. In recent decades, antibiotic-supplemented diets have been widely adopted to maximize the growth potential of livestock. However, alternative approaches have emerged, including the use of phytochemicals as substitutes for antibiotics, to enhance avian productivity. Phytobiotics, which consist of herbs and their derivatives, have numerous therapeutic effects and are available in various forms. Recently, this type of feed manipulation has gained popularity in the animal industry as an alternative to antibiotics, primarily because of the lack of adverse side effects and their ability to bolster the immune system and improve stress tolerance. In addition to enhancing intestinal integrity and reducing gut damage, phytobiotics promote increased feed intake by compensating for the nutritional demands of local and systemic immune responses. Furthermore, they reduce the concentration of pathogenic microflora in the gastrointestinal tract and mitigate the local inflammatory responses. In poultry, these benefits are demonstrated by improved feed consumption, increased digestive enzyme secretion, and enhanced immune function. Phytobiotics exhibit a wide range of biological activities, including immunity-boosting, antibacterial, antiviral, coccidiostatic, antiparasitic, anti-inflammatory, and antioxidant properties. Herbs and their derivatives have been used since ancient times for their health benefits and minimal side effects. However, recent studies have highlighted that certain herbs and their metabolites may pose risks, raising concerns among consumers regarding the safety of using these compounds as feed supplements or treatments. This chapter explores the beneficial effects and latest developments related to phytobiotics and highlights their practical applications and health advantages. Understanding these features is essential for veterinarians, scientists, pharmacists, physiologists, pharmaceutical industries, nutritionists, and animal breeders as they consider the use of phytobiotics in modern animal husbandry.

Thymus vulgaris L., a member of the Lamiaceae family, is a herb widely used in conventional medicine because of its various therapeutic properties. Thyme, mostly cultivated in the Mediterranean region, is used as a spice and medicine worldwide, owing to its antioxidant and antibacterial properties. This chapter focuses on data supporting the use of thyme as a productive enhancer in animal feed and as a partial or full substitute for antibiotics. The essential oils found in the aerial portions of thyme are a source of fragrance and therapeutic qualities. The main active constituents of thyme extract are thymol, carvacrol, and other mono- and sesquiterpenes. These compounds contribute to the flavor, fragrance, and antibacterial properties of thyme. The effect of thyme on animal performance is attributed to its bioactive compounds, which vary depending on several factors. Thyme supplementation has been documented to be advantageous in poultry production, with thymol reported to prevent oral bacterial infections and to influence the permeability of pathogenic bacterial cell walls, leading to cell death. Essential oils from thyme can also support digestive functions by stimulating endogenous enzyme activity, nitrogen absorption, and regulating the ammonia content and odor of excreta. The antibacterial properties of thyme are influenced by the chemical structure and lipophilic characteristics of its essential oils, allowing them to pass through bacterial membranes and affect the interior of the cell.

Rosemary is a phytogenic aromatic plant, abundant in phenolic acids, such as caffeic (0.69-1.0 mg/g) and rosmarinic acids (16.77-29.91 mg/g), flavonoids, and diterpenes. Additional components of rosemary include camphor, 1,8-cineole, and αpinene. Rosmarinic acid (RA) exhibits antioxidant, antiviral, antibacterial, antiinflammatory, and antimutagenic properties. Furthermore, rosemary significantly reduced the peroxidation of unsaturated lipids and enhanced the levels of reduced glutathione and antioxidant enzyme activities in the kidney and testis compared to aspartame controls. Additionally, rosemary essential oil augments the resistance of rat hepatocytes against DNA-damaging oxidative agents and serves as an effective free radical scavenger. Caffeic and rosmarinic acids have demonstrated potential in the treatment of inflammatory diseases and hepatotoxicity. Rosemary is also rich in phytochemical derivatives such as triterpenes, flavonoids, and polyphenols. This review will focus on the beneficial effects of rosemary and its application in improving the productive performance and health of livestock.

Silymarin, a polyphenolic flavonoid complex extracted from milk thistle seeds (Silybum marianum), has a wide range of therapeutic properties, including antiinflammatory, immunomodulatory, and antioxidant effects. This review explores the applications of milk thistle and silymarin in animal nutrition, focusing on their effects on productive performance, animal health, metabolic profiles, and detoxification processes. Milk thistle seeds contain various nutritional components that have been shown to improve nutrient utilization, stimulate appetite, and enhance the intestinal environment. Studies have reported that milk thistle supplementation significantly improves productive performance, carcass yield, and digestibility in growing rabbits, broilers, and quail. The hepatoprotective effects of milk thistle are attributed to its inhibition of lipid peroxidation, stabilization of membrane permeability, reduction of apoptosis in hepatocytes, and limited leakage of hepatic enzymes. The potent antioxidant properties of silymarin protect cells from oxidative stress by scavenging reactive oxygen species and inhibiting lipid peroxidation. Milk thistle extract also acts as a free radical scavenger, protecting against glutathione depletion, and enhancing glutathione peroxidase activity in the brain and kidneys. Furthermore, milk thistle supplementation has been shown to improve hematological parameters, such as leukocyte count, hemoglobin levels, and packed cell volume, in birds exposed to ochratoxin A. The beneficial effects of milk thistle on animal immunity, oxidative stress, performance, and reproduction make it a valuable candidate for use as a feed additive in animal nutrition.

Two molecules of feruloyl-CoA and one molecule of malonyl-CoA are combined to generate turmeric (Curcuma longa), also known as curcumin, through two enzymatic processes mediated by curcumin synthase (CURS) and DIKETIDE-CoA SYNTHASE (DCS). DCS and CURS are members of polyketide synthase family type III. Turmeric, a homegrown spice, has several health benefits in the medical field. One specific bioactive ingredient produced by turmeric is curcumin, a polyphenolic phytochemical with antibacterial, anti-inflammatory, anticancer, and antioxidant properties. Research indicates that turmeric can substitute for antibiotics in chicken feed and is effective. When powdered turmeric rhizomes are fed to broiler chicks, morbidity and mortality are reduced. Furthermore, it has been shown that including turmeric in chicken feed does not negatively impact the overall health of animals. The use of turmeric in animal nutrition as a helpful feed additive, as well as its bioactive components and effects on blood biochemistry, animal health, and productive performance as an antibiotic substitute, will be covered in this chapter. 

Essential oils (EOs) are aromatic products made from a combination of components extracted from plant materials used in food, cosmetics, and medicine, among several other applications. EOs are extracted using various extraction methods from the bark, seeds, leaves, peel, buds, flowers, and other components of medicinal plants. Techniques used to extract EO include steam distillation, solvent-assisted extraction, hydrodistillation, ultrasonic extraction, supercritical fluid extraction, and solvent-free microwave extraction. EO affects the intestinal health and growth efficiency of different animal species. EO has been reported to improve pancreatic amylase, trypsin, and maltase levels and increase digestibility. EO has antioxidant action, lowers lipid oxidation in meat, and enhances shelf-life. The present chapter summarizes some of the beneficial effects of oregano EO on poultry production and health. 

Zingiber officinale, commonly known as ginger, is a spicy plant with active ingredients such as gingerol and shogaol (Fig. 1). Ginger has been widely used in traditional medicine to improve digestion, as it has been shown to increase the digestive enzyme protease (zingibain). Ginger is well known for its antibacterial and antiphlogistic properties, in addition to its ability to lower cholesterol levels in the bloodstream. In this chapter, we focus on the use of ginger as a feed supplement for enhancing poultry nutrition and the impact of this phenomenon on productive efficiency, carcass characteristics, hematology, gut microbiota, and toxicity.

Bee Pollen (BP) is a mixture of nectar, salivary secretions from bees, and pollen grains collected from the flowers. It contains a wide range of nutrients, including proteins (10-40%), carbohydrates (13-55%), lipids (1-20%), vitamins (0.02-0.1%), minerals (0.5-3%), flavonoids (0.04-3%), and other bioactive substances such as phenolic compounds. BP has been reported to possess various therapeutic properties including antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial activities. The chemical composition and bioactive substances in BP may differ significantly owing to factors such as plant species, nutritional status, environmental conditions, age, and vegetation during the flowering period. BP has been shown to have beneficial effects on human health, including the prevention of prostate problems, arteriosclerosis, and tumors. In animal science, BP supplementation has been evaluated primarily in poultry with encouraging results. BP can improve the cell immune response, antibody production speed and reinforce the immunological system. The positive effects of BP on animal productive performance may be due to its nutritive value, appetite-stimulant properties, and the presence of digestive enzymes. In domestic animals such as sheep, broilers, rabbits, and quails, supplementation with BP has been reported to improve the immune response, increase feed digestibility, reduce oxidative stress, and improve animal performance. This chapter emphasizes the use of Bee Pollen in livestock nutrition as a feed supplement to improve productive performance as an eco-friendly alternative to antibiotics.

Propolis, a resinous substance collected by bees from plant exudates and buds, has gained renewed interest as a natural feed additive for animal nutrition. Its composition varies depending on the plant source, time, and place of collection; however, it is primarily composed of phenolic acids, flavonoids, and their derivatives. Egyptian propolis contains phenolic acid esters (72.7%), dihydrochalcones (6.5%), flavones (4.6%), aliphatic acids (2.4%), flavanones (1.9%), chalcones (1.7%), phenolic acids (1.1%), and tetrahydrofuran (THF) derivatives (0.7%). Turkish propolis contains flavonoids (37.83%), organic acids (18.54%), aromatic acids and their esters (35.8%), hydrocarbons (4.89%), and other undefined components (2.94%). Propolis also contains vitamins, minerals, enzymes, fatty acids, amino acids, terpenes, and polysaccharides. Its bioactive components, including CAPE, artepillin C, caffeic acid, chrysin, galangin, quercetin, apigenin, kaempferol, pinobanksin, and pinocembrin contribute to its antibacterial, antifungal, anti-inflammatory, and antioxidant properties. These characteristics make propolis a promising natural growth promoter for livestock production and a potential replacement for antibiotics. In addition, propolis has applications in food technology as a preservative, with the added benefit of its residues being beneficial to human health. Ethanol is the preferred solvent for preparing propolis, although other solvents can also be used for the extraction and identification of its constituents. Polyphenols and flavonoids in propolis have been reported to positively affect the immune systems of various species, making it a valuable addition to livestock production practices.

The use of phytogenic additives in livestock nutrition as an alternative to classical feed additives has shown promising results in improving animal performance and product quality while avoiding the negative effects of antibiotics on animal health, product quality, and human health. This book reviews the recent advances in photogenic nutrition and its application in animal nutrition as a means of antibiotic replacement and eco-friendly feed additives. This chapter summarizes the outcomes of the 11 chapters reviewed, and their possible applications in animal nutrition. Numerous possible alternatives to antibiotic growth promoters can be used in mono-gastric animal nutrition, including thyme, rosemary, milk thistle seeds, turmeric, phytogenic, essential oils, bee pollen, and propolis. These alternatives and eco-friendly feed additives serve as sources of bioactive ingredients such as flavonoids, phenols, and polyphenols [1–4]. To date, the results have been inconclusive because of the different factors involved in animal responses, such as strain and age of the animal, health conditions, housing conditions, environmental status, part of the plant, type of plant product (leaves, seeds, and roots), drying methods, extraction methods, water vs. organic solvents, dose of administration, and methods of delivery (feed and water). Thus, further studies are needed to identify the dose, bioactive substances, and application root to develop commercial products on an individual basis and/or mixed agents that need to be tested. These promising additives may partially or completely replace antibiotic growth promoters and overcome the possible problems caused by the withdrawal of antibiotics from the feed additives market [2, 5, 6]. The use of phytogenic feed supplements in farm animal nutrition as a substitute for classical feed additives has shown promising results in enhancing animal performance and product quality, while avoiding the negative effects of antibiotics on human and animal health, product quality, and food security and safety.