Phytobiotics : An Alternate for Antibiotic Growth Promoters (AGP)

Phytobiotics : An Alternate for Antibiotic Growth Promoters (AGP)

Gurusaran S¹,

¹Field veterinarian, Tamil Nadu.

Introduction:

                        In recent years, the rapid boom in population on the global stage has urged people to seek good protein sources to meet their requirements. In general, animal-based foods, especially meat sources, constitute a major source of protein because of their high biological value. Among the various types of meat, chicken meat is considered a cheap protein source to substantiate rapid globalization. This created a great demand for chicken meat globally. In the latter half of the 20th century, the development in the field of genetics led to the development of various strains that showed high growth performance in a short span. This hurt the immune system, making the birds highly disease-susceptible. To substantiate it, the use of antibiotics came into the picture. These synthetic pharmaceuticals are termed antibiotic growth promoters (AGP). Antibiotics have been successfully used for the past 50 years in the livestock and poultry industry as growth promoters. However, due to the potential risk of antimicrobial resistance in the usage of AGP and the change in public demand for organic foods, the public questioned the usage of synthetic pharmaceuticals and sought alternatives. Phytobiotics, a relatively new feed additive also known as phytogenic feed additive (PFA), is a plant-derived compound that includes essential oils, herbs, and resins and is considered an alternate option for AGP. In recent years, their usage in the poultry industry and research regarding understanding their mechanism of action for enhancing growth have gained importance.               

Table 1. common Phytobiotics and their beneficial effects.          

Beneficial effects of Phytobiotics:

Effect on gut function and palatability:

                  Phytobiotics are said to be increase the secretions, including saliva, bile, digestive, and mucosal enzymes (trypsin, maltase, amylase, and pancreatic lipase), enhancing their activity to speed up digestion. It also perks the absorption of various nutrients, thus enhancing the weight gain and feed efficiency ratio (FCR). Herbs and spices are the flavouring agents that increase palatability. The extracts from ginger and garlic showed beneficial effects on digestive tract secretion and nutrient absorption. The addition of extracts from thyme, oregano, chilli (capsaicin), and cinnamon to the diet of chickens has shown improvements in feed intake, nutrient absorption, and FCR. The addition of sanguinarine, an alkaloid from Sanguinaria canadensis, to the diet enhanced the gastric motility, gut histomorphology, and fermentation process. Even though tannin has some beneficial effects at a lower level, a high amount suppresses growth by affecting the absorption of sulfur-containing amino acids that’s necessary for growth.

Effect on blood profile and metabolism:

Phytobiotics are said to have beneficial effects on metabolism. The addition of garlic and thyme to a broiler diet increases the production of HDL cholesterol, significantly reduces the production of triglyceride and LDL cholesterol, enhances the quality of meat, and reduces the risk of metabolic diseases. In combination, the addition of tomato and chili to the diet shows hypocholesterolemia and a well-balanced metabolic profile. The addition of certain herbs like Andrographis paniculata showed hepatoprotective effect. 

Effect on Gut microbiome and antimicrobial activity:

Phytobiotics are known for their germicidal effect and maintenance of gut morphology (prebiotic effects), especially spices and herbs. The mechanism of action differs according to the active component present, and they are synergistic in action. Tannic acid, or tannin, exerts its germicidal action on bacteria like E. coli, Enterobacter, and Bacteriodes species. Saponin exhibits its action by binding with sterol on the cell wall membrane and disturbing membrane permeability. Alkaloids affect the multiplication of the organism by acting as an intercalator and inhibiting DNA synthesis. Essential oils attack the cell membrane and alter the permeability, causing leakage of vital ions that becomes detrimental and leads to collapse. The essential oils of oregano and garlic have shown antimicrobial effects against Salmonella sp., Clostridium perfringens, and E. coli. Allicin present in the garlic extract possesses antifungal activity by converting into various antimicrobial compounds, including allyl methyl trisulphide, diallyl sulphide, etc. The neem extract seems to have an inhibitory effect on the biosynthesis of aflatoxin and ochratoxin. Coccidia is an economically important disease in the poultry sector. The extract from green tea has shown a significant anti-coccidial effect. Addition of thyme (omam), cinnamon and ginger shown significant balance in the gut biome by enriching the growth of gut favorable bacteria.

Effect on immune system:

Phytobiotics action on the immune system is multidisciplinary. The active components of plant additives include polyphenols, tannins, saponins, alkaloids, essential oils, and sulfur compounds. These compounds stimulate the immune cells, including macrophages, to enhance phagocytic activity, and by stimulating B and T lymphocytes, they increase the titers of antibodies, enhance the activity of cytokines, and provide chemoprotective effects. In recent research, the addition of cashew, guava, and noni in proportion to the diet of layers and broilers enhanced the immune system. Also, the use of cinnamon oil in broiler diets has shown beneficial effects on the immune system.

Antioxidant and anti-inflammatory activity:

Reactive oxygen species (ROS), a free radical compound physiologically produced from the oxidation process, cause damage to lipids, proteins, and DNA and also quench the defense system. This may significantly affect the quality of animal products and lower their shelf life. ROS are counted by antioxidants either through enzymatic or non-enzymatic means. Phytobiotics exert their antioxidant ability through polyphenols, which include flavonoids, phenolic acids, tannins, toluene, ascorbic acid, and retinol, which activate enzymes such as superoxide dismutase, catalase, glutathione peroxidase, etc. that are responsible for countering ROS. The addition of plants such as ginger, garlic, clove, turmeric, and pepper to the broiler and layer diet enhances the meat quality by reducing lipid peroxidation. The anti-inflammatory effect of Phytobiotics due to the presence of Terpenoids and flavonoids, controls prostaglandin activity, responsible for inflammatory reaction. The addition of plants such as turmeric, cinnamon, clove, pepper, mint, etc. in the diet exerts an anti-inflammatory response.

Conclusion:

Encapsulating the impact of Phytobiotics in poultry nutrition shown, to improve digestion and absorption, control the gut microbiome, improve the defense system, enrich the antioxidant defense mechanism to counter free radicals, favorable modification of lipid profile, produce a hepatoprotective and anti-inflammatory effect, collectively led to improved growth and performance. Because of these health-promoting properties, it’s worth using Phytobiotics as an alternative to antibiotics, as it improves the quantity as well as the quality of the meat and egg obtained. At the same time, some herbs possess harmful effects, and influence to alert physiological function and product (meat and egg) quality. Hence, there is a lot of scope for research in phytobiotics as feed additives in animal nutrition, to understand the mechanism of action and to obtain a systematic usage in animal feeds.

Reference:

1. Krauze M (2021) Phytobiotics, a Natural Growth Promoter for Poultry. Advanced Studies in the 21st Century Animal Nutrition. IntechOpen. DOI: 10.5772/intechopen.99030.
2. Kikusato M. Phytobiotics to improve health and production of broiler chickens: functions beyond the antioxidant activity. Anim Biosci. 2021 Mar;34(3):345-353. doi: 10.5713/ab.20.0842. Epub 2021 Feb 14. PMID: 33705621; PMCID: PMC7961201.

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