POTENTIAL OF TANNINS AS AN ALTERNATIVE TO ANTIBIOTIC GROWTH PROMOTERS FOR POULTRY PRODUCTION
Dr. Kaushalendra Kumar
Assistant Professor, Department of Animal Nutrition, Bihar Veterinary College, Patna, India
E-mail: drkaushabvc@gmail.com
Abstract
The global demand for meat and eggs is primarily responsible for the continual expansion of the poultry industry. However, the price of feedstuffs has significantly increased as a result of this industry’s rapid expansion and the rising demand for poultry feeds. It is anticipated that the imbalance between supply and demand for balanced feed will widen, which would raise manufacturing costs. Conversely, the traditional feed ingredients are no longer able to supply the feed needs of the chicken sector. However, several issues, including bacterial contamination, coccidiosis, oxidative stress, food pad dermatitis (FPD), and environmental pollution, are being dealt with in the poultry industry that have an impact on food safety, poultry production efficiency, animal welfare, and the environment. Additionally, antibiotics included in feed have been utilized for a while as growth promoters. This has helped to increase feed conversion rates and thus lower costs. It was recently learned, nevertheless, that the usage of antibiotics might leave a residue in the meat and subsequently lead to human germs becoming resistant to some antibiotics. These complex problems forced the concerned researchers to search for substitute substances that may cover the gap. Tannins are polyphenolic chemicals that precipitate proteins. Because of their antibacterial, antioxidant, anti-inflammatory, and intestinal health-promoting properties, they are used as alternatives to antibiotic growth promoters in feed and offer answers to chicken production problems. Determining the proper dosages of supplemental tannins is crucial for their prospective implementation as a remedy for the problems encountered in the production of chicken, though, as large dosages of tannins have antinutritional consequences when fed to poultry.
Keywords: Antibiotic growth promotors, Gut health, Performance, Poultry, Tannins
Since many years ago, antibiotics have been utilized to promote growth, and they have been successful in boosting the productivity of chickens. AGP usage in poultry farming is now prohibited or limited in several nations (Hu and Cowling, 2020) due to growing public concern over the spread of antibiotic-resistant microorganisms from poultry products. Finding AGP substitutes is crucial because they must be economical, environmentally benign, and have antibacterial and growth-promoting properties without having negative effects on humans or animals (Yang et al., 2015). Tannins are secondary metabolites that are found in plants, seeds, bark, wood leaves, and fruit skins. They act as a plant’s defense system against predators since they are polyphenolic compounds that have the ability to precipitate proteins (Redondo et al., 2014). However, tannins have recently received a lot of interest in the poultry industry as an alternative to AGP due to their antibacterial, antioxidant, and anti-inflammatory characteristics (Daglia, 2012). This article primarily focuses on how tannins can help poultry producers overcome obstacles and improve the ways in which tannins are used.
Classification of tannins
Plant tannins are classified into hydrolysable tannins (HT) with tannin derivatives (e.g., gallic acid and ellagic acid) and condensed tannins (CT). A third family of tannin that is specific to brown algae is called phlorotannins (PT). Different tannins have different bioavailabilities (absorbabilities), and the degree of bioavailability varies depending on a number of factors, including the derivatives of each tannin (for example, gallic acid and ellagic acid), their affinity for protein, their molecular structure, and their molecular weight. To address several problems in the production of poultry, tannins’ bioavailability should be taken into account. In contrast, highly accessible tannins would be more advantageous as anti-inflammatory and antioxidant compounds. Tannins with poor bioavailability may have greater antibacterial properties in chickens.
Potential of tannins to mitigate the challenges in poultry production
Salmonella, Escherichia, Campylobacter, Clostridium, Listeria, Mycobacterium, and Aeromonas are major pathogenic bacteria found in poultry products (meat and eggs). These bacteria not only negatively affect chickens’ gut health and growth rate, but they also pose a threat to the public’s health by infecting people with foodborne illnesses (Thung et al., 2016). Potential mechanisms of tannins’ antibacterial effects include their direct interactions with cell wall components, which can change the structure of the cell wall and make bacteria’s membranes more permeable, as well as their suppression of microbial enzyme activities and deprivation of essential nutrients like proteins and minerals (like iron) for pathogenic bacteria (Tan, 2019). In addition to having antibacterial properties, tannins can prevent Salmonella spp. from spreading throughout the body by advantageously modifying the components of the gut ecology.
One of the most pervasive and damaging enteric diseases in the production of chicken is coccidiosis, a parasitic disease brought on by protozoa of the family Eimeridae. Through the fecal-oral pathway, Eimeria spp. infect and spread throughout the mucosal epithelial layers in the various sections of the GIT (Li et al., 2019). Tannins are known to have anticoccidial effects due to their capacity to form complexes with parasite enzymes and metal ions, both of which are necessary for Eimeria spp. and can stimulate the chickens’ immune systems (Chung et al., 1998). The antioxidant characteristics of tannins, which can repair an Eimeria-damaged gastrointestinal tract, are strongly related to tannins’ positive effects on the gut health of fowl infected with Eimeria spp. (Mishra and Jha, 2019). More thorough studies are needed to understand the mechanisms underlying the anticoccidial effects of tannins in chickens and to identify the proper concentrations and types of tannins to prevent coccidiosis in chickens, even though many studies have suggested that supplementing with tannins may benefit broiler chickens infected with Eimeria spp.
One of the main challenges facing the poultry business is heat stress, which has a detrimental influence on chicken welfare, intestinal health, meat quality, and growth performance. By scavenging ROS and controlling enzymatic antioxidants in animals, tannins are thought to alleviate or lessen the consequences of oxidative stress, particularly that brought on by heat stress (Yang et al., 2019). According to Ramnath and Rekha (2009), supplementing Brahma Rasayana, which contains a variety of tannins, increased the activity of enzymatic antioxidants like superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and reduced glutathione (GSH) in the blood of chickens raised in cold temperatures. In order to reduce oxidative stress in heat-stressed birds, feeding with the right amounts of tannins may be a successful tactic.
Growing chicken with foot pad dermatitis (FPD) develop lesions on the plantar area of their footpads. Paws are the third most important economic component of broiler chickens, and FPD can harm the chickens’ growth rate, gut health, and welfare, which results in significant economic losses in the poultry industry. Tannins’ antibacterial, antioxidant, and anti-inflammatory capabilities likely contributed to the reduction of FPD incidence and severity in broiler chickens, as oxidative stress and inflammation might worsen the severity and effects of FPD in chickens (Mayne et al., 2007). By improving faecal consistency and litter quality, supplementation of tannins has the potential to lessen the severity and incidence of FPD in broiler chickens.
Currently, the majority of studies have shown that, when used properly in monogastric diets, certain tannins can boost gut health, the intestinal microbial environment, and, ultimately, productivity. When chickens were fed diets with tannins, according to Goliomytis et al. (2015), dry matter intake, bodyweight, feed efficiency, and nutrient digestibility were reduced, but Ebrahim et al. (2015) found a reduction in feed intake and body weight increase. These variations could be the result of various tannin sources, a longer supplementation time, or particular testing settings (e.g., genetics of chickens, temperature and abundance of pathogens in the living conditions). The immune system, gastrointestinal environment, and gut microbiota of chickens reared under standard conditions can be enhanced by supplementary tannins when used in the right amounts. High feed efficiency has been related with less diversified gut microbiota in chickens, according to some authors, whereas others have found a correlation between higher bacterial community complexity and richness and improved feed efficiency. According to Viveros et al. (2011), tannins may potentially have prebiotic effects by promoting the growth of beneficial microorganisms. Because the microbiota of chickens is strongly related to the gut ecology of chickens, tannins’ ability to modulate the microbiome may help to partially explain the gut health-promoting benefits of chickens (Shang et al., 2018). Even in the absence of challenge models, supplementary tannins may help broiler chickens grow more quickly and have healthier gut microbes and ecosystems.
Conclusions
The sources and chemical makeup of tannins have an impact on their bioavailability in chickens, and the dose rate determines whether tannins have a negative or positive impact on the growth and intestinal environment of broiler chickens. Therefore, adding tannins to feed has the potential to reduce problems, replace antibiotic growth promoters, and increase poultry production effectiveness with healthy poultry produce.
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