Alternative to Antibiotics for Poultry Production

The use of “Antibiotic growth promoters (AGPs)” in poultry production is one the most debated topics of the poultry community in recent times. Since the commercialization of the poultry industry, poultry scientists are working to improve bird performance through its genetics, management, feed, and environment. But now the focus is shifting to product quality, consumer health, environment, and food safety. However, according to World Health Organization, presently human population is facing a serious threat of the development of antibiotic resistance in microorganisms due to the unattended use of these AGPs in animal diets. Because of the wide use of poultry products in human diets and the use of antibiotics in poultry diets, the public considers poultry as the major reason for this antibiotic resistance. Sweden for the first time ban the use of antibiotics in 1986, whereas European Union banned their use in 2006.

Properties of Ideal Replacement

An ideal replacement should have the following properties:

1.?????Should not induce resistance

2.?????Should not destroy microflora

3.?????Should not affect feed palatability

4.?????Should kill or inhibit the growth of pathogens

5.?????Non-toxic and has no side effects on the birds.

6.?????Be easily decomposed and not affect the environment

7.?????Be stable in feed and gastrointestinal tract (GIT)

8.?????Should increase growth performance and feed efficiency.

9.?????Easy to eliminate from the body or short-term residual effect.

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Scientists working in the field of poultry production have suggested many alternatives to antibiotics. Every alternative has its advantages and disadvantages. Some of the examples of alternatives that can be used include biologically synthesized feed additives like nanoparticles, probiotics, prebiotics, symbiotics, herbal extracts, essential oils, organic acids, enzymes, and essential amino acids that can enhance the host's health and production performance.

1)?????Phytogenic feed additives: PFAs are plant-derived compounds such as essential oils, spices, safe natural compounds, and herbs intended to provide a health benefit when added to feed. Phytogenic feed additives like herbs, botanicals, essential oils, and turmeric affect the GIT system of birds positively due to their antimicrobial, antioxidant, and immune-boosting characteristics. They enhance egg production, growth efficiency, and necessarily feed utilization. Typical PFAs are rosemary derivatives. oregano, thyme, sage, cinnamon, citrus, pepper, and anise. Their prominent characteristics are as follows:

a.?????Anti-oxidants: Families of plant-like Zingiberene (ginger, Curcuma), and Umbelliferae (anise, coriander) as well as flavonoids and anthocyanins having good antioxidative properties. Red pepper and chili are also good antioxidants but their taste is hot and smells pungent which restricted their use in bird feeding.

b.?????Antimicrobial: A blend of thymol, eugenol, curcumin, and piperin reduced the microbial load significantly like Clostridium perfringens, Bacteroides, Escherichia coli, and certain fungi.

c.??????Immunomodulators: Immunomodulators mean stimulating or suppressing change in the defense mechanism that may be cellular, humoral, or nonspecific. Plants' product positively affects the immune system of the chickens.

d.?????Improving digestibility: Phytogenic feed supplements based on oregano, cinnamon, sage, thyme, and rosemary enhance the digestibility of nutrients by improving gut health, enzyme, and beneficial microbiota activities.

e.??????Modification of gut morphology: There is a significant increase in villus height and crypt depth when we fed corn base diet supplementing with phytogenic feed additives like carvacrol, cinnamaldehyde, and capsaicin than wheat and barley-based diet.

f.???????Improving production performance: The phytogenic feed additive improves the digestibility of nutrients, and GIT microbiota, reducing oxidative stress, and immunomodulation ultimately causing improvement in growth parameters like body weight gain, carcass characteristics, and FCR.

2)?????

Essential oils: Essential oil is classified as the plant essence or benzene or terpene derivatives obtained through water and /or steam distillation. Essential oils are valuable due to their antimicrobial, antiviral, antioxidant, and antiparasitic capabilities. The addition of essential oil positively impacted avian performance and carcass characteristics. Essential oils can reduce the levels of pathogens such as gram-negative E. coli and Salmonella bacteria in the gut. Essential oils improve poultry production by increasing the activity of digestive enzymes, lowering the number of fermentation products, lowering the number of pathogens, improving nutrient digestion, enhancing intestinal accessibility of important nutrients, and enhancing antioxidant capacity and immune function. ?

3)?????Prebiotics: Prebiotics are oligosaccharides like mannan & fructose indigestible by the host animal but are utilized by a specific population of gut microorganisms. Prebiotics enable already present microorganisms to increase their numbers, reduce pathogenic bacteria, increase digestibility, increase minerals and vitamins absorbability, maintain optimal intestinal pH, and maximize nutrient utilization. Prebiotics can affect host health in several ways, such as the production of metabolites, and increased cell integrity of the epithelium. Unlike prebiotics, probiotics are microorganisms that can alter the host's health by colonizing the host GIT and providing a more balanced microbiota

4)?????

Probiotics: Probiotics can be yeast, bacteria, or fungi based and, unlike antibiotics, do not have the potential to leave a residue. Lactic acid bacteria, which produce antifungal metabolites, are common probiotic bacteria. Probiotics also known as direct-fed microbial (DFMS), are oleoresins and are also a good alternative to AGPS. Herbal products like cinnamon, ginger, pepper and are classified by FAO/WHO as “live microorganisms which when administered in adequate amounts confer a health benefit on the host” Probiotics specific to broilers include the genera Lactobacillus, Streptococcus Bacillus, and Bifidobacterium, Enterococcus, Aspergillus, Candida, and Saccharomyces. The beneficial effects of probiotics include improved performance, modulating of the intestinal microbiota, inhibiting pathogens, improved intestinal integrity, immunomodulation, and improving microbiological and sensory characteristics of broiler meat. Essential characteristics of a probiotic include being resistant to bile and acid, being strain-specific, having no side effects, reducing the number o pathogenic microorganisms, and can withstand feed processing. The most common probiotic mode of action s by lowering the gut pH through the volatile fatty acids and organic acids produced during the probiotic product breakdown. Pathogenic bacteria such as Salmonella and E. coli strains cannot grow well below a certain pH.

5)??????Organic acids: Organic acids are organic substances that have an acidic ph. Carboxylic acids such as lactic acid, propionic acid, acetic acid, formic acid, sorbic acid, citric acid, oxalic acid, uric acid, and butyric acid are the most prominent types. Organic acids are not antibiotics, but when used in conjunction with excellent nutrition, management, and biosecurity procedures, they can help poultry maintain intestinal health, improving livability, feed conversion ratios, and live weight and immunological responses. Organic acids suppress pathogenic intestinal bacteria due to their antimicrobial activity, resulting in less bacterial competition for available nutrients, lower level of harmful bacterial metabolites, improved protein, and energy digestibility, and improved avian performance as well as histological structure of the gastrointestinal tract resulting in increased villus length, improving the absorptive ability of the intestinal mucosa consequently, better nutrient absorption, maximizing nutrient utilization and improving growth performance.

6)?????Exogenous enzymes: The enzymes classified by the substrates they act upon are phytases, phytate degrading enzymes; proteases, fiber, and starch degrading enzymes; and proteases which consist of protein degrading enzymes.

a.?????Phytase is an enzyme that hydrolyzes phytate to inositol and inorganic phosphate. Poultry needs to have dietary phosphorus for maintenance and growth. Therefore, an adequate amount must be included in the diet. Even with enough total phosphorus in the diet, a portion of the total P comes from cereal grains and this P exists in a form that poultry cannot digest. The majority of P, about 60% is not accessible to non-ruminants because it is associated with phytate because phytate binds to many dietary cations such as Cu, Zn, Ca, Fe, Mg, Mn protein, fat, and vitamin resulting in a serious reduction in nutrient availability. Phytase enzymes increase the availability by up to 65%.

b.?????In poultry carbohydrates are known as non-starch polysaccharides (NSP) degrading enzymes because of the radiation xylanase and B-glucanase are common carbohydrates supplemented to the diet to improve performance and digestibility. Xylanase is an enzyme that originated from the hemicellulosic polysaccharide xylan. Xylan, a polysaccharide comprises units of D-xylose a pentose sugar. Xylans make up 30 to 35% of the cell wall material of annual plants; therefore, it is been used as a feed additive for over 20 years in poultry diets primarily to improve feed conversion ratio and weight gain.

c.??????Arabinoxylans and B-glucans are the essential antinutritive NSP in cereal grains. Wike arabinoxylan is more prevalent in wheat and rye diets and B-glucans in barley, B0glucans are susceptible to bacterial degradation through the intestinal tract. Because of the issues related t NSPs, xylanase supplementation has been added to diets to decrease litter issues such as wet litter and increase nutrient uptake.

Conclusions: The natural antibiotics growth promoter alternatives are recommended to use on a large scale as safe and healthy alternatives that have a positive immune-modulating effect, enhance productivity, and enhance digestion. Improve nutrient availability, and increase usability. Improve intestinal health, reduce the incidence of antibiotic resistance and help obtain nutritious useful, and safe organic chicken meant for human consumption.