Phytogenics, also known as phytobiotics, are plant-based feed additives utilized in animal nutrition. They are derived from herbs, spices, and extracts (such as essential oils). Phytogenics are key solutions for conventional and antibiotic-free animal nutrition. Farm animal populations are undergoing continuous selection to improve the economic efficiency of animal production, which itself is affected by a number of external as well as internal factors, that unequivocally include nutrition. Phytogenic feed additives (PFAs) present a plausible alternative, as they enhance a number of important processes in the animal body.
Key Challenges Faced in Poultry Industry:
Presently, the three key challenges faced by the poultry industry are Feed cost, Suitable alternatives of antibiotic growth promoters (AGPs), and Cocssidosis infection.
Increased Feed Cost:
The animal nutrition sector faces serious problems with respect to the supply of raw materials and pricing, partly due to the Covid-19 pandemic and partly due to changing consumer demands & expectations. Presently, the feed cost factor is the biggest problem in the poultry industry, since maize prices remain at historic high levels, whereas maize represents about 65 percent of the poultry diet, and it is a principal source of energy as the bird age increases. Furthermore, the cost of principal poultry feed ingredients viz. maize & soybean are expected to be costlier ever in 2022 and in the first and second quarters of 2023 as well. However, global poultry markets are expected to be strong in 2022-23 on the back of reopening economies, and overall stronger economic conditions.
Antibiotic Growth Promoters (AGPs):
Supplementation of antibiotics through animal feeds in chickens showed significant changes in the intestinal flora of chickens and influenced the immunity of the chickens with an increase in capacity to control diseases. The name suggests its proven effect on the growth performance of the bird. However, the uncontrolled overuse of antibiotics can cause the development of antibiotic resistance in bacteria making the host more sucessaptable to disease. Also, overuse of antibiotics increased the incidence of antibiotic residues in animal products which has harmful effects on the health of animals and the consumers of such products. As a result, European countries and the rest of the developed countries have imposed a ban on antibiotics usage in animal feeds. This has therefore warranted the urgent need for alternatives and so many natural agents have been identified through research over the past few years. Since none of these exactly match the AGPs and they are too large in number with similar effects makes an obstacle for animal producers to choose genuine single or a combination of such alternatives.
Avian coccidiosis is characterized as an infectious protozoan disease caused by gut parasites of the genus Eimeria, subclass Coccidia. This class of parasites can infect and multiply within the mucosal epithelia in different parts of bird guts via the oral route. As a result, they cause gut damage through inflammation, hemorrhage, diarrhea, etc…, morbidity, and mortality in poultry. This disease annually causes a global loss of over 2.4 billion US dollars in the poultry industry. Current approaches being practiced to tackle avian coccidiosis include the use of anticoccidial chemicals and vaccines. Anticoccidial chemicals, coccidiocides, coccidiostats, and ionophores, have long been used as a mainstream strategy to control avian coccidiosis in modern poultry production. Although this strategy is cost-effective and successful, the presence of drug resistance and public demands for residue-free meat is the pivotal concerns in the poultry industry.
The poultry industry especially the broiler and layer sectors have been affected adversely due to the following environmental challenges being faced by the poultry industry.
Regional impacts: Improper manure management practices being followed caused contamination of soil and water with nutrients, pathogens, pesticides, and heavy metals. Hence, manure should be either recycled to cropland belonging to the animal farm or sold as manure to crop farmers. Piling up manure adversely affects the life of people living in the vicinity. Flies are an additional concern for residents living near poultry facilities specifically related to animal-feed management and losses from feeding systems. Poultry facilities are a source of odor and attract flies, rodents, and other pests that create local nuisances and carry diseases. Odor emissions are caused by a large number of contributing compounds including ammonia (NH3), volatile organic compounds, and hydrogen sulfide (H2S) from poultry farms.
Water pollution: The groundwater and surface water are highly prone to contamination due to the accumulation of pesticides and predators. Moreover, flooding areas and shallow water tables are getting polluted because of non-scientific methods of poultry carcass disposal practices being followed. Furthermore, the most significant environmental issue resulting from slaughterhouse operations is the discharge of wastewater into the environment, which can even cause the death of aquatic life due to the generation of wastewater having high biochemical and chemical oxygen demand (BOD and COD). Residues of chemicals such as chlorine are used for washing. and disinfection, as well as various pathogens including Salmonella and Campylobacter may also present in the water. In addition, process wastewater may contain high levels of nitrogen and phosphorus which may cause eutrophication of the affected water bodies.
Global impacts: Environmental impacts of poultry production are not only limited to specific areas; whereas, they also include impacts of a global dimension. Two major problems of relevance are identified; (i)The production of concentrate feed and greenhouse gas production related to energy use in animal production processes, (ii) In the transport of processed products. The extraordinary performance of the poultry sector over the past three decades has partially been achieved through the soaring use of concentrate feed, particularly cereals and soybean meal Intensification of feed production, has resulted in the expansion of cropland at the expense of forested land (deforestation), pollution in water resources through pollution caused by the intensive use of mineral fertilizer, pesticides and herbicides to maintain high crop yields and it also contributes to air pollution from nitrogen fertilizer through the volatilization of ammonia. Furthermore, greenhouse gases emission got increased i.e.- Carbon dioxide, produced by the burning of fossil fuels during animal production, slaughter, transportation of processed and refrigerated products, and importantly deforestation. Nitrous oxide is produced from nitrogen fertilizer.
Owing to this scenario, the search for safer replacements for antibiotics with the same or better effects on animal production, through enhancement of feed utilization and efficiency along with anticoccidiostat & environmental factors mitigation potentials are vigorously sought.
Beneficial Role of Phytogenic Feed Additives (PFAs) in Poultry:
Literature reports screened show that PFA which contains most of the active substances of the plant, has been suggested to increase nutrient digestibility, and gut health in poultry species, and thereby improve feed conversion ratio (FCR), and European production efficiency factor (EPEF). The mechanism of action in poultry species is to control potential pathogens and beneficially modulate the intestinal microbiota through their antimicrobial, antiviral, anticoccidial, fungicidal, and/or antioxidant potentials. Giannenas et al., reported amelioration of poultry species infected coccidiocis including a reduction in lesion severity and oocyst shedding, by PFAs.
Furthermore, it has been revealed that PFAs play a pivotal role in the augmentation of nutrient utilization in the gastrointestinal tract by enhancing the production of digestive secretions and enzymatic activity. Moreover, various research investigators reported positive effects of PFAs on the morphology of small intestinal tissues, such as increased villus height, decreased crypt depth, and increased goblet cell counts. Such effects on gastrointestinal morphology have been postulated to increase the nutrient digestibility in poultry. In addition, PFAs, like AGP also reduce mucosal thickness, thus contributing to the diffusion of nutrients to the apical surface of epithelial cells and thereby increasing absorption and feed efficiency.
Azhahianambi etal. demonstrated that Phytogenic anti-coccidial formulation was an effective alternative for ionophore anticoccidial drugs in the control the coccidiosis in broiler chicken. Furthermore, one phytogenic feed additive formulation composed of Allium sativum, Berberis aristata, Picrorrhizakurroa, Azadirachta indica, Holarrhena antidysenterica, Ocimum sanctum, and Zingiber officinale has shown the efficacy to ameliorate the impact of parasite infection on broiler chickens by exerting a coccidiostatic effect against Eimeria tenella, enella, maxima, and acervulina.
Phytogenics have a beneficial role in mitigating the environmental impacts of poultry farming through improving feed efficiency which results in less burden on the usage of feed ingredients like corn and soya. This can prevent deforestation to grow cash crops. Similarly, certain herbal additives can reduce nitrogen excretion into the poultry manure, and thereby reducing contamination of the environment with nitrogenous chemicals. A good number of phytogenics are known to improve gut health thereby controlling loose droppings leading to wet litter. A dry litter attracts fewer flies and emits significantly less ammonia.
In summary, it is these beneficial potentials of PFAs that put them as replacements for AGPs with the same or better effects on animal production and solutions for feed cost optimization and mitigating environmental impacts in poultry industry.
*References are available on request