The Applications of Origanum Vulgare and Its Derivatives in Human, Ruminant and Fish Nutrition – A Review

Beyond probiotics, uses of their next-generation for poultry and humans: A review

The production of healthy food is one of the basic requirements and challenges. Research efforts have been introduced in the human's food industry to reduce the microbial resistance and use safe and healthy alternatives with a high durability. However, the conducted work about these issues in the field of livestock animal production have been started since 2015. Inappropriate and extensive use of antibiotics has resulted in the increase of antimicrobial resistance, presence of drug residues in tissues, and destruction of the gut microbiome. Therefore, discovering and developing antibiotic substitutes were urgent demands. Probiotic compounds containing living micro-organisms are important antibiotic alternative that have been beneficially and extensively used in humans, animals, and poultry. However, some probiotics show some obstacles during production and applications. Accordingly, this review article proposes a comprehensive description of the next-generation of probiotics including postbiotics, proteobiotics, psychobiotics, immunobiotics and paraprobiotics and their effects on poultry production and human's therapy. These compounds proved great efficiency in terms of restoring gut health, improving performance and general health conditions, modulating the immune response and reducing the pathogenic micro-organisms. However, more future research work should be carried out regarding this issue.

Green manure (Crotalaria juncea L.) enhances Origanum vulgare L. biomass accumulation, essential oil yield, and phytochemical properties

Green manure (GM) may reduce the use of chemical fertilizers, been an ecologically appropriate strategy to cultivation of medicinal plants. Crotalaria juncea, is one of the most used because it adapts to different climatic and high nitrogen content. Origanum vulgare. is widely used in cooking, pharmaceutical, cosmetic industries and food products. The objectives of this study were to evaluate the GM on biomass, essential oil (EO), phenolic and antioxidant. The experiment consisted: control; 150, 300, 450, and 600 g (Sh= leaves+steam) more 200 g roots (R); 600 g aerial part; 200 g roots; and soil with 300 g cattle manure per pot. The highest dry weights were observed in the presence of GM and cattle manure (90 days). The control had an EO production 75% lower in relation to the dose of 450 g GM (Sh+R). Principal component analysis showed that GM and cattle manure positively influenced the dry weight, content, yield, and EO constituents, and total flavonoids. The GM contributed to the accumulation of the major EO compounds (trans-sabinene hydrate, thymol, terpinen-4-ol). The GM management may be beneficial for cultivating, because it can increase the production of biomass and the active components, in addition to being an inexpensive resource.

Phytosterol: nutritional significance, health benefits, and its uses in poultry and livestock nutrition

Medicinal plants with active ingredients have shown great potential as natural and sustainable additives in livestock and poultry diets as growth promoters, performance, feed conversion ratio, digestibility of nutrient enhancers, and antioxidants and immune system modulators. Among active ingredients, phytosterols, which are plant-based bio-factors that may be found in seeds, fruits, grains, vegetables and legumes, are thought to be involved in the aforementioned activities but are also widely known in human medicine due to their efficacy in treating diabetes, coronary heart disease, and tumors. Nevertheless, phytosterols can also promote carcinogens production, angiogenesis inhibition, metastasis, infiltration, and cancer cells proliferation. This review focuses on the deepening of the biological role and health benefits of phytosterols and their new potential application in poultry and livestock nutrition.

Exploring the roles of phytobiotics in relieving the impacts of Edwardsiella tarda infection on fish: a mini-review

Edwardsiellosis caused by Edwardsiella tarda resulted in significant economic losses in aquaculture operations worldwide. This disease could infect a wide range of hosts, including freshwater, brackish water, and marine aquatic animals. Currently, antibiotics and vaccines are being used as prophylactic agents to overcome Edwardsiellosis in aquaculture. However, application of antibiotics has led to antibiotic resistance among pathogenic bacteria, and the antibiotic residues pose a threat to public health. Meanwhile, the use of vaccines to combat Edwardsiellosis requires intensive labor work and high costs. Thus, phytobiotics were attempted to be used as antimicrobial agents to minimize the impact of Edwardsiellosis in aquaculture. These phytobiotics may also provide farmers with new options to manage aquaculture species' health. The impact of Edwardsiellosis in aquaculture worldwide was elaborated on and highlighted in this review study, as well as the recent application of phytobiotics in aquaculture and the status of vaccines to combat Edwardsiellosis. This review also focuses on the potential of phytobiotics in improving aquatic animal growth performance, enhancing immune system function, and stimulating disease resistance.

Integration of Network Pharmacology and Molecular Docking to Analyse the Mechanism of Action of Oregano Essential Oil in the Treatment of Bovine Mastitis

The active components, potential targets, and mechanisms of action of oregano essential oil in the treatment of bovine mastitis disease were investigated using network pharmacology and molecular docking approaches. The TCMSP and literature databases were examined for the main compounds in oregano essential oil. Afterward, the physical, chemical, and bioavailability characteristics of the components were evaluated. The PubChem, BATMAN, PharmMapper, and Uniprot databases were utilized to predict the target genes of the major components of oregano essential oil. Via the databases of DrugBank, OMIM, GeneCards, TTD, and DisGenet, the disease targets of bovine mastitis were discovered. We analyzed common targets and built protein-protein interaction (PPI) networks using the STRING database. Key genes were analyzed, obtained, and compound-target-pathway-disease visualization networks were created using Cytoscape. For the GO function and KEGG pathway enrichment analysis, the DAVID database was utilized. Molecular docking via Autodock Tools was utilized to evaluate the reliability of the interactions between oregano essential oil and hub targets. Thymol, carvacrol, and p-cymene are the three major components found in oregano essential oil. The potential targets (TNF, TLR4, ALB, IL-1β, TLR2, IL-6, IFNG, and MyD88) were screened according to the visual network. The enrichment analysis suggested that the major signaling pathways in network pharmacology may include PI3K-Akt, MAPK, IL-17, and NF-κ B. Molecular docking analysis shows that thymol had good docking activity with TNF, IL-6, and MyD88, carvacrol had good docking activity with TNF, and p-cymene had good docking activity with ALB. This study clarified the mechanism of action of oregano essential oil in the treatment of bovine mastitis, thus providing data supporting the potential for the use of oregano essential oil in the development of new therapeutics for bovine mastitis.

Prebiotics can restrict Salmonella populations in poultry: a review

Antibiotics were over the years, the common supplement used for poultry production. There is a global trend to lessen antibiotics' use due to the contamination of consumed meat with antibiotic residues. Also, there is a concern that human treatments might be jeopardized due to the emergence of antibiotic-resistant bacteria. Prebiotics are attractive supplements, particularly in poultry production, because of the diversity of their effects, including pH amendments, production of short-chain fatty acids (SCFA) and the inhibition of pathogens' growth. The commonly used prebiotics are carbohydrate sources that cannot be easily broken down by chickens. However, they can efficiently be utilized by the intestinal tract's microflora. Oligosaccharides, polysaccharides and lactose are non-digestible carbohydrate sources that are typically used in poultry diets as prebiotics. This review covers current applications and prospects for using prebiotics to improve poultry performance and reduce pathogens, particularly Salmonella, in gastrointestinal tract.

Effect of environmental factors on growth performance of Nile tilapia (Oreochromis niloticus)

Aquaculture is the practice of developing aquatic animals and plants under artificial environmental conditions, either in a controlled or semi-controlled environment. Due to high animal protein demand, it is one of the world's growing food production industries. It plays a vital role in contributing to food security and lowering the unemployment rate of the world's growing population. This review article aims to scope sight on the environmental factors that affect the growth and economic production process of Nile tilapia. Many of these factors are listed and analyzed in this review, such as stocking densities; various feed frequencies and feeding rates; water quality; water temperature; dissolved oxygen concentration; water pH degree; ammonia (NH3), nitrite (NO2), and nitrate (NO3) concentration; feeding regimes; feed cost; and tank culturing system of Nile tilapia. These factors can significantly alter body weight, composition, survival, behavior, feed intake, feed conversion ratio, feeding efficiency, and the health and reproduction of Oreochromis niloticus. Furthermore, feeding, growth, disease risks, and survival rates are all affected by water quality parameters. In general, higher growth performance of O. niloticus in aquaculture can be obtained by keeping the optimum quantity of feed with proper feeding rate and frequency, maintaining a good proportion of stocking density, and regularly evaluating water quality. This review article highlights-in details-the impact of various environmental factors on growth performance criteria of Nile tilapia (Oreochromis niloticus).

Performance indicators, coccidia oocyst counts, plasma biochemical parameters and fermentation processes in the cecum of rabbits fed a diet with the addition of black cumin seed meal

The aim of this study was to determine the effects of dietary supplementation with black cumin seed meal on growth performance parameters, coccidia oocyst counts, plasma biochemical parameters and cecal fermentation processes in growing rabbits. A total of 40 male Californian rabbits at 35 days of age were divided into two feeding groups: Control (complete rabbit diet) and Black cumin (2% of the complete diet was replaced with black cumin seed meal). Dietary supplementation with black cumin did not affect growth performance parameters, but it reduced coccidia oocyst counts in the feces of 63-day-old rabbits. Increased liver weight and elevated plasma albumin levels were noted in these rabbits. A significant decrease in small intestinal digesta viscosity was also observed in rabbits fed a diet supplemented with black cumin seed meal. The above change suppressed the formation of putrefactive compounds, i.e. ammonia and branched short-chain fatty acids (SCFAs) in the cecum, but it did not decrease the production of major SCFAs, i.e. acetic, propionic and butyric acids. The current study demonstrated that the dietary addition of 2% black cumin seed meal exerted a modulatory effect on gastrointestinal function, but it did not compromise microbial enzyme activity or SCFA production in the cecum.

Potential benefits of early-life supplementation of liquid feed with fennel (Foeniculum vulgare) seeds or oregano (Origanum vulgare) leaves on growth, health, and blood metabolites in Holstein dairy calves

This study was performed to determine the early-life (first month of age) supplementation of liquid feed with fennel seed powder (FSP) or oregano leaf powder (OLP) on growth performance, health, and blood biochemical attributes in preweaning dairy calves. Holstein female calves (n = 57; 1 d of age; 34.1 ± 0.97 kg of BW; mean ± SE) were assigned randomly to receive liquid feed (colostrum and milk) with no added herbal plants (CON) or supplemented with FSP (3 g/d) or OLP (30 g/d) during the first month of age. The calves received pooled colostrum (4.5 kg/d on the first 2 d of life; total solids = 25.0% ± 1.24; mean ± SD) and then pooled waste milk (6 kg/d from d 3 to 44, 5 kg/d from d 45 to 46, 4 kg/d from d 47 to 48, and 3 kg/d from d 49 to 50 of the trial; total solids = 12.54% ± 0.50) to ensure they receive same mixed liquid feed daily. The calves had unlimited access to the starter feed and fresh water and remained in the study until weaning on d 51 of age. The average mean temperature-humidity index was 70.1 units (ranging between 61.9 to 78.2) during the experiment, indicating a borderline degree of environmental heat-load. The amount of starter feed offered and refused was recorded daily. The calves were weighed immediately after birth and every 10 d thereafter, before the morning feeding. Jugular blood samples were taken immediately before and 24 h after colostrum feeding, at first month of age, and at weaning to quantify serum concentrations of glucose, urea N, cholesterol, triglycerides, total proteins, albumin, globulin, aspartate transferase, alanine transferase, total antioxidant status, and malondialdehyde. Health checks including rectal temperature, general appearance (on a 1-5 score system), fecal score (on a 1-5 score system), and bovine respiratory disease (BRD; scored using the University of Wisconsin Calf Health Chart) were performed daily, by a veterinarian who was unaware of the calf treatment allocations, for all calves over the study period. A repeated-measures ANOVA was used to compare growth performance and blood metabolites among treatment groups, and a logistic regression model using a binomial distribution (PROC GLIMMIX, SAS v. 9.4, SAS Institute Inc.) was used to assess the chance of elevated rectal temperature (≥39.4°C), general appearance (≥2), diarrhea (≥3), and BRD. A Poisson regression model (PROC GENMOD) was also used to test group differences in the experience of days with elevated rectal temperature and general appearance, and frequency and duration of diarrhea or BRD. Total nutrient intake (DM, CP, and ME, but not ether extract) originating from milk and starter feed was greater in OLP- (but not FSP-) supplemented calves compared with CON group, being partially associated with difference in milk refusal. Calves receiving FSP and OLP had greater average daily gain, BW gain, skeletal gain (withers height or heart girth, respectively), and feed efficiency compared with CON animals with no difference between FSP and OLP. Rectal temperature was lower in FSP- (but not OLP-) supplemented calves compared with CON animals. The CON animals had a greater chance of experiencing higher rectal temperature (≥39.4°C; odds ratio = 1.55 and confidence interval = 1.12-2.15 and odds ratio = 1.33 and confidence interval = 0.92-1.90, respectively, compared with FSP and OLP) and general appearance (≥2; odds ratio = 1.99 and confidence interval = 1.45-2.74 and odds ratio = 1.45 and confidence interval = 1.03-2.05), and diarrhea (odds ratio = 1.47 and confidence interval = 1.11-1.97 and odds ratio = 1.49 and confidence interval = 1.07-2.08) compared with those receiving FSP or OLP; with the chance of BRD being lower in FSP- (but not OLP-) supplemented versus CON animals (odds ratio = 1.59 and confidence interval = 1.13-2.23). As compared with OLP and CON groups, FSP treatment resulted in shorter days with elevated rectal temperature and general appearance. Supplementing FSP or OLP decreased the duration of diarrhea and BRD but not their frequency compared with CON. Duration of diarrhea was not different between FSP- or OLP-supplemented calves but calves supplemented with FSP had shorter days with BRD compared with OLP-supplemented calves. Of the blood constituents measured on d 30, concentration of aspartate transferase was higher in FSP- (but not CON) versus OLP-supplemented calves, indicating a transient liver tissue damage or dysfunction which was subsequently ameliorated. At weaning, blood concentration of triglycerides was higher in FSP and OLP groups compared with CON group. Supplementation of the liquid feed with FSP or OLP, especially FSP, had beneficial effects on calf growth performance and health. Further experiments are warranted for optimizing the dosage and duration of feeding FSP or OLP as feed additives for dairy calves.

Antimicrobial activity of chemically and biologically synthesized silver nanoparticles against some fish pathogens

Pathogens isolated from fish appear to possess considerable antimicrobial resistance and represent a problem for the economy and public health. Natural antimicrobial substitutes to traditional antibiotics represent an essential tool in the fight against antibiotic resistance. Nanotechnology has shown considerable potential in different research fields, and the antimicrobial properties of silver nanoparticles are known. Silver has been used for medical purposes since ancient times because of its bactericidal properties, and the highly reactive surfaces of silver nanoparticles (AgNPs) indicate that they might have a function in antimicrobial applications. This work aimed to study the antimicrobial properties of biologically produced AgNPs from Origanum vulgare leaves compared to chemically produced AgNPs. Both types were characterized by UV-vis spectrophotometry, TEM, and dynamic light scattering and tested against three bacterial strains (Streptococcus agalactiae, and Aeromonas hydrophila, both isolated from Nile tilapia and Vibrio alginolyticus, isolated from sea bass) and three fungal strains (Aspergillus flavus, Fusarium moniliforme, and Candida albicans, all isolated from Nile tilapia). Disk diffusion test and evaluation of ultrastructure changes of tested microorganisms treated with AgNPs by transmission electron microscopy were performed. Moreover, the hemolytic properties of AgNPs were studied on chicken and goat red blood cells. The results obtained declare that the green biological production of silver nanoparticles is safer and more effective than the chemical one; moreover, AgNPs have interesting dose-dependent antimicrobial properties, with better results for biologically produced ones; their effectiveness against tested bacterial and fungal strains opens the way to their use to limit fish diseases, increase economy and improve human health.

Dependence of the Concentration of Bioactive Compounds in Origanum vulgare on Chemical Properties of the Soil

The aim of this study was to determine the dependence of the total phenolic, flavonoid, and extractive content in extracts of Origanum vulgare L. on the soil pH, humus, total nitrogen (N_total), and plant-available/mobile phosphorus (P₂O₅), as well as potassium (K₂O), total calcium (Ca), magnesium (Mg), and sodium (Na) concentrations. Experimental fields were formed in four locations in Lithuania. Soil and perennial O. vulgare samples were taken at three sites of each experimental field. A total of 12 samples of soil and 12 samples of the tested plant were collected and analyzed. The concentrations of bioactive compounds in plants are significantly (p < 0.05–0.01) affected by some chemical properties of the soil: the total phenolic content was reliably correlated with the soil pH, N_total, Ca, Mg, and P₂O₅; the flavonoid content was correlated with the soil P₂O₅, K₂O, Mg, and Na; and the extractive content was correlated with the soil humus, N_total, and Na. The obtained results are useful for the development of the commercial cultivation of O. vulgare.

A Multi-Biomarker Approach in European Sea Bass Exposed to Dynamic Temperature Changes under Dietary Supplementation with Origanum vulgare Essential Oil

A feeding trial for 150 days was carried out to evaluate the cross-effects between oregano essential oil (EO) dietary supplementation and dynamic temperature change in sea bass. Under exposure to rising temperature (13-25 °C), fish were fed with a control diet (CD) and two experimental diets supplemented with 100 (D100) and 200 ppm (D200) of EO. Feed inclusion of EO promoted the activity of antioxidant enzymes in sea bass exposed to increasing temperature. Consistently with the temperature rise, TBARS concentrations increased in CD and D200 groups, whereas were almost stable in D100. Trend of blood glucose in fish fed on CD was likely affected by glycogenolysis and gluconeogenesis. Similarly, the depletion of triglycerides and cholesterol in fish fed on CD likely supported the energy cost of gluconeogenesis. On the other hand, the reduction of glucose, triglycerides, and cholesterol in D100 and D200 was mainly attributable to the hypoglycemic and hypolipidemic effects of EO. The higher levels of serum protein observed in D100 and D200 groups were also associated to a reduced thermal stress compared to CD. EO dietary supplementation may be a promising strategy to alleviate the negative effects of temperature shift on sea bass physiological and oxidative state.

Neurobehavioral, physiological and inflammatory impairments in response to bifenthrin intoxication in Oreochromis niloticus fish: Role of dietary supplementation with Petroselinum crispum essential oil

This study was conceptualized in order to assess the 96-h LC₅₀ of bifenthrin (BF) in O. niloticus and also to measure the biochemical, behavioral, and molecular responses of the fish suchronically exposed to a sub-lethal concentration of the insecticide. The role of Petroselinum crispum essential oil (PEO) supplementation in mitigating the resulted neurotoxic insult was also investigated. The acute toxicity study revealed that the 96-h LC₅₀ of BF is 6.81 μg/L, and varying degrees of behavioral changes were recorded in a dose-dependent manner. The subchronic study revealed reduction of dissolved oxygen and increased ammonia in aquaria of BF-exposed fish. Clinical signs revealed high degree of discomfort and aggressiveness together with reductions in survival rate and body weight gain. The levels of monoamines in brain, and GABA and amino acids in serum were reduced, together with decreased activities of Na⁺/K⁺-ATPase and acetylcholine esterases (AchE). The activities of antioxidant enzymes were also diminshed in the brain while oxdative damage and DNA breaks were elevated. Myeloperoxidase (MPO) activity in serum increased with overexpression of the pro-inflammatory cytokines in the brain tissue. BF also upregulated the expression of brain-stress related genes HSP70, Caspase-3 and P53. Supplemention of PEO to BF markedly abrogated the toxic impacts of the insecticide, specially at the high level. These findings demonstrate neuroprotective, antioxidant, genoprotective, anti-inflammatory and antiapoptic effects of PEO in BF-intoxicated fish. Based on these mechanistic insights of PEO, we recommend its use as an invaluable supplement in the fish feed.

Approaches to prevent and control Campylobacter spp. colonization in broiler chickens: a review

Campylobacter, Gram-negative bacteria, is the most common cause of acute bacterial enteritis in human beings, both in developing and developed countries. It is believed that poultry, in particular broiler chickens, is the main host of human infection with Campylobacter. Handling and consumption of contaminated chicken meat are the usual modes of transmission. Prevention and reduction of Campylobacter colonization in poultry farms will cut off the road of infection transmission to humans throughout the food chain. With the incidence of antibiotic resistance and with growing concern about superbugs, the search for natural and safe alternatives will considerably increase in the coming years. In this review, we will discuss the prevalence and risk factors of Campylobacter colonization in broiler chickens and sources of infection. This review also provides extensive and recent approaches to prevent and control Campylobacter colonization in broiler chickens, including biosecurity measures, natural feed/drinking water additives with antimicrobial properties, bacteriocins, bacteriophages, antimicrobial peptides, and vaccination strategies to prevent and control the incidence of human campylobacteriosis.

Dietary Origanum vulgare essential oil attenuates cypermethrin-induced biochemical changes, oxidative stress, histopathological alterations, apoptosis, and reduces DNA damage in Common carp (Cyprinus carpio)

The study was designed to evaluate the possible protective roles of dietary Origanum vulgare essential oil (OVEO) against cypermethrin (CP)-induced serum biochemical changes and oxidative stress of common carp (Cyprinus carpio). Moreover, histopathological alterations, apoptosis, cell proliferation, and DNA damage in the gills and hepatic tissues were also assessed. Briefly, fish were allotted into six groups with three triplicates whereas a group fed on basal diet and did not exposed to CP and served as control (CTR), two groups were fed on diets supplemented with two levels of OVEO (0.5 % and 1.0 %), a group exposed to sub-lethal concentration of CP (1/10 of 96 h-LC₅₀ = 0.4134 μg/L), and two other groups exposed to the same concentration of CP and fed on diets supplemented with both levels of OVEO (CP + 0.5 % OVEO, and CP + 1.0 % OVEO), respectively, for 30 days. CP induced significant elevation of serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), urea, and creatinine levels indicating hepato-renal toxicity (P < 0.05). Besides, there was a significant decrease in serum catalase (CAT) and superoxide dismutase (SOD) activities (P < 0.05). Moreover, CP induced significant histopathologic alterations in gills, anterior kidneys, and hepatic tissues with activation of apoptosis (Caspase-3) and proliferating cell nuclear antigen (PCNA). Comet assay demonstrated significant DNA damage in gills and liver tissues of the CP-exposed group. Interestingly, a significant attenuation of serum ALT, AST, ALP, urea, creatinine, CAT, and SOD levels (P < 0.05) was noticed in CP-exposed fish and concurrently fed diets supplemented with either 0.5 % or 1.0 % OVEO. Moreover, histopathologic alterations and apoptosis were significantly reduced along with a concomitant significant decrease in DNA damage (P < 0.05) which indicated the mitigation of DNA damage. Conclusively, the study showed that OVEO is an effective counteractive treatment against CP-induced damage in exposed common carp and is recommended during the formulation of fish rations.

Improving the Quality of Turkey Meat via Storage Temperature, Packaging Atmosphere, and Oregano (Origanum vulgare) Essential Oil Addition

The provision of plentiful good-quality food is a primary issue in the modern world. This work was planned to study the influence of packaging atmosphere and oregano (Origanum vulgare) essential oil addition [(vacuum packaging: T1 or modified atmosphere packaging or T2 (CO2/N2 = 4:6) or T3, T2 with oregano essential oil (T2 + EO)] under various storage temperatures (0, 5, 10, and 15 °C) on the control of survival of Escherichia coli O157:H7 and associated spoilage flora in sliced smoked turkey meat. The pathogen increased by only <1.0 log colony-forming unit (CFU)/g under all packaging and temperature combinations. Moreover, T1, T2, and T3 exerted practically similar inhibitory activity against the pathogen and dominating bacteria, with a relatively low growth of E. coli O157:H7 in sliced smoked turkey during the shelf life under all storage regimes compared to the control. However, the pathogen survival was highest on the sliced smoked turkey under T1, decreasing by only 0.67, 0.74, 0.63, and 1.30 log CFU/g within 37 days if kept at 0, 5, 10, and 15 °C, respectively. Under T2 and the same condition, E. coli O157:H7 in the product declined by only 0.31, 0.50, 0.72, and 1.10 log CFU/g within 37 days of storage, respectively. In the T3 samples, the pathogen was reduced by only 0.33, 0.67, 1.72, and 3.46 log CFU/g through 37 days of storage, respectively. Under T3 were E. coli O157:H7 populations in smoked turkey eliminated (negative by enrichment) under all conditions (after 129, 95, 95, and 43 days maintained at 0, 5, 10, and 15 °C, respectively) compared with other packaging temperature combinations. Thus, T3 contributed to developing ready-to-eat smoked turkey with enhanced product quality and eliminating the pathogen.

Cinnamon (Cinnamomum zeylanicum) Oil as a Potential Alternative to Antibiotics in Poultry

The removal of antibiotic growth promoters (AGPs) as feed additives in poultry nutrition from the market in many countries has compelled researchers to find unconventional and safe alternatives to AGPs. Probiotics, prebiotics, enzymes, organic acids, herbs, immune-stimulants and essential oils (EO) have been investigated as feed additives in poultry production. Cinnamon (Cinnamomum zeylanicum), one of the oldest medicinal plants and widely used around the world, can be used in poultry rations in the form of powder or essential oil. Essential oils produced from aromatic plants have become more interesting owing to their potential effects as hypocholesterolaemic agents, antioxidants, antimicrobials, antifungals and stimulants of digestive enzymes. The potential insecticidal and antimicrobial activities of EO against pathogens that cause spoilage in agriculture crops and human diseases might be attributed mainly to the high content of volatile components (mainly cinnamaldehyde, eugenol and carvacrol) in cinnamon oil. The present review focuses on the effects of cinnamon oil as a feed additive on poultry performance, carcass traits, meat quality, hypocholesterolaemic impact, antioxidant activity, immunity and microbiological aspects.