Essential Oil Supplementation Research Articles

Essential oil supplementation in milk replacers: short- and long-term impacts on feed efficiency, the faecal microbiota and the plasma metabolome in dairy calves.

Early supplementation with oregano essential oil (EO) in milk replacer (MR) may improve growth, immune responses, the microbiota and the metabolome in dairy calves during pre-weaning and in adulthood. Sixteen female dairy calves (3 days of age) were divided in two groups (n = 8/group): the control group (no EO) and the EO group (0.23 ml of EO in MR during 45 days). After weaning, calves were kept in a feedlot and fed ad libitum. The animals were weighed, and blood and faecal samples were collected on days 3 (T0), 45 (T1) and 370 (T2) to measure the biochemical profile and characterise peripheral blood mononuclear cells (PBMCs; CD4+, CD8+, CD14+, CD21+ and WC1+), the metabolome and microbiota composition. The EO group only had greater average daily weight gain during the suckling (EO supplementation) period (P = 0.030). The EO group showed higher average CD14+ population (monocytes) values, a lower abundance of Ruminococcaceae UCG-014, Faecalibacterium, Blautia and Alloprevotella and increased abundances of Allistipes and Akkermansia. The modification of some metabolites in plasma, such as butyric acid, 3-indole-propionic acid and succinic acid, particularly at T1, are consistent with intestinal microbiota changes. The data suggest that early EO supplementation increases feed efficiency only during the suckling period with notable changes in the microbiota and plasma metabolome; however, not all of these changes can be considered desirable from a gut health point of view. Additional research studies is required to demonstrate that EOs are a viable natural alternative to antibiotics for improving calf growth performance and health.

Effects of Supplemented Coriander, Ajwain, and Dill Seed Essential Oils on Growth Performance, Carcass Characteristics, Gut Health, Meat Quality, and Immune Status in Broilers.

Numerous studies have assessed the benefits and optimal dosage of supplementation with essential oils (EOs), including extracts from plants of the Apiaceae family, as an alternative to antibiotic growth promoters (AGPs) in broilers. However, little consideration has been given to the actual chemical composition of the evaluated EOs when drawing critical conclusions, even though EO composition can vary with different extraction conditions and plant characteristics. Therefore, the present study was conducted to evaluate the effects of EOs from seeds of plants of the Apiaceae family: coriander (CEO), ajwain (AjEO), and dill (DEO), containing 56.8% linalool, 68.2% thymol, and 41.1% carvone, respectively, on the growth performance, gut health, and immune status of broilers. In total, 660 one-day-old broiler chicks were divided into 11 experimental diet groups and fed for 35 days with either the control diet, basal diet with added AGP (lincomycin, 500 mg/kg), or one of nine EO diets supplemented with CEO, AjEO, or DEO at 200, 400, and 600 mg/kg. Final body weights were improved by supplementation with not only AGP but also any EO except AjEO at 600 mg/kg; within each EO, supplementation of CEO at 400 mg/kg, AjEO at 200 mg/kg, and DEO at 200 mg/kg afforded the best growth performance. EO supplementation had beneficial effects on gut morphology, such as increased villus height in the duodenum, jejunum, and ileum, and against harmful microbiota, such as reduction of Escherichia coli and Salmonella spp. populations. Furthermore, EOs enhanced humoral immunity and improved meat quality by reducing drip loss, likely consequent to their antioxidant properties. Overall, this study presents evidence that CEO, AjEO, and DEO can each play a pivotal role in replacing AGPs, as well as providing information regarding optimal doses for broilers.

Oxidative stability in meat (pectoralis major) of broiler orally supplemented with essential oils of allium sativum, Curcuma longa, Zingiber officinale, and Cinnamomum zeylanicum.

Lipid oxidation is a normal process in living muscles, but is escalated postmortem due to the loss of inherent antioxidant defense, which causes quality deterioration of meat. This study investigates the effects of essential oil (EO) supplementation to the drinking water of broiler chicken on physical properties, antioxidants, and lipid oxidation in Pectoralis major during frozen storage. Two hundred day-old chicks of arbo acre were allocated to five groups; control (T1) and the groups supplemented with: Allium sativum (T2), Curcuma longa (T3), Zingiber officinale (T4) and Cinnamomum zeylanicum (T5) at the level of 300ml/L into drinking water throughout a 49-d study. Thereafter, birds were slaughtered and breast meat excised for assessments during a 28-d storage period at 4 °C using standard procedure. The results show that cooking loss of Pectoralis major from T1 birds was not significantly (P > 0.05) different from that of T4, and were significantly higher than those of T2, T3, and T5 birds. Meat from T5 birds showed the lowest drip loss. The results for total antioxidant activity are not similar among sampling days. In general, control group showed inferior values, but T2 and T4 had greater values on days 0 and 28. The rate of lipid peroxidation increased with time; however, EOs administration markedly reduced the peroxidation rates compared to controls. The catalase activity of breast meat was significantly declined from day 14, but was enhanced as an effect of EO consumption especially in group T5 at 21 and 28 d. Supplementation of garlic, turmeric, and cinnamon EOs to broiler chickens increased glutathione peroxidase in breast meat on days 21 and 28, while turmeric EO enhanced superoxide dismutase up to 7 d. In conclusion, EOs are valuable supplements for broiler chickens and potent in enhancing meat quality and prolonging the shelf life.

Leverage of Matricaria chamomilla L. Oil Supplementation over Ochratoxin A in Growing Quails

Ochratoxin A (OTA) is one of the mycotoxins in the agriculture and livestock sectors. The poultry sector suffered from significant economic losses due to the adverse impacts of OTA on the growth rate, feed conversion ratio, and livability. Thus, the present investigation aimed to determine the impact of chamomile essential oil supplementation against OTA toxicity in growing quails. 360 one‐week‐old growing quails were distributed into six groups (n = 60) with four replicates of 15 birds. The groups were G1 (control negative), G2 (OTA 1 mg/kg diet, control positive), G3 (chamomile oil 0.5 g/kg diet), G4 (chamomile oil 1 g/kg diet), G5 (OTA 1 mg/kg diet + chamomile oil 0.5 g/kg diet), and G6 (OTA 1 mg/kg diet + chamomile oil 1 g/kg diet). Adding OTA significantly (P < 0.05) reduced live body weight and weight gain at 5 weeks. Feed intake at 5 weeks was nonsignificantly reduced in G3 and G4 compared to G1. G4 showed a significant (P < 0.05) increase in weight gain and the lowest feed conversion ratio. The G2 showed the lowest superoxide dismutase (SOD), total antioxidant capacity (TAC), glutathione transferase (GST) activity, and the highest levels of malondialdehyde (MDA). Moreover, they showed a significant improvement in liver enzymes and kidney function tests and a significant (P < 0.05) reduction in the levels of total cholesterol and triglycerides. Chamomile supplementation alone or with OTA significantly (P < 0.05) increased immunoglobulin M, G, A, and complement 3 than OTA alone. Chamomile oil with an OTA diet or alone reduced the negative effects of OTA and improved the performance, antioxidant status, lipid profile, and immunological state of growing Japanese quails.

Essential oils improve nursery pigs' performance and appetite via modulation of intestinal health and microbiota

Optimal intestinal health and functionality are essential for animal health and performance, and simultaneously intestinal nutrient transporters and intestinal peptides are also involved in appetite and feed intake control mechanisms. Given the potential of essential oil (EO) in improving animal performance and improving feed palatability, we hypothesized that dietary supplementation of cinnamaldehyde and carvacrol could improve performance and appetite of nursery pigs by modulating intestinal health and microbiota. Cinnamaldehyde (100 mg/kg), carvacrol (100 mg/kg), and their mixtures (including 50 mg/kg cinnamaldehyde and 50 mg/kg carvacrol) were supplemented into the diets of 240 nursery pigs for 42 d, and data related to performance were measured. Thereafter, the influence of EO on intestinal health, appetite and gut microbiota and their correlations were explored. EO supplementation increased (P < 0.05) the body weight, average daily gain (ADG) and average daily feed intake (ADFI) of piglets, and reduced (P < 0.05) diarrhea rates in nursery pigs. Furthermore, EO increased (P < 0.05) the intestinal absorption area and the abundance of tight junction proteins, and decreased (P < 0.05) intestinal permeability and local inflammation. In terms of intestinal development and the mucus barrier, EO promoted intestinal development and increased (P < 0.05) the number of goblet cells. Additionally, we found that piglets in the EO-supplemented group had upregulated (P < 0.05) levels of transporters and digestive enzymes in the intestine, which were significantly associated with daily gain and feed utilization. In addition, EO supplementation somewhat improved appetite in nursery pigs, increased the diversity of the gut microbiome and the abundance of beneficial bacteria, and there was a correlation between altered bacterial structure and appetite-related hormones. These findings indicate that EO is effective in promoting growth performance and nutrient absorption as well as in regulating appetite by improving intestinal health and bacterial structure.

Investigating the Effects of Dietary Supplementation of Eucalyptus Camaldulensis Essential Oil on Haemato-Biochemical Indices, Immune Response and Oxidative Stress of Weaned Rabbits

The aim of this experiment was to investigate the effects of dietary supplementation of Eucalyptus camaldulensis essential oil on haemato-biochemical indices, immune response and oxidative stress of weaned rabbits. Sixty healthy weaned cross bred male rabbits (4 weeks of age) with initial body weight of 460.1 ± 0.25 g were grouped based on their body weight into four treatments containing treatment 1 (T1) basal diet with no Eucalyptus camaldulensis oil (ECO), T2, T3 and T4 were fed basal diet with 200 mg, 400 mg and 600 mg/kg respectively in a completely randomized design. Feed and clean water was supplied ad libitum throughout the experiment which lasted for 56 days. All haematological parameters (pack cell volume, red blood cell, haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentrations, white blood cells and its differentials) were higher (P˂0.05) in T2, T3 and T4 relative to T1. Total protein, albumin, globulin, albumin/globulin ratio, cholesterol, aspartate transaminase, alanine transaminase and alanine phosphatase values were greater in ECO supplemented diets whereas urea nitrogen, creatinine, calcium, phosphorus, potassium, sodium and bicarbonate were influenced by the treatments. However, all values were within the optimal range for healthy rabbits. Immunoglobulins, melanodialdehyde, superoxide dismutase, glutathione peroxidase, catalase and total antioxidant capacity were higher (P˂0.05) in T2, T3 and T4 than in other diet. Result revealed that ECO can be supplemented up to 600 mg/kg without negatively affecting the performance and health status of rabbits.

Effects of sage (Salvia officinalis) essential oil on growth, health and antioxidant capacity of common carp (Cyprinus carpio).

In the study, effects of S. officinalis essential oil on growth performance, health and antioxidant activity in C. carpio were investigated. The fish (13 ± 0.21g) were fed with diet containing 1 and 3 ml kg- 1 of sage oil for 60 days. At the end of study, growth performance was not affected in fish fed with sage essential oil (p > 0.05). Superoxide dismutase (SOD) activity in hepatopancreas increased with addition of 1ml kg- 1 sage oil to the diet. However, Catalase (CAT) activity and malondialdehyde (MDA) values were not significantly altered in common carp. Total protein, albumin, glucose and hepatopancreas enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)) in blood serum were not affected by sage essential oil supplementation. At the histological examinations, no pathological findings were observed in hepatopancreas and intestine of carp. Goblet cells number and villi length in intestine increased with sage supplementation (p < 0.001). In addition, fertility, granulation and number of follicles increased in common carp fed with sage essential oil. Mortality after challenged with A. hydrophila was not observed in carp fed with 1ml kg- 1 concentration of sage essential oil. As a result, use of sage oil can be recommended in carp farming to improve gut health, provide disease resistance against A. hydrophila infection, and increase of fertility.

Allium sativum Essential Oil Supplementation Reverses the Hepatic Inflammation, Genotoxicity and Apoptotic Effects in Swiss Albino Mice Intoxicated with the Lead Nitrate.

Prolonged lead (Pb) exposure impairs human health due to its interference with physiological and biochemical processes. Therefore, it is necessary to investigate natural therapeutics to alleviate Pb-induced intoxication. In the current investigation, essential oil extracted from the fresh bulbs of Allium sativum was considered as a natural remedy. Initially, in vitro antioxidant and anti-inflammatory activity of A. sativum essential oil (ASEO) were explored. The results reported that ASEO exhibits potent antioxidant and anti-inflammatory potential. Additionally, an in vivo study was conducted to elucidate its preventive role against Lead-nitrate (LN)-induced hepatic damage in Swiss albino mice. The experimental mice were allocated into six groups: Control, LN-intoxicated group (50mg/kg), LN + ASEO (50mg/kg), LN + ASEO (80mg/kg), LN + Silymarin (25mg/kg), and LN + vehicle oil control group. The entire duration of the study wasof 30days. From the results, it was determined that LN exposure elevated the Pb content in hepatic tissues which subsequently increased the serum biomarkers, inflammatory cytokines (NF-kB, TNF-α, IL-6) as well as apoptotic factors (caspase-3, BAX), all of which contribute to DNA damage. Meanwhile, it reduced anti-inflammatory (IFN-γ and IL-10) and anti-apoptotic factors (Bcl-2). Furthermore, Pb accumulation in hepatic tissues changed the histological architecture, which was linked to necrosis, central vein dilation, inflammatory cell infiltration and Kupffer cell activation. In contrast to this, ASEO administration decreased the Pb content, which in turn reduced the level of serum biomarkers, inflammatory and apoptotic factors. At the same time, it increased the anti-inflammatory and anti-apoptotic factors, thereby reduced DNA damage and restored the hepatic histology. In conclusion, exhaustive research is of the utmost demand to elucidate the precise defense mechanisms of ASEO against LN-induced hepatotoxicity.

258 Investigating the Ruminal Metagenome of Neonatal Holstein Dairy Calves fed an Essential oil-Based Feed Additive

Abstract Antibiotics remain the most effective tool for treating and preventing animal diseases in livestock production. However, the widespread use of antibiotics in food animals, as well as concerns about antibiotic resistance among bacterial pathogens, have raised awareness of the need to limit their use. As neonatal dairy calves are very susceptible to gastrointestinal infections that can result in high mortality and morbidity, the need to find alternatives to antibiotics has become a priority. Although essential oils (EO) have emerged as promising anti-microbial alternatives, their potential effects on the rumen microbiome are still poorly understood due to the complexity of their chemical components and limited understanding of their mechanisms of action. To gain further insight into the effects of EO on the bacterial communities of pre-weaned calves, we investigated the rumen metagenome of neonatal Holstein dairy calves that had been supplemented with 3.75g/feeding of a blend of EO (carvacrol, caryophyllene, p-cymene, cineole, terpinene, and thymol) as part of a previous study. Genomic DNA extracted from rumen contents collected from one of the EO-supplemented animals was used for high throughput sequencing using an Illumina Miseq (2x250) platform. Raw sequence reads were assembled into genomic contigs using custom-written Perl scripts. Coding sequences (CDS) were identified and annotated using RAST, with assignment of open reading frames (ORFs) to metabolic pathways using KEGG pathways. After assembly, a total of 3,052 contigs between 279 and 259,890 nt in length were obtained. From this set, 571 contigs affiliated to Prevotella ruminicola, representing 18.7% of total contigs built, were further analyzed. Data mining for specific functions within categories such as ‘protein metabolism’, ‘carbohydrates metabolism’, and ‘amino acids and derivatives’ was performed. This analysis resulted in the identification of all the enzymes involved in glycolysis. Two outcomes were predicted for pyruvate: conversion to lactate through lactate dehydrogenases (EC 1.1.1.27, EC 1.1.1.28), and the production of formate and acetyl-CoA through the activity of pyruvate formate-lyase (EC 2.3.1.54). Acetate (acetate kinase, EC 2.7.2.1) and propionate (Propionate kinase, EC 2.7.2.15) were other predicted end products. In addition to glucose fermentation pathways, enzymes potentially involved in the utilization of plant-based secondary metabolites were also identified, such as enzymes involved in Quinate-Chorismate metabolism: 3-dehydroquinate dehydratase (EC 4.2.1.10), Shikimate 5-dehydrogenase I alpha (EC 1.1.1.25), Shikimate kinase (EC 2.7.1.71), 5-Enolpyruvylshikimate-3-phosphate synthase (EC 2.5.1.19), and Chorismate synthase (EC 4.2.3.5). Identification of such metabolic pathways suggests that perhaps the supplemented EO additive could be used as a precursor for the synthesis of aromatic amino acids. Together, these findings indicate that EO supplementation may benefit animal health and performance by promoting the growth of bacterial species that can metabolize compounds in EO additives.

Effects of rosemary essential oil as a feed additive on performance, rumen fermentation, and blood parameters in preweaning Holstein calves

The objective of this study was to investigate the effects of rosemary essential oil (REO) supplementation on growth performance, some blood metabolites and rumen fermentation in calves throughout the suckling period. Fourty Holstein calves were randomly divided to four dietary groups. Each group consisted of 10 calves; control with no REO supplementation (CON), supplementation of 500 mg/d REO (REO1), supplementation of 1000 mg/d REO (REO2) and supplementation of 2000 mg/d REO (REO3). REO supplementation quadratically increased (P&lt;0.05) the calf starter (CS) intake, average daily gain (ADG) and feed efficiency. Calves fed REO1 and REO2 had the highest CS intake and ADG. Ruminal ammonia-N concentration was lower (P=0.02) for calves fed REO3 than calves fed REO1, but total volatile fatty acids concentration was higher (P&lt;0.01) for calves fed REO1 compared with calves fed CON and REO3. The concentrations of ghrelin, NEFA and BHBA increased linearly (P&lt;0.05) with increasing levels of REO. Calves fed REO2 and REO3 had the highest concentration of ghrelin. Cholesterol concentration decreased linearly (P&lt;0.01) with increasing REO levels on d 56. Calves fed REO2 and REO3 had the lowest cholesterol concentration. Also, serum IgG concentration was higher (P&lt;0.01) in calves fed REO2 and REO3 compared with calves fed CON on d 28. It was concluded that the addition of different amounts of rosemary essential oil can positively change some rumen and blood metabolites of calves, as well as the supplementation of REO may have a beneficial effect on growth performance by increasing ghrelin.

Doses of orange (Citrus sinensis) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether the doses of orange essential oil supplementation impact on dry matter intake (DMI), ruminal fermentation parameters, apparent nutrient digestibility, and methane production in Nellore steers fed with forage-based diet. A total of 32 rumen-cannulated Nellore steers (initial BW= 335±25 kg; age= 20±1 month) were assigned to individual pens in a randomized complete block design. Within block, steers were randomly assigned to treatments: CON= diet without orange essential oil (EO); 100EO= CON diet plus 100 mg orange EO/kg DM diet; 200EO= CON diet plus 200 mg orange EO/kg DM diet; and 500EO= CON diet plus 500 mg orange EO/kg DM diet. The main active compounds of the orange EO used were limonene (88.0 %) and myrcene (5.79 %). The experimental period lasted 28d, with 22d for adaptation and 6d for sample collection. From d23 to 27, samples of haylage, concentrate, and total fecal production were collected to determine the total tract apparent nutrient digestibility. Ruminal fluid was obtained from d28 at 0, 6, and 12 h after feeding to determine ruminal fermentation parameters and methane production. The difference was considered significant when P ≤ 0.05. No treatment effects were detected (P>0.05) to DMI or specific nutrient intake. The increasing levels of EO did not affect (P>0.05) the total apparent nutrient digestibility. No treatment effects were detected (P>0.05) for ruminal fermentation parameters in vivo. In ex situ, there was a treatment effect for acetate, total short-chain fatty acids (SCFA), methane, and relative energy loss (REL). For acetate, an increasing linear effect was observed for treatments that received EO for the variables production (g/kg) (P = 0.002) and gross energy (MJ/kg) (P = 0.002), with a higher concentration for the 500EO. For the total production of SCFA, there was an increasing linear effect of treatment with a higher concentration for 500EO for the variables production (g/kg) (P = 0.001) and gross energy (MJ/kg) (P = 0.001). For methane, a quadratic treatment effect was observed for the variables production (g/kg) (P = 0.045) and gross energy (MJ/kg) (P = 0.046), with lower concentrations for the 200EO. There was a decreasing linear treatment effect for REL(%) (P<0.001). The results for the use of orange EO as a manipulator of ruminal fermentation were promising and the dose of 500 mg/kg of DM showed a greater capacity to increase the energy efficiency of fermentation, with greater production of acids and lower production of methane, without affecting the voluntary intake of steers.

Microencapsulated essential oils influence the growth and foregut histomorphometry of Nile tilapia (Oreochromis niloticus) fingerlings

Essential oils supplementation has potential growth-promoting, antibacterial, and immunostimulatory effects for various fish species. Dietary supplementation with essential oils improves Nile tilapia's growth and intestinal morphology. The aim of the study was to assess the effect of supplementation with microencapsulated essential oils (MEOs) containing cinnamaldehyde (53.9 %), thymol (24.2 %), and carvacrol (18.7 %) in Nile tilapia fingerlings on growth parameters and foregut histomorphometry. Six thousand fishes with initial body weights and lengths of 1.20 ± 0.32 g and 2.03 ± 0.40 cm, respectively, were reared in two separate 60 m3 circular tanks (control and supplemented with 500 mg/kg of MEOs) at a 5 kg/m3 density. Growth parameters included weight and length. Ten foregut samples per tank were collected at 0-, 15- and 30-days post-treatment. The histological analysis involved the size of intestinal folds and the number of goblet cells. Our results showed that fingerling growth parameters such as final body weight and length increased by 16.9 % and 10.43 %, respectively, with MEOs supplementation compared to the control group. Furthermore, histomorphometry results showed that the supplementation of MEOs led to a significant increase in the growth of both the width and length of intestinal folds and the number of goblet cells (p < 0.05). In conclusion, the early supplementation with MEOs improved the number, length, and width of intestinal folds and increased the number of goblet cells, positively influencing intestinal morphology and health. Additionally, MEOs improved growth parameters in Nile tilapia at 30 days of supplementation.

Essential Oil Supplementation in Small Ruminants: A Review on Their Possible Role in Rumen Fermentation, Microbiota, and Animal Production

Essential oils are bioactive compounds, originating from the secondary metabolism of plants, recognized for their ability to modify rumen fermentation, gut health, and to function as antioxidant molecules in small ruminants. Indeed, small ruminant-derived products, such as milk, dairy, and meat can benefit from the utilization of essential oils, that have demonstrated antimicrobial, antioxidant and anti-inflammatory affects, in the animals’ diet. This review reports on the findings that demonstrates the possible role of essential oils in controlling greenhouse gas emissions from ruminants through the modulation of ruminal microbial populations, in sustaining animal health and welfare by affecting the gut microbiota, and in ameliorating animals’ products through enhancement of their nutritional composition from a human diet perspective. However, the current review highlighting the inconclusive findings related to the use of essential oils in small ruminant nutrition, supports the need of further studies to better understand the administration of how essential oils and to explore their specific actions at the molecular level.

Dietary oregano essential oil supplementation alters meat quality, oxidative stability, and fatty acid profiles of beef cattle

This study was conducted to elucidate the effects of oregano essential oil (OEO) supplementation on the meat quality, antioxidant capacity, and nutritional value of the longissimus thoracis muscle in steers. Steers were divided into three groups (n = 9) and fed either a basal diet, or a basal diet supplemented with 130 mg/d OEO, or 230 mg/d OEO for 390 days. The results demonstrated that dietary OEO supplementation increased the total antioxidant capacity and activity of catalase, glutathione peroxidase, and superoxide dismutase, and decreased pH30min, pH24h, cooking loss, and malondialdehyde content. OEO increased the concentrations of polyunsaturated fatty acids and conjugated linoleic acid. In contrast, saturated fatty acids decreased, accompanied by increased essential amino acids, flavor amino acids, and total amino acids in the longissimus thoracis muscle. In summary, dietary OEO supplementation promotes the nutritional and meat quality of beef by maintaining its water-holding capacity and meat color, enhancing its antioxidative capacity, and preventing lipid oxidation.

Lactational performance, rumen fermentation, nutrient use efficiency, enteric methane emissions, and manure greenhouse gas-emitting potential in dairy cows fed a blend of essential oils

The objective of this experiment was to investigate the effects of an essential oil (EO) blend on lactational performance, rumen fermentation, nutrient utilization, blood variables, enteric methane emissions and manure greenhouse gas-emitting potential in dairy cows. A randomized complete block design experiment was conducted with 26 primiparous and 22 multiparous Holstein cows. A 2-wk covariate and a 2-wk adaptation periods preceded a 10-wk experimental period used for data and sample collection. Treatments were: (1) basal diet supplemented with placebo (CON); and (2) basal diet supplemented with a blend of EO containing eugenol and geranyl acetate as main compounds. Supplementation with EO did not affect dry matter intake, milk and energy-corrected milk yields, and feed efficiency of cows, compared with CON. Milk fat and lactose concentrations were increased, and milk total solids (TS) concentration and milk fat yield tended to be increased by EO. Multiparous cows supplemented with EO tended to have slightly decreased dry matter and crude protein digestibility compared with CON multiparous cows. There was a tendency for increased ruminal pH by EO, whereas other rumen fermentation variables did not differ between treatments. Daily methane emission was not affected by EO supplementation, but methane emission intensity per kg of milk fat was decreased by 8.5% by EO. Methane emission intensity per kg of milk lactose and milk TS were decreased and methane emission intensity per kg of milk yield tended to be decreased by up to 10% in EO multiparous cows, but not in primiparous cows. The greenhouse gas-emitting potential of manure was not affected by EO supplementation. Compared with CON, fecal nitrogen excretion was increased by EO supplementation in multiparous, but not in primiparous cows, and milk nitrogen secretion (as a % of nitrogen intake) tended to be increased in EO supplemented cows. Blood variables were not affected by EO supplementation in the current study. Overall, dietary supplementation of EO did not affect lactational performance of the cows, although milk fat and lactose concentrations were increased. Most enteric methane emission metrics were not affected, but EO decreased methane intensity per kg of milk fat by 8.5%, compared with the control.

Coated organic acids with essential oils in Japanese quail’s fed restricted during the 2nd week of age: effects on performance, carcase traits, blood profile, antioxidants status, and caeca microbiota

This study aimed to evaluate the effect of Coated Organic Acids with Essential Oils (COAWEO) supplementation on performance, carcase traits, blood biochemistry, antioxidant status, and gut microbiota of Japanese quail (JQ) fed restricted during the 2nd week of age. Five hundred and forty, 7-days old JQ were distributed into 6 groups with six replicates/groups. The feed restriction (FR) was applied only at days 7, 9, 11, and 13 of age. Two levels of FR were used: −12.5 and −25.0% of the amount of feed consumed by the control group (feeding ad libitum), on the previous day. The diets (control, FR12.5 and FR25.0) were fed with or without 100 g/ton of COAWEO. The results indicate that FR and COAWEO-supplemented diets did not affect weight gain, feed intake, and carcase weight. The feed conversion ratio (FCR) was improved by FR during 7–42 days of age. The total bacterial and Lactobacilli counts in the caeca were, respectively, decreased and increased due to FR and COAWEO. Japanese quail can tolerate 12.5% FR without adverse effects on growth performance, carcase traits, blood biochemistry, and gut microbiota. FR25.0 group supplemented with COAWEO showed improved growth performance than the control without any adverse effect on carcase traits, blood biochemistry, and gut microbiota.

Doses of lemongrass (Cymbopogon citratus) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether doses of lemongrass essential oil supplementation affect DMI, apparent nutrient digestibility and methane production in Nellore steers fed forage-based diets. According to their initial fasting BW, 32 Nellore steers (BW = 332±19 kg; age = 19±1 months) rumen cannulated and castrated, were allocated in individual pens in a randomized complete block design. The treatments were randomly assigned to the animals: CON= forage-based diet without addition of lemongrass EO; 200EO= CON diet plus 200 mg/kg lemongrass EO; 400EO= CON diet plus 400 mg/kg lemongrass EO; or 600EO= CON diet plus 600 mg/kg lemongrass EO. The experimental diets contained 95% Tifton-85 haylage and 5% ground corn. The experimental period lasted 21 days, 15 days for diet adaptation and 6 days for sample collection. Samples of haylage, concentrate and total feces production were collected from day 15 to 20, to determine the total apparent digestibility of nutrients. On the 21st day at 0, 6 and 12 h after feeding, rumen fluid was collected to determine the parameters of rumen fermentation and methane production. Significant effects were adopted when P ≤ 0.05. The main active compounds of the EO of lemongrass used were geranial (42.5%) and neral (30.49%). No treatment effects were detected for DM and nutrient intake. The increasing EO levels of lemongrass did not affect the apparent digestibility of nutrients. There was an increasing linear effect (P < 0.05) of treatment in the in vivo analysis, where the highest dose had the highest valerate concentration. There was no effect for any other variables in vivo. Effects on fermentation parameters were identified in the ex situ technique. For acetate, there was a quadratic treatment effect with higher values for the 400EO for the variable production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02). There was linear increase for butyrate production (g/kg day; P = 0.04) and gross energy (Mcal/kg day; P = 0.04). There was a quadratic effect with higher values for the 400EO for production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02) of SCFA. There was a quadratic effect for REL (P = 0.01), with lower loss in the 400EO. There was no treatment effect for propionate (P ≥ 0.97) and methane production (P ≥ 0.19). In conclusion, 400 mg/kg lemongrass EO optimized ruminal fermentation, minimizing energy loss due to methane emissions.

Garlic essential oil supplementation modulates colonic microbiota compositions and regulates immune response in weaned piglets

The objective of this study was to investigate the colonic microbiome compositions and immune response and reveal their correlations in weaned piglets fed with garlic essential oil (GEO). Twelve 21-day-old crossbred piglets with the same parity and similar weight (BW = 7.07 ± 0.37 Kg) were randomly divided into control and experimental groups based on BW and sex, which fed either a basal diet (CON group), or a basal diet supplemented with 1.5 g/kg GEO (GEO group). UHPLC-QE-MS showed the main component of GEO were belonged to carbohydrates, organic acid, flavonoids, phenylpropanoids and terpenoids. GEO decreased serum IL-1β, IL-8 content and the down-regulated mRNA expression of IFN-γ, TLR2 in jejunal mucosa but increased serum IgG, IL-4 content and up-regulated the mRNA expression of IL-4, IL-1β, TNF-α in ileal mucosa. What's more, the metagenomic analysis demonstrated that GEO increased the abundance of Bacteroidetes, Euryarchaeota and Spirochaetes, while decreased the abundance of Firmicutes and Actinobacteria at Phylum level and Selenomonas_boris, Selenomonadaceae_bacterium_DSM_108025, Clostridiales_bacterium and Phascolarctobacterium_succinatutens at species level. Notably, the main function pathway of virulence factor (VFDB) enriched in GEO group were Fibronection-binding protein, Zn++ metallophrotease and Capsular polysaccharide, while the main function pathway of VFDB enriched in CON group were heme biosynthesis, Lap and FeoAB. Spearman correlation analysis indicated the Spirochaetes had a positive association with IL-6 and IL-4. Acinobacteria was positively correlated with IL-1β, while negative with the IL-6; In addition, Euryarchaeota had a positive correlation with IL-4, but a negative correlation with IL-1β; Tenericutes was negative with IL-8; Phascolarcolarctobacterium_succinatutens and was negative with IL-6; Ruminococcaceae_bacterium was negative with TNF-α. While Selenomonadaceae_bacterium_DSM_108025 had a positive correlation with IL-8. In conclusion, our results uncovered that immune regulation effects of GEO may be associated with the microbiome compositions in response to GEO.

Effects of Dietary Peppermint (Mentha piperita) Essential Oil on Growth Performance, Plasma Biochemistry, Digestive Enzyme Activity, and Oxidative Stress Responses in Juvenile Nile Tilapia (Oreochromis niloticus)

This study aimed to evaluate the supplementation of peppermint essential oil (Mentha piperita; PEO) in diets for juvenile Nile tilapia (Oreochromis niloticus). A feeding experiment with diets containing graded levels (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 g kg−1) of PEO was carried out with fish of 0.58 ± 0.08 g. The inclusion of graded levels of PEO in the diet improved the weight gain (0.52 g kg−1), feed intake (0.51 g kg−1), and feed conversion (0.51 g kg−1) of juvenile Nile tilapia in a quadratic pattern. Increasing levels of PEO also led to a linear decrease in body lipid content. The gut activity of the digestive enzymes amylase (0.54 g kg−1) and protease (0.39 g kg−1) increased quadratically, whereas lipase activity increased linearly. PEO increased the activity of the antioxidant enzymes catalase (CAT; 0.52 g kg−1) and superoxide dismutase (SOD; 0.58 g kg−1) while reducing the production of malonaldehyde (MDA; 0.40 g kg−1) and nitric oxide (NO; 0.63 g kg−1) in the liver. The results of this study provide evidence of the beneficial effects of PEO on the growth and health of Nile tilapia and recommend a dose of 0.6 g kg−1 as the optimal level of supplementation.

Effects of dietary oregano oil supplementation on performance parameters and intestinal morphology of Japanese quails (Coturnix coturnix japonica) reared under normal and cold stress situation

This study aimed to assess the effects of dietary oregano oil supplementation on growth characteristics in Japanese quails reared in normal and cold temperatures. Three hundred 1-day old Japanese quail were randomly divided into five groups: One control group and two treatment groups of 100 and 200 mg of essential oil of oregano/kg in normal temperature (groups 1, 2, and 3); One control and a treatment group of 100 mg Oregano essential oil/kg in a cold stress situation (groups 4 and 5). All the groups were subjected to the same temperature regimen until the 14th day. At the age of 14, the cold stress groups were transferred into a different house in which the temperature ranged between 10 to 13°C until the 35th day of age. At the end of the experiment, performance parameters and intestinal morphology were analyzed; performance parameters were not affected by supplementing oregano oil at normal temperature. On the other hand, dietary supplementation of oregano essential oil at the level of 100 mg/kg under cold stress situations improved Japanese quail’s body weight, FCR, and intestinal villus morphology. This study indirectly states that the supplementation of the oregano essential oil components to the Japanese quail’s diet would delay the adverse effects caused by cold stress on the birds’ performance.