Effects of thymol and isoeugenol feed supplementation on quail adult performance, egg characteristics and hatching success

Recent advances in essential oils and their nanoformulations for poultry feed

Antibiotics in poultry feed to boost growth performance are becoming increasingly contentious due to concerns over antimicrobial resistance development. Essential oils (EOs), as natural, plant-derived compounds, have demonstrated antimicrobial and antioxidant properties. EOs may potentially improve poultry health and growth performance when included in poultry feed. Nevertheless, the incorporation of EOs as nutritional additives is hindered by their high volatility, low water solubility, poor intestinal absorption, and sensitivity to environmental conditions. Recently, nanoencapsulation strategies using nanoformulations have emerged as a potential solution to these challenges, improving the stability and bioavailability of EOs, and enabling targeted delivery in poultry feed. This review provides an overview of the antioxidant and antibacterial properties of EOs, the current limitations of their applications in poultry feed, and the recent advancements in nano-engineering to overcome these limitations. Furthermore, we outline the potential future research direction on EO nanoformulations, emphasizing their promising role in advancing sustainable poultry nutrition.Highlights• Essential oils (EOs) are known as powerful antioxidants and antibacterial agents.• EOs have a high potential to replace antibiotics as feed additives.• Nanoformulations of EOs have shown improved bioactivity and storage stability of EOs.• Nanoformulation promotes the bioavailability and gut adsorption of EOs as feed additives.

Short- and long-term dynamics of the physiological and behavioral response to heat stress and thymol supplementation in Japanese quail

Organisms have evolved endogenous timing systems that enable them to predict temporal changes and to coordinate complex internal processes. However, temporal dynamics of biological responses are most often ignored in fields such as dietary supplementation of farm animals exposed to artificial environmental challenges. Herein, we hypothesized that the potential for thymol (2-isopropyl-5-methylphenol) to alleviate physiological and behavioral consequences of heat stress is time-dependent on both long-term (i.e. weeks) and short-term (i.e. within day) time scales. First, during 3-weeks adult female Japanese quail (Coturnix japonica) were exposed daily to 9h of increased environmental temperature (34.2 ± 0.1 °C). Controls remained at standard temperatures (23.6 ± 0.1 °C). Simultaneously, half received thymol dietary supplementation and the other half a control basal diet. On day 4, both thymol and heat stress decreased body weight and feed intake respect to controls (basal, standard temperature). After three weeks, feed intake recovered for thymol groups. Therefore, we performed a second experiment focused on the critical first week of treatment, sampling variables three times a day. The beneficial effects of thymol supplementation were mainly observed during the morning, including prevention of high respiratory rates and reduction in the weight of droppings induced by heat stress, and increased walking under both temperatures. In summary, thymol's potential for alleviating heat stress consequences is time-dependent, and can be conceived as an emergent property resulting from the complex interplay between the dynamics of the biological response to thymol and heat stress. Findings highlight the importance of considering time-related factors when developing supplementation protocols to mitigate environmental challenges.

Reducing cytotoxicity of poly (lactic acid)-based/zinc oxide nanocomposites while boosting their antibacterial activities by thymol for biomedical applications

In the present study, ternary blends based on poly (lactic acid)/poly (ε-caprolactone)/thermoplastic starch were prepared at different concentrations of synthesized zinc oxide nanoparticles (ZnO-NPs) and thymol. The sizes of ZnO-NPs with an average diameter of about 30-50 nm were detected by FE-SEM analysis. Moreover, the effect of ZnO-NPs and thymol on morphological, FT-IR spectrum, UV absorption, thermal stability, cytotoxicity, and antibacterial properties of neat blend was investigated. TGA analysis showed that the addition of ZnO-NPs and/or thymol diminished thermal stability of the system. Incorporating ZnO-NPs improved antibacterial activities of the neat blend, but MTT-assay and AO fluorescent staining test results depicted a decrease in cell viability to less than 20% by the addition of 5 wt% ZnO-NPs. In such a condition, the addition of thymol to the nanocomposites exhibited a dose-dependent increase in cell survival mostly due to thymol antioxidant properties. Interestingly, the antibacterial performance of compounds was also improved by the presence of thymol. Therefore, the obtained nanocomposites have potential to extend applications of innovative biomedical devices for future research in which both high cell viability and superior antibacterial properties are needed such as an antibacterial wound healing film.

Consequences of various housing systems and dietary supplementation of thymol, carvacrol, and euganol on performance, egg quality, blood chemistry, and antioxidant parameters

The present work was carried out to investigate the influences of housing system and dietary essential oils (EOs) supplementation to laying hens on the productive performance, egg quality, immunity, antioxidant parameters, and hematology. A factorial arrangement (2 × 4) was performed, including 2 housing systems and 4 different types of EOs (without EOs, thymol, carvacrol, and euganol) during the production stages (from 28–78 wk of age). Birds were randomly divided into 2 groups with each of 2,000 birds. The first group was moved to laying cages while the second group was a floor reared. Each group was randomly divided into 4 groups (5 replicates of 100 birds each): The first were considered as a control group, and the second, third, and fourth groups were treated with thymol, carvacrol, and euganol EO, respectively. The results showed that hens reared in cage system had higher egg weight (P < 0.05), egg production, egg mass, and feed intake and better feed conversion ratio (P < 0.001) than those reared in the floor system. Blood picture values (except white blood cells), phagocytic index, phagocytic activity, and blood chemistry parameters (except calcium, phosphorus, and urea values) of laying hens were not affected (P > 0.05) by housing system. The groups fed EOs showed a rapid improvement (P < 0.001) in the egg production%, egg weight, egg mass, and egg quality. Thymol group had the highest egg production (P < 0.001). Thymol and eugenol groups had the highest egg weight, egg mass, and egg quality (P < 0.001). The groups fed diets containing thymol or eugenol consumed lower feed and had better feed conversion ratio (P < 0.001) than the control group. Immunity indices (phagocytic activity [P < 0.05], avian influenza [AIH5 and AIH9], P < 0.001) were improved with the presence of EOs in the laying hen diet. These results strongly suggest that dietary EO supplementation could be a successful attempt to improve the productive performance, egg quality, and immunity of laying hens.

Early life exposure to triphenyl phosphate: Effects on thyroid function, growth, and resting metabolic rate of Japanese quail (Coturnix japonica) chicks

Triphenyl phosphate (TPHP; CAS # 115-86-6), a commonly used plasticizer and flame retardant, has been reported in wild birds and identified as a potential high-risk chemical. We exposed Japanese quail (Coturnix japonica) by in ovo injection, and once hatched, orally each day for 5 days to safflower oil (controls) or TPHP dissolved in vehicle at low (5 ng TPHP/g), mid (50 ng TPHP/g), or high (100 ng TPHP/g) nominal TPHP doses. The low TPHP dose reflected concentrations in wild bird eggs, with mid and high doses 10x and 20x greater to reflect potential increases in environmental TPHP concentrations in the future. Despite no effects on mRNA expression in thyroid-related genes, TPHP exposure enhanced thyroid gland structure in high TPHP males, but in females, suppressed thyroid gland structure and activity (all TPHP females), and circulating free triiodothyronine (high TPHP females only). Consistent with thyroidal changes, and compared to controls, mid and high TPHP chicks experienced significantly reduced resting metabolic rate (≤13%) and growth (≤53%); mid TPHP males and high TPHP females were significantly smaller. The observed thyroidal effects and suppressed growth and metabolic rate of the quail chicks suggest that TPHP may adversely affect the health of wild birds.

Dynamics of thymol dietary supplementation in quail (Coturnix japonica): Linking bioavailability, effects on egg yolk total fatty acids and performance traits

Phytogenic additives such as thymol are encountering growing interest in the poultry industry. However, there are still questions concerning dynamics of their bioavailability, biological action, optimal dosage and duration of supplementation needed to achieve meaningful effects, as well as persistence of induced changes after supplement withdrawal. We studied the link between the dynamics of free thymol concentration and the changes in fatty acids composition in quail egg yolk, both during a month-long chronic dietary supplementation and after 3 weeks of supplement withdrawal (post-supplementation). Fifty, 85 days-old, female quail of homogeneous body weights (251±1g) in egg-laying peak were used. To evaluate potential dose-dependent effects, three increasing doses 2, 4, and 6.25 g of thymol/kg of feed (THY2, THY4 and THY6, respectively) and two controls were evaluated (n = 10). In parallel, we assessed the concomitant changes in free thymol excretion, potential liver histopathological changes, and birds´ performance traits. Egg yolk and droppings show a dose-dependent increase in THY concentration after 9 days of supplementation and a decrease after post-supplementation. In egg yolk, these changes were accompanied by reduced saturated fatty acid concentrations achieved by 28 days of supplementation in THY2 and 14 days of supplementation in THY4 and THY6. However, after post-supplementation the aforementioned effect disappeared in THY2 but not in THY4 and THY6. While THY2 failed to increase polyunsaturated fatty acids, THY4 and THY6 increased polyunsaturated fatty acids by day 14 of supplementation and remained increased after post-supplementation. Fatty acids changes induced by thymol are consistent with improved nutritional quality of eggs. No treatment effects were observed in liver histopathology and female performance. Findings suggest that both dose of thymol and duration of supplementation modulate thymol and fatty acids concentrations in egg yolk and thymol concentration in droppings. Furthermore, the persistence of those effects after post-supplementation period is also a dose-dependent phenomenon.

Dynamics of thymol dietary supplementation in quail (Coturnix japonica): Dataset on thymol bioavailability, egg yolk fatty acids profile and performance traits

Dietary supplementation with thymol (2-isopropyl-5-methylphenol) has been proposed as a strategy to improve modern intensive poultry production. Moreover, its antioxidant properties and potential beneficial influence on lipid metabolism have fostered current research focusing on enhancing nutritional quality of meat and egg products. In general, studies have focused on the overall effects of dietary supplementation once the supplementation protocol has finished and using only one potential dose, without actually measuring bioactive compounds' concentration in the diet supplied or target tissues. Herein, we provide a unique dataset of the dynamics of thymol bioavailability and biological action, optimal dosage and duration of supplementation needed to achieve meaningful effects, as well as persistence of induced changes after chronic supplement withdrawal. Specifically, during a month-long supplementation period, 5 sampling points were evaluated separated by at least 1 week. Then, a last sampling point was studied after a 3-week withdrawal period. Three increasing doses of dietary thymol were used, and approximately 80 variables assessed. The measured variables were associated with free thymol concentration in feed, egg yolk and droppings, feed and egg yolk fatty acids profile (saturated, unsaturated, and polyunsaturated fatty acids), performance traits (body weight, feed intake, egg laying rate, egg physical characteristics), general welfare quality assessment (plumage state) and liver histopathology. The data can provide insights on the link between the dynamics of free thymol concentration and the changes in fatty acids profile in quail egg yolk, both during chronic thymol dietary supplementation and after supplement withdrawal. The comprehensive approach used herein for studying thymol supplementation outcome could help understanding the scope of its effects on a whole organism level.

Thymol as natural antioxidant additive for poultry feed: oxidative stability improvement

Antioxidant are regularly included in poultry feed as protection from deterioration during storage. Recently the interest for the use of natural phytochemicals in animal diets has been increased. Thymol (THY) has been proven to be an effective antioxidant for extending broiler meat quality during storage with similar action to the widely used butylated hydroxytoluene (BHT). This study evaluates whether THY can also have a protective effect on the feed mash by assessing its antioxidant potential and related changes in fatty acid (FA) balance. Feed mash was assigned to 1 of 4 treatments, control (CON, no additive), vehicle (VEH, ethanol 96%), BHT (400 mg BHT /kg feed) and THY (400 mg THY /kg feed). Three replicates of each treatment were taken after 0, 30, and 60 d of storage at room temperature (23 ± 3°C) and relative humidity (40 ± 5%). Peroxide value (PV), titratable acidity (TA) and FA relative composition were determined. As expected, there were no treatment effects on those variables at 0 d of storage. However, higher PV values were detected in the CON and VEH groups after 30 and 60 d of storage in comparison to the THY and BHT treated samples (CON = VEH > THY = BHT). While a slight increase was also observed in TA through storage time, no particular treatment effects were detected. Relative FA composition changed with storage time only in the CON and VEH group which had a decrease in polyunsaturated fatty acids and an increase in saturated FA. No changes were detected in the Thy and BHT treated feeds. The results suggest a similar THY and BHT protective effect on feed mash lipid oxidation. Thus, THY could be considered as a useful natural alternative to help sustain quality of poultry feed.

Thymol feed supplementation in quail alters the percentages of nutritionally relevant egg yolk fatty acids: effects throughout incubation

BACKGROUND

Polyunsaturated fatty acids (PUFA) are crucial components of egg yolk and particularly prone to oxidative damage, generating losses of nutrients for embryonic development and influencing the quality of eggs for human consumption. The aim of this study was to evaluate whether dietary thymol (a natural antioxidant) is related to changes in quail egg yolk total (T), triglyceride (TG) and phospholipid (PL) fatty acid composition at different stages of embryo development. Thus female Japanese quail (100 days of age) were assigned to one of two dietary treatments (12 individuals each): CON (basal diet) or THY (0.0016 mol thymol day^-1 per bird). After 2 weeks of supplementation, eggs were incubated and samples were obtained at 0, 4 and 16 days of embryonic development.

RESULTS

In 0 day THY eggs, α-linolenic acid and n-3 PUFA in T and TG, docosahexaenoic acid and PUFA in T and arachidonic acid in TG were increased, while saturated fatty acids (SFA) in T were reduced. From 4 days on, PUFA, n-3 PUFA and SFA from T and TG in THY eggs were found to be similar to those of CON eggs. The changes in PL throughout incubation were similar in both dietary treatments.

CONCLUSION

Thymol would provide the embryo with PUFA for synthesis/deposition in membranes and/or assign to supply energy. Additionally, thymol supplementation would be advisable for the production of healthier table eggs. © 2017 Society of Chemical Industry.

Thymol detection and quantitation by solid-phase microextraction in faeces and egg yolk of Japanese quail

To measure bioavailability of the active ingredients of phytogenic feed additives in poultry products and subproducts is a key element for developing a rational understanding of its mode of action and biological effects. Hence, we validated a headspace solid phase microextraction (HS-SPME) technique followed by gas chromatography-mass spectrometry as an analytical extraction procedure and as method for detection and quantitation of 2-Isopropyl-5-methylphenol (thymol) in faeces and egg yolk of quail. The suitability of this method for thymol analysis in both matrices was first proved via linearity, limit of detection, limit of quantification, and recovery using m-cresol as internal standard. The optimal HS-SPME extraction conditions were obtained at 40°C for 5min in faeces and 60°C for 30min in egg yolk. This procedure was found to be precise, sensitive and linear in the range of 2.5-100ng/gr for faeces and 20-800ng/gr for the egg yolk. Limits of detection were 0.5ng/g and 5ng/g for faeces and yolk, respectively, and the limits of quantitation were 1ng/g and 10ng/g for faeces and yolk, respectively. The method was successfully used for measuring thymol in fecal and egg yolk samples, from quails supplemented with thymol in their diets. Thus, in fresh faeces and egg yolk samples obtained from a supplemented group (80mg thymol per bird per day) were determined as 31.51ng/g for faeces and 11.83ng/g for the egg yolk.

Effect of dietary supplementation of thymol, synbiotic and their combination on performance, egg quality and serum metabolic profile of Hy-Line Brown hens

An experiment was conducted to determine the effects of dietary supplementation of thymol, synbiotic (Biomin, IMBO) and their combination in laying hen diets on laying performance, egg quality and serum metabolic profile from 24 to 36 weeks of age. Treatment groups were fed on a control diet, the control diet supplemented with thymol (250 mg/kg), the control diet supplemented with synbiotic (250 mg/kg) or the control diet supplemented with a combination of thymol (250 mg/kg) and synbiotic (250 mg/kg). Supplementation of thymol and synbiotic, separately as well as combined, improved egg weight, egg production, egg mass and feed conversion ratio from 24 to 36 weeks of age. The eggs obtained from thymol, synbiotic or their combination treatments displayed higher values of shell thickness, Haugh unit and shell percentage compared to the control. Serum cholesterol significantly decreased in the single or combined form of thymol and synbiotic supplementation treatments.

Fly emergence from manure of Japanese quail fed thymol- or isoeugenol-supplemented diets

Many problems in poultry production are caused by a combination of interrelated factors such as management, stress, nutrition, and exposure to pathogens. Saprophagous flies that develop in poultry manure are a potential route of pathogen transmission. Besides being a nuisance, defecation and regurgitation of flies soil equipment and structures and can reduce light levels of lighting fixtures. These effects clearly affect management and may contribute to reductions in poultry egg production, health, and welfare. Many essential oils or their main components have bioactive effects such as natural repellents and insecticides, antioxidants, anticholesterolemics, and antimicrobials. This study evaluated if supplementing quail feed with thymol or isoeugenol as functional food could alter the production of flies from manure. Dropping samples deposited by quail fed with a supplementation of 2,000 mg of thymol or isoeugenol per kg of feed or no supplement (control) were collected. Each sample was incubated inside an emergence cage that was inspected daily to collect emerging adult flies. Fewer flies emerged from droppings of quail fed a thymol-supplemented diet (P = 0.01) and there was a tendency to a lower emergence from droppings of isoeugenol-fed quail (P = 0.09). The number of positive containers for Musca domestica was smaller from quail droppings of thymol- (P = 0.02) or isoeugenol- (P = 0.01) supplemented feed than from the control counterparts, suggesting an oviposition repellent effect. Supplementing quail feed with thymol or isoeugenol has an overall moderate effect against flies, reducing M. domestica emergence.