Effects of thyme as a feed additive in broiler chickens on thymol in gut contents, blood plasma, liver and muscle

Current Knowledge on the Bioavailability of Thymol as a Feed Additive in Humans and Animals with a Focus on Rabbit Metabolic Processes

Simple Summary

This review provides general information on the possible health benefits in animals and humans of herbal additives, particularly thymol, whose phenolic group is responsible for the neutralisation of free radicals, and information concerning its detection through body action, bioavailability and mechanisms in rabbits. Plants containing thymol have been used in traditional medicine for the treatment of various diseases, such as cardiovascular diseases, cancer and diabetes. Although a great number of in vitro studies of cardiovascular and cancer diseases are available, in vivo studies that confirm these findings have not been sufficiently reported. To determine the beneficial dose, further clinical studies are necessary, with preclinical comprehensive research on animal models.

Abstract

The aim of this review is to describe the therapeutic effect of thymol on various human diseases, followed by its bioavailability in humans and animals. Based on our knowledge from the current literature, after thymol addition, thymol metabolites—mostly thymol sulphate and glucuronide—are detected in the plasma and urine of humans and in the plasma, intestinal content, faeces and tissues in rats, pigs, chickens, horses and rabbits after enzymatic cleavage. In rabbits, thymol absorption from the gastrointestinal tract, its distribution within the organism, its accumulation in tissues and its excretion from the organism have been described in detail. It is necessary and important for these studies to suggest the appropriate dose needed to achieve the required health benefits not only for animals but also for humans. Information from this review concerning the mode of action of thymol in animal organisms could also be applied to human medicine and may help in the utilisation of herbal medicine in humans and in veterinary healthcare. This review summarises the important aspects of thymol’s effects on health and its bioavailability in organisms, particularly in rabbits. In future, herbal-based drugs must be extensively investigated in terms of their mode of action, efficiency of administration and clinical effect.

Phytogenic Compounds for Enhancing Intestinal Barrier Function in Poultry-A Review

After the European Union ban of antibiotic growth promoters, works on different methods of improving gut health have intensified. The poultry industry is struggling with problems that were previously controlled by antibiotic growth promoters, therefore the search for optimal solutions continues. Simultaneously, there is also increasing social pressure to minimize the use of antibiotics and replace them with alternative feed additives. A variety of available alternatives is considered safe by consumers, among which phytogenics play a significant role. However, there are still some limitations that need to be considered. The most questionable are the issues related to bioavailability, metabolism of plant derivatives in birds, and the difficulty of standardizing commercial products. There is still a need for more evidence-based recommendations for the use of phytogenics in livestock. On the other hand, a positive influence of phytogenic compounds on the health of poultry has been previously described by many researchers and practical application of these compounds has auspicious perspectives in poultry production. Supplementation with phytogenic feed additives has been shown to protect birds from various environmental threats leading to impaired intestinal barrier function. Phytogenic feed additives have the potential to improve the overall structure of intestinal mucosa as well as gut barrier function on a molecular level. Recognition of the phytogenics' effect on the components of the intestinal barrier may enable the selection of the most suitable ones to alleviate negative effects of different agents. This review aims to summarize current knowledge of the influence of various phytogenic constituents on the intestinal barrier and health of poultry.

Thymol and carvacrol supplementation in poultry health and performance

BACKGROUND

Thymol and carvacrol as natural essential oils and phenol compounds are components derived from some medicinal plants, such as thyme and oregano species.

OBJECTIVES

The increasing demands in organic and healthy meat and egg consumption in human society have made it necessary to consider alternative natural compounds for the replacement of chemical compounds in poultry production. The chemical compounds can remain in meat and eggs and cause complications in human health. Therefore, these natural compounds can be fed with a higher safety in poultry production with specific effects. In this regard, the role of thymol and carvacrol as natural compounds in the poultry production has been discussed in the review.

METHODS

In this study, by searching for keywords related to thymol and carvacrol in poultry production in Google Scholar database, the articles related to different aspects of the biological effects of these two phytogenes in poultry production were selected and analyzed.

RESULTS

A review of previous studies has shown that thymol and carvacrol possess a wide range of biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, modulating of immunity response and regulating of the gut microbial population. Also, in meat type chickens can promote growth and influence feed utilization. The beneficial effect of this compound was evaluated in hepatic toxicity and demonstrated as a hepatoprotective compound in chickens. Furthermore, these compounds can affect the behavior of layers and influence egg composition, eggshell thickness, and the sensory quality of eggs.

CONCLUSION

It seems that with the increasing demand for healthy protein products, these compounds can be used to improve performance as a substitute alternative for chemical compounds in healthy poultry farms.

Effect of Essential Oil of Thyme (Thymus vulgaris L.) or Increasing Levels of a Commercial Prebiotic (TechnoMOS®) on Growth Performance and Carcass Characteristics of Male Broilers

To investigate the effect of thyme (Thymus vulgaris L.) essential oil (TEO) or increasing inclusion of a prebiotic (TechnoMOS^®) on growth performance and carcass characteristics of Ross 308 broilers, 400 one-day-old male broilers (43.5 g, as mean of body weight) were placed in 20 pens (2.0 × 1.0 m, with a floor area of 0.10 m² per bird) in groups of 20, and each pen cage was assigned to a specific dietary treatment (four replicates per each one). The dietary treatments included basic diet (no additive; CTR), basic diet including 0.025%, 0.075%, or 0.125% of TechnoMOS^® (MOS025, MOS075, and MOS125, respectively), or basic diet including 0.075% thyme extract (TEO075). All dietary treatments were offered from the beginning of the study until the end of the trial. There were no effects of MOS or TEO on carcass characteristics. No significant effects of treatment on weight gain were obtained on a week-by-week basis; however, CTR birds gained less weight during the grower phase and overall compared with MOS birds. The same contrast for feed intake revealed that CTR birds had greater feed intake than MOS birds during both the grower phase and overall (492.18 g and 486.35 g, respectively). In conclusion, treated groups showed an improved feed conversion ratio.

Effect of Sustained Administration of Thymol on Its Bioaccessibility and Bioavailability in Rabbits

Simple Summary

The purpose of this study was to investigate the bioavailability and metabolic path of thymol, a major constituent of Thymus vulgaris L., in the rabbit organism. Oral bioavailability is a key parameter affecting the efficacy of substances, but it is not surprising that it does not correlate satisfactorily with efficacy. The main limitation factors are rate of absorption, metabolism, and excretion processes. In this work, the thymol metabolic path in the rabbit organism was determined for the first time after its sustained oral administration. We confirm intensive absorption of thymol from the gastrointestinal tract; our results point to metabolism and accumulation in kidney tissue and intensive metabolic and excretion processes in the liver. Some metabolic processes were present also after thymol withdrawal. Thymol as a lipophilic substance was found only in trace amounts in fat and muscle tissue as a consequence of its conversion into hydrophilic metabolite and greater elimination in the rabbit organism. This paper highlights the insufficient knowledge of modes of action of plant compounds in animal organisms.

Abstract

The objective of this study was the detection of thymol in rabbit plasma, tissues, large intestinal content, and faeces. Forty-eight rabbits were divided into control and experimental groups (thymol 250 mg/kg feed). Thymol was administered for 21 days and then withdrawn for 7 days. Concentration of thymol in the intestinal wall (IW) was significantly higher than in plasma (p < 0.05) and liver (p < 0.05); in the kidneys it was significantly higher than in plasma (p < 0.05) and liver (p < 0.05) during thymol addition. Thymol in IW was significantly higher than in plasma also after withdrawal (p < 0.01). Significant correlation (r_s = −1.000, p < 0.01) between IW and plasma points to the intensive absorption of thymol from the intestine, while the correlation between plasma and liver (r_s = 0.786, p < 0.05) indicates intensive biotransformation and excretion processes in liver. Significant correlation between liver and kidney (r_s = 0.738, p < 0.05) confirms the intensive metabolism of thymol in the kidney. During the withdrawal period, thymol was detected above trace amounts only in faeces, and was significantly higher than in the colon during both periods (p < 0.01). Results show intensive biotransformation of thymol in the rabbit organism.

Honeybee and Plant Products as Natural Antimicrobials in Enhancement of Poultry Health and Production

The quality and safety attributes of poultry products have attracted increasing widespread attention and interest from scholarly groups and the general population. As natural and safe alternatives to synthetic and artificial chemical drugs (e.g., antibiotics), botanical products are recently being used in poultry farms more than 60% of the time for producing organic products. Medicinal plants, and honeybee products, are natural substances, and they were added to poultry diets in a small amount (between 1% and 3%) as a source of nutrition and to provide health benefits for poultry. In addition, they have several biological functions in the poultry body and may help to enhance their welfare. These supplements can increase the bodyweight of broilers and the egg production of laying hens by approximately 7% and 10% and enhance meat and egg quality by more than 25%. Moreover, they can improve rooster semen quality by an average of 20%. Previous research on the main biological activities performed by biotics has shown that most research only concentrated on the notion of using botanical products as growth promoters, anti-inflammatory, and antibacterial agents. In the current review, the critical effects and functions of bee products and botanicals are explored as natural and safe alternative feed additives in poultry production, such as antioxidants, sexual-stimulants, immuno-stimulants, and for producing healthy products.

Thymol in fattening rabbit diet, its bioavailability and effects on intestinal morphology, microbiota from caecal content and immunity

To our knowledge, no study has been carried out to evaluate the effects of thymol sustained administration on gut health and immune response in terms of its bioavailability in the rabbit organism. A total of 48 rabbits were randomly divided at 35 days of age into two dietary treatment groups (C/control or T/thymol at 0.025% addition). Thymol was added for 21 days and then withdrawn for 7 days. Thymol content in faeces (p < 0.001) and caecal content (p < 0.05) was significantly higher than in plasma during the thymol addition and withdrawal (2442 ± 451.4, 881.9 ± 231.3 ng/g DM and 46.2 ± 28.4 ng/ml, respectively; 149.5 ± 40.54, 45.76 ± 12.44 ng/g DM and 2.73 ± 0.45 ng/ml, respectively). Increasing of villi height to crypt depth ratio in small intestinal wall (p < 0.01), phagocytic activity in blood (p < 0.0001) and lactic acid bacteria in caecal appendix (p < 0.01) and faeces (p < 0.05) was still presented after withdrawn of thymol. The thymol at this concentration demonstrated its biological properties and was able to positively affect gut health and immune response of rabbits.

Dietary supplementation of essential oils and lysozyme reduces mortality and improves intestinal integrity of broiler chickens with necrotic enteritis

The objective of this study was to investigate the individual and combined effects of essential oils (EO; comprised of thymol and carvacrol) and lysozyme on experimental NE in broiler chickens. A total of 320 1-day-old chicks were randomly assigned to five treatment groups: no-challenge control (NC), NC + C. perfringens challenge (CC), CC + 120 mg/kg of EO, CC + 100 mg/kg of lysozyme, and CC + 120 mg/kg of EO + 100 mg/kg of lysozyme. The results showed that EO or lysozyme decreased the mortality, alleviated the gut lesions, inhibited the liver Enterobacteriaceae carriage, and increased the villus height of the ileum compared with CC (p < .05), although the proliferation of C. perfringens in the ileum was not inhibited (p > .05). Moreover, EO or lysozyme was found to decrease the ileal concentration of sialic acid and the Mucin2 mRNA expression (p < .05). However, the blend of EO and lysozyme did not display significant effect on the NE-associated mortality or gut damage in contrast with CC (p > .05). In conclusion, these findings suggest the similar protective effects of EO and lysozyme in NE-associated mortality and intestinal impairment, but their blend did not exhibit ameliorative effect.

Mandated restrictions on the use of medically important antibiotics in broiler chicken production in Canada: implications, emerging challenges, and opportunities for bolstering gastrointestinal function and health– A review

Chicken Farmers of Canada has been progressively phasing out prophylactic use of antibiotics in broiler chicken production. Consequently, hatcheries, veterinarians, and nutritionists have been mandated to contend with less reliance on use of preventive antibiotics. A topical concern is the increased risk of proliferation of enteric pathogens leading to poor performance, increased mortality and compromised welfare. Moreover, the gut harbors several taxa such as Campylobacter and Salmonella capable of causing significant illnesses in humans via contaminated poultry products. This has created opportunity for research and development of dietary strategies designed to modulate gastrointestinal environment for enhanced performance and food safety. Albeit with inconsistent responses, literature data suggests that dietary strategies such as feed enzymes, probiotics/prebiotics and phytogenic feed additives can bolster gut health and function in broiler chickens. However, much of the efficacy data was generated at controlled research settings that vary significantly with the complex commercial broiler production operations due to variation in dietary, health and environmental conditions. This review will summarize implications of mandated restrictions on the preventative use of antibiotics and emerging Canadian broiler production programs to meet processor specifications. Challenges and opportunities for integrating alternative dietary strategies in commercial broiler production settings will be highlighted.

Evaluation of dried papaya pomace meal in laying hen diets

In the search for alternative feed resources for laying hens, papaya pomace is available as industrial by-product but information on its nutritive value is lacking. Dried papaya pomace was included in a common laying hen diet at 0%, 2.5%, 5% and 7.5% to evaluate its effect on egg production performance, egg quality and general health parameters in Bovan brown layers. For every inclusion level, three cages with ten 20-week-old layers were used, making a total of 120 hens. The effect of dried papaya pomace inclusion on egg production, egg quality and general health parameters was evaluated. Dried papaya pomace inclusion improved egg production and laying by 6.15% and 17% respectively, while it significantly decreased feed conversion ratio by 7.5%. Eggshell weight, thickness and strength of PP5 were higher than the control by 0.3 g, 0.8 mm and 0.43 kg/cm² , respectively. There was a significant improvement in albumin weight (by 1.5 g/L), albumin height (2.1 mm), yolk weight (0.4 g/L), yolk height (0.4 mm), yolk colour (4.4 points) and Haugh unit (8 points) due to PP5 treatment. Inclusion of papaya pomace at a level of 7.5% of layers diet had negative effect on Egg production, feed conversion ratio and interior and exterior egg quality traits. Inclusion of papaya pomace affected significantly serum total cholesterol, serum triglyceride, serum low density lipoprotein, serum high density lipoprotein, aspartate aminotransferase, alanine aminotransferase and white blood cell count. However, all blood traits of the experimental animals were within the normal ranges reported for layers. Inclusion of papaya pomace in 5% of layers commercial diets improves egg production and quality without negative impact on health while decreasing feeding cost.

Effect of Thymol Addition and Withdrawal on Some Blood Parameters, Antioxidative Defence System and Fatty Acid Profile in Rabbit Muscle

Simple Summary

So far, the study of the bioactivity of thymol, a major constituent of Thymus vulgaris L., in the animal organism has received little attention. Our study could give us answers to questions about whether thymol accumulates in the rabbit organism after its sustained administration and if it is also able to exhibit its beneficial properties for a longer period. Thymol in powder form at the concentration 250-mg/kg feed was added to the rabbit diet for 21 days and withdrawn for the next seven days. We confirmed that thymol was sufficiently absorbed from the gastrointestinal tract and was able to express its biological activity not only during application but, also, after withdrawal. Further studies are needed to clarify the biotransformation and bioavailability of thymol in the rabbit organism with respect to the specific features of rabbit digestion.

Abstract

Thymol concentrations in rabbit plasma, intestinal wall (IW) and faeces were detected, and the effects of thymol application and withdrawal on biochemical, antioxidant parameters and fatty acids (FA) in blood (B) and muscle (M) were studied. Forty-eight rabbits were divided into two experimental groups (control, C and with thymol 250-mg/kg feed, T). Thymol was administered for 21 days (TA) and withdrawn for seven days (TW). Thymol in plasma correlated with that in the IW (Spearman′s correlation coefficient (r_s) = −1.000, p = 0.0167, TA) and was detected in faeces (TA and TW). In TA alkaline phosphatase (p = 0.0183), cholesterol (p = 0.0228), malondialdehyde (p = 0.003), glutathione peroxidase (p = 0.0177) in B and lactate dehydrogenase (M, p = 0.0411) decreased; monounsaturated FA (p = 0.0104) and α-linolenic acid (p = 0.0227) in M increased. In TW urea (p = 0.0079), docosapentaenoic acid (p = 0.0069) in M increased; linoleic acid (p = 0.0070), ∑ n−6 (p = 0.0007) in M and triglycerides decreased (B, p = 0.0317). In TA and TW, the total protein (p = 0.0025 and 0.0079), creatinine (B; p = 0.0357 and 0.0159) and oleic acid (M; p = 0.0104 and 0.0006) increased. Thymol was efficiently absorbed from the intestine and demonstrated its biological activity in blood and the muscles.

Chinese herb feed additives improved the growth performance, meat quality, and nutrient digestibility parameters of pigs

BACKGROUND

Since the use of antibiotics in animal feed has become a critical concern worldwide due to severe threats to human health and environment, we are in need of finding alternatives to antibiotics in pig breeding, maintaining the health of pigs, and getting high-quality pork. As traditional Chinese herbs (TCH) are rich natural resources in China and show great benefits to human health we propose to transfer this abundant resource into animal production industry as additives.

METHODS

Three groups of Chinese herbs (groups A, B, and C) were used as feed additives in the diet for pigs. In total 32 pigs were arranged in four groups (groups A, B, C, and control group, NC), fed in the same facility, eight pigs (one group) in each colony, free drinking, for 120 days. The feed:gain ratio (F/G), meat quality, total protein, and amino acid concentration of muscle were checked in the experiments.

RESULTS

After 120 days of feeding, the feed:gain ratio (F/G) of pigs in groups A, B, and C was decreased 17.56%, 9.31%, and 13.86% compared with NC treatment, respectively. The diets supplemented with Chinese herbs improved meat quality, increased loin eye area (especially group A and C showed significant difference, P < .001), the total protein (increased ratio vs NC was A = 4.54%, B = 0.38% and C = 3.53%), amino acid concentration of muscle, increased the villus height:crypt depth ratio, and induced positive effects on serum biochemical parameters and immune function (serum TC and TG concentrations were significantly lower than those in the NC group, P < .05.).

CONCLUSIONS

The use of Chinese herbal feed additives can reduce the cost of pig breeding and produce high-quality pock. The combination of these effects would contribute to better absorption ability of the intestinal tract and yield a better growth performance.

Effects of phytogenic inclusion level on broiler carcass yield, meat antioxidant capacity, availability of dietary energy, and expression of intestinal genes relevant for nutrient absorptive and cell growth–protein synthesis metabolic functions

Context Phytogenic applications in animal nutrition currently attract worldwide scientific attention for their potential to contribute positively to sustainable and high-quality animal production. However, further understanding and substantiation of dietary phytogenic functions is required. Aims The inclusion level of a phytogenic premix (PP) comprising functional flavouring substances from ginger, lemon balm, oregano and thyme was studied for its effects on broiler growth performance, carcass traits, nutrient digestibility, liver and meat total antioxidant capacity (TAC), and lipid oxidation. The expression of genes for nutrient transporter proteins (SGLT1, GLUT2, PEPT1, BOAT and LAT1), for FABP2 involved in cellular fatty acid uptake and metabolism, and for the mTORC1 complex relevant for protein synthesis were profiled along the intestine. Methods One-day-old Cobb broiler chickens (n = 500) were assigned to four treatments with five replicates of 25 chickens each. Starter (1–10 days), grower (11–22 days) and finisher (23–42 days) basal diets were supplemented with four levels of PP inclusion as treatments: 0, 750, 1000 and 2000 mg/kg diet, termed control, PP750, PP1000 and PP2000. Feed and water were available ad libitum. Data were analysed by ANOVA, taking the treatment as fixed effect. Statistically significant (P ≤ 0.05) effects were further analysed and means were compared using Tukey’s HSD test. Polynomial contrasts tested the linear and quadratic effect of PP inclusion levels. Key results Growth performance responses were not improved significantly (P &gt; 0.05) by PP inclusion level. However, carcass (P = 0.030) and breast meat yield (P = 0.023) were higher in PP1000 than in the control. In addition, PP1000 had higher (P = 0.049) apparent metabolisable energy than PP2000 and the control. Increasing PP inclusion level increased breast (P = 0.005), thigh (P = 0.002) and liver (P = 0.040) TAC. Breast and thigh meat TAC reached a plateau at PP1000, whereas liver TAC continued to increase linearly. Lipid oxidation in breast meat and liver was delayed linearly (P ≤ 0.05) with increasing PP inclusion level. Expression of genes SGLT1, GLUT2, PEPT1, BOAT and FABP2 were not affected by PP inclusion. However, PP inclusion affected the expression of LAT1 (P &lt; 0.001) in jejunum and of mTORC1 in duodenum (P = 0.010) and ceca (P = 0.025). In particular, expression increased with increasing PP inclusion level in a linear and quadratic pattern depending on the intestinal segment. Conclusions Overall, PP inclusion at 1000 mg/kg diet improved carcass and breast yield, dietary available energy, and overall meat and liver TAC. Preliminary evidence was highlighted for effects of PP in promoting expression of genes relevant for muscle protein synthesis. Implications This study has contributed new information on effects of a phytogenic premix on broiler meat yield and antioxidant capacity, digestibility, absorption and metabolic functions, further supporting phytogenic benefits for broiler production.

Dietary Tea Tree (Melaleuca alternifolia) Oil Supplementation Improves Growth Performance, Cecal Microflora, Immunity, and Antioxidant Capacity of Partridge Shank Chickens

The aim of this study was to investigate the effects of tea tree oil (TTO) supplementation on the growth performance, cecal microflora composition, immunity, and antioxidant status of Partridge Shank chickens. A total of 144 one-day-old chicks were allocated into three treatments with six replicates of eight chicks each and fed with a basal diet supplemented with 0 (Control group), 500, and 1000 mg/kg TTO for 50 days. Compared with the control group, the broilers fed with the basal diet supplemented with 1000 mg/kg TTO exhibited an increase in average daily gain from 22 to 50 days (P=0.035) and in both relative thymus weight (P<0.001) and Lactobacillus colonies in the cecal contents (P=0.045) at 50 days of age, but a reduction in the feed/gain ratio during 1 to 50 days (P=0.048). Additionally, dietary TTO supplementation, irrespective of dosage, increased the relative spleen weight (P=0.003) and total antioxidant capacity in the jejunum (P=0.049) and ileum (P=0.001) at 21 days, but decreased the malondialdehyde content in the ileum at both 21 (P=0.003) and 50 days (P<0.001) and in the jejunum at 50 days (P=0.012). The results suggested that TTO supplementation could improve the growth performance, cecal microflora composition, immunity, and antioxidant capacity of Partridge Shank chickens.

Effect of thymol on the broiler chicken antioxidative defence system after sustained dietary thyme oil application

1. The purpose of this study was to examine if the concentration of thymol as the main compound of Thymus vulgaris essential oil (TEO) influenced the antioxidant defence system in broilers. 2. Twenty-four broiler chickens were randomly divided at the day of hatching into three dietary treatment groups (0%, 0.05% and 0.1%, w/w TEO) with eight birds in each and were fed until four weeks of age. 3. Thymol content in plasma, duodenal wall and breast muscle significantly increased when 0.1% of thyme oil was added to the diet (P < 0.05). Thymol concentration in plasma significantly correlated with levels measured in the duodenal wall and feed (r_s = 0.7857, P < 0.05; r_s = 0.7647, P < 0.05). Superoxide dismutase (SOD) activity increased, and malondialdehyde (MDA) concentration decreased significantly (P < 0.05) in blood from chickens fed 0.1% TEO supplementation. Although the thymol concentration did not significantly decrease MDA amounts in breast muscle, a declining trend was observed. 4. The trial data confirmed the efficient absorption of thymol from the digestive tract into the systemic circulation, but only traces were found in breast muscle. Thymol content was sufficient for expressing its antioxidant properties in blood, but its low content in breast muscle was insufficient to significantly affect lipid oxidation and fatty acid composition.

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.

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.

Ethnoveterinary perspectives and promising future

In this review, we have discussed the recent potential effects of plants and their derivatives in treating diseases of veterinary importance in livestock. The therapeutic value of these natural products depends upon their bioactive metabolites that are developed and isolated from crude plants, thus produced a selective action on the body. The crises of drug resistance in most pathogenic bacteria and parasites that cause economic loss in animals necessitate developing new sources for drugs to overcome therapeutic failure. We summarized the different antibacterial and antiparasitic plants with their bioactive compounds that have widely used in animals. Finally, the environmental friendly feed additives that may be used as alternatives to an antibiotic growth promoter for broiler chickens were illustrated.

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.

Incorporation of Lactobacillus plantarum and zeolites in poultry feed can reduce aflatoxin B1 levels

The aim of this work was to evaluate the incorporation of a freeze-dried probiotic strain (Lactobacillus plantarum CIDCA 83114) into zeolites. The bacteria-zeolite mixture was added to poultry feed together with thyme, and the obtained product was stored for 60 days at 25 °C and 60-70% relative humidity. The ability of the obtained product to remove aflatoxin B1 (AFB1) was studied. The highest bacterial viability was observed when 50% w/w bacteria were added to zeolites. The bacterial:zeolite mixtures were then incorporated into poultry feed containing or not thyme. Initial counts of L. plantarum were in the range of 1-2 × 10⁸ CFU/g for all samples. In all cases, bacterial viability decreased one logarithmic order after 20 days of storage, and three logarithmic orders after 60 days. No significant viability loss was observed after exposure of the poultry feed to gastro-intestinal conditions. Freeze-dried L. plantarum and zeolite were able to remove AFB1, with an average reduction of 20 and 80%, respectively. Moreover, the freeze-dried bacteria-zeolite mixture was capable to remove up to 90% AFB1. This work contributes to enhance the nutritional quality of poultry feed, with a strong impact in production.

Possible Molecular Mechanisms by Which an Essential Oil Blend from Star Anise, Rosemary, Thyme, and Oregano and Saponins Increase the Performance and Ileal Protein Digestibility of Growing Broilers

Phytogenic feed additives represent a potential alternative to antibiotics with attributed health and growth-promoting effects. Chickens supplemented with an essential oil blend, a Quillaja saponin blend, or a combination of both phytogenic preparations showed a comprehensively and significantly improved apparent ileal digestibility of crude protein and amino acids compared to control birds. Accordingly, holistic transcriptomic analyses of jejunum and liver samples indicated alterations of macromolecule transporters and processing pathways likely culminating in an increased uptake and metabolizing of carbohydrates and fatty acids. Complementary analyses in Caco-2 showed a significant increase in transporter recruitment to the membrane (SGLT1 and PEPT1) after addition of essential oils and saponins. Although the penetrance of effects differed for the used phytogenic feed additives, the results indicate for an overlapping mode of action including local effects at the intestinal border and systemic alterations of macronutrient metabolism resulting in an improved performance of broilers.

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 Thyme Essential Oil Supplementation on Thymol Content in Blood Plasma, Liver, Kidney and Muscle in Broiler Chickens

The absorption and metabolism of phytogenic feed additives in poultry is studied related to the metabolism and deposition of their main compounds in tissues intended for food production. Fifty-six non-sexed Ross 308 broilers were allocated to seven dietary treatments and fed a diet containing graded levels of thyme ( Thymus vulgaris L.) essential oil (EO) (0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1%, w/w). Thymol concentration was measured in plasma, liver, kidney and breast muscle tissue using solid phase micro-extraction followed by gas chromatography/mass spectrometry. We found the highest concentrations of thymol in kidney and plasma, and the lowest in breast muscle and liver. Thymol content in plasma and kidney significantly increased when 0.05 and 0.1%, w/w, EO and in liver and breast muscle only when 0.1%, w/w, EO was added to the diet ( p<0.05). Our results indicate intensive metabolism of thymol in liver and its accumulation in kidney tissue. We confirm low deposition of thymol in the muscle tissue. It is necessary to keep in mind the selection of a sufficient concentration of EO in the feed additive for animals without the risk of thymol residues in edible tissues.