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

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.

Effect of enterocin M and durancin ED26E/7 supplementation on blood parameters, immune response and jejunal morphometry in rabbits.

Natural feed additives application in rabbit nutrition can help to control and prevent digestive disturbances and improve gut health and immunity around the critical weaning period. While probiotics are frequently used in rabbits, in vivo administration of bacteriocins is often limited. Therefore, the present study evaluates the effect of enterocin EntM, durancin EntED26E/7 and their combination on serum biochemistry, phagocytic activity and jejunal morphometry of rabbits. Eighty rabbits (aged 35 days, meat line M91, both sexes) were divided into experimental groups E (EntM; dose 50 µl/animal/day, activity 25,600 AU/ml), D (EntED26E/7; 50 µl/animal/day, 12,800 AU/ml), E + D (50 µl EntM + 50 µl EntED26E/7 /animal/day) and control group (C). Additives were administrated in drinking water for 21 days. Both enterocins positively influenced tested serum parameters, with emphasis on durancin EntED26E/7 administration, alone and/or in combination with EntM. Increased total proteins (E, D: p < 0.001), urea (D: p < 0.001), albumin (D: p < 0.05) and triglycerids (E, D, E+D: p < 0.001) were found. Hypocholesterolaemic effect of both additives was recorded (p < 0.001), with the lowest HDL concentration in E + D. The most of tested hepatic enzymes were positively influenced by enterocins combination (E + D; p < 0.001). The lowest AST was noted in group D (p < 0.001). Mineral profile was also improved (p < 0.001), with the highest values in D. Oxidative stress, was not evoked during enterocins application. Both additives showed a tendency to improve phagocytic activity (prolonged effect of EntED26D/7; D, E+D: p < 0.05) and jejunal morphometry parameters (increased villus cut surface; E, D, E+D; p < 0.001). Diet supplementation with EntM and mostly with EntED26E/7 can improve serum biochemistry, phagocytic activity and jejunal morphometry.

Thymol in the intestinal tract of broiler chickens after sustained administration of thyme essential oil in feed.

Plant compounds occurring in phytogenic feed additives are involved in different pharmacological activities in the animal organism. Since the digestive tract acts as a first line of defence against foreign compounds, it is necessary to outline its response to dietary supplementation with bioactive plant components. Little information is available on the bioactivity of thymol as the main bioactive compound of Thymus vulgaris L. essential oil (TEO). The main objective of the present study was to provide a detailed view of the concentrations of thymol in plasma and the content of individual intestinal segments (duodenum, jejunum, ileum, caecum and colon) of broiler chickens after 4 weeks of dietary supplementation with different TEO concentrations. 32 one-day old Ross 308 hybrid broilers were randomly divided into four dietary treatment groups (0.00%, 0.01%, 0.05%, 0.1% w/w of TEO in the diet). Thymol concentrations in the duodenal chyme presented around 7% on average from the thymol amount administered in the feed. A significantly increased thymol amount was observed after 0.1% TEO addition to the diet compared with 0.01% TEO enrichment in the duodenal wall and gut content of jejunum, ileum, caecum and colon (p < 0.05). Thymol levels in the colon were significantly higher than in the ileum and about 1.7 times higher on average than those in the caecum. Significant coefficient of correlation was observed between thymol concentrations in plasma and feed, gut content of all intestinal segments as well as duodenal wall. Our results point to intensive thymol absorption in the initial sections of the digestive tract. In the current study, the role of intestine in biotransformation of thymol was observed, and it would be desirable to investigate whether thymol itself or thymol metabolites are responsible for beneficial effects in intestine.

Effects of herbal nutraceuticals and/or zinc against Haemonchus contortus in lambs experimentally infected.

BACKGROUND: The gastrointestinal parasitic nematode Haemonchus contortus is a pathogenic organism resistant to several anthelmintics. This study assessed the efficacy of a medicinal herbal mixture (Herbmix) and organic zinc, as an essential trace element for the proper functioning of both unspecific and specific immune defensive mechanisms, against experimental infections with H. contortus in lambs. All lambs were infected orally with approximately 5000 third-stage larvae of a strain of H. contortus susceptible to anthelmintics (MHco1). Twenty-four female lambs 3-4 months of age were divided into four groups: unsupplemented animals (control), animals supplemented with Herbmix (Hmix), animals supplemented with organic zinc (Zn) and animals supplemented with Herbmix and organic zinc (Hmix+Zn). Eggs per gram (EPG) of faeces were quantified 20, 28, 35, 42, 49, 56, 62 and 70 d post-infection and mean abomasal worm counts were assessed 70 d post-infection. Samples of blood were collected from each animal 7, 35, 49 and 70 d post-infection. RESULTS: Quantitative analyses of the bioactive compounds in Herbmix identified three main groups: flavonoids (9964.7 µg/g), diterpenes (4886.1 µg/g) and phenolic acids (3549.2 µg/g). Egg counts in the lambs treated with Hmix, Zn and Hmix+Zn decreased after 49 d. The EPGs in the Zn and Hmix+Zn groups were significantly lower on day 56 (P < 0.05 and P < 0.01, respectively), and the EPGs and mean worm counts were significantly lower on day 70 in all supplemented groups (P < 0.05 and P < 0.01). Hemograms of complete red blood cells of each animal identified clinical signs of haemonchosis after day 35. Serum calprotectin concentrations and IgA levels were significantly affected by treatment. The treatment influenced serum malondialdehyde concentrations (P < 0.05) and sulfhydryl groups (P < 0.01) of antioxidant status. The mineral status was unaltered in all lambs. CONCLUSION: A direct anthelmintic impact on the viability of nematodes was not fully demonstrated, but the treatments with herbal nutraceuticals and zinc likely indirectly contributed to the increase in the resistance of the lambs to nematode infection.

Effects of Different Dietary Selenium Sources on Antioxidant Status and Blood Phagocytic Activity in Sheep.

The objective of this experiment was to investigate the effects of feed supplementation with equivalent doses of selenium from sodium selenite (SS) or selenized yeast (SY) on Se deposition, selenoenzyme activity and lipid peroxidation in tissues as well as in bacterial and protozoal fractions of rumen contents in sheep. The phagocytic activity of monocytes and neutrophils in whole blood was also assessed after 3 months of dietary treatment. While animals in the control group were fed with unsupplemented basal diet (BD) containing only background Se (0.16 mg/kg DM), the diet of the other two groups (n = 6) consisted of identical BD enriched with 0.4 mg Se/kg DM either from SS or SY. Concentrations of Se in blood and tissues were found to be significantly increased in both supplemented groups. No response in Se deposition was recorded in the musculus longissimus dorsi of sheep given dietary SS. The intake of SY resulted in a significantly higher Se level in the blood, kidney medulla, skeletal muscles, heart, intestinal and ruminal mucosa than in the case of SS supplementation. No differences appeared between tissue Se contents in the liver and kidney cortex due to the source of added Se. Regardless of source, Se supplementation to feeds significantly increased the glutathione peroxidase (GPx) activity in blood and tissues except the kidney medulla and jejunal mucosa. Supplementation with SY resulted in significantly higher activity of thioredoxin reductase in the liver and ileal mucosa, and also reduced malondialdehyde content in the liver and duodenal mucosa. Dietary Se intake increased Se concentrations in the total rumen contents and bacterial and protozoal fractions. The accumulation of Se in rumen microbiota was associated with increased GPx activity. Phagocytic cell activity was enhanced by Se supplementation. Our results indicate that Se from both sources has beneficial effects on antioxidant status in sheep and can be utilized by rumen microflora.

Effect of thyme oil on small intestine integrity and antioxidant status, phagocytic activity and gastrointestinal microbiota in rabbits.

The effects of 0.5 g thyme oil per kg dry matter (DM) of diet on duodenal tissue integrity, antioxidant status, phagocytic activity and selected microbiota in the caecum and faeces of rabbits were studied. Twenty-four rabbits were divided into two groups and were fed a commercial granulated diet for growing rabbits (CD) with access to water ad libitum. The first group was fed the CD, while to the CD of the second group thyme oil was added. Intestinal integrity was tested by measuring the transepithelial electrical resistance (TEER). Thyme oil significantly increased the value of total antioxidant status (TAS) in the blood plasma and glutathione peroxidase (GPx) activity in the liver, and it decreased malondialdehyde (MDA) concentration in the duodenal tissue. Thyme oil resulted in strengthened intestinal integrity, as the essential oil supplementation significantly increased TEER values in the experiment. The faecal microbiota of rabbits was almost completely balanced in both groups, and only a slight decrease was found in the microbial population at day 42 of the trial. In both groups, the bacterial counts were generally lower in the caecum than in the faecal samples. In conclusion, dietary supplementation with 0.5 g/kg DM thyme oil may improve intestinal integrity, and it may have an antioxidant effect. A tendency was also found for thyme oil to stimulate the abundance of some microbes beneficial in the rabbit gut.

Effect of lignin on oxidative stress in chickens fed a diet contaminated with zearalenone.

The effect of lignin supplementation to a diet contaminated with zearalenone (ZEA) on antioxidant status was studied in female chickens of the ISA BROWN laying strain. From the day of hatching to 2 weeks of age, four groups of chickens were fed the same uncontaminated control diet. After 14 days, Group 1 (control) continued to receive the uncontaminated diet, while Group 2 was fed an identical diet enriched with 0.5% chemically modified lignin. Simultaneously, chickens of Group 3 were switched to a diet contaminated with 7.9 mg/kg ZEA and those of Group 4 to an identical contaminated diet supplemented with 0.5% lignin. At 6 weeks of age blood and tissue samples were collected. Feeding of a diet contaminated with a high level of ZEA resulted in elevated glutathione peroxidase (GPx) activity in the duodenal mucosa and kidney tissues, and an increased γ-glutamyltransferase (GGT) activity in the plasma, indicative of oxidative stress. In the liver tissue, no mycotoxin-induced response in GPx and thioredoxin reductase (TrxR) activities occurred, and the malondialdehyde (MDA) level was even reduced. Neither the plasma levels of retinol and α-tocopherol nor the activities of superoxide dismutase in erythrocytes and GPx in blood were affected in birds fed the contaminated diet. The only effect of lignin supplemented to the contaminated feed was that it prevented the increase of GPx activity in the duodenal mucosa as an indicator of oxidative stress.