Iveta Plachá

The positive effect of thymol on gut health largely depends on its absorption from the intestinal tract and its biotransformation processes in the intestinal wall. A total of 32 rabbits were randomly divided at 35 days of age into a control (CG) and an experimental group (EG) that received thymol at 250 mg/kg feed. Thymol concentration was significantly higher in the caecum than in the ileum (p < 0.05), which is likely associated with caecotrophy and reduced enzymatic activity in the distal segments of the small intestine. Coliform bacteria (p = 0.0095) and lactic acid bacteria (LAB; p = 0.0002), Staphylococcus spp. (p = 0.0002), and Enterococcus spp. (p = 0.0002) in the duodenum; LAB (p = 0.0003) and Enterococcus spp. (p = 0.0002) in the ileum; and other Enterobacteriaceae (p = 0.0002) and LAB (p = 0.0068) in the caecum were significantly higher in the EG. Despite the significantly lower thymol concentration in the ileum compared to the caecum, the beneficial LAB was positively affected. A decrease in immunoglobulin A in all parts of the intestinal tract except the colon was a result of the modulation of mucosal immunity. Thymol at this concentration modulated the gut ecosystem without disrupting its beneficial components, thereby helping maintain intestinal homeostasis.

Antimicrobial proteinaceous postbiotic substances (PS) and/or bacteriocins can beneficially influence animal health, as previously shown with enterocins from non-autochthonous enterococcal strains. Therefore, the effectiveness of PS 412, produced by our beneficial autochthonous strain Enterococcus faecium EF 412, was assessed in horses. In the pilot experiment, PS 412 was administered to 12 horses of various ages and breeds for 21 days via a small feed ball. Sampling was performed on days 0/1, 21, and 42 (after a 3-week cessation of PS 412). The horses served as their own controls. Although the number of horses was limited, the microbiological analysis showed significant decreases in enterococci, other lactic acid bacteria, and campylobacters (p < 0.05; p < 0.001). Staphylococci decreased slightly. Coliforms, aeromonads (p < 0.001), and pseudomonads also decreased. In next-generation sequencing at the phylum level, 15 phyla were detected at higher abundance, with Bacteroidota (35.38%) and Bacillota (32.25%) the most abundant. After PS 412 (activity 51,200 AU/mL), the relative abundance of several phyla decreased. On day 21, phagocytic activity was higher (69.00 ± 3.91%). The metabolic profiles and hematologic values were mostly within the reference range. Although continued testing is necessary, postbiotics appear to be a tool for supporting equine health.

Thymol gastro-resistant self-emulsifying pellets were used to achieve thymol targeted release on the side of the intestine with the most intensive absorption to enhance its oral bioavailability. Forty-eight rabbits (35 d of age) were divided into two groups fed with a standard diet containing gastro-resistant enteric pellets (control, CG; without thymol, initial live weight 1350.0 ± 18.0, and experimental, EG; with thymol 250 mg/kg, initial live weight 1352.0 ± 19.9 g). The experiment lasted 28 days: thymol was administered for 21 days and then withdrawn for 7 days. Thymol was significantly higher in duodenal wall (DW) than in plasma during both periods (p = 0.0053, p < 0.0001). Significant correlation was established between thymol concentration in plasma and DW during its application (r_s = 0.9333, p < 0.001). Thymol was below the limit of quantitation in plasma, spleen and muscle only after its withdrawal, and its significantly higher concentration in kidney and fat than in plasma (p = 0.0182, p = 0.0003) and muscle (p = 0.0236, p = 0.0004) indicates its efficient accumulation. Thymol in gastro-resistant form prevented its degradation due to adverse conditions in the stomach and ensured its release at the site of greatest absorption in the small intestine.

Thymol gastro-resistant self-emulsifying pellets were used to achieve thymol targeted release on the side of the intestine with the most intensive absorption to enhance its oral bioavailability. Forty - eight rabbits (35 d of age) were divided into two groups fed with a standard diet containing gastro-resistant enteric pellets (control, CG; without thymol and experimental, EG; with thymol 250 mg/kg). The experiment lasted 28 days; thymol was administered for 21 days and then withdrawn for 7 days. Thymol was in balance in all parts of the intestinal tract, significantly higher in duodenal wall (DW) than in plasma during both periods (p = 0.0053, p < 0.0001), and a significant correlation was established between thymol concentration in plasma and DW during thymol applica-tion (rs = 0.9333, p < 0.001), which points to the efficient release of thymol from enteric pellets in the small intestine with an intensive absorption rate. Thymol was below the limit of quantitation in plasma, spleen and muscle only after its withdrawal, and its significantly higher concentration in kidney and fat than in plasma (p = 0.0182, p = 0.0003) and muscle (p = 0.0236, p = 0.0004) indicates its efficient accumulation.

Background: Using bacterial (probiotic) strains can influence beneficial health statuses, e.g., through dairy products; however, they must be assessed as safe before consumption; broiler rabbits represent a suitable model for this purpose. This study evaluated the safety and effect (functionality) of the dairy-derived, plantaricin-producing strain Lactiplantibacillus plantarum LP17L/1 using broiler rabbits. The following parameters were assessed to evaluate safety and functionality: microbiota, phagocytic activity (non-specific immunity parameter), blood serum biochemistry, oxidative stress enzyme, growth performance, cecal hydrolytic activity, and jejunal morphometry. Methods: Previously validated methods were used for the analyses. The appropriate administrations approved the experiments. Results: Although only up to 1.0 colony forming unit (CFU)/g (log10) LP17L/1 reached the gastrointestinal tract of the rabbits, the total lactic acid bacteria and amylolytic streptococci were significantly increased (p < 0.001). The other microbiota were not influenced, meaning there was no negative influence on phagocytic activity, growth parameters, and biochemistry in the analyzed blood serum. Conversely, lower GPx values were measured in the experimental group than in the control group, meaning LP17L/1 did not induce oxidative stress. LP17L/1 caused an increase in villi length to crypt depth ratio, while hydrolytic activity was also significantly increased (p < 0.01, p < 0.001). Conclusions: L. plantarum LP17L/1 was confirmed as safe. Regarding the functionality, no negative influence on the microbiota was noted, and the tested parameters were not negatively influenced. Demonstrating that the LP17L/1 strain is safe provides further chances for its industrial application. Additional studies are being conducted.

Nowadays, the use of probiotics, postbiotics, parabiotics and other beneficial natural substances dominate health status sustainability in animals. Mundticin-like substance EM 41/3 (MLS) is a thermo-stable substance of proteinaceous character—a bacteriocin (postbiotic) with a broad antimicrobial (inhibitory) spectrum produced by the horse-derived strain Enterococcus mundtii EM 41/3. The aim of this study was to find if this new one bacteriocin can have an effect and/or a similar effect in rabbits as was achieved previously by using enterocins detected and characterized in our laboratory. In addition, these tests have been conducted to secure the health of rabbits as food-derived animals. Moreover, the aim of this study was also to test the effect of MLS EM 41/3 in broiler rabbits as an animal model before its use in horses. The parameters tested were analyzed by validated methods. Administration of MLS EM 41/3 lead to a significant increase in the non-specific immunity parameter (phagocytic activity, p < 0.05), while microbiota in feces, caecum and appendix were not negatively influenced. However, the total enterococcal count was significantly increased in the EG compared to the CG (p < 0.001). Application of MLS EM 41/3 did not have a negative impact on blood biochemistry. No oxidative stress was noted. However, higher growth parameters were noted and also hydrolytic activity was increased after MLS EM 41/3 application. Finally, to check physico-chemical parameters, no negative influence on rabbit meat quality was noted. Postbiotic MLS EM 41/3 administration seems to be a contributing factor in the feeding strategy for animal health status sustainability.

Nowadays, animal breeders look for effective innovations to care animal health. Use of probiotics, postbiotics, parabiotics and the other beneficial natural substances are dominated. Mundticin-like substance EM 41/3 is thermo-stable bacteriocin (postbiotic) with a broad antimicrobial spectrum. In this study its effect in broiler rabbits was assessed. Rabbits represent food-derived animal and they are also suitable animal model. The parameters tested were analyzed by validated methods. Administration of MLS EM 41/3 produced by non-autochthonous strain Enterococcus mundtii EM 41/3 lead to significant increase of parameter immunity-phagocytic activity, while it did not influence microbiota composition. It also did not influence blood biochemistry and no oxidative stress was noted. Moreover, higher growth parameters were noted and also stimulated hydrolytic activity. Finally, no negative influence on rabbit meat quality was noted. Postbiotic MLS EM 41/3 administration in feeding strategy seems to be contributing fact for rabbit health status maintaining.

The increasing frequency of methicillin-resistant (MR) staphylococci in humans and animals need special attention for their difficult treatment and zoonotic character, therefore novel antimicrobial compounds on a natural base against antibiotic-resistant bacteria are requested. Currently, bacteriocins/enterocins present a new promising way to overcome this problem, both in prevention and treatment. Therefore, the preventive and medicinal effect of dipeptide enterocin EntA/P was evaluated against MR Staphylococcus epidermidis SEP3/Tr2a strain in a rabbit model, testing their influence on growth performance, glutathione-peroxidase (GPx) enzyme activity, phagocytic activity (PA), secretory (s)IgA, and jejunal morphometry (JM). Eighty-eight rabbits (aged 35 days, meat line M91, both sexes) were divided into experimental groups S (SEP3/Tr2a strain; 1.0 × 10⁵ CFU/mL; dose 500µL/animal/day for 7 days, between days 14 and 21 to simulate the pathogen attack), E (EntA/P; 50 µL/animal/day, 25,600 AU/mL in two intervals, for preventive effect between days 0 and 14; for medicinal effect between days 28 and 42), E + S (EntA/P + SEP3/Tr2a; preventive effect; SEP3/Tr2a + EntA/P; medicinal effect) and control group (C; without additives). Higher body weight was recorded in all experimental groups (p < 0.001) compared to control data. The negative influence/attack of the SEP3Tra2 strain on the intestinal immunity and environment was reflected as decreased GPx activity, worse JM parameters and higher sIgA concentration in infected rabbits. These results suggest the promising preventive use of EntA/P to improve the immunity and growth of rabbits, as well as its therapeutic potential and protective role against staphylococcal infections in rabbit breeding.

Goat milk is gradually becoming the preferred milk by consumers worldwide, including Slovakia. It is also demanded as a functional and/or nutraceutical drink as it is rich in bioactive components. However, another new development is the research into the beneficial autochthonous strains used to enrich goat dairy products. Among individual species, representatives in raw goat milk are also involved in lacticaseibacilli. Bacteriocin-like inhibitory substance-producing Lacticaseibacillus paracasei LPa 12/1 was isolated from raw goat milk. This study focuses on its potential as a new additive in dairy products. No mortality was found when checking the safety of the LPa 12/1 strain using Balb/c mice. The strain reached higher counts in ewe–goat milk yoghurt (up to 6.1 cfu/g log 10) than in cow milk yoghurt (almost 5.0 cfu/g log 10). Cow milk yoghurts remained in more stable consistency after LPa 12/1 supplementation compared with ewe–goat milk yoghurts, although specific organoleptic tests were not performed. However, LPa 12/1 has survived sufficiently in both types of yoghurts. This bacteriocin-like inhibitory substance-producing strain LPa 12/1 in its encapsulated form applied in yoghurts seems suitable to supplement dairy products.