Application of Autochthonous Biofilm-Forming Enterococcus hirae Kr8 Strain in Relation with Enterocin M in Broiler Rabbits and Their Effect on the Rabbit Meat Quality: Risk or Protection?

Around weaning, rabbits are sensitive to gastrointestinal diseases, mostly of bacterial origin, including enterococci (Enterococcus hirae), clostridia, and coliforms. Preventive use of postbiotics-enterocins-as feed additives can reduce this problem. Therefore, simulation of spoilage/pathogenic environment applying the autochthonous, biofilm-forming E. hirae Kr8+ strain in rabbits and its influence on rabbit meat quality as well as the protective effect of Ent M on rabbit meat properties and quality in infected animals was tested. Ninety-six rabbits aged 35 days, both sexes, meat line M91 breed were divided into one control (CG) and three experimental (EG1, EG2, and EG3) groups. The rabbits in CG received standard diet, without any additives, rabbits in EG1 received 108 CFU/mL of Kr8+ strain (at a dose of 500 µL/animal/day), to rabbits in EG2 the Ent M (50 µL/animal/day), and in EG3, combination of the Kr8+ and Ent M was applied in their drinking water during 21 days. The experiment lasted 42 days. The Kr8+ strain did not attack the gastrointestinal tract and have any adverse effect on the meat quality of rabbits. Moreover, improved weight gains, carcass parameters, and higher essential fatty acid (EAA) and amino acid (EAA) content of rabbit meat point rather to its possible beneficial potential in rabbit nutrition. Administration of Ent M improved most of the tested parameters: animal weight and meat physicochemical and nutritional properties, with a focus on EFA and EAA. During combination of both additives, their synergistic impact was noted, improving the nutritional quality, mostly the EAA content of rabbit meat.

Enterocin M in Interaction in Broiler Rabbits with Autochthonous, Biofilm-Forming Enterococcus hirae Kr8 Strain.

Young rabbits are susceptible to gastrointestinal diseases caused by bacteria. Enterococcus hirae can be associated with diseases. But enterocins produced by some enterococcal species can prevent/reduce this problem. Therefore, the interaction of enterocin M with a biofilm-forming, autochthonous E. hirae Kr8+ strain was tested in rabbits to assess enterocin potential in vivo. Rabbits (96), aged 35 days, both sexes, meat line M91 breed were divided into four groups, control C and three experimental groups. The rabbits in C received the standard diet, rabbits in experimental group 1 (E1) received 108 CFU/mL of Kr8+, a dose 500 µL/animal/day, E2 received Ent M (50 µL/animal/day), and E3 received both Kr8+ and Ent M in their drinking water over 21 days. The experiment lasted 42 days. Feces and blood were sampled at day 0/1 (at the start of the experiment, fecal mixture of 96 animals, n = 10), at day 21 (five fecal mixtures per group, n = 5), and at day 42 (21 days after additives cessation, the same). At days 21 and 42, four rabbits from each group were slaughtered, and cecum and appendix were sampled for standard microbial analysis. Ent M showed decreased tendency of Kr8+. Using next-generation sequencing, the phyla detected with the highest abundance were Firmicutes, Verrucomicrobia, Bacteroidetes, Tenericutes, Proteobacteria, Cyanobacteria, Saccharibacteria, and Actinobacteria. Interaction of Ent M with some phyla resulted in reduced abundance percentage. At day 21, significantly increased phagocytic activity (PA) was found in E1 and E2 (p < 0.001). Kr8+ did not attack PA and did not stimulate oxidative stress. But Ent M supported PA. The prospective importance of this study lies in beneficial interaction of enterocin in host body.

Preventive Potential of Dipeptide Enterocin A/P on Rabbit Health and Its Effect on Growth, Microbiota, and Immune Response.

The present study investigated the effect of the dipeptide enterocin (Ent) A/P on growth, immune response, and intestinal microbiota in rabbits. Eighty-eight rabbits (aged five weeks, M91 meat line, both sexes) were divided into three experimental groups: E (Ent A/P; 50 µL/animal/day for 14 days; between 0-14 days); S (methicillin-resistant Staphylococcus epidermidis SE P3/Tr2a strain; 500 µL/animal/day for 7 days starting at day 14 to day 21); and E + S (Ent A/P between 0-14 days and SE P3/Tr2a strain between 14-21 days) groups, and the control group (C). The additives were administered in drinking water. Administration of Ent A/P lead to an increase in weight gain, reduction of feed conversion; phagocytic activity was stimulated and gut microbiota were optimized due to reduction of coliforms, total bacterial count, and methicillin-resistant staphylococci. Good health and increased weight gain also showed that methicillin-resistant S. epidermidis SE P3/Tr2a strain did not have any pathogenic effect on rabbits' health status.

Benefits of Enterocin M and Sage Combination on the Physico-chemical Traits, Fatty Acid, Amino Acid, and Mineral Content of Rabbit Meat.

Higher rabbit meat consumption can be ensured by increasing of its quality due to its improved nutritional properties. The effect of enterocin M (EntM) and sage on growth performance, physico-chemical properties, fatty acid (FA), amino acid (AA), and mineral concentrations of rabbit meat was evaluated. Sixty-four rabbits (M91 meatline, both sexes) were divided into three experimental: E (EntM), S (sage), E + S (EntM + sage) groups and control group (C). The additives were administrated in drinking water during 21 days. Lower pH (E, S: P < 0.05; E + S: P < 0.001) and decrease in water content were noted in all experimental groups compared with controls (C). Higher values of lightness (L*), yellowness (b*), and redness (a*; except group E) were measured. The sage administration increased the fat and protein contents (P < 0.05), the meat energy value (S vs. C: P < 0.01; S vs. E and E + S: P < 0.05), the concentrations of arachidonic (P < 0.05), eicosapentaeonic (P < 0.05), and oleic acids (P < 0.01), magnesium (P < 0.05), and potassium (P < 0.01) content. The additives did not influence the rabbit meat AA composition. The sage diet inclusion could improve the quality of rabbit meat due to its higher protein, fat, and energy contents and enhance the PUFA and mineral content of rabbit meat. Moreover, the effect of EntM on meat color parameters, FA and AA composition, has not been tested in rabbits previously.

Lantibiotic Nisin Applied in Broiler Rabbits and Its Effect on the Growth Performance and Carcass Quality.

Nisin is a bacteriocin marketed as Nisaplin. The aim of this study was to follow the effect of commercial lantibiotic nisin on the growth performance and carcass quality of broiler rabbits. The increase of average daily gain (by 9.4%) was recorded in the nisin group. The treatment did not have a negative influence on the pH, colour, water-holding capacity, protein and fat contents or energetic value of the rabbit carcass. Inferring from the higher average daily gain and the higher protein and lower fat content, we conclude that the diet supplementation with nisin may enhance the quality of rabbit meat.

Benefits of combinative application of probiotic, enterocin M-producing strain Enterococcus faecium AL41 and Eleutherococcus senticosus in rabbits.

This study presents the effects of the probiotic and enterocin M-producing strain Enterococcus faecium AL41 on microbiota, phagocytic activity (PA), oxidative stress, performance and biochemical parameters when applied individually or in combination with Eleutherococcus senticosus in rabbits. The novelty of the study lies in the use of our non-rabbit-derived strain (AL41 = CCM8558) which produces new enterocin M. Ninety-six post-weaned rabbits (Hyplus breed) aged 5 weeks were divided into three experimental groups, 24 in each: E. senticosus (ES, 30 g/100 kg) in feed, E. faecium AL41 (10(9) CFU/mL marked by rifampicin to differentiate it from other enterococci) in water, and ES + AL. AL41 colonized sufficiently in rabbits to reduce coliforms, staphylococci, pseudomonads and clostridia. Slight decrease in bacteria was also found in the caecum and appendix. Phagocytic activity was significantly increased in the experimental groups compared to the control group (CG) (p < 0.001; p < 0.05). Applications did not evoke oxidative stress. Biochemical parameters in blood and caecal organic acids were slightly influenced. Average daily weight gain was slightly higher in ES and AL + ES. Combinative application of E. faecium with E. senticosus can be beneficial in rabbits. AL41 strain alone and in combination with ES produced reduction in spoilage bacteria; the highest stimulation of PA was in the AL41 + ES group.

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.

Enterococcus faecium AL 41: Its Enterocin M and Their Beneficial Use in Rabbits Husbandry.

Enterococci are ubiquitous microbiota constituting a large proportion of autochthonous microflora in animals. Some produce bacteriocins mostly enterocins; some of bacteriocin-producing strains also possess probiotic properties. Enterococcus faecium AL 41, Ent M-producing strain was tested for beneficial effect in rabbits. Five-week-old animals (72, Hycole) were divided into experimental groups (E1, E2) and control (C); 24 animals in each. Rabbits in E1 were administered AL 41 (500 µl per animal/day, 10(9) cfu/ml) in water for 21 days; rabbits in E2 were administered Ent M (50 µl/animal/day, activity 12,800 AU/ml) in water for 21 days. Rabbits in C fed a commercial diet. The experiment lasted 42 days. Sampling of faeces and blood was provided on day 0-1 and 21, 42; 3 animals per group were slaughtered. Caecum and appendix were separated. AL 41 colonized rabbits intestines <1.0 (log10) cfu/g, but stimulation of immunity was noted (P < 0.01; P < 0.001). Antimicrobial activity of both was noticed in faeces and/or caecum against pseudomonads. Significant decrease of coliform bacteria in faeces of E1 was noted on day 42 comparing with E2 (P < 0.05). On day 21, S. aureus cells were not detected in E1, E2. On day 42, S. aureus was not found in E2; in E1 their counts were <1.0 cfu/g, while in C it was in the count more than 1.0 cfu/g. In appendix, on day 21, significant decrease of not specified bacteria was found in E1, E2 comparing with C (P < 0.01). Administration of additives has not evoked oxidative stress. Biochemical parameters were not influenced. Higher average daily weight gains were detected by both, AL 41 and Ent M.