Enterocins as Novel Feed Additives in Rabbit Diet: Enterocin Ent M and Durancin Ent ED26E/7, Their Combination, and Effects on Microbiota, Caecal Fermentation, and Enzymatic Activity

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.

Lactic acid bacteria reduce bacterial diarrhea in rabbits via enhancing immune function and restoring intestinal microbiota homeostasis

BACKGROUND

Numerous previous reports have demonstrated the efficacy of Lactic acid bacteria (LAB) in promoting growth and preventing disease in animals. In this study, Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 were isolated from the feces of healthy rabbits, and both strains showed good probiotic properties in vitro. Two strains (108CFU/ml/kg/day) were fed to weaned rabbits for 21 days, after which specific bacterial infection was induced to investigate the effects of the strains on bacterial diarrhea in the rabbits.

RESULTS

Our data showed that Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 interventions reduced the incidence of diarrhea and systemic inflammatory response, alleviated intestinal damage and increased antibody levels in animals. In addition, Enterococcus faecium ZJUIDS-R1 restored the flora abundance of Ruminococcaceae1. Ligilactobaciiius animalis ZJUIDS-R2 up-regulated the flora abundance of Adlercreutzia and Candidatus Saccharimonas. Both down-regulated the flora abundance of Shuttleworthia and Barnesiella to restore intestinal flora balance, thereby increasing intestinal short-chain fatty acid content.

CONCLUSIONS

These findings suggest that Enterococcus faecium ZJUIDS-R1 and Ligilactobaciiius animalis ZJUIDS-R2 were able to improve intestinal immunity, produce organic acids and regulate the balance of intestinal flora to enhance disease resistance and alleviate diarrhea-related diseases in weanling rabbits.

The effect of enterocin A/P dipeptide on growth performance, glutathione-peroxidase activity, IgA secretion and jejunal morphology in rabbits after experimental methicillin-resistant Staphylococcus epidermidis P3Tr2a Infection

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.

Impact of coprophagy prevention on the growth performance, serum biochemistry, and intestinal microbiome of rabbits

BACKGROUND

Coprophagy plays a vital role in maintaining growth and development in many small herbivores. Here, we constructed a coprophagy model by dividing rabbits into three groups, namely, control group (CON), sham-coprophagy prevention group (SCP), and coprophagy prevention group (CP), to explore the effects of coprophagy prevention on growth performance and cecal microecology in rabbits.

RESULTS

Results showed that CP treatment decreased the feed utilization and growth performance of rabbits. Serum total cholesterol and total triglyceride in the CP group were remarkably lower than those in the other two groups. Furthermore, CP treatment destroyed cecum villi and reduced the content of short-chain fatty acids (SCFAs) in cecum contents. Gut microbiota profiling showed significant differences in the phylum and genus composition of cecal microorganisms among the three groups. At the genus level, the abundance of Oscillospira and Ruminococcus decreased significantly in the CP group. Enrichment analysis of metabolic pathways showed a significantly up-regulated differential metabolic pathway (PWY-7315, dTDP-N-acetylthomosamine biosynthesis) in the CP group compared with that in the CON group. Correlation analysis showed that the serum biochemical parameters were positively correlated with the abundance of Oscillospira, Sutterella, and Butyricimonas but negatively correlated with the abundance of Oxalobacte and Desulfovibrio. Meanwhile, the abundance of Butyricimonas and Parabacteroidesde was positively correlated with the concentration of butyric acid in the cecum.

CONCLUSIONS

In summary, coprophagy prevention had negative effects on serum biochemistry and gut microbiota, ultimately decreasing the growth performance of rabbits. The findings provide evidence for further revealing the biological significance of coprophagy in small herbivorous mammals.

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.