Beneficial effects of Enterococcus faecium EF9a administration in rabbit diet

Forty-eight rabbits aged five weeks (Hycole breed, both sexes) were divided into experimental (EG) and control (CG) groups, 24 animals in each, and fed a commercial diet with access to water ad libitum . Rabbits in EG had Enterococcus faecium EF9a probiotic strain added to their drinking water (1.0×10 9 colony forming units/mL 500 μL/d/animal) for 28 d (between 35 and 63 d). The experiment lasted for 42 d. The animals remained in good health condition throughout the experiment, and no morbidity and mortality was noted. There was a higher live weight at 63 d of age (+34 g; P <0.0001), final live weight at 77 d of age (+158 g; P =0.0483), and average daily weight gain between 63 and 77 d of age in the EG group rabbits than in CG group rabbits (+8 g/d; P <0.0001). No significant changes in caecal lactic acid and total volatile fatty acid concentrations, jejunal morphological parameters and phagocytic activity were noted during the treatment. The tested serum parameters were within the range of the reference values. EF9a strain sufficiently established itself in the rabbit’s gastrointestinal tract. At 63 d of age, a significant decrease in coliforms ( P <0.05), coagulase-positive staphylococci ( P <0.01), pseudomonads ( P <0.01) and coagulasenegative staphylococci (CoNS, P <0.001) was noted in the faeces of the EG group rabbits compared to the CG rabbits. Antimicrobial effects of EF9a strain in the caecum against coliforms ( P <0.001), CoNS ( P =0.0002) and pseudomonads ( P =0.0603) and in the appendix (coliforms, P <0.05) were detected.