Vegetative Bacillus amyloliquefaciens cells do not confer protection against necrotic enteritis in broilers despite high antibacterial activity of its supernatant against Clostridium perfringens in vitro

Abstract

1. In this study, the effect of Bacillus amyloliquefaciens on Clostridium perfringens was tested in vitro and in vivo.

2. Using an agar well diffusion assay, the inhibitory activity of B. amyloliquefaciens supernatant was analysed against a large collection of netB-positive and netB-negative C. perfringens strains. Although strong growth inhibiting activity was detected against all C. perfringens isolates, it was significantly higher against virulent netB-positive C. perfringens strains compared with avirulent netB-negative isolates.

3. Subsequently, the efficacy of in-feed administration of lyophilised vegetative cells of B. amyloliquefaciens to prevent necrotic enteritis was tested in vivo using an established experimental infection model in broilers. Ross 308 broilers received either B. amyloliquefaciens supplemented or unsupplemented feed throughout the experiment. No significant differences could be detected between the untreated positive control group and the B. amyloliquefaciens treated group in body weight, the number of chickens that developed necrotic lesions and in pathological lesion scores.

4. These results demonstrate that despite its substantial inhibitory activity in vitro, lyophilised vegetative B. amyloliquefaciens cells had no beneficial effect against necrotic enteritis in the in vivo model used here.

ACKNOWLEDGEMENTS

This work was supported by the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT) [grant number 101170]. Evelyne Delezie from the Institute for Agricultural and Fisheries Research (Melle, Belgium) is acknowledged for formulation of the feed. The authors thank Herman De Rycke from the Department of Nutrition, Genetics and Ethology for the assistance with the lyophilisation process. The excellent assistance of many PhD students from the Department of Bacteriology, Pathology and Avian Diseases was gratefully appreciated.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT) [grant number 101170].