Administration of a Multi-Genus Synbiotic to Broilers: Effects on Gut Health, Microbial Composition and Performance

SIMPLE SUMMARY: Since the use of antibiotics as growth promoters has been banned, the poultry sector is searching for alternatives to support production efficiency. Synbiotics, which consist of a mixture of prebiotics and probiotics, appear to be a promising way to do so by sustaining chickens’ gut health. In this study, the synbiotic PoultryStar(®) sol was tested on three broiler flocks, reared in separate farms under typical field conditions. Compared to control chickens, those fed with the synbiotic throughout the productive cycle generally exhibited less histopathological lesions and had higher villi at intestinal level, and ultimately performed better in terms of body weight gain, feed conversion efficiency and liveability. The composition of the caecal microbial ecosystem was also studied, proving that synbiotic supplementation influenced the abundance of several bacterial populations. To fully understand the exact implications of these changes, further studies are required, which will be informed and facilitated by the present data. ABSTRACT: In recent years, the applicability of prebiotics, probiotics and their mixtures, defined as synbiotics, in poultry production has received considerable attention. Following the increasing regulation of antibiotic use, these nutraceuticals are seen as an alternative way to sustain production efficiency and resistance to pathogens and stressors by modulating birds’ gut health. The aim of this study was to evaluate the benefits provided under field conditions by administering the multi-species synbiotic PoultryStar(®) sol to broilers in drinking water. To this purpose, three Ross 308 broiler flocks, representing separate progenies of a breeder flock which was treated with the same synbiotic, were housed in separate farms, divided into treatment and control groups, and followed throughout the productive cycle. Synbiotic administration was shown to improve gut health even in absence of a challenge, with limited changes in terms of macroscopic intestinal lesions and more overt differences related to histopathological scores and villi length. Synbiotic-fed chickens performed consistently better in terms of body weight gain, feed conversion ratio and survivability. Lastly, the evaluation of the caecal microbiome through next-generation sequencing highlighted the effects of synbiotic supplementation on the composition of the bacterial population, the implications of which will, however, require further studies to be better comprehended.