Double lactobacillus strain-based probiotic and postbiotic in broiler diet- composition and effects on performance, immunity and health

Since the ban of antibiotics growth promoters, intensive efforts were developed to find alternatives to sustain broiler growth and health, including probiotics and postbiotics. Probiotics are “live micro-organisms which, when administered in adequate amount, confer a health benefit to the host”. Nevertheless, viability of a probiotic is not always necessary to confer beneficial effects, and recently a trend emerged to use postbiotics, which are “a preparation of inanimate microorganisms and/or their components that confer health benefit on the host”. Lactobacillus rhamnosus CNCM-I-3698 and Lactobacillus farciminis CNCM-I-3699 are two probiotic bacteria used in a co-fermentation process to produce a probiotic (Pro) and a postbiotic (Post). Both Pro and Post showed positive effects on the performances and health of monogastric farm animals, including pig and poultry. The precise composition and biological effects of Pro and Post when used as a probiotic and a postbiotic, however, remain poorly understood.

The project will focus on unravelling the composition and mode of action of Pro and Post, to understand its effects on performance and health in broilers.

Three sub-objectives are identified:

1. Identify major compounds of Pro and Post
2. Identify and unravel Post effects in vitro on a model of chicken innate immune cells
3. Evaluate and unravel Pro and Post effects in vivo on broiler performance, microbiota, immunity, metabolism and gut health

During the project, the following methods will be used for the in vitro approach:

1. Mass spectrometry in order to characterise Pro and Post composition
2. The chicken macrophage-like cell line HD11 as an in vitro model to investigate Post effect on innate immunity and the underlying mechanisms

For the in vivo approach, three experiments will be carried out. A first experiment will study broilers performances, microbiota, adaptive immune response and blood biochemical parameters to Pro and Post under different dietary conditions (standard and challenge). A second experiments will focus on the effects of Pro and Post on broiler performance and blood parameters under two types of challenging diet. A last experiment will focus on unravelling Pro and Post effects regarding broiler performance and gut health, nutrients digestibility, blood transcriptome, intestinal transcriptome, microbiome and metabolome.

This study will therefore allow to improve our the understanding of Pro and Post composition and to document their effects on broiler immunity, physiology and performances, in relation with diet characteristics.