Effects of a gut microbiota transfer on emotional reactivity in Japanese quails (Coturnix japonica)

The interaction between the gut microbiota (GM) and the brain has led to the concept of the microbiota- gut-brain axisbut data in birds remain scarce. We tested the hypothesis that colonization of germ-free chicks from a quailline selected for a high emotional reactivity (E+) with GM from a line with low emotional reactivity (E-) would reduce their emotional behaviour in comparison with germ-free chicks from E+ line colonized with GM from the same E+ line. The GM composition analysis of both groups revealed a shift in term of microbial diversity and richness between Day 21 and Day 35 and the GM of the two groups of quailswere closer to each other at Day 35 than at Day 21 at a phylumlevel. Quailsthat received GM from the E- line expressed a lower emotional reactivity than the quailscolonized by GM from the E+line in the tonic immobility and the novel environment tests proceeded during the second week of age. This result was reversed in a second tonic immobility test and an open-field run two weeks later. These behavioural and GM modifications over time could be the consequence of the resilience of the GM to recover its equilibrium present in the E+ host, which is in part driven by the host genotype. This study shows for the first time that a gut microbiota transfer can influence emotional reactivity in Japanese quailsstrengthening the existence of a microbiota- gut-brain axisin this species of bird.