The gut microbiota is involved in host behaviour and memory in mammals. Consequently, it may also influence emotional behaviour and memory in birds.
Quail from two genetic lines with different fearfulness (LTI: long tonic immobility, n = 37; STI: short tonic immobility, n = 32) were either or not supplemented with a probiotic (Pediococcus acidilactici) from hatching. Emotional reactivity was measured in a tonic immobility test (d6 and 7 of age) and two open-field tests (d13–15; d22–24). Memory was measured in a test rewarded with mealworms, where quail had to remember the cups previously visited (d34–36). Quail endured a 5-days stress period from days 17 to 21 to help revealing the potentially beneficial effect of the probiotic.
As expected, STI quail were less fearful compared to the LTI quail (p < 0.05). Probiotic supplementation had no effect on most measures of emotional reactivity (p > 0.05), except in the tonic immobility test where supplemented STI quail had lower immobility duration (p = 0.0001). Regarding the memory test, the two lines had similar performances. Quail fed with probiotics made fewer errors (p = 0.040). There was no significant correlation between traits of emotional reactivity and of memory.
In conclusion, the supplementation with Pediococcus acidilactici as a probiotic, affected a specific trait of emotional reactivity in STI quail, and improved memory in both lines, whichstrengthens the idea that the influence of gut microbiota on the host behaviour and memory seen in mammals is shared by birds.