Ingestion of Lactobacillus rhamnosus modulates chronic stress-induced feather pecking in chickens

Feather pecking (FP) is a stress-induced neuropsychological disorder of birds. Intestinal dysbiosis and inflammation are common traits of these disorders. FP is, therefore, proposed to be a behavioral consequence of dysregulated communication between the gut and the brain. Probiotic supplementation represents a promising new therapeutic to mitigate widespread FP. We monitored FP, gut microbiota composition, immune markers and amino acids related to the production of neurochemicals with Lactobacillus rhamnosus supplement (Lacto) or a placebo in laying hens. Data demonstrate that, when stressed, the incidence of FP increased significantly, however, Lacto prevented this increase. Lacto showed strong immunological effects by increasing the regulatory T cell population of the spleen and the cecal tonsils, in addition to limiting cecal microbiota dysbiosis. Despite minimal changes of aromatic amino acid levels, data suggest that catecholaminergic circuits may be an interesting target for further studies. Overall, our findings provide the first data supporting the use of a single-strain probiotic to reduce stress-induced FP in chickens and has promise to improve the welfare of domestic birds.