Temperament affects the impact of dietary tryptophan on the gut-liver-brain axis in sheep1
Year: 2025
Type: article
Abstract: • Dietary tryptophan affects sheep temperament via the gut–liver–brain axis. • The microbiome activates SCFA and tryptophan metabolites pathways in a temperament-specific manner. • Nutrition strategies tailored to temperament could improve sheep welfare. Temperament, similarly to personality, is defined by a consistency in the response of an individual to a challenge, for example, calm or agitated responses. Temperament is partly determined by genetic factors but can also be modulated by internal factors that act on the brain pathways that control temperament. In monogastric animals, the gut-brain axis (GBA) influences temperament. Recently, it has been shown that signals from the liver can impact both brain function and the gut microbiome in a three-way interaction named the GLBA. The role of the liver in GLBA signalling in the expression of temperament is unknown. Here, we report the first broad investigation on the impact of dietary tryptophan (Trp), a supplement that is known to affect temperament, on the communication pathways of the GLBA in Hu sheep of calm (C) or nervous (N) temperaments. In the rumen, Trp supplementation (T) increased the abundance of Chloroflexi and Bdellovibrionota abundance, with Flexilinea enriched in CT and Monoglobus and Sediminispirochaeta enriched in NT. Changes in the abundance of specific genera and phyla probably caused the observed changes in circulating levels of SCFAs, amino acids, and tryptophan metabolites. Changes in the rumen microbiome could partly explain the impact of dietary Trp on the temperament of nervous Hu sheep that was observed previously. The results of a metabolomics analysis of samples from the colon microbiome and the liver suggests that amino acid metabolism and SCFAs from these two tissues could be involved in the expression of temperament. Our findings highlight the GLBA as a potential signalling network modulating temperament in ruminants, with SCFAs, Trp metabolites, and microbial interactions as key mediators. Our data provide the first evidence that, in sheep, Trp affects behaviour through GLBA-dependent pathways and suggest that nutritional strategies, tailored for individuals’ temperament, would improve welfare in precision livestock farming.
Authors: Feifan Wu, Luoyang Ding, Shane K Maloney, Dominique Blache, Mengzhi Wang
Language: English
Subfield: Agronomy and Crop Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $1,000
OpenAlex ID: W7082988279