The temperament of ruminants has been investigated for several decades and has similarities with human temperament. Temperament represents an animal’s response to situations perceived as challenging. This behavioral trait can influence numerous biological functions, primarily the stress axis, affecting production characteristics and animal welfare. A crucial aspect of temperament expression lies in how individuals perceive stressors. Molecular research has begun to elucidate the central pathways involved in the expression of temperament. Recent investigations suggest that the rumen microbiome may influence temperament, like the way that the effect of the gut microbiota on the brain in monogastric species. Further research is necessary to understand the relationship between the gut microbiome and ruminant temperament. Future applications may include modifying the temperament of production animals through the manipulation of the rumen microbiota and potentially enhancing their health and welfare.