Faecal microbiota composition associates with systemic inflammatory marker and cytokine profiles in periparturient dairy cattle

The period around calving is challenging for dairy cattle, as many diseases and metabolic issues manifest, alongside major endocrine changes. A plethora of physiological modifications have been described at this time, including hormonal, metabolic, immunological and even gut microbiota-related changes. Nevertheless, there is little evidence regarding the potential relationships between these factors. The objective of the present study was to provide a comprehensive description of the immune status and responsiveness, whilst also exploring the possible associations with the faecal microbiota. To achieve this objective, blood and faecal samples were collected from a cohort of 411 dairy cows across 25 dairy farms before and after parturition. Whole blood was stimulated ex vivo with lipopolysaccharide, and cytokine secretion was assessed using a 15-plex cytokine and chemokine assay. Faecal microbiota was assessed using 16 S rRNA metabarcoding. The study identified four distinct cytokine-based profiles that were associated with the cytokine production around calving. The four cytokine-based clusters did not demonstrate a clear distinction based on microbiota. However, the variability in expression of individual cytokines could be explained in part by the microbiota (up to 9.4% for CCL3). Several individual cytokines, including IL-17 A, IL-1α and IL-1β, were identified as being associated with different microbial taxa. Furthermore, higher levels of Clostridium sensu stricto 1 were associated with elevated IL-17 A levels, while lower levels of Monoglobus were associated with elevated IL-1α levels. These findings support the hypothesis that the pre-calving gut microbiota may contribute to shaping post-calving inflammatory responses and highlight its potential as a source of early microbial indicators of immune challenge during the transition period.