Association between castration-induced changes in circadian body temperature rhythms and gut microbiome diversity in...

Castration is a routine management practice in livestock production, used to control temperament, reproduction, and carcass traits. Beyond these intended outcomes, castration induces substantial physiological changes, particularly in energy metabolism and thermoregulation. Recent studies have revealed close interactions between host circadian physiology and the gut microbiome, suggesting that disturbances in this relationship may influence animal performance and welfare. However, the effects of castration-induced alterations in circadian body temperature (CBT) rhythms on intestinal microbial composition remain poorly understood in ruminants. This study investigated the association between castration, CBT rhythmicity, and gut microbiota composition in goats. Castration significantly modified CBT rhythms in both early- and late-castrated animals. Linear mixed-effects cosinor analysis demonstrated distinct changes in the amplitude and acrophase of CBT oscillations, with more pronounced effects observed in late-castrated goats. These physiological changes were accompanied by shifts in intestinal microbial β-diversity, as shown by distance-based redundancy analysis, suggesting that castration-induced alterations in host circadian regulation were associated with changes in microbial community structure. Given the small sample size, this study should be considered exploratory and hypothesis-generating. These findings provide new insights into the interplay between host circadian biology and the gut microbiome in ruminants. The present study may inform future research and management approaches aimed at improving animal health and productivity.