Intermittent photoperiod interactions with gut microbiota. Intermittent photoperiod improves the circadian rhythms of the biological clock through interactions with gut microbiota

The gut microbes are essential for the health and production performance of laying hens. Intermittent photoperiod has been proved to improve the health and production performance in laying hens. However, the circadian rhythm of the gut microbes and how it interacts with the host under intermittent photoperiod are not clear. We used laying hens as a model to evaluate the circadian rhythms of the gut microbes and the biological clock genes under different intermittent photoperiods. Intermittent photoperiod (IP1: 16 [3 h-L/1 h-D]: 8D) enhanced the circadian rhythms of cBmal1, cBmal2, cCry1, and cCry2 in the hypothalamus, and increased the expression of cClock, cBmal1, and cCry2 in the liver and seven clock genes in the cecal wall. Intermittent photoperiod also significantly altered the composition and metabolic function of the cecal microbiota via the melatonin pathway. The concentrations of SCFAs and the abundance of SCFAs-producing genera such as Odoribacter increased significantly under IP1 treatment and might further fed back and strengthened the peripheral and central rhythm by activating the SCFAs receptor gene pathway in cecum wall. These findings disentangle mediation mechanisms for circadian rhythms of central circadian clock and highlight the role of intermittent photoperiod-induced regulation of the interaction between host clock and cecal microbial community.