Sodium butyrate reduces ammonia production in the cecum of laying hens by regulating ammonia-producing bacteria

Sodium butyrate is a commonly used feed additive and can reduce ammonia (NH3) emissions from laying hens, but the mechanism of this effect is unknown. In this study, the sodium butyrate and cecal content of Loh-mann pink laying hens were measured, and in vitro fermen-tation experiments and NH3-producing bacteria coculture experiments were carried out to explore the relationship between NH3 emissions and its associated microbiota metabolism. Sodium butyrate was found to significantly reduce NH3 emission from the cecal microbial fermentation of Lohmann pink laying hens (P < 0.05). The concentration of NO3--N in the fermentation broth of the sodium buty-rate-supplemented group increased significantly, and the concentration of NH4+-N decreased significantly (P < 0.05). Moreover, sodium butyrate significantly reduced theabundance of harmful bacteria and increased the abun-dance of beneficial bacteria in the cecum. The culturable NH3-producing bacteria consisted mainly of Escherichia and Shigella, such as Escherichia fergusonii, Escherichia marmotae and Shigella flexnerii. Among them, E. ferguso-nii had the highest potential for NH3 production. The cocul-ture experiment showed that sodium butyrate can significantly downregulate the expression of the lpdA, sdaA, gcvP, gcvH and gcvT genes of E. fergusonii (P < 0.05), thus reducing the NH3 emission produced by the bac-teria during metabolism. In general, sodium butyrate regu-lated NH3-producing bacteria to reduce NH3 production in the cecum of laying hens. These results are of great signifi-cance for NH3 emission reduction in the layer breeding industry and for future research.

Automated summary

This study found that sodium butyrate can significantly reduce ammonia (NH3) emissions from the cecal microbial fermentation of Lohmann pink laying hens. Sodium butyrate can also regulate the abundance of harmful and beneficial bacteria in the cecum. Culturing experiments showed that sodium butyrate can reduce NH3 emission from bacteria metabolism.