Grassland Saline-Alkaline Degradation-Induced Excessive Iron and Sodium Intake Potentially Increases the Transmission Risk of Fecal Pathogenic Bacteria in Cattle

The environmental transmission of pathogens from domesticated ruminants presents a significant risk to the well-being of both humans and animals. However, the risk of pathogen release from grazing ruminants in natural grasslands has received comparatively little attention. The threat of pathogen release from grazing ruminants may be increasing owing to grasslands in arid and semi-arid regions experiencing prevalent saline-alkaline degradation. Therefore, further risk assessment of pathogen release driven by saline-alkaline degradation is warranted. Here, we investigated the impact of saline-alkaline degradation in grasslands on the fecal pathogenic bacteria of domestic ruminant cattle by comparing cattle subjected to long-term grazing on undegraded (UG) and severe saline-alkaline degraded (SG) grasslands. Our results showed that the relative abundance of potential pathogenic bacteria including <i>Streptococcus</i>, <i>Mogibacterium</i>, and <i>Alistipes</i> in the SG cattle group was higher than that of the UG group. Notably, the results for correlation analyses showed that the <i>Paludibacter</i> had a positive effect on these three potential pathogenic bacteria. Moreover, we found that excessive intake of sodium and iron is associated with these microbes that have potential pathogenic risks. Our results indicate that the continued global saline-alkaline degradation of grasslands will significantly elevate the risk of animal diseases, and may also pose a serious threat to human health through environmentally mediated transmission.