Impact of Dietary Supplementation with Pogostemon cablin Essential Oil on the Rumen Fermentation and Rumen Health in Heat-Stressed Beef Cattle

This study aimed to investigate the effects of <i>Pogostemon cablin</i> essential oil (PEO) on rumen development in heat-stressed beef cattle. Eighteen male Jingjiang cattle were randomly assigned to two groups and fed a diet containing PEO at 0 mg/kg (Control) and 50 mg/kg in the feed concentrate (n = 9 per group). The rumen fluid samples had lower ammonia nitrogen and higher cellulase activity, propionate and total volatile fatty acids concentrations in the 50 mg/kg PEO group. Compared with the control group, 50 mg/kg dietary supplementation with PEO increased crude protein and neutral detergent fiber digestibility. Additionally, the ruminal tissue papilla height, the papilla surface area, and the activities of glutathione peroxidase, total superoxide dismutase, and total antioxidant capacity were also higher, while the malondialdehyde content was lower for the heat-stressed cattle in the 50 mg/kg PEO group. Furthermore, PEO increased the average optical density values and mRNA expression of zonula occludens-1 (ZO-1) and occludin (<i>p</i> < 0.05). Transcriptomics analysis of the rumen epithelium showed that PEO upregulated the expression levels of genes related to tight junction proteins and the DNA replication/repair pathways, while it downregulated pro-apoptotic genes. In summary, dietary PEO supplementation improved nutrient digestibility, enhanced rumen antioxidant capacity, and promoted the repair of damaged rumen epithelium in heat-stressed cattle, indicating that PEO exerts a prominent protective effect on rumen function.