Effects of abomasal supplementation of quercetin on performance, inflammatory cytokines, and matrix metalloproteinase genes expression in goats fed a high-grain diet

Ten abomasally fistulated male goats fed twice daily at a constant rate of 4% of body weight were used to investigate the effects of abomasal supplementation of quercetin on rumen fermentation and the mRNA expression of inflammatory cytokines in the rumen epithelium, liver and hoof tissues, and the expression of matrix metalloproteinase genes in hoof tissues. The goats were placed in individual pens (1.2 × 1.2m) with free access to water and randomly divided to two groups: one group fed an high grain diet (HG) without quercetin (control, n = 5) and the other group fed HG and treated with quercetin (treatment, n = 5) for 4 weeks. Results showed that abomasal supplementation of quercetin increased the average daily feed intake (P < 0.001) and body weight (P < 0.01). The concentration of free lipopolysaccharide (LPS) (P < 0.05) in rumen fluid was higher in goats supplemented with quercetin compared with the control group. Quercetin supplementation did not affect the mRNA expression of IL-1β, IL-6, TNF-α, IL-10, IL-12, and IFN-γ in the ruminal epithelial tissue (P > 0.05). Quercetin supplementation decreased the IL-1β mRNA expression (P < 0.05) and increased IL-10 mRNA expression (P < 0.05) in the liver tissues. Quercetin supplementation downregulated the mRNA expression of IL-1β (P < 0.01) and tended to downregulate the TNF-α mRNA expression (P > 0.05) in the hoof. Quercetin supplementation also lowered the mRNA expression levels of MMP-2 (P < 0.05) and MMP-9 (P < 0.01) in the hoof tissue. In conclusion, abomasal supplementation of quercetin improved the performance, decreased the mRNA expressions of inflammatory cytokines in the liver and hoof tissues, and reduced the risk of laminitis in goats.