Background
Zinc nanoparticles (NPs) are characterized by high bioavailability, small size, and high absorbability. The
Conclusion
Zn-NP supplementation up to 70 d improved feed-use efficiency and influenced ammonia-N concentration and activities of hydrolases in the rumen. The active ruminal fermentation affected the health of the ruminal papillae and epithelium in the lambs, regardless of the application's form, dose, or duration. However, by affecting rumen microbial fermentation, Zn-NPs could alter fermentation patterns, thereby increasing the capacity of host rumen epithelial cells to transport short-chain fatty acids.
Results
After 24 h of incubation, dry matter digestibility was higher for ZnO-NP and ZnP-NP substrates than the control in an in vitro experiment (P < 0.001). The total bacterial population in the STE was lower (P < 0.001) in the ZnP-NP group than in the control and ZnO-NP groups, but the protozoan populations were not significantly different. The ammonia-N concentration in LTE was lowest in the ZnO-NP80 group (P = 0.002), but the activities of carboxymethyl cellulase (P < 0.001) and xylanase (P = 0.002) were higher in the ZnO-NP40, ZnO-NP80, and ZnO-80 groups than in the control group. Morphological observation after STE and LTE revealed histological changes (e.g. inflammation of the epithelium or edema of the connective tissue) in the rumen of lambs.