Effects of supplementary nano-ZnO on in vitro ruminal fermentation, methane release, antioxidants, and microbial biomass

Abstract

The effects of nano-ZnO on in vitro ruminal fermentation, methane release, total antioxidant capacity (TAC), and microbialbiomass production (MBP) were assessed using an in vitro gas production technique. Treatments included a control diet and dietscontaining 20, 40, or 60 mg of supplemental Zn per kg dry matter (DM) as ZnO or nano-ZnO. As a result of this study, supplementationof 20 mg of Zn as nano-ZnO, similar to ZnO, decreased methane production and protozoa enumeration but improved (P 0.05). The diets containing 40 and 60 mg of supplementary Zn,as nano-ZnO or ZnO, had no advantage over the diet containing 20 mg of Zn in terms of methane decline and TAC, TDS, and MBPincrements. Overall, nano-ZnO had no adverse effect on in vitro ruminal fermentation. The addition of 20 mg of Zn as nano-ZnO perkg diet DM was enough to improve the in vitro ruminal fermentation in terms of methane release, TAC, and MBP. Thus, the highersupplementary Zn levels (40 and 60 mg/kg DM) are not recommended.