Influence of dietary protein levels on nano-encapsulated Yucca schidigera extract and its effects on in vitro ruminal greenhouse gas production and fermentation dynamics.

The influence of nano-encapsulated Yucca schidigera extract (YSE) on total gas (GP), ruminal methane (CH), carbon monoxide (CO), hydrogen sulphide (HS) production, and fermentation activities of diets based on two different protein levels were investigated. A completely randomized experimental design with a factorial arrangement (2 × 4 × 4) with three replications was used. Factor 1 was the dietary protein levels (14%and 18%), factor 2 was the types of extracts used (TE; negative control (without extract), positive control (empty chitosan nano-capsules), Y. schidigera extract nano-capsules, and crude Y. schidigera extract), and factor 3 the doses of each type of extract (ED; 0-, 0.25-, 0.5-, and 1.0- mL extract/g DM). Nano-chitosan reduced the GP production with a higher protein level by 24.9% after 48 h while the crude extract elevated it. At both crude protein levels, the interaction of crude extract at an ED of 0.25 mL extract/g DM generated a higher volume of CH at 6 h (p = 0.001 and 0.001 respectively) compared to the volume generated by the negative control. The 0.25 mL extract/g DM extract for both the crude extract and nano-extract elicited higher and lower CO production at 6 h (p < 0.0001), respectively. Nano-chitosan at 0.25 mL extract/g DM resulted in less HS produced at 6 h than when crude extract was used at the same dose and a higher protein level (p = 0.027). The ED did not significantly affect any of the parameters under consideration as used under lower protein levels. However, TE affected pH and dry matter degradability (p < 0.0001) while the interaction of both TE and ED impacted both CH:SCFA and CH:ME (p = 0.045) with higher and lower values obtained for nano-chitosan and the negative control, respectively. In conclusion, nano-chitosan at a higher protein level proved its antimicrobial property, and although the production of CO increased at 14% protein, in vitro fermentation indicated its ability to minimize the production of GP, methane and hydrogen sulphide in the rumen, and to boost the degradability of DM and methane conversion efficiency.