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 (CH₄), carbon monoxide (CO), hydrogen sulphide (H₂S) 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 CH₄ 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 H₂S 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 CH₄:SCFA and CH₄: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.