Potential and Valorization of Salix babylonica Waste Leaf Extract to Mitigate Equine Fecal Production of Methane, Carbon Monoxide, and Hydrogen Sulfide

This investigation was aimed to analyze the pivotal role of Salix babylonica waste leaves extract on the sustainable mitigation of equine fecal biogases production. The fecal content as the inoculum source was collected from 3 groups (3 horses per group) of horses. Each group received the first feed of the day with S. babylonica at 0 (F0), 60 (F60), and 120 (F120) mL/day per animal. Further, the fecal contents as the inoculum source from the group F0, F60, and F120 were mixed with different doses of S. babylonica extract (0-, 0.6-, 1.2-, and 1.8- mL/g DM). The extract at 1.8 mL/g DM of dose in F60 group significantly (linear = 0.0046) increased the asymptotic gas production. The fecal × extract dose interaction revealed significant effect on asymptotic gas production (P = 0.0272) and rate of gas production (P = 0.0441). The supplementation of S. babylonica extract at 1.8 mL/g DM mitigated the rate of methane (CH4) production (linear = 0.0114; quadratic = 0.0239) and lag period (linear = 0.0007; quadratic = 0.0066) in F0 group. Moreover, 1.8 mL/g DM of the extract reduced CH4 emission up to 37 h. The reduction in asymptotic carbon monoxide (CO) production was estimated by supplementing varied doses of extract in F0 group but the effect was not significant (P > 0.05). The extract at 0.6 mL/g DM showed reduction in CO emission at 33 h. Similarly, the addition of 1.2 and 1.8 mL/g DM of extract in F120 group mitigated the production of hydrogen sulphide (H2S) but the effect was not significant (P > 0.05). Moreover, the inclusion of 1.2 mL/g DM of the extract decreased the emission of H2S up to 48 h. In addition, the fecal × extract dose interaction showed no significant (P > 0.05) changes in pH level, SCFA production, DMD, and ME. Findings of this study indicated the potency of S. babylonica waste leaves extract in the mitigation of CH4, CO, and H2S from equines.