Effects of In Vitro Fermentation of Different Roughage on Dry Matter Digestibility, Gas Production Kinetics, Methane Emission and Fermentation Products

Abstract

This study aimed to evaluate the fermentation characteristics of six types of roughages, either alone (100%) or in a 50:50 ratio with concentrate, using an in vitro technique. The parameters assessed were in vitro dry matter digestibility (IVDMD), gas production kinetics, and fermentation end-products. The roughage sources included sugarcane (SC), baby corn stover (BS), pineapple stalk (PS), leucaena (LC), rice straw (RS), and Napier grass (NG). The experimental design followed a Completely Randomized Design (CRD). The results revealed that when fermented alone, SC, BS, and PS exhibited significantly higher digestion rates and cumulative gas production compared to RS and NG (P < 0.01). Furthermore, PS showed the highest values for IVDMD and short-chain fatty acid (SCFA) concentrations at 24 hours of fermentation. The RS and NG groups exhibited the lowest IVDMD and SCFA concentrations (p < 0.01). Regarding gas production per gram of dry matter digested, SC recorded the highest value, whereas PS showed the lowest (P < 0.01). When fermented in combination with concentrate, SC exhibited higher cumulative gas production than LC, RS, and NG (p < 0.01), although gas production rates did not differ significantly (p > 0.05). Meanwhile, PS achieved the highest IVDMD and SCFA concentrations (p < 0.01). However, SC recorded the highest total gas, methane, and carbon dioxide production per gram of dry matter digested (p < 0.01). Ammonia nitrogen concentrations were not significantly different across all treatment groups (p > 0.05). In conclusion, PS is a promising roughage, comparable to BS, for enhancing digestibility and mitigating greenhouse gases, whereas SC exhibits lower digestibility and higher relative gas emissions.