Utilization of Silkworm (Bombyx mori) pupae meal and Javanese bird grasshopper (Valanga nigricornis) meal as alternative protein sources to replace meat and bone meal in ruminant feed: An in vitro study

This study aimed to evaluate the effects of replacing meat and bone meal (MBM) with insect-based protein sources, Silkworm pupae (Bombyx mori) meal (SPM), and Javanese bird grasshopper (Valanga nigricornis) meal (FGM) on rumen degradability, fermentation characteristics, total gas production, and methane emissions in vitro. Six experimental diets, each with five replicates, were tested, namely P1 (100% Napier grass), P2 (80% Napier grass + 20% MBM), P3 (80% Napier grass + 20% full-fat SPM (FSPM)), P4 (80% Napier grass + 20% defatted SPM (DSPM)), P5 (80% Napier grass + 20% full-fat FGM (FFGM)), and P6 (80% Napier grass + 20% defatted FGM (DFGM)). The result showed that the total gas and methane production were significantly lowered by insect-based protein meal and MBM (P < 0.05). In vitro dry matter degradability (IVDMD) and in vitro organic matter degradability (IVOMD) of insect-based protein meal were not significantly different from MBM and control diet (IVDMD: P = 0.87; IVOMD: P = 0.966). Insect-based protein meal and MBM reduced total volatile fatty acid (VFA) and propionate proportion while also increasing NH3-N and acetate:propionate ratio, as evidenced by P < 0.05. These results showed that insect-based proteins, particularly DSPM and FGM, had a similar digestibility to MBM, reduced methane emissions, and could effectively replace MBM in ruminant diets.