Use of Black Soldier Fly Larvae (Hermetia illucens) to Substitute Soybean Meal in Ruminant Diet:An In Vitro Rumen Fermentation Study

Aim: This experiment aimed to evaluate substitution of soybean meal (SBM) by black soldier fly (BSF) larvae meal in a napier grass diet as performed by an in vitro rumen fermentation system.
Materials and Methods: Samples of napier grass, SBM, and BSF larvae age 1 week (BSF1) and 2 weeks (BSF2) were arranged according to the following dietary treatments (dry matter [DM] basis): T1, 100% napier grass; T2, 60% napier grass+40% SBM; T3, 60% napier grass+40% BSF1; T4, 60% napier grass+40% BSF2; T5, 60% napier grass+20% SBM+20% BSF1; and T6, 60% napier grass+20% SBM+20% BSF2. The samples were determined for their chemical composition and were incubated in vitro using buffered rumen fluid for 48 h at 39 °C. In vitro incubation was carried out in three runs and represented by two incubation bottles per run.
Results: Supplementation of BSF, both BSF1 and BSF2, increased ether extract, neutral- and acid-detergent insoluble crude protein contents of T3-T6 diets. The T3 or T4 diet resulted in lower ruminal ammonia concentration, in vitro DM digestibility, and in vitro organic matter (OM) digestibility as compared to those in T2 (p<0.05). Diet supplemented with BSF produced lower methane emission in comparison to that of supplemented with SBM (p<0.05). Diet containing BSF2 produced lower methane and methane per digestible OM than that containing BSF1 (p<0.05).
Conclusion: Substitution of SBM by BSF in ruminant diet results in a lower nutritional value in vitro but with an advantage of lowering ruminal methane emission.