Fermentation characteristics and nutritional value of whole and defatted black soldier fly larvae meal for ruminants using in vitro techniques

This study aimed to evaluate the chemical composition, fermentation characteristics, and nutritional value of whole and defatted black soldier fly larvae (BSFL) meal using the <i>in vitro</i> gas production technique and the Holden method. Samples were prepared and incubated for 2, 4, 6, 8, 12, 16, 24, 36, 48, 72, and 96 h. Rumen fluid was collected from three fistulated sheep fed a diet containing 40% concentrate and 60% forage at maintenance level for one month prior to sampling. The results indicated that defatting BSFL increased crude protein content from 38.10% to 42.85% and reduced ether extract from 24.20% to 16.40%. Defatted BSFL produced significantly greater cumulative gas volumes at all incubation times compared with whole larvae. Gas production at 24 h was 81.96 and 79.03 mL per 200 mg of dry matter, and increased to 141.83 and 114.85 mL at 96 h for defatted and whole larvae, respectively. The fractional rate of gas production (c) was slightly higher for whole larvae than for defatted larvae (0.045 vs. 0.030 mL·h⁻¹). Organic matter digestibility (OMD), metabolizable energy (ME), net energy for lactation (NEL), and short-chain fatty acid (SCFA) production were higher for defatted BSFL compared with whole larvae (91.23% vs. 89.48%, 13.91 vs. 12.61 MJ·kg⁻¹ DM, 10.48 vs. 9.29 MJ·kg⁻¹ DM, and 1.23 vs. 1.21 mmol, respectively). In addition, digestibility values estimated using the Holden method were greater for defatted larvae than for whole larvae (60.90 vs. 55.50%). Overall, the results suggest that defatting black soldier fly larvae enhances their nutritional value and fermentability, indicating their potential as a high-quality feed ingredient for ruminant animals.