47 Inclusion of black soldier fly (Hermetia illucens) larvae frass as an alternative protein source in the diet of Florida native yearling ewes.

Abstract The objective of the study was to evaluate the effects of partially replacing soybean meal (SBM) with black soldier fly larvae frass (BSFL) on nutrient digestibility, growth performance, and blood profile of ewes consuming diets with approximately 10% SBM on a DM basis. Six yearling Florida native ewes, averaging (mean ± SD) 44 ± 3 kg BW were enrolled in a replicated 3 × 3 Latin square design with 3 experimental periods of 21 d each (14 d adaptation + 4 d samples collection + 3 d washout). First 14 d of each period, ewes were housed in 7.4 × 1.8 m individual pens with rubber mats, one automatic waterer and two plastic feeders. During collection, ewes were moved to 1.4 × 0.7 m metabolic crates equipped with an individual waterer and feeder and two trays for the collection of feces and urine. Animals were fed TMR ad libitum twice daily at 0730 and 1530 h consisting of different levels of SBM replacement with BSFL, as follows: no replacement (CON), partial replacement of SBM with 25% BSFL (BSFL25) and 50% BSFL (BSFL50) on a DM basis. Data on DM and nutrient intake, excretion, and apparent digestibility, and also plasma concentrations of glucose and blood urea nitrogen (BUN), and urine concentrations of allantoin, urine blood nitrogen, and uric acid, were collected. Data were analyzed with SAS 9.4 evaluating orthogonal polynomial contrasts to determine linear and quadratic effects of SBM replacement with BSFL for each response variable. The intakes of DM, NDF, ADF, EE, and starch were greater for BSFL25 compared with control (Quadratic effect; P 0.01) while no differences were observed between BSFL25 and BSFL50. Similarly apparent digestibilities of DM, NDF, ADF and starch was less for BSFL25 than CON (Quadratic effect; P ≤ 0.01). Intake of CP linearly increased (P 0.01) with BSFL, while apparent digestibility of CP linearly decreased and that of EE increased, with inclusion of BSFL. There was a quadratic effect of BSFL on total feces excretion (P 0.01) and water consumption (P 0.01) being greater in BSFL25 compared with CON. Urine BUN (P 0.01) and urine nitrogen (P 0.01) linearly increased with BSFL inclusion. Results indicate that partial replacement of SBM with BSFL in the diet of yearling Florida native ewes may quadratically increase feed intake and decrease nutrient apparent digestibility. Further research is needed to explore the long-term implications of incorporating BSFL into animal diets, considering their impact on overall growth and performance.