PS7-10. Utility and Functionality of Black Soldier Fly Larvae in Extruded Diets on Nutrient Digestibility, Fecal Metabolites, and Serum Chemistry in Senior Dogs.

Abstract Black Soldier Fly Larvae Meal (BSFLM), a sustainable insect protein source, shows promise as a beneficial alternative ingredient in pet food formulations due to its high protein content and beneficial oil composition. Chitin, an insoluble fiber present in BSFL, may also modulate gut microbiota and production of short-chain fatty acids, although it may slightly reduce nutrient digestibility when added at higher levels. Limited research has evaluated the effects and optimal inclusion levels of BSFL meal (BSFLM) and oil in extruded diets for senior dogs. This study aimed to assess de-fatted BSFLM and BSFL oil as a partial replacement for chicken by-product meal and chicken fat in extruded diets for healthy senior dogs, and its effects on nutrient digestibility and fecal metabolites. Additionally, the effects of different extrusion processing methods were evaluated, comparing high-thermal-energy and high-mechanical-energy methods. A replicated 4x4 Latin square design with a 14-day adaptation phase was conducted in which 8 female senior beagles (mean age 8.3 ± 0.8 years) were fed one of 4 diets: 1) Control diet containing chicken by-product meal and 10% chicken fat using a twin-screw extruder, 2) 0% BSFLM with 5% BSFL oil using a single-screw extruder (O), 3) 20% BSFLM with 5% BSFL oil using a single-screw extruder (S), and 4) 20% BSFLM with 5% BSFL oil using a twin-screw extruder (T). At the end of each 21-day period, fresh fecal samples were collected to measure metabolites, pH, fecal score, and microbiota. Feed intake, fecal output, fecal score, and pH did not differ across diets (P > 0.05). Apparent total tract digestibility of dry matter, organic matter, crude protein, and digestible energy were not significant (P > 0.05), indicating that inclusion of BSFLM and BSFL oil, regardless of extruder type, did not negatively affect nutrient digestibility. Fecal acetate concentrations were higher (P = 0.0142) in dogs fed diet S and T (348.3, 328.9 µmol/g, respectively) compared with dogs on the Control diet (226.29 µmol/g), suggesting that inclusion of BSFLM may increase acetate-producing microbial activity and support a healthy gut microbiome in senior dogs. These findings suggest that BSFL can be used as a partial replacement for traditional protein and fat sources in extruded diets for senior dogs without negatively affecting nutrient digestibility, while also supporting gastrointestinal health. In addition, extrusion method using either a high-thermal or high-mechanical energy system did not affect physiological outcomes measured