PS7-11. Black Soldier Fly Larvae in Extruded Diets for Senior Dogs: Effects on Skin Barrier Function and Coat Quality.

Abstract With increasing interest in sustainable alternatives to conventional ingredients in pet foods, insect-derived ingredients have emerged as viable options. Black soldier fly larvae (BSFL) are of particular interest as a novel ingredient due to their capacity to function as both a high-quality protein source and a functional lipid source. In addition to providing a balanced amino acid profile, BSFL contain a lipid fraction rich in medium-chain fatty acids, particularly lauric acid, which has been associated with antimicrobial activity and potential benefits for gastrointestinal health and skin barrier function. Despite growing research on BSFL as a protein ingredient, their role as a combined protein and lipid source in extruded pet foods remains insufficiently characterized, particularly in senior dogs, a population with unique metabolic and physiological needs. Therefore, the objective of this study was to evaluate the effects of BSFL meal (BSFLM) and BSFL oil as partial replacements for chicken by-product meal and chicken fat, respectively, in extruded diets for healthy senior dogs, with a focus on skin and coat quality. Following a replicated 4x4 Latin square design with a 14-day adaptation period, eight senior female beagles (body weight: 10.6 ± 0.88 kg; age: 8.3 ± 0.80 years) were assigned to one of four dietary treatments: (1) Control diet containing chicken by-product meal and 10% chicken fat (CON; twin-screw extrusion), (2) 0% BSFLM with 5% BSFL oil (BSFLo; single-screw extrusion),(3) 20% BSFLM with 5% BSFL oil (BSFLs; single-screw extrusion), and (4) 20% BSFLM with 5% BSFL oil (BSFLt; twin-screw extrusion). Dogs were rotated through all four dietary treatments across four 21-day experimental periods, receiving a different diet each period. At the end of each period, three blinded evaluators assessed coat characteristics, including gloss, softness, coat feel, dander, and overall skin and coat quality. Instrumental measurements were also collected in triplicate to evaluate trans-epidermal water loss (TEWL), skin hydration, and sebum concentration at the left and right pinna, inguinal region, and upper back. Subjective skin and coat assessments did not differ among treatments (P > 0.05). Sebum concentrations at the left pinna were higher (P = 0.0001) in dogs fed BSFLo compared with CON and BSFLt, while BSFLs differed only from BSFLt. At the upper back, BSFLs had the highest sebum values and differed from all other diets. Trans-epidermal water loss (TEWL) measurements at the upper back were higher in BSFLo compared with CON, while BSFLs and BSFLt were intermediate and did not differ. Skin measurements varied across body locations, limiting the ability to draw definitive conclusions. Overall, dietary inclusion of BSFL meal and oil showed site-specific changes in sebum production and skin barrier-related measurements, indicating their potential to support skin and coat health in senior canine diets.