Abstract
Insects like the black soldier fly larvae (Hermetia illucens; BSFL) have been proposed as protein-rich feed ingredients to support the growing demand for meat. The BSFL hold also promise for use as a protein source in pet foods and, as such, it has been studied for palatability, nutritional quality and health effects in dogs and cats. This study aimed to evaluate the effects of including BSFL meal in a dry, extruded food on nutritional quality and health in healthy adult cats. Two similar compositions of dry, extruded foods were formulated to meet the FEDIAF nutrition guidelines for adult cats of which one was chicken meal-based (control, with 34.3% chicken meal) and the other BSFL meal-based (inclusion of 37.5% BSFL meal). BSFL meal contained 95.0% dry matter, 53.1% crude protein, 14.3% crude fat, 6.0% ash (Protix, Dongen, The Netherlands). Two groups of four cats were each fed one of the two foods for two 28-d periods in a crossover design, with sample collection during the last 7 d of each period. Cats were housed in groups of the same sex during the first 21 d of each period. Both foods were well-accepted by the cats. No health problems (including coat and skin condition) were noted throughout the study. Food type did not impact body weight (P = 0.850). Food intake was greater when cats were fed the BSFL-based food (P < 0.001). Consistency scores of fresh feces were optimal and did not differ between the foods. Compared with the control food, the food with BSFL meal had decreased apparent fecal digestibility values for dry matter, organic matter, nitrogen, and gross energy (P < 0.05) although all values were high. Digestibility values for acid-hydrolyzed fat were similar for both foods (P = 0.628). Diets resulted in changes in fermentation product concentrations, like fecal ammonia was less when cats fed this food compared with the control food (P < 0.001), but the fecal concentrations of the short-chain fatty acids and biogenic amines were generally increased (P < 0.05). Moreover, reduced fecal bacterial diversity and affected bacterial relative abundance suggested that inclusion of BSFL meal steered the microbial composition in the distal gut of cats. It was observed increased relative abundance of bacteria genus considered beneficial for host health like Bifidobacterium (P < 0.001) and Megasphaera (P < 0.036); and inhibition of genus Negativibacillus and Lachnoclostridium (P < 0.001), previously associated to digestive issues and negative for gut health. Overall, the data gathered in this study suggests that BSFL meal is an adequate alternative ingredient for extruded dry cat foods and may exert a prebiotic effect on intestinal microbiota.