Protein hydrolysates from Tenebrio molitor and Hermetia illucens as novel food sources for dogs

There has been a growing interest in insect meals as a sustainable alternative protein source for animal food and feed. In parallel, insect hydrolysates have been investigated in vitro for their bioactive properties, but the impact of dietary inclusion on dog’s nutritional parameters needs to be elucidated. This study aimed to evaluate the chemical composition and bioactive properties of four insect hydrolysates obtained from the enzymatic hydrolysis of Tenebrio molitor and Hermetia illucens using ALCALASE 2.5L and Corolase PP enzymes and investigate the effects of their dietary inclusion on diet palatability, digestibility, and fecal characteristics and metabolites of adult Beagle dogs. Four two-bowl tests were performed using 12 adult Beagle dogs to assess palatability by the pairwise comparison between the control diet (a commercial diet with 3% of shrimp hydrolysate) and each of the four experimental diets (control diet with the replacement of 3% (w/w) of shrimp hydrolysate by 3% of each insect protein hydrolysate). A digestibility trial designed according to a replicated Latin square 5 × 5 design, with ten adult dogs, five periods of 10 d each, and five diets was performed to evaluate the effects on food intake, fecal characteristics and metabolites, apparent total tract digestibility, and estimated metabolizable energy content of the control and experimental diets. Chemical composition and in vitro antioxidant and antihypertensive activities of insect hydrolysates depended on the insect species and enzyme used. No differences were observed in the first diet approached or tasted, but the inclusion of hydrolysates of T. molitor obtained from Corolase PP hydrolysis showed a greater intake ratio (P = 0.032). Food intake, diet digestibility and fecal characteristics were not different between diets, except for an increased fecal caproate concentration in dogs fed the control diet (P = 0.024). The dietary inclusion of insect hydrolysates did not affect nutritional parameters, and further investigation is needed to evaluate their health-promoting properties for pet foods and supplements.