Unraveling the role of shrimp hydrolysate as a food supplement in the immune function and fecal microbiota of beagle dogs.

The inclusion of protein hydrolysates from animal by-products in petfood may enhance the industry's sustainability, while contributing to dogs' health due to their nutritional and functional properties. However, inconsistent results of protein hydrolysates on gut microbiota, immune responses, among other health parameters, have been observed in dogs. This study aimed to evaluate the effects of diets supplemented with 5% shrimp hydrolysate, compared to non-supplemented diets, on hematological parameters, serum chemistry profile, innate and adaptive immune function, and fecal microbiota composition in adult Beagle dogs during a 12-week feeding trial. Dietary inclusion of shrimp hydrolysate decreased blood eosinophils (P = 0.017) and glucose levels (P = 0.023), while increasing levels of white blood cells (P = 0.002), platelets (P = 0.038), neutrophils (P = 0.036), and CD4 (P < 0.001) and CD8 T cells (P < 0.001) single producers of tumor necrosis factor-alpha. It also led to a more extensive proliferation of CD4 T cells in response to LipL32 antigen (P = 0.020) and to a decrease in superoxide production in stimulated cells (P = 0.002). Additionally, supplemented diets increased Oscillospiraceae (P-adj = 0.005) and Clostridia (P-adj = 0.017) abundance, and decreased such of Sellimonas (P-adj = 0.025). Overall, the results indicate that diet supplementation with shrimp hydrolysate at 5% modulates the immune response and fecal microbiota, highlighting its potential to be included in hypoallergenic and gastrointestinal diets, and in diets for diabetic dogs.