Integrated effects of dietary supplementation of Spirulina platensis in working dogs: nutritional, biochemical, antioxidant, immunological, gut-related microbial and nutrigenomic insights

Abstract

BACKGROUND: The present study investigated the effects of daily dietary supplementation with Spirulina platensis powder at two inclusion levels (0.04 g and 0.08 g/kg body weight) for working dogs. Spirulina platensis is a nutrient-rich microalgae containing high-quality protein, vitamins, minerals, and antioxidant pigments. These constituents are reported to possess immunomodulatory, antioxidant, and gut health-promoting effects. Dose-dependent effects on nutritional status, metabolic profiles, antioxidant and inflammatory status, gut integrity, immune function, and systemic gut health-related nutrigenomic responses were assessed in working dogs. A total of 15 adult male German Shepherd working dogs (age 2-3 years, weight range 24-26.5 kg) were randomly assigned to 3 groups (n = 5) over a 7-week experimental period, with evaluations at weeks 0, 3, and 7. The groups were as follows: first group, control (CON), fed on a basal diet; the second group (SP1) fed on the basal diet plus 0.04 g/kg body weight/day Spirulina powder; the third group (SP2) fed on the basal diet plus 0.08 g/kg body weight /day Spirulina powder. RESULTS: Body weight, body condition score, daily food intake, fecal score, and fecal moisture did not differ among the three groups during the trial (P > 0.05). Indeed, Spirulina supplementation was significantly associated with higher serum total protein, albumin, and globulin concentrations (P < 0.05). Moreover, a significant difference in lipid profile was observed, characterized by reduced total cholesterol, triacylglycerol, low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL), and increased high-density lipoprotein (HDL) levels (P < 0.05). Similarly, lower aspartate aminotransferase (AST), alanine aminotransferase (ALT), and urea concentrations were observed in Spirulina-supplemented groups (P < 0.05). Furthermore, supplemented groups exhibited enhanced total antioxidant capacity (T-AOC) and reduced malondialdehyde (MDA) concentrations (P < 0.05). Regarding serum gut barrier integrity-related genes, there is a significant upregulation of occludin (OCLN) and a reduction in fatty acid binding protein 2 (FABP2) in the supplemented groups (P < 0.05). In terms of inflammatory and immune biomarkers, there is significant downregulation of interleukin-6 (IL-6) and tumor necrosis factor-receptor associated factor 6 (TRAF6) in the serum of dogs supplemented with Spirulina (P < 0.05). Interestingly, Spirulina-supplemented groups showed a significant decrease in calprotectin and increase in fecal IgA levels (P < 0.05). In addition, Changes in selected culturable fecal bacterial populations were observed in the Spirulina-supplemented groups indicated by significant increased total bacterial count and lactobacillus count accompanied by a lower coliform level (P < 0.05). For the parameters that showed significant differences, treatment, time, treatment × time interaction were all significant (P < 0.05). In most parameters, the higher inclusion level (0.08 g/kg) produced more pronounced effects. CONCLUSION: Short-term dietary supplementation of Spirulina platensis, particularly at 0.08 g/kg body weight inclusion level, was associated with modulation of biochemical profile, antioxidant status, inflammatory and immune biomarkers, selected microbial markers, and overall intestinal health in working dogs. These findings suggest potential systemic biological effects; however, considering the limited sample size and exploratory design, the results should be interpreted cautiously and warrant confirmation in larger, longer-term studies.