Black soldier fly larvae: a one health approach to investigate gut, and organ health and meat quality response in slow-growing chickens

Background: The inclusion of sustainable protein sources in poultry feed has become essential for improving animal welfare in livestock production. Black soldier fly larvae are a promising solution due to their high protein content and sustainable production. However, most research has focused on fast-growing poultry breeds, while the effects on native breeds, such as the Bianca di Saluzzo, are less explored. This study aimed to evaluate the impact of BSFL supplementation in the diet of slow-growing chickens, with a focus on growth, intestinal health and meat quality for final consumers. Results: The study demonstrated that Black soldier fly larvae supplementation, both in dehydrated and live form, improved growth performance, with an increase in final weights compared to the control group. No significant differences were found in feed conversion ratio, liver and spleen weight or histomorphometry between groups. Black soldier fly larvae supplementation did not negatively affect immune function or liver metabolism. Higher production propionic acid was detected in the black soldier fly larvae fed groups compared to the control, suggesting an effect on volatile fatty acid production. Gut microbiota analysis showed an increase in beneficial bacteria, such as Faecalibacterium, in the live larvae group. Furthermore, the meat fatty acid profile and atherogenicity and thrombogenicity indices did not undergo significant changes, implying a low potential risk to consumers’ cardiovascular health. Conclusions: Black soldier fly larvae supplementation in the diet of Bianca di Saluzzo improved growth without compromising animal health or meat quality. Moreover, the increase in beneficial volatile fatty acids and the modulation of gut microbiota suggest a positive impact on gut health. Finally, the absence of negative effects on meat lipid profiles confirms nutritional safety for consumers, making black soldier fly larvae a valid alternative in poultry feed. These results offer new perspectives for the use of Black soldier fly larvae in the nutrition of local breeds, contributing to sustainability in line with the One Health approach.