Extruded Spirulina and enzyme supplementation modulate hepatic proteome and metabolism in broilers

Limnospira platensis (Spirulina) is prized for its nutritional and functional benefits, yet its effects on the broiler liver proteome, especially at high inclusion levels and following pre-treatments, remain underexplored. We evaluated four dietary treatments: a control (CTR) and three experimental diets, each containing 15 % Spirulina: unprocessed (SP), extruded (SPE) and extruded plus 0.21 % enzyme blend (SPEM). Hepatic proteomic profiling identified 25 proteins whose abundance differed significantly (P < 0.05) among treatments. Proteins decreased in all Spirulina-fed groups were predominantly involved in lipid and amino-acid metabolism: hydroxymethylglutaryl-CoA lyase, S-adenosylmethionine synthase, homocysteine-binding protein, dimethylglycine dehydrogenase, acetyl-CoA acyltransferase 1, 5-aminoimidazole ribonucleotide synthase and aspartate aminotransferase. Conversely, proteins increased with Spirulina inclusion were mainly associated with carbohydrate catabolism and mitochondrial energy production: fructose-bisphosphate aldolase B, glucose-6-phosphate isomerase, UTP-glucose-1-phosphate uridylyltransferase, multiple NADH dehydrogenase subunits (α, β, 75 kDa), and the voltage-dependent anion channel protein. Importantly, the magnitude of these proteomic shifts was greatest in the SPE and SPEM groups, indicating that extrusion enhances algal cell-wall disruption and nutrient accessibility, while supplemental enzymes further liberate bioactive components. This metabolic reprogramming suggests a shift in the broiler liver toward enhanced glycolytic flux and mitochondrial oxidative phosphorylation. Such adaptations may underpin improvements in hepatic function, support more efficient growth performance and bolster overall metabolic health in poultry. To our knowledge, this is the first study to demonstrate that targeted processing of Spirulina can selectively modulate the avian liver proteome, offering a promising strategy for functional feed design.