Extrusion and Pancreatin Superdosing Modulate the Metabolic Impact of 20% <i>Chlorella vulgaris</i> Inclusion in Broiler Diets

Microalgae such as Chlorella vulgaris are gaining attention as sustainable and nutritionally valuable feed ingredients, with the potential to partially replace soybean meal in broiler diets. However, dietary inclusion of 20% C. vulgaris has been attempted, but negatively affected growth performance due to limited digestibility. This study examined the effects of including 20% Chlorella vulgaris (C. vulgaris) in broiler diets, either alone, extruded, or combined with 0.3% pancreatin supplementation, on blood parameters, plasma biochemistry, and liver composition. From day 7 to 35 of age, four dietary treatments were applied: a standard control diet (CTR), a diet with 20% C. vulgaris (CV), a diet with 20% C. vulgaris supplemented with 0.3% pancreatin (CVEN), and a diet containing 20% extruded C. vulgaris (CVEX). Findings showed that C. vulgaris dietary incorporation, regardless of treatment, led to a significant reduction in growth performance and an increase in specific plasma lipid parameters (p < 0.05) when compared with the CTR diet. However, in CVEN animals, such adverse effects were mitigated, resulting in improvements in final body weight and average body weight gain. Dietary inclusion of C. vulgaris modulated hepatic composition without affecting total hepatic lipid content. Chlorella-based diets lowered PUFA/SFA and n-6/n-3 ratios and increased specific fatty acids, particularly C16:0 and 20:5n-3. Hepatic cholesterol and antioxidant-related compounds, including β-carotene, chlorophyll a-like pigments, α-tocopherol, and, in untreated C. vulgaris, γ-tocopherol and γ-tocotrienol, were increased, and multivariate analysis clearly separated CTR diet-fed birds from Chlorella-fed groups. Multivariate analysis identified treatment-related patterns in both blood and liver samples. PCA of plasma parameters clearly separated all dietary groups. Conversely, hepatic PCA distinguished control from C. vulgaris treatments, which clustered together regardless of processing or enzyme supplementation, indicating consistent liver responses to microalgae dietary inclusion. Overall, these findings indicate that a 20% inclusion level of C. vulgaris requires digestibility-enhancing strategies to sustain broiler growth performance. Pancreatin supplementation effectively restored performance at this inclusion level to levels comparable to those of conventional maize-soy diets, highlighting the potential of enzyme-treated C. vulgaris as a viable main ingredient that supports both production outcomes and health-related attributes.