Impact of dietary Chlorella vulgaris and carbohydrate-active enzymes incorporation on plasma metabolites and liver lipid composition of broilers

Background Chlorella vulgarishas been proposed as a sustainable green feedstock in poultry nutrition due to its ease of cultivation, minimal environmental impact and balanced nutritional composition. However, the majority of studies documents the use ofC. vulgarisas a dietary supplement in broilers instead of a feed ingredient. To the best of our knowledge, no report has shown the effect of a high-level incorporation (>2 % in the diet) ofC. vulgarison plasma metabolites and hepatic lipid composition of broilers. One hundred and twenty Ross 308 male birds were housed in 40 wired-floor cages and randomly distributed by the following experimental diets at 22 days of age (n = 10) during 15 days: (1) a corn-soybean meal based diet (control); (2) based diet with 10% ofC. vulgaris; (3) diet2supplemented with 0.005% Rovabio®Excel AP; and (4) diet2supplemented with 0.01% of a pre-selected four-CAZyme mixture. Results The inclusion ofC. vulgarisat 10% in the diet, regardless of the presence of exogenous CAZymes, changed plasma metabolites but did not compromise broilers growth. Plasma total lipids increased in broilers fedC. vulgariscombined with the two feed CAZymes (p< 0.001) compared with the control diet. Moreover, the supplementation with Rovabio®increased total cholesterol and LDL-cholesterol, while the addition of the four-CAZyme mixture increased triacylglycerols, VLDL-cholesterol and ALP activity. In opposition, HDL-cholesterol levels decreased in broilers fed microalga alone (p = 0.002). Regarding hepatic composition, the inclusion ofC. vulgarisin broiler diets, individually or combined with exogenous CAZymes, had a minor effect on fatty acids but improved then-6/n-3 ratio and total carotenoids. Conclusions In summary, the inclusion of a high level (10%) ofC. vulgarisin broiler´s diet, regardless of the presence of exogenous CAZymes, improved hepatic antioxidant composition and did not impair broiler’s performance. In addition, the feed supplementation with CAZymes increased broilers lipemia. Therefore, dietaryC. vulgarisat this incorporation level seems to be safe for animal health and do not compromise performance traits, with no need of CAZymes supplementation.