Effects of dietary supplementation with a postbiotic and phytogenic formulation on growth performance and immune responses of whiteleg shrimp (Litopenaeus vannamei)

• Both postbiotic and phytogenic treatments did not increase growth performance but significantly improved the immune response (THC, GC, HC, PO activity, RES, and SOD) of shrimp over the 45-day trial. • Shrimp fed postbiotics exhibited notably higher granulocyte counts and PO activity, indicating enhanced cellular immune response. • SCFP postbiotics may serve as more effective immunostimulants than vegetable essential oil phytogenics for improving innate immunity in shrimp aquaculture. This study looked at how adding a postbiotic and a phytogenic supplement to the diet affects the growth and immune system of whiteleg shrimp ( Litopenaeus vannamei ). A 45-day feeding trial was conducted using three treatments: a control group, a postbiotic-supplemented group (Ps; 0.45% SCFP, DVAqua®), and a phytogenic-supplemented group (Ph; 0.02% plant essential oil, Biomin® P.E.P. MGE 150). All shrimp were fed a commercial diet (De Heus, codes 9802 and 9803). After 45 days of dietary supplementation, there were no statistically significant differences in growth performance indicators, including final weight (Wf), weight gain (Wg), specific growth rate (SGR), and average daily gain (ADG) among the treatment groups and the control. However, shrimp that received postbiotic and phytogenic supplements showed better results in several immune system measures, such as total hemocyte count (THC), granulocyte count (GC), hyalocyte count (HC), phenoloxidase activity (PO), respiratory burst activity (RES), and superoxide dismutase activity (SOD), compared to the control. Notably, the postbiotic group exhibited higher granulocyte density and phenoloxidase activity than the phytogenic group. These results indicate that although short-term (45 days) dietary supplementation of postbiotics and phytogenics did not improve growth performance, both additives contributed to enhancing the immune response of shrimp, with the postbiotic group (Ps; 0.45% SCFP) showing a more pronounced immunostimulatory effect. This highlights their potential as a functional feed additive that can improve the immune preparedness of whiteleg shrimp.