Effects of Dietary Algae Meal Supplementation on Growth, Whole-Body Composition, Histological and Immune Responses of Pacific White Shrimp, Penaeus Vannamei

Algae meal is an emerging shrimp feed additive due to its essential nutrient composition, such as fatty acids, amino acids, vitamins, and minerals. A 60-day feeding trial examined the effects of algae meal as an additive on growth, whole-body composition, and histological and immune responses of Pacific white shrimp, Penaeus vannamei. Six iso-protein and iso-lipid treatment diets were formulated and prepared using Best Mix feed formulation software and pelletizer, respectively. The diet without supplementation of algae meal was used as a control. Two treatment diets included algae meal at 0.5% (T1-AM) and 1% (T2-AM). After pelletization, another three treatment diets were vacuum coated with algae meal at 0.5% (T3-AM), 1% (T4-AM), and a combination of 0.5% algae meal and 0.5% probiotic (T5-AMP). A total of 900 juvenile shrimp, with an initial average weight of 3.12±0.07 g, were evenly distributed into 18 rectangular cages in three indoor cement tanks (5.0 m × 3.0 m × 1.2 m). Each diet was randomly allotted to triplicate groups of 50 shrimps (average weight of 3.12 ± 0.07 g) per treatment and fed thrice daily (9:00, 13:00, and 17:00). The results showed that significantly higher water stability of feed, water absorption (%), and dry matter retention were observed in the T5-AMP diet (P<0.05). Similarly, higher weight gain, protein efficiency ratio, specific growth rate, and better feed conversion ratio were observed in the shrimp-fed T5-AMP diet (P<0.05). The whole-body proximate and amino acid composition of shrimp were not affected by the inclusion and coating of algae meal and probiotic diets (P>0.05). Moreover, no significant abnormalities were found in the histology analysis of the hepatopancreas and intestine of shrimp-fed experimental diets. The relative mRNA expression of immune-related genes was significantly upregulated in shrimp fed a T5-AMP diet (P<0.05). In conclusion, this study indicated that 0.5% algae meal blended with probiotics through vacuum coating could improve the feed quality, nutrient utilization, growth performance, and immune responses of P. vannamei. A blend of algae meal and probiotics could help to develop nutritious immune-boosting shrimp feed and ensure sustainable shrimp farming practices.