Pterocladia capillacea Polysaccharide Enhances Growth, Immunity, Digestive Enzyme, Antioxidant Activities, and Gene Expressions of Litopenaeus vannamei

Mohamed Ashour^1*Fawzia S Ali¹Ahmed Mamoon²Ahmed I A Mansour¹Mohamed M Mabrouk²Abdallah Tageldein Mansour^3*Ehab Mohamed^4*Ahmed F Abdelhamid²

• ¹National Institute of Oceanography and Fisheries (NIOF), Alexandria, Egypt
• ²Fish Production Department, Faculty of Agriculture, Al-Azhar University, Cairo, Egypt
• ³Department of Fish and Animal Production, College of Agricultural and Food Sciences, King Faisal University, Al-Hassa, Eastern Province, Saudi Arabia
• ⁴College of Agriculture and Veterinary Medicine, United Arab Emirates University, AlAin, Abu Dhabi, United Arab Emirates

This work evaluated the effects of dietary supplementation with the seaweed polysaccharide (PS) extracted from red seaweed, Pterocladia capillacea, on the growth, feed efficiency, whole-body composition, immunological response, antioxidant activity, digestive enzyme activities, and gene expression of the whiteleg shrimp, Litopenaeus vannamei. Four isonitrogenous and isoenergetic diets with different SP levels were formulated. The basal experimental diet (control diet) had no seaweed polysaccharide added (PS 0 ). Diets 2-4 (PS 1 , PS 2 , and PS 3 ) were formulated to contain PS at levels of 1, 2, and 3 g/kg diet, respectively. Six hundred postlarvae (PLs 15 ; with an initial body weight of 1.62±0.12 g/PL) of the whiteleg shrimp L. vannamei were randomly selected and distributed into triplicate hapas per treatment. For the duration of the 60-day trial, the PLs were fed their corresponding diets three times a day at 10% of their body weight.Compared with those in the control diet and PS 3 , the shrimp reared in groups PS 1 or PS 2 showed significant (p < 0.05) improvements in the specific growth rate, survival rate, length gain rate, and weight gain rate. The individuals in the PS 2 group showed the greatest significant (p < 0.05) values of the feed conversion ratio, feed efficiency ratio, and protein efficiency ratio. In addition, the shrimps in the PS 2 group showed the highest significant values (p < 0.05) of lysozyme, amylase, lipase, and SOD, and the highest significant value of MDA, whereas the shrimp in the PS 3 group showed the highest significant values (p < 0.05) of catalase. The expression levels of investigated growthrelated genes (GH, IGF-1, and IGF-II) and immunity-related genes (Proph, SOD, and Lys) in the PS 2 group were significantly (p < 0.05) increased. In conclusion, the supplementation rate of 2 g/kg PS significantly improved the growth, nutrient utilization efficiency, nonspecific immunity, antioxidant and digestive enzyme activities, and improved the immunity-and growth-related gene expression of L. vannamei shrimp.However, future works are recommended to understand the mechanism by which PS enhances physiological status and modulate genes expression in whiteleg shrimp.