The effect of different levels of dietary-phlorotannins-rich extract on the growth and nutritional indices of whiteleg shrimp (Litopenaeus vannemei)

In the present study, the effect of using different levels of dietary -phlorotannins (1, 3 and 5%) extracted from Sargassum brown seaweed on growth function, nutrition, digestive enzyme activity and body chemical composition of white leg shrimp (Litopenaeus vannemei) was studied during a culture period of 35 days. During 5 weeks, the length and weight of all treatments increased significantly (P<0.05), however, the rate of increase was different in different groups and the highest rate was achieved in phlorotannins treatment of 5% (P<0.05). The best records of final weight, percentage of body weight index, growth rate, specific growth rate and feed conversion ratio, resulted in diet containing 5% phlorotannins (P>0.05). The relative activity of major digestive enzymes namely amylase, protease and lipase as well as protein and lipid content was higher in treatment containing 5% phlorotannins compared to other treatments (P<0.05). The results showed that the use of phlorotannins as a natural bioactive compound at the level of 5% in the diet can improve the growth, nutrition, activity of digestive enzymes and chemical composition of white leg shrimp during the culture period.