Effect of dietary supplementation of Ulva rigida C. Agardh extract on several of physiological parameters of grey mullet, Mugil cephalus (Linnaeus)

The present research was aimed to assess the effect methanol extract from Ulva rigida on biochemical response and digestive enzyme activities in Mugil cephalus. A control diet without and three other experimental diets were supplemented by U. rigida extract (UE diet) at the inclusion levels of 5, 10 and 15 g kg-1 diet, respectively. One hundred and twenty grey mullets with the mean weight of 14.95 ± 2.01 g were randomized into 12 tanks and fed twice per day (09:00 and 17:00) for 60 days. After 60 days of the feeding trial, serum total protein and globulin levels of the fish receiving UE diet had incremental trend and better performance, except for samples fed UE5. The UE10 diet resulted in the highest amylase, lipase and protease activities. Significantly different was observed in survival rate, glucose and triglyceride levels between control and UE supplemented groups (p< 0.05). There was significant reduction in glucose and triglyceride levels in the fish received UE diet compared to the control (p<0.05). According to the present results, U. rigida extract as a new introduced dietary supplement is suitable for improving metabolism of carbohydrate and enhancing digestive enzyme activities in grey mullet.