Effect of dietary supplementation of Ulva rigida C. Agardh extract on biochemical response and digestive enzyme activities of grey mullet, Mugil cephalus (Linnaeus)

This study was aimed to assess the effect methanol extract from Ulva rigida C. Agardh on biochemical response and digestive enzyme activities in grey mullet, Mugil cephalus (Linnaeus). A control diet without and three other experimental diets were prepared with supplementation of U. rigida extract (UE diet) at the inclusion levels of 5, 10 and 15 g kg-1 diet, respectively. One hundred twenty grey mullet with an initial mean weight of 14.95 g were randomly distributed into twelve tanks and fed twice a 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 fed diets containing UE showed an increasing trend of better performance except to those fed UE5 better. The highest amylase, lipase and protease activities was observed in fish fed diet containing UE10. Significantly different was observed in survival rate, glucose and triglyceride levels between control and UE supplemented groups (P< 0.05). There was significant decline (P<0.05) in glucose and triglyceride levels in those fish which received UE diet over the control. The present study elucidates the suitability of U. rigida extract as a novel dietary supplement in grey mullet diet for improving metabolism of carbohydrate and enhancing digestive enzyme activities in grey mullet.

Keywords:

Ulva rigida , Mugil cephalus , Biochemical response , Digestive enzymes , Dietary supplement