Carbohydrate sources influence growth and intestinal enzyme activity in thin-lip grey mullet (Liza ramada) fry

This work is designed to examine the influence of using four different dietary carbohydrate sources (rice-bran RB, wheat-bran WB, wheat-flour WF, and yellow-corn YC) on growth, feed utilization, relative gut length, biochemical composition, blood glucose, and intestinal enzyme activity in thin-lip grey mullet (Liza ramada) fry. Five diets were evaluated during a 68 days using fifteen glass aquaria (30×40×100 cm) contained 22 L. ramada (0.3 g/fry) per aquarium which included the marine water. The first set remained in a basal regime (∼25% CP), whereas the other four groups provided the tested carbohydrate source separately. Fry feeding was applied three times per day throughout the whole experimental duration. Findings designated an enhancement in growth and feed utilization for fry nourished on both RB and WF contained diets as compared to the corresponding's for fish fed the YC diet. The weight gain values ranged between 0.98 and 1.28 g/fry for YC and RB respectively. Moreover, a significantly (P ≤ 0.05) higher lipid contents (32.33%) and relative gut length (2.6) of the fry fed the RB diet remained detectable in comparison to other diets. In addition, these results showed significantly variances in concentrations amongst nutritional treatments for highest average blood glucose value (126.33 u/ml), lipase (14 u/ml), and amylase (1982.7 u/ml) in fry fed RB enzymes and liver glycogen (107.3 mg/g) for YC.