Effect of dietary seaweed supplementation on growth, feed utilization, digestibility co-efficient, digestive enzyme activity and challenge study against Aeromonas hydrophila of nile tilapia Oreochromis niloticus

The present study aimed to determine the growth, digestibility co-efficient, digestive enzyme activity and disease resistance of juvenile GIF tilapia fed with Ulva seaweed meal supplemented diet.

The study was undertaken with different inclusion levels of Ulva seaweed meal (USM) such as raw (UR) and fermented (UF) Ulva meal (UR-5, UR-10, UR-15, UF-5, UF-10 and UF-15% of diet) and control feed (C) for a period of 60 days.

GIFT fed with fermented Ulva meal at a 10% inclusion level in their diet exhibited the highest growth performance (41.43 g) followed by UF5 (41.07±0.43 g), UR5 (39.65±0.36 g), control (39.09±0.20 g), UF15 (38.67±0.26 g), UR10 (38.47±1.47 g) and UR15 (35.77±0.35 g) diet. The highest apparent digestibility coefficient (ADC) with crude protein (85.14±0.91%) was observed in fishes fed with fermented Ulva meal at 10% inclusion rate than that of other treatments group for dry matter, ether extract and gross energy. The digestive enzymatic activities, amylase (0.029±0.00 units/mg protein/min), protease (0.147±0.0 units/mgprotein/min) and Lipase (0.273±0.05 units/mg protein/min), showed higher level in fishes fed with diet containing 10% fermented Ulva meal compared to other treatment groups including control. Moreover, at the end of the trial, increased survival rate (86.66%) was observed with fishes fed with Ulva based diets challenged against Aeromonas hydrophila. The histopathological study showed a lower level of infection in fishes fed with 10% fermented Ulva meal supplementation. The present study concluded that the requirement of Ulva meal in fish diet shows the following trend 10% of Ulva Fermented (UF) and UF-5, Ulva Raw (UR) 5%, control (C), UF-15, UR-10 and UR-15 diet that can improve the health status of the GIF tilapia.