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

Abstract

Background: The present study aimed to determine the growth, digestibility co-efficient, digestive enzyme activity and disease resistance of juvenile GIFT tilapia fed with Ulva seaweed meal supplemented diet. Methods: 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. Result: 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) for Crude Protein (85.14±0.91%) was observed in fishes fed with fermented Ulva meal at a 10% inclusion rate than other treatments and the control groups for Dry Matter, Ether Extract, and Gross Energy. The enzymatic activities of digestive enzymes, namely Amylase activity (0.029±0.00 units/mg protein/min), Protease activity (0.147±0.0 units/mgprotein/min) and Lipase activity (0.273±0.05 units/mg protein/min), showed higher levels in the group of fishes fed with a diet containing 10% fermented Ulva meal, as compared to the other treatment groups and the control. Increased survival rate (86.66%) was observed when the fishes were challenged with Aeromonas hydrophila at the end of the trial for Ulva based diets. The results obtained on histopathology showed the presence of lower degree levels of infection in 10% fermented Ulva meal supplementation.The present study concluded that dietary Ulva meal requirement for juvenile GIFT tilapia can be at 10% of Ulva Fermented (UF) and UF-5, Ulva Raw (UR) 5%, control (C), UF-15, UR-10 and UR-15 diet respectively.