Survival, Growth, Feed Efficiency and Carcass Composition of Rabbitfish, Siganus Rivulatus, Fed Different Dietary Energy and Feeding Levels

Abstract

A feeding trial was conducted to study the effects of dietary energy level and feeding level or daily energy density (DED) on growth, feed conversion, nutrient retention efficiencies, carcass composition, apparent nutrient digestibility and cost benefit analysis for fingerling of rabbitfish, Siganous rivulatus. Twelve net cages, each with dimensions of 1x1x0.4m were stocked with 10 fingerlings (10g/fish initial weight). The fish were fed three isonutrogenous diets (25% CP), with varying three oil supplement (0,5 and 10%), and digestible energy levels (3882, 4056 and 4360 kcal/kg diet), at of 2 and 4% body weight/day (BW/d), corresponding six daily energy densities based on calorie per 1g BW of fish per day. Fish were fed the experimental diets three times daily, six days a week for 98 days. Fish were weighed every two week intervals and feed amounts were adjusted on the basis of the new fish weight. Final body weight, gain and specific growth level (SGR) were increased with an increase in dietary energy level at 2% feeding level but no trends were evident at 4% feeding level. Feed conversion (FCR), protein efficiency ratio (PER), productive protein value (PPV%) and energy retention (ER%) were higher when fish were fed at 2% than 4% feeding level. Furthermore, increasing daily energy density resulted in an increase in SGR until level of 162.4cal/g BW of fish. However the differences in SGR above 155.2cal/g BW were not significant (P >0.05). There are a positive effect between energy density and SGR (y= 0.099x+0.5, r 2 = 0.88). Fat content of carcass increased by increasing both energy and feeding levels while protein content did not affected.