RESUMO
Two separate feeding trials were undertaken to benchmark a series of commercial diets and determine the nutrient and energy apparent digestibility coefficients of a variety of protein-based feed ingredients when fed to sobaity seabream, Sparidentex hasta. In Experiment 1, triplicate groups of fish (initial body weight: 330.5 ± 2.6 g) were fed with one of three locally available diets containing crude protein (CP) levels ranging from 44 to 46% of dry matter (DM), each with ~12% crude fat. Fish grew at around 3.2 g day-1 with a specific growth rate (SGR) of 0.7% day-1. Both the feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly better in fish fed diets, which contained the highest (46.4%) crude protein level. Overall, the data from these preliminary studies suggest that the best performance by sobaity seabream was obtained with a diet containing 46% crude protein, 20 MJ/kg, and a protein-to-energy ratio of 23 mg/kJ. In Experiment 2, fish with an initial body weight of 319 ± 7 g were held in 11 tanks and fed reference (D1) and test diets (D2-D11) for 7 days before fecal collection. This process was repeated twice in a blocking arrangement to generate three replicates. Each of the ten test diets contained 30% of a test ingredient, with the remaining 70% proportionally identical to the D1 diet. Diet apparent digestibility coefficients (ADCs) were measured, and the diet ADCs were then used to derive the protein and energy ADCs for the individual test ingredients. Ingredient protein ADC ranged between 75.5 and 93.9%, while ingredient energy ADC ranged between 66.8 and 81.2%.
RESUMO
A 12-week experiment was conducted to quantify dietary lysine requirement of fingerling Catla catla (3.65 ± 0.05 cm; 0.58 ± 0.02 g) by feeding casein-gelatine-based diets (33.0 % crude protein; 14.3 kJ/g digestible energy) with six levels of L-lysine (1.25, 1.50, 1.75, 2.00, 2.25 and 2.50 % dry diet). The experiment was conducted in eighteen 70-L indoor polyvinyl circular troughs provided with a water flow-through system (1-1.5 L/min). Live weight gain (LWG), feed conversion ratio (FCR), protein deposition (PD), lysine retention efficiency (LRE%) and RNA/DNA ratio were used as the response criteria. Second-degree polynomial regression analysis at 95 % maximum and minimum response of LWG and FCR data exhibited the lysine requirement between 1.8 and 1.9 % dry diet, corresponding to 5.5-5.7 % dietary protein. Regression analysis of PD, LRE and RNA/DNA ratio yielded the requirement between 1.7 and 1.8 % dry diet, corresponding to 5.2-5.5 % dietary protein. Since live weight gain and protein deposition are the key parameters for estimating nutrient requirement, these tools were used to recommend the lysine requirement of fingerling C. catla which ranges between 1.7 and 1.8 % dry diet. Data generated during this study will be useful to formulate lysine-balanced feed for intensive culture of this fish.