Whole-body amino acid pattern of juvenile,preadult, and adult pacu,Piaractus mesopotamicus,with an estimation of its dietary essential amino acid requirements

In the present study, juvenile (live body weight, 54.3 ± 8.2 g), preadult (live body weight, 822.5 ± 33.9 g), and adult (live body weight, 1,562.8 ± 41.8 g) pacu, Piaractus mesopotamicus, were used to estimate their dietary essential amino acid (EAA) requirements using the whole-body amino acid (AA) pattern. The results showed that whole-body moisture, crude protein, total lipid, and ash contents expressed on a wet weight basis (%) were significantly different among the studied growth phases. No significant differences were observed in the dietary EAA requirements estimated for the three growth phases of pacu. These dietary EAA requirements were found to be different than those previously estimated for the same fish through its muscle AA pattern. Based on whole-body EAA to total EAA ratios {A/E ratios; [(each EAA/total EAA) × 1,000]}, EAA requirements were estimated to be histidine (0.42%), arginine (1.36%), threonine (0.82%), valine (0.90%), methionine (0.45%), isoleucine (0.83%), leucine (1.29%), phenylalanine (0.74%), lysine (1.64%), and tryptophan (0.14%) for pacu. These estimated requirements may serve as a reference line in the formulation of practical and experimental diets until dose–response-based optimum EAA requirements are available for pacu.     

Dietary methionine requirement of fingerling Indian major carp, Cirrhinus mrigala (Hamilton)

Indian major carp, Cirrhinus mrigala fingerling (3.85 ± 0.50 cm, 0.50 ± 0.02 g) were fed isonitrogenous and isocaloric diets (40% CP, 4.28 kcal g⁻¹, GE) containing casein, gelatin and crystalline amino acids with graded levels of L- methionine (0.50, 0.75, 1.00, 1.25, 1.50 and 2.00 g/ 100 g, dry diet) with 1.00% cystine fixed, to determine its dietary methionine requirement. A feeding trial was conducted in triplicate for six weeks. Diets were fed twice a day at 0800 and 1600 h at 5% of body weight/day. The ration size and feeding regime were worked out prior to the start of the feeding trial. Weight gain (158%) and food conversion ratio (1.45) were significantly (P < 0.05) higher in fish fed diet containing 1.00% methionine with 1.00% cystine fixed. Second degree polynomial regression analysis of the weight gain data indicated the dietary methionine requirement to be 1.20 g/100 g of dry diet, corresponding to 3.00% of dietary protein. Second degree polynomial regression analysis was also employed to determine the relationship between food conversion ratio (FCR) and dietary methionine levels which indicated that the best FCR occurred at approximately 1.20% dietary methionine level. Carcass composition of fish fed diet containing graded levels of methionine varied significantly (P < 0.05) except carcass ash content which showed insignificant (P > 0.05) differences among the dietary methionine levels. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dietary folic acid requirement of fingerling Catla,Catla catla (Hamilton)

The dietary folic acid requirement of fingerling Catla catla (3.4 ± 0.17 g; 7.6 ± 0.41 cm) was evaluated by feeding casein–gelatin‐based isonitrogenous (350 g/kg crude protein) and isocaloric (16.72 kJ/g GE) diets containing different concentrations of folic acid (0, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0 mg/kg) to triplicate groups to apparent satiation at 08:00, 12:30 and 17:30 hr for 16 weeks. Absolute weight gain (AWG; 40.07 g/fish), specific growth rate (SGR; 2.25%), feed conversion ratio (FCR; 1.53), protein retention efficiency (PRE; 31.42%) and protein gain (PG; 6.74) improved significantly (p < .05) with increasing folic acid levels up to 0.4 mg/kg diet and then reached a plateau. However, maximum liver folic acid concentration increased up to 0.6 mg/kg diet. Dietary folic acid levels also significantly affected (p < .05) body composition of fish. No significant change (p > .05) in haematological parameters except in fish fed folic acid‐free diet was noted. Antioxidant and immune parameters increased with increasing concentration of dietary folic acid up to 0.4 mg/kg diet. Broken‐line regression analysis of AWG, FCR, PRE, PG, HCT and liver folic acid concentrations of fingerling C. catla against dietary folic acid levels indicated optimum growth, FCR, PRE, PG, HCT and liver folic acid saturation ranging between 0.22 and 0.56 mg/kg diet, respectively.     

Dietary Vitamin C Requirement of Fingerling,Cirrhinus mrigala (Hamilton), Based on Growth,Feed Conversion,Protein Retention,Hematological Indices,and Liver Vitamin C Concentration

This study was conducted to quantify dietary vitamin C requirement of fingerling, Cirrhinus mrigala, (0.79 ± 0.07 g; 3.51 ± 0.15 cm) by feeding casein‐gelatin based purified diets (400 g/kg crude protein; 3.45 kcal/g digestible energy) containing nine levels of vitamin C as l‐ascorbyl‐2‐polyphosphate (0.0, 5, 15, 25, 35, 45, 55, 75, and 95 mg vitamin C equivalent/kg diet) to triplicate groups of fish to apparent satiation for 16 wk. Absolute weight gain (AWG, g/fish), feed conversion ratio (FCR), protein retention efficiency (PRE%), RNA/DNA ratio, hemoglobin (Hb, g/dL), and hematocrit value (Hct%) were taken as the response criteria to determine vitamin C requirement of mrigal. Fish fed diet with 35 mg/kg vitamin C had significantly higher AWG (9.94 g/fish), FCR (1.39), PRE (27.72%), RNA/DNA ratio (4.18), Hb (11.15 g/dL), and Hct (34.44%) values. However, liver vitamin C concentration was found to be higher (64.92 µg/g wet tissue) in diet containing 45 mg vitamin C/kg. Broken‐line regression analysis of AWG data estimated the requirement of 35.65 mg/kg, whereas that of the liver vitamin C concentration data projected the requirement to 41.99 mg/kg.     

The effect of varying dietary protein level on the growth, food conversion, protein utilization and body composition of tropical catfish Mystus nemurus (C. & V.) cultured in static pond water system

Tropical catfish, Mystus nemurus (C. & V.) (25.89 ± 0.7 g) were stocked semi-intensively in 0.03-ha earthen ponds at the rate of 10 000 ha”^-1 and fed six iso-energetic practical diets ranging from 27% to 50% protein for 8 weeks. Each diet was fed in three replicate ponds twice daily to satiation. Experimental fish were also reared extensively, in control ponds, without supplementary feed. Fish fed the 42% protein diet had the highest standing crop, weight gain and protein utilization values and the differences from other diets were statistically significant (P > 0.05). Protein efficiency ratio (PER) decreased as dietary protein increased. The experiment indicated that natural food organisms contributed to some degree if not significantly to the catfish production. Weight gain, food conversion ratio (FCR). PER and SGR (specific growth rate) indicated that a 42% protein diet with digestible protein-to-energy ratio (D/E) of 27.57 mg kj^_1 produced maximum growth in the static pond system.     

Dietary tryptophan requirement of fingerling Indian major carp, Cirrhinus mrigala (Hamilton)

An 8‐week feeding trial was conducted to evaluate the effects of dietary tryptophan concentration on weight gain and feed efficiencies of fingerling Indian major carp, Cirrhinus mrigala. Six isonitrogenous (40% crude protein) and isocaloric (17.90 kJ g^?1) amino acid test diets containing casein, gelatin and l ‐crystalline amino acids with graded levels of l ‐tryptophan (0.06, 0.16, 0.26, 0.36, 0.46 and 0.56 g 100 g^?1 dry diet) were formulated. Fish (4.25±0.30 cm, 0.62±0.02 g) were randomly stocked in triplicate groups in 70 L (water volume 55 L) flow‐through (1–1.5 L min^?1) indoor circular tanks and fed experimental diets at 5% of their body weight/day in two feedings at 08:00 and 16:00 hours. Maximum live weight gain (277%), lowest feed conversion ratio (FCR) (1.50) and highest protein efficiency ratio (PER) (1.66) were measured at 0.36% dietary tryptophan. The relationship between dietary tryptophan levels and weight gain, FCR and PER data were described using second‐degree polynomial regression analysis indicating the tryptophan requirement at 0.42, 0.39 and 0.38 g 100 g^?1 of dry diet respectively. Whole body moisture decreased with increasing tryptophan up to 0.36%. Significantly (P<0.05) higher protein content was evident in fish fed diet containing 0.36% tryptophan. Body fat increased significantly (P<0.05) in fish fed with different tryptophan concentrations except those fed 0.36% tryptophan where a significantly lower fat content was noted. Significantly (P<0.05) higher ash content was reported at 0.06% and 0.16% tryptophan levels. Survival was 100% in fish fed all the diets except those fed 0.06% tryptophan. Based on the results, diets for fingerling C. mrigala should contain tryptophan at 0.38 g 100 g^?1 dry diet, corresponding to 0.95 g 100 g^?1 dietary protein for optimum growth and efficient feed utilization.     

Effects of dietary protein levels on growth,feed utilization,protein retention efficiency and body composition of young <Emphasis Type="Italic">Heteropneustes fossilis</Emphasis> (Bloch)

An 8-week growth trial was conducted to assess the effect of dietary protein on growth, feed utilization, protein retention efficiency, and body composition of young Heteropneustes fossilis (10.02 ± 0.09 g; 9.93 ± 0.07 cm). Isocaloric (4.15 kcal g⁻¹, GE) diets with varying levels of protein (25, 30, 35, 40, 45, and 50% of the diet) were fed near to satiation to triplicate groups of fish. Optimum dietary protein was determined by analyzing live weight gain (LWG%), feed conversion ratio (FCR), protein efficiency ratio (PER), specific growth rate (SGR%), and protein retention efficiency (PRE%) data. Maximum LWG% (167), best FCR (1.42), PER (1.75), SGR (1.76), and PRE (31.7%) were evident in fish fed 40% protein diet (Diet 4). Body protein data also supported the above level. However, second-degree polynomial regression analysis of the above data indicated that inclusion of dietary protein in the range of 40–43% is optimum for the growth of young H. fossilis.     

Effect of ration size on growth, conversion efficiency and body composition of fingerling mrigal, Cirrhinus mrigala (Hamilton)

Optimum ration size of Indian major carp, Cirrhinus mrigala fingerlings was determined by feeding purified diet (40% crude protein (CP); 3.61 kcal g^?1) at five ration sizes (2%, 4%, 6%, 8% and 10% of body weight per day) for 6 weeks. Feeding trial was conducted in triplicate. Fishes were randomly stocked at the rate of 20 fish per trough fitted with water flow‐through system. The best feed conversion ratio (FCR), specific growth rate (%) and protein efficiency ratio (PER) were evident at the ration size of 4–6% body weight. Second‐degree polynomial regression analysis of the FCR, PER, and protein and energy retention data indicated the breakpoints at ration size of 5.16%, 5.24%, 5.52% and 5.42% body weight per day. Carcass composition of fish fed different ration sizes varied significantly. Maximum carcass protein and minimum moisture content were noticed at 4% and 6% ration levels. A linear increase in fat content was evident with increasing ration levels up to 6% body weight. Ash content remained insignificantly different among various ration levels except at 2%, showing the significantly highest value. Water temperature, dissolved oxygen, free carbon dioxide, pH and total alkalinity were recorded regularly during the length of the experiment. No mortality was observed during the feeding trial. Based on the above results, it is recommended that feeding in the range of 5–5.5% body weight per day corresponding to 20 g protein and 181 kcal energy to 22 g protein and 199 kcal energy per kg of the diet per day is optimum for the growth and efficient feed utilization of C. mrigala.     

Dietary lysine requirement of fingerling Catla catla (Hamilton) based on growth, protein deposition, lysine retention efficiency, RNA/DNA ratio and carcass composition

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.     

Dietary L‐tryptophan requirement of fingerling stinging catfish,Heteropneustes fossilis (Bloch)

To quantify dietary L‐tryptophan requirement of fingerling Heteropneustes fossilis (6.66 ± 0.08 g), casein–gelatin‐based isonitrogenous (38% CP) and isoenergetic (14.72 kJ g^?1 DE) purified diets with eight levels of L‐tryptophan (0.12%, 0.16%, 0.20%, 0.24%, 0.28%, 0.32%, 0.36%, 0.40% dry diet) were fed to triplicate groups of fish twice daily to apparent satiation for 12 weeks. Incremental levels of dietary tryptophan from 0.12 to 0.28% significantly (P < 0.05) improved absolute weight gain (AWG; 14.3–65.9 g fish^?1), feed conversion ratio (FCR; 5.9–1.5), protein retention efficiency (PRE; 6.2–32.2%), haemoglobin (Hb; 6.5 to 11.9 g dL^?1) and haematocrit (Hct; 23.5–33.8%). To determine the precise information on tryptophan requirement, data were subjected to broken‐line and second‐degree polynomial regression analysis. Broken‐line regression analysis reflected highest R² values for AWG g fish^?1 (0.999), PRE% (0.993), Hb g dL^?1 (0.995) and Hct% (0.993) compared with R² values obtained using second‐degree polynomial regression analysis of AWG g fish^?1(0.949), PRE% (0.890), Hb g dL^?1(0.969) and Hct% (0.943), indicating that data were better fit to broken‐line regression analysis. Hence, based on broken‐line regression analysis at 95% maximum response, tryptophan requirement of fingerling H. fossilis is recommended between 0.24% and 0.27% dry diet (0.63–0.71% protein).