Amino Acid Test Diets Research Articles

Effects of Dietary Phenylalanine: Tyrosine Ratio on Growth, DNA/RNA, Serum Biochemistry, Digestive Enzyme Activities and Physiological Responses of Heteropneustes fossilis

Stinging catfish (Heteropneustes fossilis) has high consumer demand due to its high iron and calcium contents. Also, being a lean fish, it is very suitable for people who do not prefer to consume animal fats. In view of its nutritional and therapeutic significance and lack of data on dietary phenylalanine: tyrosine ratio, a dose-response experiment was conducted to determine phe: tyr ratio for H. fossilis fry (4.1±0.3g). Six isonitrogenous (380 g/kg crude protein) and isocaloric (15.3 kJ/g digestible energy) amino acid test diets were prepared by adjusting 26.6 g/kg of total phenylalanine and tyrosine in varying ratios of phenylalanine/tyrosine (30:70, 40:60, 50:50, 60:40, 70:30, 80:20) on molar basis. Quadruplicate groups of fishes were fed with diets indicated for 12-weeks to apparent satiation, thrice daily. Mathematical analyses of Daily Growth Coefficient (DGC%), Specific Growth Rate (SGR%/day), Feed Conversion Ratio (FCR) and Erythrocyte Osmotic Fragility (EOF) as quadratic-broken line regression analyses, exhibited optimum dietary phenylalanine: tyrosine ratio of 64.94: 35.06 corresponding to 15.83 g/kg: 8.55 g/kg on equimolar basis. Data of this study would be of high significance to ensure that optimum phenylalanine and tyrosine ratio of fish is met while using a greater variety of cost-effective dietary protein feedstuffs for sustainable aquafarming of this fish.

Effect of dietary phenylalanine levels on growth, hemato-biochemical composition and tyrosine replacement value for phenylalanine in stinging catfish Heteropneustes fossilis –Bloch 1974 fingerling

Two 10-week feeding experiments were conducted to determine the total aromatic amino acid requirement and tyrosine (Tyr) replacement value for phenylalanine (Phe) for fingerling Heteropneustes fossilis by feeding casein + gelatin based amino acid test diets [400 g/kg crude protein (CP); 17.90 MJ/ kg gross energy (GE)]. In experiment 1, Phe was determined by feeding six test diets containing graded levels of Phe (4.5–14.5 g/kg diet, as fed) with 6.0 g/kg Tyr fixed and fed in triplicate groups of 20 fish each in 60-L troughs fitted with continuous flow-through. Significantly (P < 0.05) highest live weight gain (LWG%), best-feed conversion ratio (FCR), highest protein efficiency ratio (PER) and body protein deposition (BPD) was reported at 10.5 g/kg dietary Phe with constant level of Tyr 6.0 g/kg fed group. Quadratic regression analysis of live weight gain, FCR, PER and BPD data indicated Phe requirement at 11.08, 10.75, 10.45 and 10.45 g/kg of diet, respectively. Based on the above results, Phe requirement of H. fossilis is recommended at 10.8 g/kg of diet. A second experiment under similar experimental design was conducted containing graded levels of Tyr (2.1–12.1 g/kg diet, as fed) with 10.8 g/kg Phe fixed in all the diets to determine the replacement value of Tyr for Phe. Significantly (P < 0.05) highest LWG%, best-FCR, PER and BPD values were obtained at 8.1 g/kg dietary tyrosine level. Quadratic regression analysis of LWG%, FCR, PER and BPD data indicated Tyr requirement at 8.7, 8.7, 8.05 and 8.05 g/kg of diet, respectively. The above results suggest that 8.4 g/kg Tyr, corresponding to 21.0 g/kg of protein would be useful for optimum growth of H. fossilis at fingerling stage and the replacement value of Tyr for Phe is 43.75% on weight and 39.89% on molar basis. Thus, the total aromatic amino acid requirement was recommended to be 19.2 g/kg of diet, corresponding to 48.0 g/kg of protein for optimum growth of H. fossilis.

Growth, feed conversion and body composition of fingerling stinging catfish Heteropneustes fossilis (Bloch) fed varying levels of dietary l ‐threonine

An 8-week feeding trial was conducted to assess the effects of dietary l-threonine on growth, protein utilization, threonine retention efficiencies, nucleic acid indices and body composition of fingerling Heteropneustes fossilis (6.6 ± 0.1 g; 10.9 ± 0.2 cm). Casein–gelatin based isonitrogenous (38% crude protein; CP) and isocaloric (15.3 kJ g−1 digestible energy; DE) amino acid test diets with six levels of dietary l-threonine (0.75%; 1.0%; 1.25%; 1.5%; 1.75%; 2.0% dry diet) were prepared and hand-fed to quadruplicate groups of fingerling to apparent visual satiation twice daily. Weight gain (WG; 46.3 g fish−1), feed conversion ratio (FCR; 1.98), protein utilization efficiency (PUE; 0.25), threonine retention efficiency (TRE; 0.69), lipid productive value (LPV; 0.45), body protein (18.2%) and RNA/DNA ratio (3.6) of fish fed graded levels of dietary threonine increased significantly (P < 0.05) up to 1.49% threonine of dry diet. To generate precise information, the WG, RNA/DNA and LPV data were subjected to broken-line and quadratic regression analyses. The two models were superimposed and requirement was determined by establishing the point, where the quadratic curve first intersected the plateau of broken-line. Based on the above mathematical analyses, optimum dietary threonine requirement of fingerling H. fossilis was estimated to range between 1.62% and 1.69% of the diet, corresponding to 4.26–4.44% protein.

Dietary tryptophan requirement of fingerlingCatla catla(Hamilton) based on growth, protein gain, RNA/DNA ratio, haematological parameters and carcass composition

A 12-week feeding trial was conducted in eighteen 70 L indoor polyvinyl circular troughs provided with a water flow-through system (1–1.5 L min−1) at 28 ± 1 °C to evaluate the dietary tryptophan requirement of fingerling Catla catla (3.45 ± 0.24 cm; 0.60 ± 0.13 g). Six casein-gelatin-based amino acid test diets (330 g kg−1 crude protein; 13.6 kJ g−1 digestible energy) containing graded levels of L-tryptophan (1.0, 1.4, 1.9, 2.3, 2.8, 3.4 g kg−1 dry diet) were fed to triplicate groups of fish near to satiation at 08:00, 12:30 and 17:30 h. Absolute weight gain, feed conversion ratio, protein gain, RNA/DNA ratio, hepatosomatic index, viscerosomatic index, condition factor and haematological indices improved with the increasing levels of tryptophan from 1.0 to 2.3 g kg−1 of dry diet. Significantly higher carcass protein was obtained at 2.3 g tryptophan per kilogram of the dry diet. Exponential analysis of absolute weight gain, feed conversion ratio, protein gain and RNA/DNA ratio against dietary tryptophan levels at 95% maximum and minimum responses displayed the tryptophan requirement at 2.5, 2.3, 2.5 and 2.1 g kg−1 dry diet, respectively. Inclusion of dietary tryptophan in the range of 2.1–2.5 g kg−1 dry diet, equivalent to 6.4–7.6 g kg−1 dietary protein, is recommended in formulating tryptophan-balanced feed for the culture of this fish species.

Dietary phenylalanine requirement and tyrosine replacement value for phenylalanine for fingerling Catla catla (Hamilton)

Abstract Two 12-week experiments were conducted to determine the dietary phenylalanine requirement and tyrosine replacement value for phenylalanine for fingerling Catla catla. In experiment I, phenylalanine requirement was determined by feeding six casein–gelatin based amino acid test diets (330 g kg− 1 CP; 16.72 kJ g− 1 GE) with graded levels of phenylalanine (3.9, 6.4, 8.7, 11.2, 13.8, 16.2 g kg− 1 dry diet) at a constant level (10 g kg− 1) of dietary tyrosine to triplicate groups of fish (3.95 ± 0.24 cm; 0.68 ± 0.19 g) near to satiation. Live weight gain (LWG%), specific growth rate (SGR % day− 1), feed conversion ratio (FCR), protein retention efficiency (PRE%), phenylalanine retention efficiency (PHRE%) and RNA/DNA ratio responded positively with the increasing concentrations of phenylalanine reaching the highest values at 11.2 g kg− 1 of dry diet. Quadratic regression analysis of LWG, SGR, PRE, PHRE and RNA/DNA ratio at 95% of maximum response against varying levels of dietary phenylalanine exhibited the requirement at 10.3, 10.1, 9.9, 9.7 and 10.6 g kg− 1 dry diet, respectively. The above analysis revealed that inclusion of phenylalanine at 10.1 g kg− 1 of dry diet, corresponding to 594 g kg− 1 of lysine is optimum. In experiment II, six diets with different levels of l -tyrosine (1.9, 3.8, 5.9, 8.1, 9.8, 11.8 g kg− 1 dry diet) with 10.1 g kg− 1 phenylalanine (determined in experiment I) fixed in all the test diets were fed to fish (3.85 ± 0.25 cm; 0.66 ± 0.16 g) to determine the tyrosine requirement under identical conditions. Quadratic regression analysis of LWG, SGR, PRE, PHRE and RNA/DNA ratio at 95% of maximum response against dietary tyrosine concentrations indicated the requirement at 6.3, 6.5, 6.5, 7.1 and 7.3 g kg− 1 dry diet, respectively. Hence, inclusion of tyrosine at 6.8 g kg− 1 of dry diet, corresponding to 378 g kg− 1 of lysine is taken as the tyrosine required for optimum utilization of phenylalanine. Based on above data, a total requirement of phenylalanine and tyrosine for fingerling C. catla was found to be 16.9 g kg− 1 (10.1 g kg− 1 phenylalanine + 6.8 g kg− 1 tyrosine) of dry diet, corresponding to 939 g kg− 1 of lysine. Tyrosine replacement value for phenylalanine was computed to be 37% on molar basis.

Dietary threonine requirement of fingerling Indian major carp,Catla catla(Hamilton) estimated by growth, protein retention efficiency, threonine deposition, haematological parameters and carcass composition

A 12-week feeding trial was conducted to determine the dietary threonine requirement of fingerling Indian major carp, Catla catla (3.35 ± 0.11 cm; 0.59 ± 0.06 g). Six casein-gelatin based (33% crude protein; 3.23 kcal g−1 digestible energy) amino acid test diets with graded levels of analysed threonine (0.74%, 0.96%, 1.21%, 1.48%, 1.72% and 1.93% dry diet) were fed to satiation to triplicate groups of fish. Absolute weight gain (g per fish), feed conversion ratio, protein retention efficiency, threonine deposition, RNA/DNA ratio and carcass protein significantly improved with the increase in dietary threonine and peaked at 1.48% of the dry diet. Haematological indices were also found to be best in fish fed at 1.48% threonine diet. Quadratic regression analysis of absolute weight gain, feed conversion ratio, protein retention efficiency, threonine deposition, RNA/DNA ratio, carcass protein, haemoglobin (g dL−1), haematocrit (%) and RBCs (106 × mm−3) at 95% of maximum and minimum response exhibited the threonine requirement of fingerling C. catla between 1.35% and 1.48% dry diet, corresponding to 4.09–4.48% dietary protein. Present finding would be useful in formulating threonine-balanced feeds for the intensive culture of C. catla.

Total sulfur amino acid requirement and cystine replacement value for fingerling stinging catfish, Heteropneustes fossilis (Bloch)

Abstract Heteropneustes fossilis is found in most of the Asian countries and has high consumer demand due to its recuperative and medicinal qualities. Being a lean fish with high iron content, it is recommended to people suffering from anemia and cardiac diseases. In view of the above, two 8-week feeding trials were conducted to determine total sulfur amino acid requirement (TSAA) and cystine replacement value for fingerling Singhi, H. fossilis . In experiment I, six casein gelatin based isonitrogenous (380 g kg − 1 CP) and isocaloric (17.9 MJ kg − 1 GE; 15.3 MJ kg − 1 DE) amino acid test diets with graded levels of methionine (6.5, 8, 9.5, 11, 12.5, and 14 g kg − 1 of the dry diet) were prepared. Cystine was maintained at 4 g kg − 1 in all the diets. The diets were fed to quadruplicate groups of randomly assigned fingerlings (6.9 ± 0.1 g; 10.9 ± 0.2 cm) to apparent satiety twice daily at 28 °C water temperature in a flow-through system (1–1.5 L min − 1 ). Based on the quadratic regression analysis at 95% maximum and minimum response of absolute weight gain (AWG g fish − 1 ), feed conversion ratio (FCR), protein deposition efficiency (PDE%), energy deposition efficiency (EDE%), RNA:DNA ratio and methionine retention efficiency (MRE%), methionine requirements were found to range between 10.3 and 10.7 g kg − 1 of dry diet, corresponding to 27.1–28.2 g kg − 1 of the dietary protein. Hence, TSAA requirement was found to be 14.7 g kg − 1 of the dry diet (10.7 g kg − 1 methionine + 4 g kg − 1 cystine). To find out the cystine replacement value for methionine, six diets with various ratios of methionine:cystine (90:10, 80:20, 70:30, 60:40, 50:50, and 40:60) on equimolar sulfur basis as per the TSAA requirement determined in experiment I (14.7 g kg − 1 ) were prepared and fed to fingerling H. fossilis (7.2 ± 0.2 g; 11.3 ± 0.1 cm) under identical laboratory conditions. The quadratic regression analysis of AWG g fish − 1 , FCR, PDE%, EDE%, RNA:DNA ratio and MRE% at 95% maximum and minimum quadratic response projected that cystine could replace from 39.6 to 40.2% of methionine requirement on an equimolar sulfur basis without hampering growth. On the basis of the above results, the total sulfur amino acid requirement of the H. fossilis is recommended to be 14.7 g kg − 1 dry diet (7.1 g kg − 1 methionine + 7.6 g kg − 1 cystine) of which 39.9% was spared by cystine.

Dietary Histidine Requirement for Juvenile Large Yellow Croaker, Pseudosciaena crocea R.

Dietary histidine requirements for large yellow croaker (initial average weight, 6.0 ± 0.10 g) were quantified by feeding isonitrogenous (crude protein 44%) and isocaloric (20 KJ/g) amino acid test diets with graded levels of histidine [0.45% (D1), 0.66% (D2), 0.78% (D3), 0.98% (D4), 1.24% (D5) and 1.40% (D6) of dry diet]. Each diet was randomly assigned to triplicate floating sea cages (1.0 × 1.0 × 1.5 m), 60 fish/cage. At the end of the 51 day experiment, the final weight (FW) and weight gain (WG) of large yellow croaker showed a positive correlation to increasing dietary histidine content (up to 0.78%), and thereafter declined. The growth of fish fed the D6 diet was significantly lower than fish maintained on the D2 and D3 diets; however, there were no significant differences in the growth of large yellow croaker among all the dietary treatments except D6. Fish fed the D3 diet had the highest FW and WG. The shift in feed efficiency (FE) values of fish fed D1 to D5 diets increased as dietary histidine content increased, and significantly decreased in fish fed the D6 diet. Based on the second-degree polynomial regression analyses of the growth data, optimum histidine requirement for juvenile large yellow croaker was 8.7 g/kg dry diet, (18.8 g/kg–20.8 g/kg of dietary protein within 95% confidence interval).

Dietary Arginine Requirement of Fingerling Indian Major Carp, Catla catla (Hamilton)

AbstractDietary arginine requirement of fingerling Catla catla (3.55 ± 0.05 cm; 0.61 ± 0.02 g) was determined by feeding casein–gelatin‐based isonitrogenous (33% crude protein) and isocaloric (3.40 kcal/g digestible energy) amino acid test diets containing six graded levels of l‐arginine (1, 1.25, 1.5, 1.75, 2, and 2.25% dry diet) for 12 wk. Maximum absolute weight gain (6.93 g/fish), protein efficiency ratio (2.13), protein deposition (0.36), arginine retention efficiency (78%), and best feed conversion ratio (1.42) were recorded in fish fed 1.75% arginine of the dry diet. Maximum carcass protein (15.57%) and RNA/DNA ratio (4.79) were also recorded for the group fed 1.75% arginine of the dry diet. Quadratic regression analysis at 95% maximum or minimum response of above growth parameters yielded optimum arginine requirement of fingerling C. catla at 1.67% of the dry diet. On the basis of the above analysis of the growth parameters, it is recommended that the inclusion of dietary arginine at 1.67% of the dry diet is optimum for formulating arginine‐balanced, cost‐effective quality feeds for the mass culture of fingerling C. catla.

Dietary amino acid l -histidine requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and whole body protein and fat composition

An eight-week feeding trial was conducted to determine the dietary histidine requirement of Indian catfish, Heteropneustes fossilis (6.20 ± 1.25 cm, 4.65 ± 0.48 g) in 75-L flow-through circular troughs. Six isonitrogenous (40%) and isoenergetic (17.90 kJ g−1) amino acid test diets with graded levels of l-histidine (0.25–0.75%, dry diet), in gradation of 0.10% histidine were formulated. Fish were randomly stocked in triplicate groups and fed experimental diets at 4% BW per day at 08:00 and 18:00 h. Maximum live weight gain (288%), best FCR (1.40) and PER (1.78) were occurred at 0.55% dietary histidine level. For the live weight gain, FCR, PER and body protein deposition data were examined using quadratic regression analysis, the breakpoints indicating requirements for histidine at 0.58, 0.54, 0.53 and 0.54% of dry diet, respectively. Significantly (P < 0.05) low moisture and higher whole body protein content were obtained in the 0.55% histidine diet, while body fat showed an increasing trend with the increase in dietary concentrations. Ash content remained insignificantly (P > 0.05) low among all dietary groups, except in diet I and diet II. Based on the above results, the recommended diet for young H. fossilis should contain histidine at 0.54% of dry diet, corresponding to 1.35% of dietary protein for optimum growth and efficient feed utilization.

Dietary isoleucine requirement of fingerling catla, Catla catla (Hamilton), based on growth, protein productive value, isoleucine retention efficiency and carcass composition

In order to determine the dietary isoleucine requirement of fingerling catla, Catla catla (4.25 ± 0.15 cm, 0.61 ± 0.04 g), six isonitrogenous (33.0 % crude protein) and isocaloric (13.7 kJ/g digestible energy) amino acid test diets containing casein, gelatin and l-crystalline amino acids with graded levels of isoleucine (0.5, 0.75, 1.0, 1.25, 1.5 and 1.75 % of the dry diet) were prepared. Triplicate groups of fish were randomly stocked in eighteen 70-l indoor polyvinyl circular troughs at a density of 25 fingerling per trough provided with a water flow-through system (1–1.5 l min−1). The experimental diets were fed to fish to apparent satiation at 08:00, 12:30 and 17:30 h for 12 weeks. Growth of the fish was found to increase with the incremental levels of dietary isoleucine up to 1.25 % of the dry diet. Quadratic regression analysis at 95 % maximum response of absolute weight gain (6.18 g fish−1), protein productive value (0.32), isoleucine retention efficiency (71.91 g fish−1), RNA/DNA ratio (4.81) and carcass protein (15.7 %) yielded the optimum isoleucine requirement in the range of 1.13–1.18 % of the dry diet, corresponding to 3.42–3.58 % of dietary protein. Data generated in this experiment would be useful to formulate isoleucine-balanced, cost-effective quality feeds for fingerling catla.

Dietary histidine requirement of Singhi,Heteropneustes fossilisfry (Bloch)

Amino acids are vital for all living organisms including fish and histidine is an essential amino acid for fish. In view of this, dietary histidine requirement of fry Heteropneustes fossilis was determined by feeding casein–gelatin-based isonitrogenous (430 g kg−1 CP) and isocaloric (17.9 MJ kg−1 GE; 15.5 MJ kg−1 DE) amino acid test diets (10 to 20 g histidine kg−1 dry diet) to quadruplicate groups of randomly assigned fish to apparent satiety for 12 weeks. Maximum absolute weight gain (AWG; 44 g fish−1), protein retention efficiency (PRE; 20%), protein efficiency ratio (PER; 1.04), haemoglobin (Hb; 11.24 g dL−1), haematocrit (Hct; 35.11%), red blood count (RBCs; 2.98 × 109 mL−1) and lowest erythrocyte sedimentation rate (ESR; 1.92 mm h−1) were obtained at 16 g histidine kg−1 dry diet. The 95% maximum quadratic response of above data exhibited the requirement to be at 15.2, 15.1, 15.6 and 15.5 g histidine kg−1 diet. As histidine is found in higher concentration in haemoglobin, requirement obtained for Hct% and Hb is 4% greater than that required for maximizing weight gain and protein retention. Based on these results, dietary histidine requirement of H. fossilis fry is recommended between 15.1 and 15.6 g kg−1, corresponding to 35.1–36.3 g kg−1 protein.

Dietary amino acidl-methionine requirement of fingerling Indian catfish,Heteropneustes fossilis(Bloch-1974) estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g−1) and isoenergetic (17.90 kJ g−1) amino acid test diets were formulated with gradation of 0.1 g 100 g−1 containing graded levels of l-tryptophan (0.04–0.54 g 100 g−1, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g−1 tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g−1 of dry diet, respectively. Significantly (P 0.05) among treatments except for diets 0.04 and 0.14 g 100 g−1. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g−1, dry diet, corresponding to 0.80 g 100 g−1 dietary protein for optimum growth and efficient feed utilization.

Dietary arginine requirement of fingerling Indian catfish (Heteropneustes fossilis, Bloch)

An 8-week feeding trial was conducted to determine the dietary arginine requirement of fingerling Indian catfish, Heteropneustes fossilis (6.25 ± 1.30 cm, 4.8 ± 0.65 g). Six isonitrogenous (400 g Kg−1) and isoenergetic (17.90 kJ g−1) amino acid test diets were formulated with gradation of 2.5 g Kg−1 containing graded levels of l-arginine (8.5–21.0 g Kg−1, dry diet). Fish were randomly stocked in triplicate groups, in 75-l circular trough with flow-through system and fed experimental diets at 4 % BW/day at 0800 and 1800 h. Maximum live weight gain (277 %), best feed conversion ratio (FCR) (1.52) and protein efficiency ratio (PER) (1.64) were obtained in fish fed diet containing 16.0 g Kg−1 arginine. However, quadratic regression analysis of live weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary arginine at 16.80, 16.30, 16.11 and 16.10 g Kg−1 of dry diet, respectively. Significantly (p 0.05) low among all the treatments except at diet I and diet II. Based on the above results, it is recommended that the diet for young H. fossilis should contain arginine at 16.32 g Kg−1, dry diet, corresponding to 40.80 g Kg−1 dietary protein for optimum growth and efficient feed utilization.

Dietary amino acid l-tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g⁻¹) and isoenergetic (17.90 kJ g⁻¹) amino acid test diets were formulated with gradation of 0.1 g 100 g⁻¹ containing graded levels of L-tryptophan (0.04-0.54 g 100 g⁻¹, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g⁻¹ tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g⁻¹ of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g⁻¹ dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g⁻¹. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g⁻¹, dry diet, corresponding to 0.80 g 100 g⁻¹ dietary protein for optimum growth and efficient feed utilization.

Effects of dietary arginine levels on growth, feed conversion, protein productive value and carcass composition of stinging catfish fingerling Heteropneustes fossilis (Bloch)

A 12-week feeding trial was conducted to evaluate the effects of varying levels of dietary arginine on growth, feed conversion, protein productive value and carcass composition of fingerling Heteropneustes fossilis (10.11 ± 0.14 cm; 5.87 ± 0.07 g). Casein and gelatin-based isonitrogenous (38% crude protein) and isocaloric (14.72 kJ g−1 digestible energy) amino acid test diets with varying levels of l-arginine (1.00, 1.25, 1.50, 1.75, 2.00 and 2.25 g 100 g−1 of dry diet) were fed to randomly assigned triplicate groups of fish to apparent satiation twice daily at two feeding schedules (08.00 and 17.30 h). Thermal growth coefficient (TGC; 0.86), feed conversion ratio (FCR; 1.97) and protein productive value (PPV; 0.25) were best attained by the group fed diet containing 1.75 g arginine 100 g−1 of dry diet (D4). Carcass protein content also peaked at the above level of dietary arginine whereas carcass lipid showed consistent drop with the increase in dietary arginine level up to 1.75 g 100 g−1 of dry diet. Second-degree polynomial regression analysis at 95% maximum and minimum response of thermal growth coefficient, feed conversion, protein productive value, carcass protein and lipid productive value against varying levels of dietary arginine yielded that dietary arginine in the range of 1.51–1.66 g 100 g−1 of dry diet, corresponding to 3.97–4.37 g 100 g−1 protein is adequate to optimize growth, feed conversion, protein productive value and improve carcass quality in fingerling H. fossilis.

Dietaryl-lysine requirement of fingerling stinging catfish,Heteropneustes fossilis(Bloch) for optimizing growth, feed conversion, protein and lysine deposition

Dietary lysine requirement of fingerling Heteropneustes fossilis (6.96 ± 0.05 g) was quantified by conducting 12-week feeding trial in a flow-through system at 28°C. Casein–gelatin based isonitrogenous (38% CP) and isocaloric (14.7 kJ g−1 DE) amino acid test diets with six levels of dietary lysine (1.5%, 1.75%, 2.0%, 2.25%, 2.5%, 3.0% dry diet) were fed to apparent satiation in triplicates. Broken-line and second-degree polynomial regression analyses at 95% plateau of absolute weight gain (AWG; g fish−1), feed conversion ratio (FCR), protein deposition (PD; g fish−1) and lysine deposition (LD; g fish−1) exhibited lysine requirement between 2.0% to 2.3% of the dry diet, corresponding to 5.3–6.1% protein.

Dietary methionine requirement of Indian major carp fry,Cirrhinus mrigala(Hamilton) based on growth, feed conversion and nitrogen retention efficiency

This study was aimed at quantifying methionine requirement of Indian major carp fry, Cirrhinus mrigala (2.2 ± 0.2 cm; 0.19 ± 0.02 g) by conducting a 12-week feeding trial. Casein–gelatine-based isonitrogenous (40 g 100 g−1 crude protein) and isoenergetic (15.42 kJ g−1 DE) amino acid test diets were prepared to contain six levels of l-methionine (1.1, 1.3, 1.5, 1.7, 1.9 and 2.1 g 100 g−1 dry diet) at a fixed level of cysteine (0.85 g 100 g−1 dry diet) and fed to apparent satiation thrice daily to triplicate groups of fish. When absolute weight gain (g per fish), feed conversion ratio, protein deposition (g per fish) and nitrogen retention efficiency data were subjected to broken-line and second-degree polynomial regression analysis, 95% of the plateau of above parameters was achieved at dietary methionine concentrations between 1.60 and 1.69 g 100 g−1 dry diet or 0.10 to 0.11 g methionine kJ−1 DE, corresponding to 4.1–4.22 g 100 g−1 protein or 0.44–0.47 g methionine kJ−1 DE. Based on these results, dietary methionine requirement of fry C. mrigala is recommended 1.60–1.69 g 100 g−1 diet or 0.10–0.11 g methionine kJ−1 DE.

Dietary arginine requirement of Heteropneustes fossilis fry (Bloch) based on growth, nutrient retention and haematological parameters

Dietary arginine requirement of Heteropneustes fossilis fry (3.0 ± 0.5 cm; 5.1 ± 0.3 g) was determined by feeding casein-gelatin-based isonitrogenous (400 g kg−1 crude protein) and isocaloric (17.97 kJ g−1) amino acid test diets containing graded levels of l-arginine (15, 17, 19, 21, 23 and 25 g kg−1 dry diet) for 12 weeks. Maximum absolute weight gain (AWG) (44.4), best feed conversion ratio (FCR) (1.22), highest protein retention efficiency (PRE%) (41%), energy retention efficiency (ERE%) (75%), best condition factor, hepatosomatic index and viscerosomatic index were noted at 21 g kg−1 arginine of the dry diet. Maximum body protein (189.8 g kg−1) was also obtained in fish fed above diet. Highest haematocrit value (35%), Hb concentration (9.54 g dL−1), RBC count (3.44 × 109 mL−1) and lowest Erythrocyte sedimentation rate (ESR) (1.93 mm h−1) were obtained at the above level of arginine in the diet. AWG, FCR, PRE% and ERE% data were analysed using broken-line and an exponential fit to obtain more precise dietary arginine requirement. On the basis of broken-line and exponential analyses of AWG, FCR, PRE and ERE data, inclusion of dietary arginine in the range of 20.4–22.6 g kg−1 dry diet, corresponding to 51–56.5 g kg−1 dietary protein, is recommended for formulating arginine-balanced feeds for rearing H. fossilis fry.

Effect of dietary l-lysine levels on growth, feed conversion, lysine retention efficiency and haematological indices of Heteropneustes fossilis (Bloch) fry

Effect of varying dietary lysine levels on growth, feed conversion, nutrient retention, lysine retention efficiency and haematological indices of Heteropneustes fossilis fry (2.97 ± 0.11 cm; 4.78 ± 0.31 g) was studied by conducting a 12-week feeding trial. Isonitrogenous (450 g kg−1 CP) and isocaloric (17.97 kJ g−1 GE) amino acid test diets with graded concentrations of l-lysine (18, 20, 22, 24, 26, 28 g kg−1 dry diet) were fed to triplicate groups of fish to apparent satiation twice daily at 17 and 17:30 h. Maximum thermal growth coefficient (TGC, 0.82), best feed conversion ratio (FCR, 1.28) highest protein retention efficiency (PRE, 36%), energy retention efficiency (ERE, 79%) and lysine retention efficiency (LRE, 75%) were noted at 24 g kg−1 lysine of dry diet. Body protein was also found to be in line with growth data and peaked at 24 g kg−1 lysine of dry diet. Similarly, superior somatic and haematological indices were exhibited by the groups fed dietary lysine at 24 g kg−1 of the dry diet. However, exponential analysis of dietary lysine intake against TGC, lysine retention and protein retention indicated that inclusion of dietary lysine in the range of 13.24–14.14 g kg−1 dry diet, corresponding to 29.42–31.42 g kg−1 dietary protein, is essential for faster growth of this fish.