Apparent digestibility coefficients for common feed ingredients in formulated diets for tropical catfish, Mystus nemurus (Cuvier & Valenciennes)

Abstract Apparent digestibility coefficients were determined for six feedstuffs, subsequent to their processing into pelleted feed for tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes), using a reference diet and test diets composed of 70% reference diet and 30% test ingredient. It was found that most ingredients were fairly well digested except maize and chicken viscera. Digestibility coefficient for protein (P), dry matter (DM) and energy (E) were: (1) fish meal: 97·8% P,97% DM. 77·88% E: (2) soybean meal: 86% P,95·55% DM, 67·89% E: (3) rice bran: 81% P,85·81% DM, 67·93% E: (4) copra meal: 79·90% P, 86% DM, 71·89% E: (5) maize: 51·93% P, 49·0% DM, 63·40% E and (6) chicken viscera: 37% P,29% DM, 52% E. Digestibility coefficients for feedstuffs indicated that animal protein product, such as fish meal and grain by-product, such as rice bran were more digestible than starchy and fibrous feed, e.g. maize. Chicken viscera was poorly digested largely due to inefficient processing. As most feedstuffs were well digested, ingredient selection should, therefore, be based primarily on their protein content, amino acid composition and palatability.     

The dietary protein requirement of a bagrid catfish, Mystus nemurus (Cuvier & Valenciennes), determined using semipurified diets of varying protein level

Triplicate groups of Mystus nemurus (Cuvier & Valenciennes) were fed isoenergetic semipurified diets containing seven dietary protein levels from 200 to 500 g kg^–1 diet for 10 weeks. Dietary protein was supplied by graded amounts of a protein mixture (tuna muscle meal:casein:gelatine) at a fixed ratio of 50:37.5:12.5. Mystus nemurus fingerlings of initial weight 7.6 ± 0.2 g were fed close to apparent satiation at 2.5% of their body weight per day in two equal feedings. Growth performance and feed utilization efficiency increased linearly with dietary protein level from 202 to 410 g kg^–1 diet and declined with protein levels of 471 g kg^–1 diet or above. Protein efficiency ratio and apparent net protein utilization started to decline when the fish were fed with dietary protein levels exceeding 471 g kg^–1 diet. Fish fed with lower protein diets (202–295 g kg^–1 diet) had significantly ( P  < 0.05) higher carcass lipid content compared with fish fed with higher protein diets. Carcass lipid contents were inversely related to moisture content. Dietary protein did not significantly affect fish carcass protein and ash content. Using two-slope broken-line analysis, the dietary protein requirement for M. nemurus based on percentage weight gain was estimated to be 440 g kg^–1 diet with a protein to energy ratio of 20 mg protein kJ^–1 gross energy. This level of protein in the diet is recommended for maximum growth of M. nemurus fingerlings weighing between 7 and 18 g under the experimental conditions used in this study.     

Reproductive biology of a tropical catfish, Mystics nemurus Cuvier & Valenciennes, in Chenderoh reservoir, Malaysia

Abstract. The reproductive biology of a popular and abundant freshwater catfish, Mystus nemurus Cuvier & Valenciennes, was examined, including sex ratio, gonadosomatic index, ova diameter and fecundity. The numerical ratio of male to female was 1:1.06 and was not significantly different (P > 0.05). Mean female gonadosomatic indices (GSI) in April and September corresponding to north-east and south-west monsoons were significantly different (P < 0.05) from the dry season (May, June, July and August). Thus the apparent GSI maxima in April and September were indicative of peak spawning period. However, there were no significant differences (P > 0.05) in the fluctuation of the measure of GSI except for those in the dry months, which probably suggested the existence of a protracted breeding season. Mean male GSI in February and November were similarly significant (P < 0.05) to the dry season, although not statistically different (P > 0.05) from those of January, March, April, July, August, October and November. This was probably attributable to an extended breeding period with spawning peaks in February and November corresponding to early and late monsoons. The aseasonal reproduction is common in tropical fishes. GSI were positively correlated with rainfall and water level fluctuations. Fecundity varied from a minimum 6900 to a maximum 93510 in specimens with total lengths of 34.8cm and 45.0cm respectively. Fecundity was found to increase linearly with length and weight and was significantly different (P < 0.05) from them.     

Evaluation of crude palm oil and refined palm olein as dietary lipids in pelleted feeds for a tropical bagrid catfish Mystus nemurus (Cuvier & Valenciennes)

The effects of different dietary lipids on the growth, feed utilization and tissue fatty acid composition of a tropical bagrid catfish Mystus nemurus (Cuvier & Valenciennes) were investigated. Eight isonitrogenous and isoenergetic semi‐purified diets were fed to triplicate groups of M. nemurus fingerlings for 10 weeks. Diet lipid levels were fixed at 10%, with 1% coming from residual oil in fishmeal and the remainder from cod liver oil (CLO), corn oil (CORN), soybean oil (SBO), crude palm oil (CPO), refined, bleached and deodorized palm olein (RBDPO) or various combinations of these oils. Catfish fed diets supplemented with 9% RBDPO showed significantly (P < 0.05) higher growth rates compared with fish fed the other seven diets. No significant differences in growth performance or feed efficiency ratio were observed between M. nemurus fed 9% CLO, CORN or CPO or fish fed diets containing 4% CLO with either 5% CORN, SBO, CPO or RBDPO. Based upon these results, palm oil‐based diets can be used effectively for M. nemurus without compromising growth or feed utilization efficiency. Muscle and liver fatty acid composition of M. nemurus reflected that of the dietary oils added in pelleted diets fed to the fish. Considering the lower cost and availability of palm oil (compared with imported vegetable oils and fish oils) in many tropical countries, its use in dietary formulations for M. nemurus, and possibly other catfish species, will make these fish feeds less expensive.     

Improved survival and growth performances with stocking density manipulation and shelter availability in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae

Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L^?1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L^?1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L^?1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L^?1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L^?1 with the availability of shelter for optimal larviculture condition.     

Improved survival and growth performances with photoperiod and feeding schedule manipulation in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae

Manipulation of photoperiod: 24 h light (24L), 12 h light:12 h dark (12L:12D) and 24 h dark (24D); and feeding schedules: day and night feeding (DNF), day feeding (DF) and night feeding (NF) was conducted to determine effects on survival, cannibalism and growth of larval bagrid catfish Mystus nemurus 2–14 days after hatching (dAH). Photoperiod insignificantly affected all parameters. Feeding schedule significantly affected survival and total length at 6 (P < 0.049; P < 0.009), 10 (P < 0.033; P < 0.000) and 14 dAH (P < 0.013; P < 0.000), respectively, but affected cannibalism at 10 (P < 0.043) and 14 dAH (P < 0.013). Survival for DNF was significantly higher than DF. Cannibalism for DNF was significantly lower than NF at 10 and 14 dAH. Total length for DNF was significantly higher than DF and NF at 10 and 14 dAH. At 14 dAH, feeding schedule significantly affected feed intake, final weight and coefficient of variation. For feed intake and final weight, DNF was significantly higher than DF and NF. For coefficient of variation, NF was significantly higher than DF. This study suggests that larval bagrid catfish can be reared at 24L, 12L:12D or 24D but should be fed day and night for improved growth, survival and reduced cannibalism.     

In vivo and in vitro protein digestibility in juvenile bagrid catfish Mystus nemurus (Cuvier and Valenciennes 1840) fed soybean meal‐based diets

In vivo and in vitro protein digestibility of 0% to 60% soybean meal protein (SBM) substitution from fishmeal protein was conducted for bagrid catfish Mystus nemurus juveniles. Seven experimental diets containing 35% protein and 15% lipid were fed to bagrid catfish to determine the in vivo protein digestibility. In vitro methods were determined using pH stat, pH shift, spectrophotometric assay and sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) with different enzyme mixtures (crude intestinal extract of bagrid catfish, Lazo 1‐enzyme, Hsu 3‐enzyme, Saterlee 4‐enzyme). In vivo and in vitro protein digestibility decreased with increased SBM protein substitution with highest tolerance level of 10% (in vivo). pH stat and pH drop methods showed the highest degree of hydrolysis (DH) and relative protein digestibility (RPD) using Saterlee 4‐enzyme system. However, pH stat method showed highest correlations (r² = 0.9263) with the in vivo results using crude intestinal enzyme extract compared to other enzyme systems. The highest correlation of the in vitro methods using crude intestinal enzyme extracts of bagrid catfish was determined using spectrophotometric assay (r² = 0.9284) followed by pH stat (r² = 0.9263), SDS‐PAGE (r² = 0.8348) and pH drop (r² = 0.6777). All the in vitro methods tested are suitable to rapidly determine protein digestibility for bagrid catfish except for pH drop.     

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.     

Effects of feeding rate on growth, feed utilizationand body composition of a tropical bagrid catfish

A 10 week experiment was conducted to determine theeffects of feeding rate on growth, feed utilizationand body composition of the tropical bagrid catfish,Mystus nemurus. Catfish fingerlings with anaverage initial body weight of 12 g were fed apractical diet (36.2% protein, 16.5 kJ/g diet) atrates of 1, 2, 2.5, 3, 3.5, 4 or 5% of their bodyweight (BW) per day in two equal meals. Watertemperature was approximately 29 °C throughoutthe experiment. Percent weight gain increased almostlinearly with increasing feeding rates up to 2.5%BW/day beyond which no significant (P > 0.05)improvement in weight gain was observed. The specificgrowth rate of catfish fed rations of 1% BW/day was0.72%/day and this increased significantly to anaverage of 1.39%/day for catfish fed 2.5% BW/day andbeyond. Feed utilization did not differ significantly(P > 0.05) between fish fed 1.0 to 2.5%BW/day but decreased when rations were increased to3.0% BW/day and above. Feed efficiency ratio was0.79 for catfish fed 1.0% BW/day compared to a ratioof 0.27 for fish fed at 5% BW/day. Catfish fed 1.0%BW/day had the lowest condition factor, hepato- andviscerosomatic indices, but the highest carcass tobody weight ratio. These fish also had lowerproportions of whole body dry matter, lipid andprotein, carcass dry matter and lipid, and visceraldry matter and lipid than fish in other groups. Therewere no significant differences in either conditionindices or relative body composition of fish fedrations of 2.0 to 5.0% BW/day. Based on the growth,feed efficiency and body composition data obtained, afeeding rate of 2.5% BW per day is recommended forM. nemurus fingerlings raised at 29 °C.     

Dietary protein requirement for fingerling Channa punctatus (Bloch), based on growth, feed conversion, protein retention and biochemical composition

An 8-week feeding trial was conducted in a flow-through system (1–1.5 L min⁻¹) at 27°C to determine dietary protein requirement for Channa punctatus fingerlings (4.58 ± 0.29 g) by feeding six isocaloric diets (18.39 kJ g⁻¹, gross energy). Diets containing graded levels of protein (300, 350, 400, 450, 500 and 550 g kg⁻¹) were fed to triplicate groups of fish to apparent satiation at 09:00 and 16:00 h. Maximum absolute weight gain (AWG; 8.11 g fish⁻¹), specific growth rate (SGR; 1.82%) and best feed conversion ratio (FCR; 1.48) were recorded in fish fed diet containing 450 g kg⁻¹ protein, whereas protein efficiency ratio (PER; 1.52), protein retention efficiency (PRE; 25%), energy retention efficiency (ERE; 78%) and RNA/DNA ratio (3.01) were maximum for the group fed dietary protein at 400 g kg⁻¹. Second-degree polynomial regression analysis of AWG, SGR and FCR data against varying levels of dietary protein yielded optimum dietary protein requirement of fingerling between 462.24 and 476.72 g kg⁻¹, whereas the regression analysis of PER, PRE, ERE and RNA/DNA ratio data showed a lower protein requirement of 438.28–444.43 g kg⁻¹ of the diet. Considering the PER, PRE, ERE and RNA/DNA ratio as more reliable indicators, this protein requirement is recommended for developing quality protein commercial feeds for C. punctatus fingerlings.     

Utilization of different carbohydrate sources and starch forms by bagrid catfish (Mystus nemurus) (Cuv & Val)

Two experiments were conducted to ascertain the utilization of different carbohydrate sources and different forms of starch present in bagrid catfish (Mystus nemurus) fry. The nutritional quality and starch forms of cornstarch, dextrin, broken rice, and sago flour were evaluated in a 4 × 2 factorial design. All diets were formulated to be isonitrogenous (400 g kg^?1 crude protein) and isolipidic (150 g kg^?1 crude lipid), fed to triplicate groups of bagrid catfish fry (initial weight 6.04 ± 0.04 g). Growth studies, enzymatic response and postprandial plasma glucose were observed. A two‐way anova (P > 0.05) analysis of the data obtained showed that the final body weight, specific growth rate (SGR) and food conversion ratio (FCR) were significantly affected by carbohydrate source, but not significantly affected by starch form. Fish fed broken rice and corn starch had similar SGR and FCR compared to fish fed with dextrin and sago flour. The postprandial plasma glucose trend in fish fed with corn starch and broken rice showed a gradual increase while sago flour and dextrin‐fed fish peaked at 2 and 3 h, respectively. Lipogenic enzyme (G6PDH) activity were more pronounced than gluconeogenic enzyme (ME) in M. nemurus irrespective of carbohydrate source and starch form. Therefore, we suggest that raw broken rice and corn starch are suitable carbohydrate sources in the M. nemurus diet.     

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.     

Effect of dietary protein on growth, feed conversion, body composition and survival of pike perch fingerlings (Sander lucioperca)

Triplicate groups of pike perch (Sander lucioperca) juveniles were fed six experimental diets containing protein levels varying from 263 to 619 g kg⁻¹ dry matter (d.m.) for 56 days. Dietary protein was supplied by graded amounts of fish meal (with 720 g kg⁻¹ crude protein). Crude lipid and gross energy content of 101–107 g kg⁻¹ and 19.9–20.6 MJ kg⁻¹ remained constant between experimental diets. Pike perch with an initial body weight of 1.05 ± 0.05 g were randomly distributed in 18 tanks of two similar recirculation systems and fed on gradually decreasing feeding rates of 10 to 6% of their body weight per day. Growth performance and feed conversion increased with dietary protein level from 263 to 549 g kg⁻¹ d.m. but did not decline at highest dietary protein level. Protein efficiency ratio declined linearly with increasing dietary protein. Survival ranged between 89.7 and 93.9% and was not affected by dietary composition. Dry matter and crude lipid content of pike perch fingerlings decreased with increasing dietary protein supply and significantly the lowest dry matter and crude lipid levels were observed in fish fed diets containing 619 g kg⁻¹ of crude protein. The dietary protein requirement for pike perch fingerlings calculated by broken‐line and second‐order polynomial regression ranged between 529 and 577 g kg⁻¹, respectively.     

Effect of glycine betaine, a feed attractant affecting growth and feed conversion of juvenile freshwater prawn Macrobrachium rosenbergii

A feeding experiment was conducted to determine the effect of the feeding attractant, glycine betaine (betaine hydrochloride) on the growth and feed conversion of juveniles of Macrobrachium rosenbergii (deMan) (mean initial weight 1.12 g). Three types of diets were prepared with the incorporation of glycine betaine at 5, 10 and 15 g kg^?1 levels along with an unsupplemented control. After 60 days, weight gain, feed intake and food conversion ratio (FCR) were higher in prawn fed the three glycine betaine‐added diets compared with the control feed. Among the glycine betaine‐added diets, prawn fed glycine betaine at 5 g kg^?1 level showed highest weight gain (2.73 g) by registering 61.5% increase in growth over control and also higher feed intake (5.79 g) and good FCR (2.12). There were highly significant differences (P < 0.01) in weight gain, feed intake, per day growth and FCR among treatments. There was no significant difference (P > 0.05) in survival among treatments.     

Effect of dietary protein levels on growth,feed utilization and carcass composition of endangered bagrid catfish Horabagrus brachysoma (Gunther 1864) fingerlings

An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg^?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg^?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg^?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg^?1 diet.     

Growth, feed efficiency and body mineral composition of juvenile vundu catfish (Heterobranchus longifilis, Valenciennes 1840) in relation to various dietary levels of soybean or cottonseed meals

This study aimed to assess the effect of soybean meal (SBM) and cottonseed meal (CSM), as partial replacement of dietary fish meal on growth, feed efficiency (FE) and body mineral composition of juvenile vundu (Heterobranchus longifilis). Five iso‐nitrogenous (390 g kg^?1 crude protein) and iso‐caloric (18 kJ g^?1, gross energy) diets (Control, SBM30, SBM60, CSM30 and CSM60) were fed to triplicate groups of 40 fish (initial mean weight: 12 g) in each tank (0.9 m³). Over a 7‐week feeding period, significant differences (P < 0.05) were observed on growth, FE and body mineral composition between treatments. Fish‐fed CSM‐based diets and 600 g kg^?1 SBM‐based diet had reduced growth and reduced feed and protein efficiencies when compared with those fed diet containing 300 g kg^?1 SBM or the control diet. Data from body mineral composition in response to dietary treatment could be divided into two groups. The first group refers to elements such as Mg and Fe for which carcass and fillet composition did not show significant differences with dietary level of SBM or CSM. Ca, P, K, Zn and Mn composed the second group of minerals whose concentrations in fish body were significantly reduced in fish‐fed SBM60. In conclusion, the results of this study indicate that although solvent‐extracted SBM and CSM are often reported safe for fish, they can only partially replace fish meal as a source of protein in compound feed for vundu at a limited amount between 300 and 600 g kg^?1 for SBM and <300 g kg^?1 for CSM.     

Dietary l‐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.