Diets For African Catfish Research Articles

Replacement of dietary fish oil with palm fatty acid distillate elevates tocopherol and tocotrienol concentrations and increases oxidative stability in the muscle of African catfish, Clarias gariepinus

An 8-week feeding trial was conducted to determine the effect of substituting fish oil with palm fatty acid distillate (PFAD), a by-product from crude palm oil refining, on growth, feed utilization, vitamin E deposition, and oxidative stability in the muscles of African catfish. Five isonitrogenous, isoenergetic, and isolipidic (10%) practical diets were formulated to contain 0%, 25%, 50%, 75%, or 100% substitution of fish oil with PFAD. Growth of African catfish was significantly ( P<0.05) better in fish fed the 25% PFAD diet compared to fish fed the control diet, with fish oil as the sole lipid source. Higher levels of dietary PFAD supplementation did not cause further improvement in growth performance of catfish. Muscle concentrations of α-tocopherol, α-tocotrienol, and γ-tocotrienol increased linearly in response to increasing dietary concentrations originating from the added PFAD. α-Tocopherol constituted 68.5–80.2% of the vitamin E composition of catfish muscle, with total tocotrienols maintaining an equilibrium of 13.4–26.7% irrespective of dietary composition. Thiobarbituric acid-reactive substance (TBARS) concentrations in the muscles of catfish decreased significantly with increasing levels of dietary PFAD. The present study showed that the use of PFAD in catfish diets could offer protection against lipid peroxidation in muscles that would translate to longer shelf-life for seafood products. In fish meal-based diets for African catfish, PFAD can totally replace added fish oil. The use of PFAD is a practical and cost-effective way to produce high-energy diets without the damaging side effects of increased lipid radicals.

Dietary lipid and palm oil source affects growth, fatty acid composition and muscle α-tocopherol concentration of African catfish, Clarias gariepinus

The effects of various dietary lipids on the growth performance and muscle fatty acid and α-tocopherol concentrations of African catfish were examined. Seven isonitrogenous and isoenergetic semipurified diets were formulated with 10% lipid coming from either cod-liver oil (CLO), sunflower oil (SFO), refined, bleached, deodorized palm olein (RBDPO), crude palm oil (CPO), crude palm kernel oil (CPKO), or combinations of 5% CLO with either 5% of palm fatty acid distillates (PFAD) or 5% of residual oil in spent bleaching clay (SBC), respectively. Catfish fed with the CLO diet showed significantly ( P<0.05) lower growth and feed utilization efficiency compared to fish fed with the other six diets after 7 weeks. The growth response among catfish fed with the other diets was not significantly different. Blending CLO with either PFAD or SBC alleviated the growth reduction observed in fish fed with diets having CLO as the sole lipid source. Dietary lipid source did not affect the whole-body composition or muscle lipid level among catfish fed with the various diets. The fatty acid and α-tocopherol concentration of muscle lipids in African catfish generally reflected the fatty acid profile and α-tocopherol concentration of the dietary oil that was fed. It was concluded that products from the palm oil industry could be successfully used in the diets for African catfish, and possibly other tropical catfish species, without negatively affecting growth and feed utilization efficiency. The availability, lower cost, low polyunsaturated fatty acids (PUFA) content and high vitamin E concentration of palm oil make it the vegetable oil of choice for the formulation of fish feeds in tropical countries.

Potential of mealworm (Tenebrio molitor ) as an alternative protein source in practical diets for African catfish, Clarias gariepinus

Two separate 7-week feeding trials were conducted to evaluate the use of mealworm, Tenebrio molitor, as an alternative protein source for African catfish, Clarias gariepinus. In Experiment 1, six isonitrogenous (40% crude protein) and isoenergetic (14.64 kJ g−1) practical diets were formulated. The fish meal component of the diets was progressively substituted at 0, 20, 40, 60, 80 and 100% with mealworm meal. The experimental diets were fed to triplicate groups of catfish fingerlings (mean initial weight of 5.1 ± 0.2 g) at 4% body weight day−1. Growth performance and feed utilization efficiency of catfish fed diets with up to 40% replacement of fish meal with worm meal were not significantly different (P > 0.05) compared to fish fed the control diet without any worm meal. Catfish fed diets with up to 80% replacement of fish meal with the worm meal still displayed good growth and feed utilization efficiency. In Experiment 2, the nutritive value of mealworms was compared with a commercial catfish pellet. Three dietary treatments consisting of fish fed catfish pellets only, catfish pellets and mealworms, and mealworms only were tested. Catfish fed solely on mealworms displayed a slight depression in growth performance but when fed in combination with the catfish pellets grew as well or better than fish fed the commercial catfish pellet only. In both experiments, mealworms, whether used as such or transformed into a dry meal, were found to be highly palatable to the African catfish. Catfish fed mealworm-based diets also tend to have significantly higher lipids in their carcass. Results indicate that mealworm was an acceptable alternative protein source for the African catfish.

Inclusion of a commercial poultry by-product meal as a protein replacement of fish meal in practical diets for African catfishClarias gariepinus(Burchell 1822)

This study examined the full and partial replacement of the fish meal component of practical diets with commercial poultry by-product meal (PBM) for juvenile African catfish Clarias gariepinus (Burchell 1822). Six test diet formulations were based on a low temperature Norwegian fish meal (LT94) as the reference protein source. Dietary inclusion levels of PBM at 20%, 40%, 60%, 80% and 100% substitution of total protein content were compared with the fish meal-based control diet (100% fish meal). All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were significant differences (P < 0.05) between the final average weights of fish at the end of a 10-week feeding trial. Growth performance, feed intake, feed conversion ratio, protein efficiency ratio and specific growth rate were all depressed for catfish fed the highest levels of PBM diets compared with the fish meal group. It was inferred that amino acid profile and digestibility of protein were mainly responsible for these effects, together with reduced palatability. PBM may successfully replace up to 40% of the protein component in practical feeds for this species. Histological examination of liver tissue showed alterations in hepatic structure of those fish fed diets with higher levels of PBM.

Dietary palm oil level affects growth performance, protein retention and tissue vitamin E concentration of African catfish, Clarias gariepinus

A 9-week feeding trial was carried out to determine the effect of increasing dietary palm oil levels on growth, protein utilization efficiency and body composition of African catfish. Seven isonitrogenous and isoenergetic practical diets were formulated to contain 4%, 8%, 12% or 16% refined, bleached, deodorized palm olein (RBDPO) or 8%, 12% or 16% crude palm oil (CPO), in addition to a control diet which was not supplemented with palm oil. Growth performance of African catfish responded significantly ( P<0.05) in a positive manner to palm oil additions of up to 8% and no further improvement in growth was observed with higher levels of palm oil supplementation in the diet. Growth and protein utilization efficiency of African catfish fed diets with RBDPO or CPO at the same inclusion level were not significantly different. Significantly higher nitrogen retention was observed in catfish fed diets with 8%, 12% or 16% RBDPO compared to catfish fed 4% RBDPO or the control diet. Whole-body and muscle lipid content increased when fish were fed with increasing levels of dietary palm oil. Alpha-tocopherol concentrations in muscle and liver tissues increased linearly in response to increasing dietary α-tocopherol originating from RBDPO and CPO. Catfish fed CPO-supplemented diets had about three and five times higher concentrations of α-tocopherol in their muscle and liver tissues, respectively, compared to fish fed RBDPO-supplemented diets at all inclusion levels. It may be concluded that, under the present experimental conditions, the inclusion of at least 8% RBDPO or CPO in African catfish diets improves growth performance, protein retention and fillet vitamin E concentration of this fish.

Use of soybean flour (dehulled, solvent-extracted soybean) as a fish meal substitute in practical diets for African catfish, Clarias gariepinus (Burchell 1822): growth, feed utilization and digestibility

Growth and digestibility trials were conducted using African catfish, Clarias gariepinus (Burchell 1822): (1) to obtain apparent digestibility coefficient (ADC) values for capelin fish meal, soybean flour and corn meal; (2) to formulate diets based on ADC values of the protein feedstuffs; and (3) to evaluate the effects of replacing 25%, 50% and 75% of fish meal in control diets with soybean flour on growth, feed utilization efficiency and carcass composition. Supplemental methionine was added to the diet formulation in which soybean flour replaced 75% of the diet. Diets were formulated (400 g digestible protein kg−1 and 15 kJ digestible energy g−1 dry diet) and fed to catfish fingerlings (13.1 ± 0.5 g) to apparent satiation twice daily for 70 days. The protein and energy digestibilities of fish meal and soybean flour were high (>90% and >80%, respectively; P 0.05) growth and feed utilization efficiency to those fed the control diet. The carcass compositions of catfish in all diets were similar (P > 0.05) and the liver histology of catfish fed any of the diets showed no alterations. The results obtained indicate that 50% of fish meal protein in practical catfish diets can be replaced with soybean flour and that catfish can effectively utilize supplemental methionine, thereby allowing up to 75% of the dietary fish meal protein to be replaced by soybean flour.

An evaluation of mineral supplementation of fish meal-based diets for African catfish

Thirteen minerals have been demonstrated to be essential components of the diet of most terrestrial animals, and they may also be essential for fish (Davis and Gatlin 1991). However, unlike terrestrial animals, fish are able to absorb some minerals from their external aquatic environment, and this can complicate the determination of mineral requirements. Nevertheless, minerals are required for the maintenance of normal metabolic and physiological functions, and the lack of an essential mineral in fish diets may lead to several deficiency signs (NRC 1993; Watanabe et al. 1997). Consequently, aquafeed manufacturers usually supplement their feed formulations with mineral premixes. Fish meals contain high concentrations of minerals, including phosphorus in the form of bone ash. Additional phosphorus is usually added to fish diets but with growing concerns for the environmental effects of phosphorus discharge from aquaculture systems, research is being carried out to determine the minimum required amount of phosphorus supplementation (NRC 1993; Li et al. 1996; Eya and Lovell 1997). The need for dietary mineral supplementation for African catfish (Clarias gariepinus) fed practical diets containing high levels of fish meal has not been evaluated. The present study was conducted to evaluate the need for mineral supplementation, and also the suitability of two mineral supplements (a formulated mineral mix and a commercial Orykta TM mineral supplement) in practical diets for the African catfish.

Use of full-fat winged bean Psophocarpus tetragonolobus seed meal as a protein feedstuff in fish-meal free diets for African catfish Clarias gariepinus

Mature winged bean Psophocarpus tetragonolobus seeds were quick-cooked and the full-fat meal derived was used to completely replace menhaden fish meal as a dietary protein source for the African catfish Clarias gariepinus. Five dry practical diets (400 g crude protein kg−1 and 17.5 kJ gross energy g−1 dry diet) containing menhaden fish meal (diet 1) or winged bean meal with or without graded levels of supplemental L-methionine (diets 2, 3, 4 and 5; 0, 5, 10 and 15 g kg−1, respectively) were fed to catfish fingerlings (5.8 + 1.2 g) for 70 days. Weight gain, growth rate, feed conversion and protein utilization by catfish fed a winged bean meal diet without L-methionine supplementation (diet 2) was inferior (P > 0.05) to that in catfish fed the other diets, where performance differed nonsignificantly. Carcass protein of catfish was lower (P < 0.05) while liver protein was higher (P < 0.05) in catfish fed the winged bean meal diet without methionine supplementation. Results suggest that winged bean meal cannot replace fish meal as a protein source in catfish diets except with a minimum supplementation with 5 g L-methionine kg−1 diet.

Short Communication Apparent digestibility of various oilseed cakes/meals in African catfish diets

Short Communication Apparent digestibility of various oilseed cakes/meals in African catfish diets

Muscle and hepatic fatty acid profiles and α-tocopherol status in African catfish (Clarias gariepinus) given diets varying in oxidative state and vitamin E inclusion level

AbstractOn termination of a 56-day feeding trial, the effect of dietary oxidized oil and all-rac-α-tocopheryl acetate on fatty acid and α-tocopherol status of juvenile African catfish (Clarias gariepinusj muscle and liver was investigated. Clarias of mean initial weight 15·8 (s.e. 0·29) g were given food at -proportionately 0·03 body weight per day on diets of two oxidative states (fresh or oxidized) at two levels of supplemental α-tocopheryl acetate (20 or 100 mg/kg dry matter).As well as having a significant detrimental effect on final body weight (P &lt; 0·001), oxidation of the dietary lipid source was responsible for decreasing muscle but not hepatic polyunsaturated fatty acids (PUTAs). Liver tissue was suspected of actively synthesizing longer chain PUT As in response to consumption of oxidized oils, as indicated by decreases in the proportions of linoleate (18:2 n-6) and linolenate (18:3 n-3) and the increased abundance of eicosatetraenoic acid (20:4 n-6, arachidonate) and docosahexaenoic acid (22: 6 n-3, DHA). This phenomenon has not been described in fish nutrition and therefore possible mechanisms are discussed. Additionally, oxidized oils in catfish diets caused significant depletion of a-tocopherol from both muscle and liver (P &lt; 0·05).Modulation of the effects of oxidized lipids was achieved at the higher dietary tocopherol concentration. Appearance of an unknown aliphatic compound (equivalent chain length (ECL) = 13·1), believed to be a product of lipid peroxidation, demonstrated that catfish given rancid/low-tocopherol diets had been subjected to heightened oxidative nutritional stress. Values obtained for this peak were significantly correlated with dietary regime (P &lt; 0·02), Once more, dietary α-tocopheryl acetate moderated this effect. It was concluded that elevated inclusion of all-rac-α-tocopheryl acetate into diets for African catfish could abrogate the effects of oxidized dietary lipids on muscle and liver fatty acids and α-tocopherol.