Corresponding author: Baidya Nath Paul ( bnpaulcifa@gmail.com ) Academic editor: Jolanta Kiełpińska
© 2021 Baidya Nath Paul, Debnarayan Chowdhury, Arabinda Das, Rathindra Nath Mandal, Puja Singh, Subhendu Adhikari, Partha Pratim Chakrabarti, Shiba Sankar Giri, Koushik Ghosh.
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Citation:
Paul BN, Chowdhury D, Das A, Mandal RN, Singh P, Adhikari S, Chakrabarti PP, Giri SS, Ghosh K (2021) Effect of dietary lipid levels on growth, body composition, and enzyme activities of larvae of butter catfish, Ompok bimaculatus (Actinopterygii: Siluriformes: Siluridae). Acta Ichthyologica et Piscatoria 51(3): 289-298. https://doi.org/10.3897/aiep.51.67079
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The Indian butter catfish, Ompok bimaculatus (Bloch, 1794), is a high-value catfish that has gained immense consumer preference in South-East Asia. However, information on the nutritional requirements of this species is scanty. Hence, an experiment was conducted to evaluate the effects of varying dietary lipid levels on growth, body composition, and activities of digestive and metabolic enzymes in larvae. Three isonitrogenous (40% crude protein) diets were formulated by supplementing fish and vegetable oil (1:1) at 4.5% (D1), 7% (D2), and 9.5% (D3) levels (containing crude lipid 5.7%, 8.0%, and 10.45%, respectively in diets D1–D3) to a fish meal- and oilcake-based formulated diet. Experimental diets were fed to butter catfish larvae (0.15 ± 0.01 g) in triplicate groups for a period of 42 days. Proximate compositions of the experimental diets, as well as fish carcass, were analyzed using standard procedures (
lipid, larvae, Ompok bimaculatus, growth, lipase, metabolic enzyme
The Indian butter catfish, Ompok bimaculatus (Bloch, 1794), is indigenous to the South East Asian countries (
The successful culture of any fish species largely depends on the accessibility of nutritionally balanced practical diets. Although species of the genus Ompok have been generally recognized as carnivorous to omnivorous, reports on nutritional requirements of the species are scanty (
However, dietary protein requirements are known to be affected by the amount of non-protein energy sources in the diet (
Vegetable and fish oils are rich in different fatty acids, which were recognized as effective for diverse freshwater fish species (
Three experimental diets were formulated by incorporating equal proportions of fish oil (cod liver oil) and vegetable oil (sunflower oil) (1:1) at 4.5% (D1), 7% (D2), and 9.5% (D3) levels to a basal mixture of fish meal (FM), soybean meal (SBM), and groundnut oil cake (GNOC). After analysis of lipid content of the feed, it was noticed to contain 5.7%, 8.0%, and 10.5% crude lipids, respectively. The amount of lipid sources used was adjusted at the expense of wheat flour. A vitamin–mineral premix was added to the diets as per
The experiment was conducted at the Regional Research Centre of ICAR-Central Institute of Freshwater Aquaculture, Rahara, Kolkata. Farm-raised larvae of the butter catfish were collected from ICAR-Central Institute of Freshwater Aquaculture, Kalyani Field Station, and acclimatized to the laboratory condition for one week in fiber-reinforced plastic (FRP) tanks with the provision of continuous aeration. During this period the larvae were fed a basal formulated diet and natural food (mixed zooplankton and chopped tubifex). After acclimatization, the larvae (mean weight 0.15 ± 0.02 g; length 22.65 ± 1.70 mm; 14 days old) were randomly distributed in 9 FRP tanks at a stocking density of 50 fish per tank. Thus, there were three replicates for each dietary group. The experiment was conducted in 150 L FRP tanks, each containing 50 L of water, with continuous aeration and water exchange at every 5 days interval. The powdered feed mixtures were made to soft dough with distilled water and the fish were fed ad libitum to apparent satiation twice daily, at 10.00 and 16.00 h, for 42 days. Feed consumption and mortality in each tank were recorded separately, and the survival rate was calculated. During the experimental period, water quality parameters were monitored on weekly basis following the standard methods of the American Public Health Association (
Proximate compositions of the experimental diets, as well as fish carcass, were analyzed using standard procedures portrayed by the Association of Official Analytical Chemists (
At the end of the feeding trial fish were collected from each tank, weighed, and analyzed for calculating the growth parameters. Net weight gain [%], specific growth rate (SGR [% · day−1]), feed conversion ratio (FCR), protein efficiency ratio (PER), apparent net protein utilization (ANPU), and survivability [%] were calculated following standard methods described by
Digestive enzymes (amylase, alkaline protease, pepsin, and lipase) of fish from each experimental set were estimated at the termination of the experiment. For each replicate, digestive tracts of 20 experimental fish from each tank were dissected out, washed thoroughly with chilled distilled water, taken on an ice-cooled Petri plate, and weighed. A 10% homogenate with chilled 0.1 (M) phosphate buffer (pH 7) was prepared and centrifuged at 10 000 rpm (10 min, 4°C). The ensuing supernatant was used as the enzyme extract to appraise the activities of the digestive enzymes. The protein content of the extract was estimated after
Following the collection of the digestive tracts, hepatic tissues were removed, collected separately and a 10% homogenate was made in sucrose solution (0.25 M, pH 7.4). Remains of the cell along with nuclei were removed by centrifugation (1000 g, 30 min, 4°C), and the supernatants were further centrifuged (10 000 g, 15 min, 4°C) to get the mitochondrial pellets (
Hexokinase (HK) activity was measured by the reduction of NADP to produce NADPH according to
Glucose-6-phosphate dehydrogenase (G6PD) activity was analyzed using glucose-6-phosphate (substrate) and NADP following
Alanine transaminase (ALT) activity was determined using α-ketoglutarate and DL-Alanine as substrates (
The data were analyzed by one-way analysis of variance (ANOVA) as per
The ingredients and proximate composition of the experimental diets are presented in Table
Feed formulation and proximate composition (% DM Basis) of the experimental diets.
Parameter | Experimental diet | ||
---|---|---|---|
D1 | D2 | D3 | |
Fish meal | 53.00 | 53.0 | 53.00 |
Groundnut oil cake | 15.00 | 15.0 | 15.00 |
Soybean meal | 10.00 | 10.0 | 10.00 |
Wheat flour | 10.50 | 8.0 | 5.50 |
Carboxy methyl cellulose | 2.00 | 2.0 | 2.00 |
Fish:Veg. oil (1:1) | 4.50 | 7.0 | 9.50 |
Vitamin-mineral mix* | 5.00 | 5.0 | 5.00 |
Proximate composition [% DM basis] | |||
Dry matter | 92.85 ± 0.06 | 92.37 ± 0.23 | 92.06 ± 0.05 |
Crude protein | 40.46 ± 0.06 | 40.18 ± 0.49 | 40.61 ± 0.83 |
Crude lipid | 5.70 ± 0.20 | 8.00 ± 0.25 | 10.45 ± 0.45 |
Total Ash | 14.40 ± 0.30 | 15.40 ± 0.20 | 16.50 ± 0.30 |
Nitrogen free extracts | 29.50 ± 0.37 | 27.61 ± 2.05 | 21.80 ± 0.28 |
Crude protein:crude fat | 7:1 | 5:1 | 4:1 |
Energy [kJ g−1] | 13.85 ± 0.02 | 14.09 ± 0.08 | 14.39 ± 0.08 |
The growth performance of O. bimaculatus larvae fed varying levels of dietary lipid for 42 days is depicted in Table
Growth performance in Ompok bimaculatus larvae fed with graded levels of lipid.
Parameter | Experimental diet | ||
---|---|---|---|
D1 | D2 | D3 | |
Initial weight [g] | 0.15 ± 0.02 | 0.14 ± 0.01 | 0.15 ± 0.01 |
Final weight [g] | 1.10 ± 0.12a | 1.40 ± 0.07b | 1.06 ± 0.03a |
Net weight gain | 0.95 ± 0.12a | 1.31 ± 0.06b | 0.91 ± 0.03a |
Specific growth rate [%] | 4.73 ± 0.35a | 5.50 ± 0.05b | 4.66 ± 0.22a |
Daily growth coefficient | 0.73 ± 0.02a | 1.003 ± 0.05b | 0.76 ± 0.09a |
Survivability | 83.85 ± 6.15 | 83.85 ± 6.15 | 79.55 ± 5.46 |
Number of dead fish | 25 | 25 | 31 |
Feed conversion ratio | 1.86 ± 0.10b | 1.39 ± 0.05a | 1.74 ± 0.07b |
Protein efficiency ratio | 1.31 ± 0.09a | 2.39 ± 0.17b | 1.30 ± 0.08a |
Apparent net protein utilization | 16.09 ± 0.92a | 23.19 ± 1.10b | 17.18 ± 0.82a |
Proximate carcass compositions of the butter catfish larvae fed experimental diets are presented in Table
Carcass composition [g · 100 g−1] of O. bimaculatus larvae fed different levels of lipid.
Constituent [g · 100 g−1] | Experimental diet | ||
---|---|---|---|
D1 | D2 | D3 | |
Moisture | 79.37 ± 0.09a | 80.93 ± 0.22b | 79.80 ± 0.17a |
Crude protein | 13.93 ± 0.09 | 14.40 ± 0.21 | 14.03 ± 0.08 |
Crude lipid | 2.50 ± 0.06a | 2.90 ± 0.12b | 2.77 ± 0.07b |
Ash | 1.70 ± 0.06 | 1.97 ± 0.09 | 1.80 ± 0.06 |
Digestive enzymes i.e., amylase, alkaline protease, lipase, and pepsin of the butter catfish larvae fed diets with varied lipid levels are given in Fig.
Activities of the hepatic enzymes involved in the intermediary metabolism of carbohydrate, protein, and lipid are depicted in Table
Specific activity [U mg protein–1] of metabolic enzymes of Ompok bimaculatus larvae fed varying levels of lipid.
Enzyme | Experimental diet | ||
---|---|---|---|
D1 | D2 | D3 | |
Hexokinase | 9.82 ± 0.35 | 10.27 ± 0.47 | 10.54 ± 0.51 |
Pyruvate kinase | 5.6 ± 0.24a | 6.2 ± 0.27b | 6.4 ± 0.29b |
Lactate dehydrogenase | 0.845 ± 0.03c | 0.507 ± 0.02a | 0.690 ± 0.03b |
Malate dehydrogenase | 2.35 ± 0.11 | 2.24 ± 0.09 | 2.20 ± 0.11 |
Glucose 6 phosphatase | 4.05 ± 0.13a | 4.38 ± 0.17ab | 4.62 ± 0.22b |
Fructose 1,6 bis phosphatase | 3.10 ± 0.11a | 3.42 ± 0.14ab | 3.72 ± 0.15b |
Alanine aminotransferase | 3.88 ± 0.16b | 3.55 ± 0.09a | 3.78 ± 0.12b |
Aspartate aminotransferase | 6.55 ± 0.17b | 6.15 ± 0.12a | 6.45 ± 0.14b |
Glutamate dehydrogenase | 5.12 ± 0.20 | 5.20 ± 0.23 | 5.28 ± 0.27 |
Glucose-6-phosphate dehydrogenase | 32.6 ± 0.81b | 27.5 ± 0.76a | 26.4 ± 0.72a |
Lipid peroxidation | 0.92 ± 0.06 | 0.96 ± 0.004 | 1.02 ± 0.006 |
During the experimental rearing of the O. bimaculatus larvae, water temperature varied within a narrow range (28–30°C) that was considered suitable since a temperature of around 30°C was suggested as optimum for the growth of catfish (
In the presently reported study, formulated diets were readily accepted by the 14 day old O. bimaculatus larvae. The study suggests that 8% lipid in a diet with 40% crude protein might support the growth and survivability of the butter catfish larvae during early development. The required lipid level detected in the presently reported study was close to the suggested lipid levels documented for other catfishes. For example, 6.5% and 7% optimum dietary lipid requirements were reported for Ompok pabda (Hamilton, 1822) fry (
The presently reported study revealed that an increase in the dietary lipid level from 5.7% to 8% was associated with maximum growth and increased SGR [% · day−1 ] of the butter catfish larvae. Similarly, the lowest FCR and the maximum PER and ANPU values were recorded in the larvae fed diets with 8% crude lipid (D2). Our result was in compliance with the preceding reports indicating that increase in the dietary lipid up to a certain level might aid in efficient protein utilization that results in improved growth of the fish (
An increase in dietary lipid levels seems to be an important consideration for the food fishes as it might have a significant effect on the carcass quality (
Although the ontogeny of the digestive enzymes during the early development of the O. bimaculatus has been documented by some authors (
The presently reported study appraised activities of some major metabolic enzymes to evaluate the effects of the varying dietary lipid levels. Activities of the amino acid catabolizing enzymes were influenced by the dietary lipid levels. The fish liver is the hotspot for transdeamination with ALT and AST as the major enzymes (
Results of the presently reported study indicated that 8% crude lipid in the diet with 40% crude protein might assure optimum growth and survival of Ompok bimaculatus larvae during early development. An appraisal on growth, body composition, and digestive as well as metabolic function in the butter catfish larvae recorded in the study might provide some important information to consider the application of formulated diets for the larviculture of Ompok bimaculatus.
The authors greatly acknowledge the help and support of Dr. S.K. Swain, the Director, ICAR-Central Institute of Freshwater Aquaculture and Head, Department of Zoology, the University of Burdwan for providing the necessary facility to conduct the work.