Nutritional requirement and feed formulation of Mystus gulio fry
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Date
2023-06-01
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Department of Zoology, OUAT, Bhubaneswar
Abstract
Three different experiments of 90 days duration each were conducted to determine the optimum dietary protein and lipid requirement (Experiment 1), dietary carbohydrate level (Experiment 2) and formulation and evaluation of practical diets based on the nutrient requirement (protein, lipid and carbohydrate) in long whiskers catfish, Mystus gulio fry (Experiment 3). For the Experiment 1, nine semi-purified diets containing three levels of protein (35.0%, 40.0% and 45.0%) and three levels of lipid (8.0%, 12.0% and 16.0%) were prepared. The prepared experimental diets were fed ad libitum to M. gulio fry (0.16 ± 0.00 g) in triplicate groups 20 fish/replicate in 27 flow-through fiber-reinforced plastic (FRP) tanks with 50 L of water. Fish were batch-weighed in every 15 days interval to determine growth and general health status of fish. Results of the experiment showed that the fish fed diet containing 40.0% protein and 12.0% lipid resulted in significantly higher (P <0.05) weight gain (4.62 g), specific growth rate (SGR; 3.77%/day), protein efficiency ratio (PER;1.52), protein productive value (PPV; 23.39%), energy productive value (EPV; 64.74%) and lower (P < 0.05) feed conversion ratio (FCR; 1.64). However, the lipid productive value (LPV; 30.56%)
was significantly higher (P < 0.05) in 40.0% protein and 8.0% lipid. The whole body protein (15.28%) and lipid contents (5.33%) were significantly higher (P < 0.05) in fish fed diets containing 40.0% protein and 12.0% lipid diet and 35.0% protein and 16.0% lipid diet, respectively. Second-order polynomial regression analysis of weight gain and FCR against the optimum dietary protein and lipid requirement of M. gulio fry is 40.9-41.1% protein diet and 12.2-12.6% lipid diet, respectively. For Experiment 2, five iso-proteinous (40.0%) and iso-lipidic (12.0%) semi-purified diets with 10.0, 15.0, 20.0, 25.0 and 30.0% carbohydrate level were
prepared. Experimental diets were fed ad libitum to M. gulio fry (0.33 ± 0.004 g) in triplicates 10 fish/replicates using 15 FRP tanks (50 L). At the end of the feeding period, the diet containing 20.0% carbohydrate diet had significantly higher (P < 0.05) weight gain (8.39 g), SGR (3.62%/day), PER (1.52), PPV (24.08%), LPV (27.13%), EPV (66.89%) and lower (P < 0.05) FCR (1.65) as compared to other diet fed groups. The fish fed with carbohydrate beyond 20.0% diet had significantly higher (P < 0.05) hepatosomatic index and viscerosomatic index than the lower carbohydrate fed groups. While the whole body protein (15.79%) content is significantly (P < 0.05) higher in 20.0% carbohydrate diet and the lipid content (5.77%) was significantly higher (P < 0.05) in 30.0% carbohydrate diet. Second order polynomial regression analysis of weight gain FCR,
PPV, PER and SGR against the dietary carbohydrate had showed that the optimum dietary carbohydrate requirement of M. gulio fry is 19.78-20.73%. For Experiment 3, six fish meal: oil cake: bran based practical diets were formulated were formulated in which 40.0% crude protein and 12.0% lipid were maintained as per the nutrient requirement of the M. gulio fry studied earlier (Experiment 1). Diets were designated as groundnut oil cake (GNOC; D-1), soybean meal (SBM;D-2), mustard oil cake (MOC; D-3), sesame oil cake (SOC; D-4), mahua oil cake (MAOC; D-5) and Mixed (combination of all oil cakes; D-6) based on the main oil cakes used as plant protein source. The formulated diets were fed ad libitum to M. gulio fry (0.33 ± 0.004 g) in triplicates 10 fish/replicate in 18 FRP tanks (50 L). At the end of the experiment, the diet containing soybean meal (SBM) had significantly better (P < 0.05) weight gain (5.22 g), SGR (3.11%/day), PER (1.43), PPV (22.16%), LPV (27.09%), EPV (73.35%) and lower (P < 0.05) FCR (1.68) as compared to other fed groups. The whole body protein (15.49%) and lipid (5.26%) content is significantly better (P < 0.05) in SBM diets. Hence, the fish meal: soybean meal: bran based diet (D-2) is suggested to use in rearing of M. gulio fry.