Effect of feeding different carbohydrate to lipid ratios on the growth performance and body compositionof nile tilapia ( oreochromis niloticus ) fingerlings 1

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Effect of feeding different carbohydrate to lipid ratios on the growth performance and body compositionof nile tilapia ( oreochromis niloticus ) fingerlings 1
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  Anim. Res. 50 (2001) 91–10091©INRA, EDP Sciences, 2001 1 Dedicated to Prof. Dr. Wilhelm Hartfiel on his 75th birthday.* Correspondence and reprintsTel.: (416) 289 2107; fax: (416) 289 6606; e-mail: amanata @ hotmail.com; URL: www.geocities.com/bionutriagPresent address: BioNutriAg Consultant, 567 Scarborough Golf Club Road, #1611, Toronto, Ontario,Canada M1G 1H5. Original article Effect of feeding different carbohydrate to lipid ratioson the growth performance and body compositionof Nile Tilapia ( Oreochromis niloticus ) fingerlings 1 Amanat A LI * , Nasser A. A L -A SGAH Zoology Department, College of Science, King Saud University, PO Box 2455,Riyadh 11451, Saudi Arabia(Received 14 June 1999; accepted 12 October 2000) Abstract —In this study, we evaluated the growth performance and body composition of Niletilapia ( Oreochromis niloticus ) fed five isonitrogenous and isoenergetic diets(A, B, C, D and E)containing varying levels of carbohydrates (18.27–40.37%) and lipids(8.14–19.53%)with carbo-hydrate-to-lipid(CHO/LIP) ratios ranging from 4.95 to 0.94. Significant ( P < 0.05) differences wereobserved in the body weight gain, condition factor, specific growth rate (SGR) , feed conversionratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparentnet energyretention (ANER) values of fish fed diets with different CHO/LIP ratios. The A, B and C diets withCHO/LIP ratios ranging from 4.95 to 2.06 did not result in any difference ( P > 0.05) in fish perfor-mance. Decreasing the CHO/LIP ratio to 1.38 (diet D) significantly ( P < 0.05) reduced growth rateand feed efficiency . A further decrease in the CHO/LIP ratio to 0.94 (diet E), however, did not affect( P > 0.05) these values any more. The hepatosomatic index (HSI) increased with a decrease in theCHO/LIP ratio and was the highest (1.81) with a CHO/LIP ratio of 0.94 and lowest (1.33) with aCHO/LIP ratio of 4.95. No significant ( P > 0.05) differences were observed in the HSI valuesbetween the fish fed diets B, C and D with CHO/LIP ratios ranging from 3.33 to 1.38. The bodycompositions of the fish were significantly affected ( P < 0.05) by different CHO/LIP ratios in the diets.Body moisture and crude protein contents decreased whereas fat and ash contents increased withdecreasing CHO/LIP ratios. The CHO/LIP ratio in the diets did not, however, affect ( P > 0.05) thegross energy content of the fish. The results of the present study indicate that the optimal dietaryCHO/LIP ratio for a maximum growth performance of Oreochromis niloticus ranges between 2.06and 4.95. Oreochromis niloticus /  carbohydrate to lipid ratio / feeding / growth / body composition  A. Ali, N.A. Al-Asgah 92 1. INTRODUCTION Protein is the single most expensiveingredient in fish diets. The fact that highlevels of dietary protein may lead to the con-sumption of protein for energy purposes,has led to the investigation of the use of nonprotein energy sources in fish diets[12–14]. Providing adequate energy fromcarbohydrates and lipids in fish diets canminimize the use of costly protein. The uti-lization of carbohydrates and lipids by fishis species specific. Although lipids are wellutilized by most fish, excessive levels mayreduce fish growth or produce fatty fish [11,16, 36]. On the contrary, lipid deficient dietsmay result in growth retardation and otherphysiological symptoms [10, 36]. No spe-cific dietary requirement for carbohydrateshas been demonstrated in fish [24]. Anappropriate level of carbohydrates in fishdiets is, however, required to avoid any dis-proportionate catabolism of proteins andlipids for the supply of energy and metabolicintermediates [35, 38].The carbohydrate to lipid (CHO/LIP)ratio in fish diets has been investigated by anumber of authors. Palmer and Ryman [26]suggested that there may be an optimumcarbohydrate to lipid ratio value in troutdiets which could maximize the metabolismof glucose through hepatic glycolysis andthe overall efficiency of glucose use.Accept-able carbohydrate to lipid ratios for chan-nel catfish diets have been reported to bebetween 0.45 and 4.5 [16]. Bieber-Wlaschnyand Pfeffer [5] observed a better growth rateand enhanced protein and energy retentionin rainbow trout ( Salmo gairdneri R.) whenthe diets consisted of both fat and starch ascompared to diets containing either only fator starch. El-Sayed and Garling [13]reported that Tilapia zillii can efficientlyutilize both carbohydrates and lipids asenergy sources and that these can be sub-stituted at a rate of 1/2.25 commensuratewith their physiological fuel values.Nematipour et al. [25] reported that hybridstripped bass efficiently utilize both carbo-hydrates and lipids as energy sources but Résumé — Effets de divers régimes alimentaires à base de glucides et de lipides sur la croissanceet la composition corporelle du Tilapia ( Oreochromis niloticus ) fingerling. Cette étude avait pourbut d’évaluer les performances de croissance et la composition corporelle du Tilapia ( Oreochromisniloticus ) alimenté avec différents régimes isoazotés et isoénergétiques (A, B, C, D, et E) contenant18,27 à 40,37 % de glucides (CHO) et 8,14 à 19,53 % de lipides (LIP), dans des proportions CHO/LIPvariant de 4,95 à 0,94. Des différences significatives ( P < 0,05) ont été observées sur les valeurs degain de poids corporel, de coefficient de condition (k), de taux de croissance spécifique (SGR),d’indice de consommation (FCR), de coefficient d’efficacité protéique (PER), de rétention protéiquenette (NPR) et de rétention en énergie nette apparente (ANER). Les performances de croissancen’ont pas été significativement différentes ( P > 0,05) entre les régimes A, B et C (rapport CHO/LIPvariant de 4,95 à 2,06). En revanche, la diminution du rapport CHO/LIP à 1,38 (régime D) a diminuéle taux de croissance et l’efficacité alimentaire ; une diminution plus importante jusqu’à 0,94 (régime E)n’a pas eu d’effet plus notable ( P > 0,05). L’indice hépatosomatique (HSI) a augmenté avec ladécroissance du rapport CHO/LIP et a atteint un maximum (1,81) avec une valeur de CHO/LIPégale à 0,94 et un minimum (1,33) avec une valeur de 4,95. Aucune différence significative ( P > 0,05)n’a été observée entre les régimes B, C et D (CHO/LIP variant de 3,33 à 1,38) pour les valeurs de HSI.Les teneurs corporelles en eau et en protéines ont été diminuées alors que celles en gras et en cendresont augmenté avec la diminution du rapport CHO/LIP ( P < 0,05). En revanche, la teneur en énergiebrute n’a pas été affectée ( P > 0,05). Les résultats de l’étude montrent que le rapport CHO/LIP opti-mal pour une croissance maximale du tilapia ( Oreochromis niloticus ) se situe entre 2,06 et 4,95. Oreochromis niloticus  / glucide/ lipide / alimentation / performance de croissance / compositioncorporelle  Optimum carbohydrate to lipid ratio in Nile Tilapia diets the oxygen supply. Regular monitoring of water quality parameters was carried out.These values ranged from 7.1–8.0 for pH ,5.6–6.7 mg.L –1 fordissolved oxygen,0.12–0.20 mg.L –1 for ammonia nitrogen,0.33–0.58 mg.L –1 fornitrite nitrogen and235–350 mg.L –1 foralkalinity as CaCO 3 . Five isonitrogenous and isoenergetic dietscontaining different levels of carbohydratesand lipids were prepared using a pellet presswith a 2 mm die (Tab. I). The maize grainwas used as a source of carbohydrate. It wasreplaced gradually with equal amounts of corn oil and cod-liver oil on an energyequivalent basis. α -cellulose was added tobalance the diet composition. The diets weredried at 60 °C and then stored at –18 °Cthroughout the experimental period. Theproximate chemical compositions of thediets are given in Table II. The gross energycontents of the diets were calculated on thebasis of their protein, fat and carbohydrate(NFE) contents using the equivalents of 23.64, 39.54, and 17.15 MJ.kg –1 respec-tively [21]. Each diet was fed ad libitum to3 replicates in a completely randomizeddesign, twice daily for a period of 63 days.Daily feed intake and fortnightly weightgains were recorded. In order to quantifythe exact amount of feed intake any feedrefusal was siphoned out immediately, driedand weighed. The experiment was con-ducted under artificial light with a light anddark cycle of 12:12 hours. At the end of theexperimental period all the fish were killedand their body weights and lengths wererecorded. Five fish from each tank were dis-sected and their livers were removed andweighed. To determine the whole bodycomposition, the rest of the fish from eachtank were cut into pieces, minced, homog-enized and immediately frozen at –30 °Cfor further analysis. The proximate chemicalcomposition was determined according toAOAC methods [3]. The gross energy (GE)contents of the fish were calculated fromthe fat and protein contents using theequivalents of 39.54 MJ.kg –1 crude fat and23.64 MJ.kg –1 crude protein [21].suggested that lipids be partially replacedwith carbohydrates to improve fish qualityand productivity. Erfanullah and Jafri [15]observed that the growth of walking catfish( Clarias batrachus ) fed diets containingvarying CHO/LIP ratios (0.02 to 43.00) dif-fers significantly. Limited information is available on theoptimal level of CHO/LIP ratio in the dietsof Oreochromis niloticus. Shimeno et al.[33] studied the metabolic response of dietary carbohydrate to lipid ratios in Oreo-chromis niloticus. They reported that fishgrowth performance and protein sparingeffects are elevated with an increase indietary carbohydrate to lipid ratios. The pre-sent study was therefore conducted to deter-mine the optimum carbohydrate to lipid ratioin practical diets of Oreochromis niloticus fingerlings. 2. MATERIALS AND METHODS Oreochromis niloticus fingerlings withan average weight of 10.29 ±0.33 g werecollected from the fish hatchery of the KingAbdulaziz City for Science and Technol-ogy (KACST) Deerab, Riyadh. The fishwere acclimatized to the experimental con-ditions for a period of two weeks before thestart of the actual experiment. During thisperiod, they were kept on the same standarddiet as fed previously at the hatchery. Thirtyrandomly captured fish (divided into threereplicates of 10 fish each) were killed imme-diately. After recording their body weightand length, they were stored at –30 °C untildetermination of their initial body compo-sition at a later stage [3]. One hundred andfifty fish were then randomly divided into5 different groups with 3 replicates contain-ing 10 fish in each replicate. The fish werekept in glass tanks (100 × 42.5 × 50.0 cm)containing dechlorinated and well aeratedtap water and fitted with a waste filtrationfacility. The water temperature was main-tained at 28 ±1 ° C with the help of a ther-mostatically controlled heating system.Compressed air was used to maintain 93  A. Ali, N.A. Al-Asgah Feed conversion ratio (FCR), specificgrowth rate (SGR), protein efficiency ratio(PER), net protein retention (NPR), appar-ent net energy retention (ANER) and hep-atosomatic index (HSI) were calculated asfollows:– Feed conversion ratio = kg dry feed con-sumed per kg wet weight gain.– Specific growth rate (as percentageof body weight gain per day) = 100 [ln finalwt. (g) – ln initial weight (g)] / time (days). 94 Table I. Composition of the experimental diets (%). IngredientsDiets ABCD E Fish meal45.0045.50 46.00 46.50 47.00 Wheat bran 13.00 13.00 13.00 13.00 13.00 Maize grain 35.00 28.00 21.00 14.00 7.00 Cod liver oil 1.50 3.00 4.50 6.00 7.50 Corn oil 1.50 3.00 4.50 6.00 7.50 Gelatin 1.00 1.00 1.00 1.00 1.00 α -Cellulose 0.00 3.50 7.00 10.50 14.00 Mineral mixture 1 2.00 2.00 2.00 2.00 2.00 Vitamin mixture 2 1.00 1.00 1.00 1.00 1.00 Total 100.00 100.00 100.00 100.00 100.00 1 One kg of the premix contained: CaHPO 4 , 530 g; K 2 HPO 4 , 80 g; Na 2 HPO 4, 90 g; MgCl 2 . 6H 2 O, 100 g; KCl,67.5 g; K 2 SO 4 , 80 g; NaCl, 30 g; KI, 0.05 g; ZnSO 4 .7H 2 O, 2.5 g; SeO 2 , 0.03 g; CuSO 4 .5H 2 O, 0.15 g; FeSO 4 .7H 2 O,18 g; (NH 4 ) 6 Mo 7 O 24 .4H 2 O, 0.01 g; MnSO 4 .H 2 O, 0.5 g; NaF, 1.2 g; CoCl 2 .6H 2 O, 0.01 g. 2 One kg of the premix contained: Vitamin A, 400 000 IU; D 3 , 200 000 IU; E, 5 000 IU; K 3 , 1 g; B 1 , 1 g;B 2 , 1.5 g; B 6 , 1 g; Pantothenic acid, 5 g; Niacin, 3 g; Folic acid, 0.5 g; B 12 , 2 mg; Biotin, 100 mg; Vitamin C, 20 g. Table II. Proximate chemical composition of fish diets (on % dry matter basis). ParametersDiets ABCD E Dry matter (%) 91.68 91.83 92.01 91.82 92.19 Crude protein 38.02 37.96 38.12 37.83 37.24 Crude fibre 32.19 34.78 38.05 11.23 14.12 Total fat 38.14 10.56 14.01 16.84 19.53 Ash 11.38 11.51 10.90 10.84 10.74 Nitrogen free extract (NFE) 40.27 35.19 28.92 23.26 18.37 Gross energy (MJ.kg –1 ) 19.12 19.18 19.50 19.58 19.66 CP/CHO/LIP ratio 1 47/36/17 47/31/22 47/25/28 46/20/34 46/15/39 CHO/LIP ratio 2 34.95 33.33 32.06 31.38 30.94 P / E ratio (g protein.MJ –1 ) 3 19.88 19.79 19.55 19.32 18.94 1 Proportionate gross energy ratio from crude protein, carbohydrates and lipids. 2 Carbohydrate to lipid ratio on a weight basis. 3 Crude protein to gross energy ratio.  Optimum carbohydrate to lipid ratio in Nile Tilapia diets 3. RESULTS Significant differences ( P < 0.05) wereobserved for the body weight gain of fishfed different CHO/LIP ratios (Tab. III). Nosignificant differences ( P > 0.05) wereobserved for the body weight gain of fishfed diets A, B and C with CHO/LIP ratiosranging from 4.95 to 2.06. Decreasing thecarbohydrate to lipid ratio to 1.38 (diet D)significantly reduced ( P < 0.05) the bodyweight gain in fish. A further decrease inthe CHO/LIP ratio to 0.94 (diet E), how-ever, did not reduce ( P > 0.05) the bodyweight gain any more. Similar trends wereobserved for the specific growth rate andcondition factor. The relationship betweenbody weight gain and carbohydrate to lipidratios, determined using the second orderpolynomial model, is shown in Figure 1.Although the optimal dietary CHO/LIP ratiofor the maximum growth performance of fish ranged from 2.06 to 4.95, the maximumweight gain appeared to be at a dietaryCHO/LIP ratio of 3.4. No fish mortality wasobserved during the whole experimentalperiod. Similarly, no visual abnormalitieswere seen in fish livers. – Protein efficiency ratio = liveweight gain(g) / protein consumed (g).– Net protein retention = [increase in car-cass protein / protein fed] × 100.– Apparent net energy retention (ANER =[(final body GE KJ.g –1 ) – (initial body GEKJ.g –1 ) / KJ GE fed ] × 100).– Hepatosomatic index = (liver weight / fishweight) × 100.The condition factor (k) was calculatedaccording to the equation k = [W(g) / L(cm) 3 ] × 100, where W is the wet weight of fish in grams and L is the length in cen-timeters. The results were subjected to sta-tistical analysis using the analysis of vari-ance technique and the means werecompared by the Fisher LSD test accordingto Snedecor and Cochran [34]. A secondorder polynomial model (quadratic-linearmodel) was used to determine the optimalCHO/LIP ratio for the maximum growth of the fish [7]. The model used was: Y i = α + β 1 x i + β 2 x i2 + ε i ,i = 1, 2, 3 ..…., n where ε i ~ N (0, σ 2 ). 95 Figure 1. Relationship between CHO/LIP ratio and body weight gain.
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