Effect of Fishmeal Substitution by Plant Protein Sources on Growth Performance and Body Composition of gilthead sea bream (Sparus aurata ) Fingerlings

Gilthead sea bream production in Mediterranean countries  increased from 30 000 tons in 1996 to 90 000 tons in 2005,which mean that sale prices dropped considerably, from 6.6 € / kg in 1996 to 5 € / kg in 2005, with an historic minimum of 4 € / kg in 2002 (APROMAR, 2006). To maintain the profitability of gilthead sea bream farms, cutting production costs is necessary, mainly through feeding, which represents between 38 and 45% of operational costs (Lisac & Muir, 2000 and Merinero et al., 2005). Reductions in feeding costs can be obtained by optimizing feeding strategies, nutrient levels in diets, and by using vegetable sources as substitutes for fish oil and fish meal. This aspect is also very important to improve the sustainability of aquaculture, as it would reduce dependence on fish sources (Martinez-Llorens et al., 2009). The requirements of dietary protein for gilthead sea bream are 45 - 50 % (Kissil et al., 2000). Therefore, it is urgent to find out alternative protein sources to replace such imported ones (Abdelhamid et al., 2001, 2004, 2005 a&b). In the last decade, the increasing demand, price and world supply fluctuations of fish meal (FM) has emphasized the need to look for alternative protein sources in aquafeeds. Some plant ingredients have been studied in gilthead sea bream (lupin seed meal, extruded peas and  rapeseed meal) but Poaceae and Fabaceae seeds and their by- products, among which corn gluten and soybean meal, in particular, are widely used in fish nutrition because of their high protein content (40-60%), low cost and relative widespread availability. Therefore, soybean meal being the most nutritive and it is used as the major protein source in many fish diets. Partial or even total replacement of dietary fish meal by soybean meal protein sources had successfully accomplished with tilapia diets (Soltan et al., 2001; Fagbenro and Davies, 2002; Wilson, et al., 2004, Abdelhamid et al., 2006 and Magdy, 2006). Some studies with gilthead sea bream have shown that partial replacement of FM by PPs is possible (Robaina, et al., 1995; Hassanen, 1997a, b; 1998; Kissil, et al., 2000; Sitja-Bobadilla et al., 2005 and Martinez-Llorens et al., 2009). Studies with sea bass have also reported some success to partial replacing of FM by PPs (Lanari, 2005 and Tibaldi, et al., 2006). Studies of using corn gluten to feed carnivorous fish (sea bream) are very limited; therefore, the scope of the present study was to evaluate the effect of partial or complete replacement of fish meal with increasing levels of plant protein origin like corn gluten and soybean meal on growth performance, feed utilization, body composition and cost production of sea bream fingerlings´ diets. 

Five isocaloric and isonitrogenous diets were formulated based on Fish meal as the only animal protein source or a mixture of PPs (Corn gluten and Soybean meal) as plant protein sources (Table 1). The diets formulated to be almost containing 45% crude protein by replacing 25, 50, 75 and 100% of the FM (fishmeal protein) in control diet. Crystalline amino acids (L-lysine and DL-methionine) were added to diets PPs 25, 50, 75 and PPs100% to become similar to control diets. Fish oil and soybean oil were added as dietary lipid sources (Table 1). The diets were pelleted using grinder of kitchen aid with a 1.5 mm diameter and kept frozen until the experiment was started. During the growth period (120 days), each diet was randomly allocated to triplicate tanks of fish. Feed was offered by hand at two meals / day (8:00h and 15:00) at 3% of body weight daily and the amount of diets were readjusted after each weighing.

1- Mixture of fish oil and soybean oil (1:1 w/w).

2- Each Kg vitamin & mineral mixture premix contained  Vitamin A, 4.8 million IU, D₃, 0.8 million IU; E, 4 g; K, 0.8 g; B₁,

    0.4 g; Riboflavin, 1.6 g; B₆, 0.6 g, B₁₂, 4 mg; Pantothenic acid, 4 g; Nicotinic acid, 8 g; Folic acid, 0.4 g Biotin,20 mg     

    , Mn, 22 g; Zn, 22 g; Fe, 12 g; Cu, 4 g; I, 0.4 g, Selenium, 0.4 g and Co, 4.8 mg.

3- Cr2O3: Chromic Oxide

* obtained from the local market.

1. Based on 5.64 Kcal/g protein, 9.44 Kcal/g fat and 4.11 Kcal/g carbohydrate (NRC, 1993).

2. Protein/Energy Ratio (mg Protein/Kcal).

Sea bream fingerlings were obtained from a private fish farm in Damietta governorate. Fish were acclimated to laboratory conditions for 2 weeks before being randomly distributed into fiberglass tank of 300-L water capacity each, in Ashtom Elgamel, Port-Said governorate. The water was obtained from channel comes from Mediterranean sea. Fish of 10±0.2 g initial body weight were distributed into 15 experimental tanks in triplicate groups of 50 fish each.  The photoperiod was regulated to be 12h light: 12h dark. Water temperature was maintained at 25ºC by a 250- watt immersion heater with thermostat. Water temperature and dissolved oxygen were recorded daily (by Metteler Toledo, model 128.s/No1242), other water quality parameters including pH and ammonia were measured every two days by pH meter (Orion model 720A, s/No 13062) and ammonia meter (Hanna ammonia meter). Water salinity was 34ppt. The average water quality criteria of all tanks are presented in Table 3.  All fish in each tank were weighed every 10 days.

Table3: Average water quality parameters in the experimental tanks used in the study. 

The tested diets and feaces were analyzed for crude protein (CP %), ether extract (EE %), crude fiber (CF %), ash (%) and moisture while whole body composition of sea bream fish samples was also analyzed except for crude fiber (CF %) according to the procedures described by A.O.A.C. (1995) as shown in Table 2 and Table 5. The nitrogen free-extract (NFE %) was calculated by difference. Blood samples were collected using heparinized syringes from caudal vein of the experimental fish at the termination of the experiment. Blood was centrifuged at 3000rpm for 5 minutes to allow separation of plasma which was subjected to determination of plasma total protein (Armstrong and Carr, 1964) and plasma albumin (Doumas, et al., 1977). Apparent protein digestibility was determined using the method of Furukawa and Tasukahara (1966). For determination of protein digestibility the diets and faeces were collected during the last 15 days of the experimental period. Any uneaten feed or faeces from each tank was carefully removed by siphoning about 30 min after the last feeding. Faeces were collected by siphoning separately from each replicate tank before feeding in the morning. Collected faeces were then filtered, dried in an oven at 60^oC and kept in airtight containers for subsequent chemical analysis.

All data of growth performance, body composition and blood parameters were analyzed by one-way analysis of variance (ANOVA) using the general linear models procedure of statistical analysis system (SAS) version 8.02, (1998). Duncan´s multiple range test (Duncan, 1955) was used to resolve differences among treatment means at 5% significant level using the following model.

   Yij =µ+Ti +Eij

      Where

 µ = over all mean.  

 Yij =the observation of the individual from T treatment           

        Ti= the fixed effect of T diet.

       Ei j = the experimental random error associated with individual J.   

The growth performance of gilthead sea bream (sparus aurata) fingerlings which fed different diets is shown in Table 4. Average body weight (g) of sea bream fingerlings fed the experimental diets at the start did not differ, indicating that groups were homogenous. At the end of growth experimental period (120 days ), the group of fish fed on fishmeal diet as a sole source of protein and groups of fish fed diets contained  25 and 50 PPs% had a significantly (P≤0.05) higher weight gain than the rest of experimental groups. Whereas the lowest body weight BW (68.9g) was achieved by group of fish fed on diet containing 100%PPs (FM was totally replaced by plant protein sources). On the other hand, the groups of fish fed on FM or 25 and 50 PPs % had a significantly (P≤0.05) higher specific growth rate (SGR %/ d) than the rest of experimental groups, however at the end of the experiment, SGR values were 1.93, 1.91, 1.87 and 1.78 %/d for group of fish fed on FM, 25PPs, 50PPs, and 75PPs%, respectively. The lowest SGR was found to be 1.72%/ d   in the group   fed on free fish meal diet (100%PPs). Results of feed utilization in terms of FCR, PER and FE are presented in Table 4. An averages of feed conversion ratio (FCR) of the FM, 25,50,75 and 100%PPs groups were found to be 1.64,1.67,1.75,2.13 and 2.31, respectively. These results indicated that the best (P≤0.05) FCR recorded were obtained by the FM and 25%PPs followed by 50 and 75%PPs. The worst FCR was observed by diet 100%PPs. The same trend was reported with protein efficiency ratio (PER) which was found to be 1.35, 1.32, 1.27, 1.04 and 0.95, respectively. Also, the results of feed efficiency (FE) followed the same trend as FCR and PER which were found to be 0.61 and 0.60 for diets FM and 25%PPs and 0.43 for diet 100%PPs. Results also revealed that, the plant protein sources PPs (corn gluten and soybean meal) could replace up to 50% of fishmeal protein in growing sea bream fingerlings diets without any adverse effects on growth performance and feed utilization parameters. 

Results of apparent protein digestibility (APD) were affected by the level of PPs in the diets which were decreased with the increasing level of PPs replacement in the diets as reported in Table 4. Results give evidence that varying feed acceptance may be a reason for this observation. However, at the end of the experiment, APD were 88.25, 87.39, 86.09 and 73.16% for groups of fish fed on FM, 25PPs, 50PPs, and 75PPs%, respectively. The lowest APD was found to be 62.32% in the group of fish fed on free fish meal diet (100%PPs). 

Blood measurements         

Results of blood measurements at the end of the experiment showed that there was no effect of the experimental diets on plasma total protein, plasma albumin and plasma total globulins of fish fed the experimental diets in comparison with the control diet (Table 4). 

Results of body composition presented in Table (5) showed that no statistical differences were observed with protein content for fish fed on groups FM, 25%PPs and 50%PPs but it was decreased significantly (P≤0.05) by the increasing levels of fishmeal replacement in diets. Partly or totally substitution of fishmeal by PPs decreased lipid content and ash content with group of fish fed on diets 75% and 100%PPs. However the moisture was increased with increasing level of plant protein substitution.

Hepato-somatic index decreased significantly (P≤0.05) with the increasing level of PPs in the experimental diets. However, at the end of the experiment, HSI was 3.2, 2.97, 2.93 and 2.71 % for groups of fish fed on FM, 25PPs, 50PPs, and 75PPs%, respectively. The lowest HSI was found to be 2.56 % in the group   fed on free fish meal diet (100%PPs) as repotted in Table 4.

The economic evaluation showed that the incorporation of PPs in sea bream diets seemed to be economic and sharply reduced the feed cost of sea bream fingerlings diets as reported in Table 6. These results indicate that incorporation of PPs in Sea bream diets reduced the total feed costs. However, high replacing levels of fishmeal by PPs (75 and 100) adversely affected all the growth and feed utilization parameters (Table 4), but the incorporation of PPs in sea bream diets seemed to be economic as incorporation of PPs in the diets sharply reduced feed costs by 18.71, 29.50 and 38.13% for PPs25, PPs50 and PPs75, respectively. The survival rate was high for all experimental groups. 

Values in the same row with a common superscript letter are not significantly different (P≥0.05).

    6-   Apparent protein digestibility, APD (%)

    7-   Plasma Total Protein, PTP (g/dl)

    8-   Plasma albumin, PA (g/dl)

    9-   Plasma total globulins= plasma total protein- plasma albumin,  PTG (g/dl)

   10- Survival rate =No of survive fish/total No. of fish at the beginning X100 

 Discussion            

Results of the present study indicate that PPs (corn gluten and soybean meal) can replace 25% to 50% of fish meal protein in sea bream diets with no significant differences (P≥0.05) in growth performance compared to the control. This conclusion is in agreement with Gomes et al (1995a & b) for rainbow trout. They reported that replacement of fishmeal by plant protein sources had no adverse effects on growth. The optimal rate of substitution found in the present research was closed   with Lanari (2005), he reported that soybean meal can substitute up to 25% of total protein of the sea bass diets without any negative effect on growth performance. Higher value than reported in the present study was reported by Gallagher (1994) in diets for hybrid striped bass, where soybean meal substituted 44% of fish meal without evidencing a negative effect on the feed intake and he also reported that up to 75% of fishmeal protein can be replaced with soybean meal. Moreover, Sitja-Bobadilla et al., (2005) reported that up to 75% of fishmeal protein can be replaced by plant protein sources for juvenile sea bream, which also is in agreement with the present study for sea bream fingerlings. In the recent years, significant amount of researches has been conducted on the replacement of FM by different PPs. The suitability of this replacement in terms of growth performance has resulted to be highly variable among fish species and experimental conditions. Thus, specific trials have to be performed for each species. In European sea bass (D.labrax) (Kaushik et al., 2004) and gilthead sea bream (S.aurata) (Pereira and Oliva-Teles, 2003 and Gómez-Requeni et al., 2004), recent short-term studies have shown that at least 60-75% of FM can be replaced by mixture of PPs without compromising growth performance. In the present study, the effects of FM replacement were studied on growth performance and feed utilization. This scenario, a high level of FM replacement by (50-75PPs %) produced a slight reduction in growth performance. Concerning the results of feed utilization in terms of FCR, PER and FE in the present study, the same trend was showed with growth performance. These results of feed utilization related to apparent protein digestibility of diets used in the experiment which showed worst feed utilization of sea bream  fed on diets containing high mixture of PPs (corn gluten meal and soybean meal) was possibly due to the low biological value of such based diets, which are in agreement with Robaina, et al.,( 1995), Boonyaratpalin et al.,(1998), Regost et al.,(1999), Lanari (2005), Sitja-Bobadilla et al. (2005), and Tibaldi, et al.,(2006). Regarding to digestibility, several investigations were conducted to evaluate using of PPs and it´s digestibility by fish. These investigations allow presenting a consolidated, core discussion. In fish, protein digestibility is generally high ranging from 75% to 95% and the apparent digestible coefficient of proteins from fish meal is often higher than 90% in salmonids (NRC, 1993). Soybean meal contains various anti-nutritional factors such as the anti-trypsin and an anti chimotrypsin factors, lectine, oligosaccharides and a low level of methionine, corn gluten has also a low level of amino acid lysine reduces the protein digestibility and amino acid availability of these plant protein ingredients. Increasing temperature can increase digestibility of soybean meal from 45% to 75% (Smith, 1976). Soybean meal can substitute up to 90% of the fishmeal in extruded diets for rainbow trout without causing redaction in the growth rate and net protein utilization and poorer FCR especially with diets containing high levels of soybean meal. Corn gluten meal (CGM) is considered to have a good digestibility (NRC, 1993).Diet containing 20% of CGM meal had a very good digestibility, in accordance with the results of Morales et al.(1994) and Gomes et al. (1995 a) in rainbow trout fed diets containing about 20% corn gluten meal. In contrast, apparent digestible coefficient of diets with high levels of plant proteins was very low. In common carp, Pongmaneerat et al. (1993) observed that the apparent protein digestibility had to be near 94% in a diet without fish meal (corn gluten meal, soybean and meat meal). Moreover, the supplementation of amino acids to diets which containing high levels of PPs give better growth performance which was reported by Rodehutscord et al.(1995). They observed that fish meal could be completely replaced by a mixture of wheat gluten and crystalline amino acids without negative influences on growth of rainbow trout. Results of apparent protein digestibility in the present study recorded that the dietary inclusion of high levels of corn gluten and soybean meal in replacement of fish meal led to a significant decrease in protein digestibility which are in agreement with Lanari (2005),  Tibaldi et al.(2006) and Sampaio-Oliveira and Cyrino(2008). The value of hepato-somatic index was found to be similar to that reported for sea bass by Ballestrazi et al., (1994) and Dias et a. ,(1998), they reported that the values of  HSI were 2-3% or above. Effect of the experimental diets on hepato-somatic index confirmed that the fish fed on diets containing high levels of corn gluten meal and soybean meal evidenced a significant (P≤0.05) decrement of the HSI in relation to the utilization of glycogen, stored as an energy source.The results are in agreement with Lanari (2005) and Sampaio-Oliveira and Cyrino(2008). Effects of the experimental diets on whole body protein concentration were very small with exception of fish diet containing FM, 25 and 50%PP which showed a significant difference (P≤0.05) compared to the other experimental diets (75 and 100%PP). Fish body fat content decreased with increasing level of PPs substitution. The low percentage of fat stored with diets containing high level of PPs is due to the limited ingestion of the feed or to probable use of the body fat as energy source and may be also related to the carbohydrate levels and type of the diets. These results are in agreement with Lanari (2005), Tibaldi et al.(2006) and Sampaio-Oliveira and Cyrino (2008) for sea bass D. labrax and Peres and  Oliva-Teles (2009) for sea bream S. aurata. Results of blood measurements showed no significant differences (P≥0.05) in plasma total protein, plasma albumin and plasma total globulins of fish fed the experimental diets in comparison with the control diet. These findings are in agreement with Soliman (2000) and Mohamed (2007), they noted that increasing the plasma total protein indicates the improvement of the nutritional value of the diet. Calculation of the economical efficiency of the tested diets was based on the costs of feed because the other costs were equal for all studied treatments. As described in Table (6) feed costs (L.E) were the highest for the fishmeal diet and gradually decreased with increasing the replacing levels of plant protein sources. These results indicate that incorporation of PPs in sea bream diets reduced the total feed costs. However, high replacing levels of fishmeal by PP (75 and 100%PP) adversely affected all the growth and feed utilization parameters (Table 4), but the incorporation of PPs in sea bream diets seemed to be economic as incorporation of PPs in the diets sharply reduced feed costs by 13.71, 27.29, 39.64 and 52.44% for 25PPs, 50PPs, 75PPs and 100%, respectively. The reduction of feed costs was easily observed for the feed costs per Kg weight gain which decreased with increasing incorporation levels of PPs in agreement with Soltan (2005) for Nile tilapia and Eid and Mohamed (2007) for sea bass fingerlings. 

 

The local market price were 8LE for fish meal, 2.50LE for gluten,  1.70LE for soybean meal, 1.00 LE for yellow corn, 9 LE for oil, 5 LE for Vit. &  Min.

From the aforementioned results, it could be concluded that incorporation of plant protein sources (corn gluten and soybean meal) can replace fish meal protein in sea bream fingerlings´diets at levels of 25 and 50 PPs% of fish meal protein under similar experimental conditions.

 

Abdelhamid, A.M., Khalil, F.F., Zaki, V.H., El-Shaieb, A.F. and El-Mezaien, A.M.M. (2001). Effect of feeding systems on performance of caged gilthead seabream (Sparus aurata) under Egyptian conditions. Egypt. J. Nutr. and Feeds, 4(2): 139- 152.

Abdelhamid, A.M., Salem, M.F.I. and Khalafalla, M.M.E. (2006). Substitution of soybean meal by waterhyacinth hay in diets of Nile tilapia (Oreochromis niloticus). The 2^nd Inter. Sci. Con. For Environment " Recent Environment Problems and Social Shrement" , 28-30 March, South Valley University. Pp: 114- 126 ( engormix. com Aquaculture Technical Articles, 2007, 6p).

Abdelhamid, A.M., Salem, M.F.I. and Tolan, A. E. (2004). Evaluation of sesame meal as a dietary protein source for Nile tilapia (Oreochromis niloticus) fingerlings. J. Agric. Sci. Mansoura University., 29 : 6887 - 6897.

Abdelhamid, A.M., Salem, M.F.I. and Tolan, A. E. (2005a). Evaluation of linseed meal as feed ingredient in diets on growing Nile tilapia (Oreochromis niloticus). J. Agric. Res. Tanta University, 31 (3): 385 - 402.

Abdelhamid, A.M., Salem, M.F.I. and Tolan, A. E. (2005b). Utilization of black seed meal (Nigella sativa) in Nile tilapia (Oreochromis niloticus). J. Agric. Res. Tanta Univ., 31 (3) : 403 -419.

A.O.A.C. (1995). Association of Official Analytical Chemists, Official Methods of Analysis. 16th edition, AOAC, Arlington, VA. 1832pp.

APROMAR., (2006). Asociacio´ n Empresarial de Productores de Cultivos Marinos de Espan, La  Acuicultura Marina de Peces en ,Espan˜a. Informes anuales. Ca´ diz, Spain, 56 pp

Armstrong, W. D. and Carr, C. W.,(1964). Physiological Chemistry Laboratory Directions. (3^rd ed.). Burges Publishing Co., Minneapolis, Minnesota.

Ballestrazi, R., Lanari, D., D´Agaro, E., and Mion, A., (1994). The effect of dietary protein level and source on growth, body composition, total ammonia and reactive phosphate excretion of growing sea bass Dicentrarchus labrax . Aquaculture, 127: 197-206. M.

Boonyaratpalin,M., Suraneiranat,P., and Tunpibal,T..(1998). Replacement of fish meal with various types of soybean products in diets for the Asian seabass, Lates calcarife, Aquaculture,161:  67-78.

Dias, J., Alvarez, M.J., Diez, A., Arzel, J., Corraze, G., Bautista, J.M.and Kaushik, S.J. (1998).  Regulation of hepati lipogenesis by dietary proteinrenergy in juvenile European seabass  Dicentrarchus labrax .Aquaculture 161 : 169-186.

Doumas, B. T., Waston, W. and Biggs, H. H., (1977). Albumin standards and the measurements of Serum albumin with Bromocresol Green. Clinical Chemistry Acta,  31: 87-96.

Duncan, N. B. (1955). Multiple range and multiple F-test. Biometrics, 11 : 1-24.

Eid, and Mohamed., K.,(2007).Effect of fishmeal substitution by plant protein sources on growth performance of seabass fingerlings (Dicentrarchus labrax).  Agricultural Research Journal, Suez Canal University, 7 (3): 35-39.

Fagbenro, O.A. and Davies, S.J. (2002). Use of oilseed meals as fishmeal replacer in tilapia diets. Proceeding of the fifth international symposium on tilapia aquaculture. Rio de Janeiro- RJ, Brazil 1: 145-153.

Furukawa, A. and Tasukahara, H., (1966). On the acid digestion method for determination of chromic oxide as an index substance in the study of digestibility of fish feed. Bulletin of the Japanese Society of Scientific Fisheries, 32: 502-506.

Gallagher, M.L. (1994). The use of soybean meal as a replacement for fishmeal in diets for hybrid striped bass (M. saxatiles  X M. chroy sops) Aquaculture, 126 (1-2) : 119-127.

Gomes, E. F, Rema, P. and Kaushik, S. (1995a). Replacement of fishmeal by plant proteins in the diet of rainbow trout (O. mykiss) digestibility and growth performance. Aquaculture, 130: 177-186.

Gomes, E. F, Rema, P. and Kaushik, S. (1995b). Replacement of fishmeal by plant proteins in diets for rainbow trout (O. Mykiss) : Effect of the quality of the fishmeal based control diets on digestibility and nutrient balances. Water Science and Technology, 31: 205-211.

Gomez-Requeni, P., Mingarro, M., Calduch-Giner, J.A., Medale, F., Martin, S.A.M., Houlihan, D.F., Kaushik, S., and  Perez-Sanchez, J., (2004). Protein growth performance, amino acid utilization and somatotropic axis responsiveness to fish meal replacement by plant protein sources in gilthead sea bream (Sparus aurata). Aquaculture, 232:  493-510.

Hassanen, G.D.I. (1997a). Nutritional value of some unconventional proteins in practical diets for sea bass (D. labrax) fingerlings. Egyptian J. Nutrition and Feeds,1(special Issue ):335-348.

Hassanen, G.D.I. (1997b). Effect of diet composition and protein level on growth, body composition and cost of production of gilthead sea bream (Sparus aurata). Egyptian .J. Aquat. Biol & Fish.,  2: 1-18.

Hassanen, G.D.I. (1998). Lupin seed meal compared with soybean meal as partial substitutes for fish meal in gilthead sea bream (Sparus aurata) diets. J. Agric. Sci. Mansoura Univ., 23(1) : 141-154.

Kaushik, S.J., Coves, D., Dutto, G. and  Blanc, D. (2004). Almost total replacement of fish meal by plant protein sources in the diet of a marine teleost, the European seabass, Dicentrarchus labrax.  Aquaculture, 230: 391 - 404.

Kissil, G.W., Lupatsch, I., Higgs, D.A,  and Hardy, R.W. (2000). Dietary substitution of soy and rapeseed protein concentrates for fish meal, and their effects on growth and nutrient utilization in gilthead sea  bream Sparus aurata L. Aquaculture Research, 31:  595-601.

Lanari,D´.A., (2005). Alternative plant protein sources in sea bass diets, ITAL.J. ANIM. Sci. .4 : 365-374.

Lisac, D.  and Muir, J. (2000). Comparative economics of offshore and on shore mariculture facilities. In: Mediterranean Offshore Mariculture. Options Me´diterrane´ennes (Serie B: E´tudes et  Recherches) (Muir, J. & Basurco, B. Eds), pp. 203-211. Publication Based on the Contents of the Advanced Course of the CIHEAM Network on Technology of  Aquaculture in the Mediterranean (TECAM) Zaragoza, Spain, 1997.

Magdy M G. (2006). Partial and complete replacement of fish meal by broad bean meal in feeds for Nile tilapia, Oreochromis   niloticus, L., fry. Aquaculture Research, 37:985.

Martınez-Llorens, S.,Vidal, A.T.; Garcia, I.J.; Torres, M.P. and Cerda, M.J. (2009) . Optimum dietary soybean meal level for maximizing growth and nutrient utilization of on growing gilthead sea bream (Sparus aurata), Aquaculture nutrition.15: 320- 328.

Merinero, S., Martı´nez-Llorens, S., Toma´ S, A. and Jover, M. (2005). Ana´ lisis econo´ mico de alternativas de produccio´ n de Dorada en jaulas marinas en el litoral Mediterra´neo espanñol.   Aquatic, 23: 1-19.

Mohamed, K. A., (2007). Effect of using probiotic and yeast as growth promoters in commercial diet of tilapia (Oreochromis niloticus) fingerlings. Agricultural Research Journal, Suez Canal University, 7 (3): 41- 47.

Morales, A.E., Cardenete, G., De La Higuera, M.,and Sanz, A. (1994). Effects of dietary protein source on growth, feed conversion and energy utilization in rainbow trout, Oncorhynchus  mykiss. Aquaculture 124: 117-126.

NRC .(1993). Nutrient Requirement of Fish. National Academy Press, Washington DC.

Pereira, T.G. and  Oliva-Teles, A., (2003). Evaluation of corn gluten meal as a protein source in diets for gilthead sea bream (Sparus avrata L.) juveniles. Aquaculture. Research, 34: 1111-1117.

Peres, H. and  Oliva-Teles .A ., (2009). The optimum dietary essential amino acid profile for  gilthead sea bream(Sparus aurata) juveniles. in press, Accepted Manuscript, Available on line 13 May 2009,  Aquaculture.

Pongmaneerat, J., Watanabe, T., Takeuchi, T.,  and Satoh, S., (1993). Use of different protein  Meals  as  partial or total substitution for fish meal in carp diets. Bull. Jpn. Soc. Sci. Fish, 59: 1249- 1257.

Regost, C., Arzel,J., and Kaushik.S.J.(1999). Partial or total replacement of fish meal by corn  gluten  meal   in diet for turbot (Psetta maxima), Aquaculture 180:  99-117.

Robaina, L., Izquierdo, M.S., Moyamo, F.J., Socorro, J., Vergara, J.M., Montero, D. and Fernandez-Palacios, H.,(1995). Soybean and lupine seed meals as protein sources in diet for gilthead seabream (Sparus aurata), Nutritional and histological implication. Aquaculture, 130: 219-233.

Rodehutscord, M., Mandel, S., Pack, M., Jacobs, S., and Pfeffer, E., (1995). Free amino acids can Replace protein-bound amino acids in test diets for studies in rainbow trout Oncorhynchus  mykiss . J. Nutr.,  125 : 956-963.

Sampaio-Oliveira,A.M.B.M., and Cyrino,J.E.P.. (2008). Digestibilty of plant protein-based diets by  largemouth bass Micropterus Salmoides, Aquaculture Nutrition , 14:  318-323.

SAS Institute, 1998. SAS statistical guide for personal computer , SAS Institute Inc. Cary , NC.

Sitja-Bobadilla, A., Pena-Llopis, S., Gomez-Requeni, P., Medale, F., Kaushik, S., and Perez-  Sanchez,J. (2005). Effect of fish meal replacement by plant protein sources on non-specific  difference mechanisms and oxidative stress in gilthead sea bream (Sparus aurata).  Aquaculture, 249:  387-400

Smith, R.R.  (1976). Metabolizable energy of feedstuffs for trout. Feedstuffs,48 : 16-21.

Soliman, A. K. (2000). Utilization of Carcass fish wastes in diets of Nile tilapia, Oreochromis niloticus. Proceeding of the fifth international symposium on tilapia in aquaculture 1: 215-220, 3-7 September 2000, Rio de Janeiro Brazil.

Soltan, M.A. (2005). Potential of using raw and proceed canola seed meal as an alternative fishmeal protein source in diets for Nile tilapia (O. niloticus). Egyptian. J. Nutr and Feed 8, (1): 1111 - 1128.

Soltan, M.A., Ibrahim, M.K; Fatma, A. and FathElbab,  A.F. (2001). Effect of partial and total replacement of fishmeal by soybean meal on growth and proximate analysis of Nile tilapia.  Egyptian J. Nutrition and Feed, (4 special issue) 799: 812.

Tibaldi, E., Hakim, Y., Uni, Z., Tulli, F., Francesco. D. M., Luzzana. U. and Harpaz. S., (2006). Effect of the partial substitution of dietary fish meal by differently processed  soybean meals on growth performance, nutrient digestibility and activity of intestinal brush border enzymes in the European sea bass ( Dicentrarchus labrax ). Aquaculture, 261. 182-193.        

Wilson, M. Furuya. L. E. Pezzato, M.M., Barros, A. C., Pezzato, V. R. Furuya, B.  and  Edma C. M. (2004). Use of Ideal protein concept for precision formulation of amino acid levels in fish-meal-free diets for juvenile Nile tilapia (Oreochromis niloticus L.), Aquaculture Research, 35: 1110-1116.