Sanchez-lozano 2007 Girasol

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Growth and economic profit of gilthead sea bream

(Sparus aurata, L.) fed sunflower meal

Nury Beatriz Snchez Lozano, Ana Toms Vidal, Silvia Martnez-Llorens,Silvia Nogales Mrida, Javier Espert Blanco, Andrs Moino Lpez,

Marcial Pla Torres, Miguel Jover Cerd

Aquatic Resources Research Group, Animal Science Department, Polytechnic University of Valencia, Spain

Received 28 February 2007; received in revised form 25 July 2007; accepted 25 July 2007

Abstract

The utilisation of sunflower meal as a substitute for fish meal was evaluated in juvenile (44 g4.6 on average) gilthead sea

bream fed diets containing four levels of sunflower meal (0, 12, 24 and 36%). The experiment was divided into two phases; in the

first one (until day 90), fish reached a weight of 189, 198, 187 and 174 g, respectively, the diet containing 36% gave the lowest

specific growth rate (SGR) and the diet containing 12% sunflower meal the highest. In the second phase (from day 91 to day 248),

fish growth was not significantly affected by treatments. In relation to feed intake (FI) and feed conversion ratio (FCR), the diet

containing 36% sunflower meal gave the worst results in both phases. There were no statistical differences in body composition,

but energy and protein efficiency were lowest in fish fed the diet containing 36% sunflower meal. Sensory differences between seabream fed diets containing 0% and 24% sunflower meal were not detected. Optimum dietary level of sunflower meal for growth

and feed conversion obtained from quadratic regression was 1012%, but when economic aspects were considered, the optimum

dietary level was 1415% sunflower meal.

2007 Elsevier B.V. All rights reserved.

Keywords: Sparus aurata; Fish meal replacement; Sunflower meal; Alternative protein sources; Economic analysis

1. Introduction

The substitution of fish meal by plant proteins indiets for sea bream (Sparus aurata, L.) to reduce the cost

of feeding and to improve aquaculture sustainability has

been researched by several authors. Good results have

been obtained with dietary inclusion levels between 40

and 60% of corn gluten meal (Robaina et al., 1997;

Pereira and Oliva-Teles, 2003), between 20 and 40% of

soybean meal (Kissil et al., 2000; Martnez-Llorens

et al., 2007), lupin meal at 20% (Robaina et al., 1995;Pereira and Oliva-Teles, 2004) and extruded peas at

20% (Pereira and Oliva-Teles, 2002).

Although plant ingredients contain a wide variety of

anti-nutritional substances such as protease inhibitors

(Alarcn et al., 1999; Francis et al., 2001), or present

some lysine and methionine deficiencies (Gaylord et al.,

2004), vegetable ingredients are widely used by fish

feed companies to reduce the cost of diets.

Sunflower meal is widely available on the market and

its inclusion could diminish the diet costs. It has been

Available online at www.sciencedirect.com

Aquaculture 272 (2007) 528534www.elsevier.com/locate/aqua-online

Corresponding author. Polytechnic University of Valencia, Camino

de Vera, 14, 46071, Valencia, Spain. Tel.: +34 96 3877434; fax: +34 96

3877439.

E-mail address: [email protected] (M.J. Cerd).

0044-8486/$ - see front matter 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.aquaculture.2007.07.221
mailto:[email protected]://dx.doi.org/10.1016/j.aquaculture.2007.07.221http://dx.doi.org/10.1016/j.aquaculture.2007.07.221mailto:[email protected]


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tested in some diets for freshwater fish obtaining goods

results, such as rainbow trout at 42% of sunflower meal

dietary inclusion (Sanz et al., 1994), tilapia fingerlings at

22% (Olvera-Novoa et al., 2002), European eel at 35%

and 68%, with supplement of amino acids (Garca-

Gallego et al., 1998) and Atlantic salmon at 27% partiallydehulled and extruded sunflower meal (Gill et al., 2006).

Nevertheless, sunflower meal has not been tested as a

protein sourcein Mediterranean marine fish and this could

be of great interest in the Mediterranean given the

proximity of the sunflower production and price, 0.39

kg1 of protein in sunflower, 0.55 kg1 of protein in

soybean meal, and 1.74 kg1 of protein in fish meal.

The aim of this trial was to study the possibility of the

inclusion of sunflower meal as an alternative to fish

meal in gilthead sea bream diets.

2. Methods

2.1. Production system

The trials were conducted in 12 cylindrical fibreglass tanks

(1750 L) within a recirculating saltwater system. During the

experiment, the temperature was 241 C, dissolved oxygen

was over 6 mg L1, salinity was 31.4 mg L1, pH was 6.6 and

ammonium value was 0.0 mg L1. Photoperiod was natural

throughout the experimental period and all tanks had similar

lighting conditions.

2.2. Fish and experimental design

The trial lasted 248 days (from July 2005 to March 2006)

and was divided into two phases. The first lasted until day 90,

with an initial average fish weight of 44 g, and the second

phase was from day 91 until day 248, with an initial average

fish weight of 187 g. The experiment finished when fish

reached the marketable weight. The fish were brought from a

marine farm (Valencia, Spain) and randomly distributed in

experimental tanks (25 per tank). All fish were weighed every

30 days approximately. Previously, fish were anaesthetised

with 30 mg L1 of clove oil (Guinama , Valencia, Spain)

containing 87% of eugenol.At the end of each phase, 10 fish per tank were sampled and

stored at30 C to determine body composition and sensory

evaluation.

2.3. Diets and feeding

Composition of the ingredients (Source: Dibaq S.A.,

Segovia, Spain) used in the experimental diets is shown in

Table 1. Four isonitrogenous (45% crude protein) and isolipidic

diets (20% crude lipid) were formulated containing 0, 12, 24 and

36%not dehulled sunflower meal (Table 2). Diets were prepared

by cooking extrusion processing with a semi-industrial twin-screw extruder (CLEXTRAL BC-45, St. Etienne, France). The

processing conditions were as follows: 100 rpm speed screw,

110 C temperatures, and 4050 atm pressure and from 2 to

Table 1

Proximate composition of ingredients used in experimental diets

Ingredient

(International feed number)

Dry matter

(%)

Crude protein

(% dm)

Crude lipid

(% dm)

Crude fibre

(% dm)

Ash

(% dm)

N-free extract

(% dm)

Fish meal, herring (5-02-000) 91.4 63.2 19.1 1.0 17.4 0

Sunflower meal (5-04-739) 91.4 35.6 5.4 21.1 7.2 30.7

Wheat (4-05-268) 91.3 10.3 3.5 2.8 1.8 81.6

Table 2

Formulation of the experimental diets and their proximate composition

Ingredients (g kg1) Diet

0 12 24 36

Fish meal, herring (5-02-000) 586 533 482 430

Sunflower meal (5-04-739) 0 118 235 353Wheat (4-05-268) 211 142 73 3

Fish oil (7-08-048) 143 147 150 154

Maltodextrin 50 50 50 50

VitaminmineralAA mix a 10 10 10 10

Analysed composition (% dry matter basis)

Dry matter (DM) 91.8 92.2 92.3 91.6

Crude protein (CP) 45.0 46.6 45.8 44.5

Crude lipid (CL) 19.5 18.2 17.7 18.8

Ash 11.0 10.9 11.2 11.0

Crude fibre (CF) 1.1 3.4 5.5 7.8

N-free extract (NFE)b 23.4 20.9 19.8 17.9

Lysine (g/100 g) 3.01 2.23 2.16 2.00

Methionine (g/100 g) 1.32 1.26 1.18 1.12

Calculated values

GE (MJ kg1) c 22.6 22.1 21.5 21.3

CP/GE (g MJ1) c 19.9 21.1 21.3 20.9

a Vitamin mineral and amino acids mix (values are g kg1): Premix:

5; Choline, 2; DL--tocopherol, 1; ascorbic acid, 1; (PO4)2Ca3, 1.

Premix composition: retinol acetate, 1,000,000 IU kg1; calcipherol,

500 IU kg1; DL--tocopherol, 10; menadione sodium bisulphite, 0.8;

thiamin hydrochloride, 2.3; riboflavin, 2.3; pyridoxine hydrochloride,

15; cyanocobalamin, 25; nicotinamide, 15; pantothenic acid, 6; folic

acid, 0.65; biotin, 0.07; ascorbic acid, 75; inositol, 15; betaine, 100;

polypeptides, 12; Zn, 5; Se, 0.02; I, 0,5; Fe, 0.2; CuO, 15; Mg, 5.75;

Co, 0.02; Met, 1.2; Cys, 0.8; Lys, 1.3; Arg, 0.6; Phe, 0.4; Trcp, 0.7;

except 1000 g (Dibaq-Diproteg).b NFE calculated: 100-%CP-%CL-%Ash-%CF.c GE: Gross energy: Calculated using: 23.9 kJ g1 proteins, 39.8 kJ

g1 lipids and 17.6 kJ g1 carbohydrates.

529N.B. Snchez Lozano et al. / Aquaculture 272 (2007) 528534


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4.5 mm diameter pellets. Experimental diets were assayed intriplicate.

Fish were fed by hand twice a day to apparent satiation.

Pellets were distributed slowly, allowing all fish to eat.

2.4. Proximate composition and amino acids analysis

Composition of diets and fish body composition were

analysed following AOAC (1990) procedures: dry matter

(105 C to constant weight), ash (incinerated at 550 C to

constant weight), and crude protein (N6.25) by the Kjeldahl

method after an acid digestion (Kjeltec 2300 Auto Analyser,

Tecator Hganas, Sweden), crude lipid extracted with dichlor-omethane-methanol (Soxtec 1043 extraction unit, Tecator) and

crude fibre by acid and basic digestion (Fibertec System M.,

1020 Hot Estractor, Tecator). All analyses were performed in

triplicate.

Following the method previously described by Bosch et al.

(2006), lysine in diets was analysed in a Waters HPLC system

(Waters 474, Waters, Milford, MA, USA) consisting of two

pumps (Mod. 515, Waters), an auto sampler (Mod. 717,

Waters), a fluorescence detector (Mod. 474, Waters) and a

temperature control module. Aminobutyric acid was added as

an internal standard before hydrolysation. The amino acids

were derivatised with AQC (6-aminoquinolyl-N-hydroxysuc-cinimidyl carbamate). Methionine was determined separately

as methionine sulphone after oxidation with performic acid.

Amino acids were separated with a C-18 reverse-phase column

Waters Acc. Tag (150 mm3.9 mm).

2.5. Sensory evaluation

The effect of diet on sensorial properties of fish fillets was

studied by comparing fish fed the diet without sunflower meal

with fish fed the diet containing 24% sunflower meal. As

specified in the ISO-4120 norm (1983), a triangle test was

performed in a total of seven sessions with four panellists,

three men and one woman, trained as set out in ISO-8586-1

norm (1993). One fish from the group fed the diet without

sunflower meal and one from the group fed the diet containing

24% sunflower meal were used in each session. Fish were

thawed at 4 C for 24 h and then filleted and skinned. The two

fillets from each fish were vacuum-packed in plastic bags.

Each fillet, weighing between 46.5 and 50.5 g, was cooked in a

water-bath at 80 C for 10 min and then cut into nine piecesweighing between 5 and 6 g each. The resulting 36 equally-

sized pieces were coded with a three-digit number and

wrapped in aluminium foil. The pieces were organised for

8 triangle tests per session (two for each panellist) and were

stored at 40 C in thermo-regulated boxes for the duration of

the session. So that possible differences could not be attributed

to the fillet portion, samples from the same fish portion were

compared in each test.

As a difference, one piece should be identified in each test

and the judges were invited to describe the characteristic of the

difference: flavour intensity and flavour descriptors (fresh,

sweet, fat), compactness and juiciness. The comments wererecorded in cases of correct differentiation.

In a triangle test, the assumption of no difference between

treatment is rejected if the number of correct responses is

Table 3

Effect of dietary sunflower meal level on growth and feed utilisation of

gilthead sea bream at the end of two phases considered

Parameter Diet

Phase I (090 days) 0 12 24 36 SEM

Live weight (g) 189b 198c 187b 174a 2.02SGR (% day1)v 1.63b 1.68c 1.62b 1.53a 0.01

FI(g 100 g fish1 day1)w 2.36b 2.37b 2.53b 3.38a 0.11

FCRx 1.74b 1.69b 1.86b 2.59a 0.08

CPE (%)y 25.88bc 26.79c 23.54b 16.62a 0.80

GEE (%)z 36.54c 36.85c 31.47b 23.67a 0.92

Phase II (91248 days)

Live weight (g) 432 455 427 421 13.89

SGR (% day1)v 0.53 0.56 0.52 0.51 0.02

FI(g 100 g fish1 day1)w 0.86b 0.82b 0.87b 1.09a 0.03

FCRx 1.89b 1.70b 1.87b 2.28a 0.06

CPE (%)y 21.92 22.27 21.25 19.49 0.84

GEE (%)z 29.68a 38.62b 35.72b 28.42a 1.03

Data in the same row with different superscripts differ at Pb0.05.Initial weight in each phase was considerer as covariable for live

weight and SGR.vSpecific growth rate (% day1), SGR=100ln (final weight/initial

weight)/days.wFeed Intake ratio (g 100 g fish1 day1), FI =100 feed consumption

(g)/average biomass (g)days.xFeed Conversion ratio, FCR=feed offered (g)/weight gain (g).yCrude protein efficiency, CPE (%) =(Fish protein gain, g) 100/

(protein intake, g).zGross energy efficiency, GEE (%) =(Fish energy gain, kJ) 100/

(energy intake, kJ).

Table 4

Second-order polynomial fitting of growth and nutritive parameters

and dietary sunflower level (SW)

1st Phase 2nd Phase

SGR Model SGR = 1.63 +

0.00557SW

0.000237SW2

r2 84% Not significant

Optimum

SW level

11.7%

FI Model FI =2.380.0222

SW+0.00137SW2FI=0.81

0.00971SW+

0.000434SW2

r2 82% 83%

Optimum

SW level

8.2% 11.2%

FCR Model FCR = 1.750.0236

SW+0.00129SW2FCR=1.880.0259

SW+0.00103SW2

r2 87% 82%

Optimum

SW level

9.7% 12.6%

530 N.B. Snchez Lozano et al. / Aquaculture 272 (2007) 528534


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greater than or equal to the critical value or a standard normal

value (z

= t,). Tabled values are provided in the ISO-4120

(1983) norm.

2.6. Economic analysis

The Economic Conversion Ratio [ECR ( kg1 fish)=

feed conversion ratio (kg diet kg1fish)price of diet ( kg1

diet)] and the Economic Profit Index [EPI ( fish1)=final

weight (kg fish1)fish sale price ( kg1)ECR ( kg1

fish)weight increase (kg)] developed by Martnez-Llorens

et al. (2007) were used to evaluate the diets from an economic

point of view.

2.7. Statistical analysis

Growth data and feed utilisation were treated using one-

way analysis of variance (ANOVA), introducing the initial live

weight as covariate (Snedecor and Cochran, 1971). Newman

Keuls test was used to assess specific differences among diets

at 0.05 levels (Stat graphics, Statistical Graphics System,

Version Plus 5.1, Herndon, Virginia, USA).

Quadratic regression analyses were applied, where specific

growth rate (SGR), feed intake (FI), feed conversion ratio

(FCR), economic conversion ratio (ECR) and economic profit

index (EPI) were a function of sunflower meal level using the

expression Y= a + bX+ cX2. Optimum sunflower meal level

was obtained by deriving this equation and equalising to zero.

3. Results

3.1. Growth and feed utilisation

Growth data were analysed every month, but differences in

growth were not observed among groups until day 90 of the

experiment, so this period was considered the first phase. At the

end of the first phase, gilthead sea bream fed 36% sunflowermeal presented the lowest weight values and SGR, 174 g and

1.53% day1, respectively, whereas fish fed 12% sunflower meal

diet had thehighest growth, 198g and1.68% day1, respectively

(Table 3). Likewise, fish fed the diet containing 36% sunflower

meal had the highest feed intake, 3.38 g 100 g fish1 day1, and

feed conversion ratio, 2.59, compared with the other three

treatments.

At the end of the second phase (day 248), no significant

differences were observed in live weight and SGR among

treatments (Table 3), but FI and FCR were higher for fish fed

36% sunflower meal, 1.09 g 100 g fish1 day1 and 2.28,

respectively.To obtain optimal levels of sunflower meal, some quadratic

regressions were developed independently with data for the

two growth periods (Table 4). The relationship between SGR

and sunflower meal level in first phase was significant, and the

optimum content of sunflower meal was 11.7%, but in the

Table 5

Effects of dietary sunflower meal level on body composition of

gilthead sea bream at the end of two phases considered

Diet

Parameter Initial 0 12 24 36 SEM

Day 90Moisture (%) 69.5 60.16 61.34 62.94 62.24 0.69

Crude protein (% ww) 16.0 18.0 18.7 17.9 17.0 0.31

Crude lipid (% ww) 10.9 19.1 17.7 15.9 17.3 0.93

Ash (% ww) 4.7 3.9 3.4 3.5 4.1 0.27

Day 248

Moisture (%) 60.0 58.4 59.3 60.5 0.66

Crude protein (% ww) 17.5 17.3 17.6 17.4 0.27

Crude lipid (% ww) 19.2 20.9 19.8 19.0 0.82

Ash (% ww) 3.9 3.8 3.8 3.8 0.19

Data in the same row with different superscripts differ at Pb0.05.

Table 6

Global results of economic parameters at the end of the experiment (0

248 day)

Diet

Parameter 0 12 24 36 SEM

Cost of diet ( kg1)x 0.96 0.90 0.85 0.79

ECR ( kg1)y 1.75ab 1.53c 1.60bc 1.90a 0.06

EPI ( fish1)z 1.27b 1.43c 1.31b 1.15a 0.03

Data in the same row with different superscripts differ at Pb0.05.x Calculated from following price of ingredients (January 2007): Fish

meal=1.155 kg1; Sunflower meal = 0.135 kg1; Wheat=

0.185 kg1; Fish oil=0.680 kg1; Maltodextrin=1.000 kg1;

VitMinAA Mix= 9.120 kg1.y Economic efficiency ratio, ECR, ( kg fish1)=feed conversion

ratio feed cost ( kg1)/weight gain (kg).z Economic profit index ( fish1), EPI=final weight (kg fish1)

fish sale price (

kg

1

)

ECR (

kg fish

1

)weight increase (kg).Gilthead sea bream sale price is calculated at 4.5 kg 1.

Fig. 1. Second-order polynomial fitting of economic parameters andoptimum dietary sunflower level (SW).



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second phase the regression was not significant. The quadratic

model for feed intake (FI) was significant in both phases,

obtaining an optimum content of sunflower meal of 8.2% and

11.2%, respectively. The regression was also significant for

feed conversion rate (FCR) in both phases, with optimum

levels of 9.7% and 12.6%, respectively.

In the first phase, difference was obtained in protein and

energy efficiency (Table 3); in both cases, sea bream fed 36%

sunflower meal had the lowest values (16.62 and 23.67%,

respectively) whereas fish given the diet containing 0% and

12% sunflower meal presented the highest energy efficiency

(36.54 and 36.85%, respectively). By the end of the second

phase, fish fed the diets containing 12 and 24% sunflower meal

(Table 3) obtained the highest energy retention (38.62 and

35.72%, respectively), although significant differences were

not observed in the protein retention.

Fish body analysis (Table 5) indicated no significant

differences in body composition (protein, lipids and ash).

3.2. Sensory analysis

Only 39 of the 108 responses from panellist identified the

correct different sample, the -risk was 0.001, which means

that there were no differences between sensory characteristics

from fish fed 0% and 24% sunflower meal.

3.3. Economic analysis

The cost of diets was reduced with sunflower meal

replacement (Table 6). The economic conversion ratio (ECR)

of the diet containing 36% sunflower meal was the highest(1.90 kg1) and ECR of the diet containing 12% sunflower

meal was lowest (1.53 kg1). Likewise, the highest

economic profit index (EPI) was obtained with fish fed the

12% sunflower meal (1.43 fish1) and the lowest with fish

fed 36% sunflower meal diet (1.15 fish1). Optimum

sunflower levels for ECR and EPI, 15.4 and 14.3%

respectively, were obtained from quadratic regressions (Fig. 1).

4. Discussion

Growth of gilthead sea bream was higher than that

obtained in previous trials under similar conditions(Martnez-Llorens et al., 2007), because fish reached a

final weight ranged 421455 g in 248 days, whereas in

cited trial fish weighed 303349 g in 309 days.

Results from the analysis of variance in Phase I show

that the maximum level of sunflower meal in diets for

sea bream juveniles is 12% sunflower meal, because the

growth was the highest and FCR was similar up to 24%

sunflower meal. The sea bream on-growing, Phase II,

could be fed 24% sunflower meal, because although no

differences were obtained for growth with the four diets,

the feed conversion ratio was clearly worse in sea bream

fed 36% sunflower meal.

When results were analysed by quadratic regression,

as suggested by Shearer (2000), an optimum sunflower

level of 11.7 and 9.7% was obtained for maximising

growth and for minimising feed conversion of sea bream

juveniles, respectively. On the contrary, the quadratic

effect of sunflower meal on growth of sea bream on-growing was not significant, but an optimum level of

12.6% sunflower meal was obtained for feed conversion.

It seems that dietary sunflower meal content for sea

bream cannot be as high as with some plant proteins, such

as gluten at dietary levels between 40 and 60% (Robaina

et al., 1997; Pereira and Oliva-Teles, 2003) or soybean

meal at dietary levels between 20 and 40% (Kissil et al.,

2000; Martnez-Llorens et al., 2007). Nevertheless,

maximum dietary inclusion level of sunflower meal,

around 20%, is similar to that obtained with lupin meal

(Robaina et al., 1995; Pereira and Oliva-Teles, 2004) andextruded peas (Pereira and Oliva-Teles, 2002).

Low growth with high levels of sunflower meal in

sea bream juveniles could be due to a lower lysine

content, which was 50% lower in diet containing 36%

sunflower meal, 20.0 g kg1, compared with the control

diet, 30.1 g kg1, but this does not seem to be the

reason, because the feed intake was increased with

sunflower dietary level, and lysine and methionine

intake in sea bream fed 36% sunflower meal was higher

(0.68 and 0.38 g kg1 day1, respectively) than in sea

bream fed 12% sunflower meal (0.53 and 0.30 g kg1

day1, respectively) which gave the best growth in firstphase. The lysine and methionine content in sunflower

meal does not seem to be limiting, because Sanz et al.

(1994) obtained the same result of growth and feed

conversion ratio in rainbow trout fed with 40% dietary

sunflower level, with and without lysine and methionine

supplementation, compared to a control diet without

sunflower meal. Nevertheless, when the sunflower meal

inclusion level was as high as 64%, Garca-Gallego et al.

(1998) obtained a lower growth in European eel fed

diets without amino acids supplementation, whereas the

supplemented diet containing 64% sunflower meal, or adiet containing 35% sunflower, gave as good results as

the control diet.

The difference could be because sunflower meal

presents a higher fibre content (21% instead 6.1% in

soybean meal, for example), which could affect the

digestibility of protein or energy, but results from Sanz

et al.(1994) in rainbow trout showed a higher proteinand

lipid digestibility in diets containing 35% sunflower

meal, and although the digestibility of carbohydrate was

lower, the energy digestibility was similar. Protein

digestibility was not reduced by sunflower meal in

European eel (Garca-Gallego et al., 1998), tilapia



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(Olvera-Novoa et al., 2002) or Atlantic salmon (Gill

et al., 2006), but energy digestibility was lower in

Atlantic salmon with inclusion of 27% (Gill et al., 2006).

Likewise, the lower energy content in diets contain-

ing 36% sunflower meal was compensated by sea bream

with a higher feed intake in both phases, but energyefficiency was higher in diets containing 0 and 12%

sunflower meal in the first phase and in diets containing

12 and 24% sunflower meal in the second phase. Protein

efficiency was lower in sea bream juveniles fed 36%

sunflower meal in first phase and similar for all diets in

second phase. Nevertheless, the protein and energy

efficiency of sea bream fed 0, 12 and 24% sunflower

meal was higher than cited in sea bream fed 20, 30, 40 or

50% soybean meal (Martnez-Llorens et al., 2007).

Anti-nutritional substances cited in plant protein

(Alarcn et al., 1999; Francis et al., 2001) do not seemto have any effect in the case of sunflower meal, because

dietary sunflowerlevels as high as 35% in rainbow trout or

64% in European eel have given goods results of growth.

Regarding economic efficiency, the reduction in cost

of diets related to sunflower meal inclusion (from 0.96

to 0.79 kg1) did not compensate for the higher feed

conversion ratio and lower growth, because economic

conversion ratio (ECR) and economic profit index (EPI)

were poorer with 36% sunflower meal, and better with

12% sunflower meal. From quadratic regression, the

optimum sunflower level for sea bream was 1415%.

Averagecost of diets washigher than cited by Martnez-Llorens et al. (2007), 0.875 instead of 0.477 kg1,

because these authors used a lower fish meal content

(between 195 and 370 g kg1), although EPI was similar.

In the present trial, optimum sunflower level was 14.3%

sunflower meal for maximising economic profit index,

1.41per fish, whereas optimum soybean meal obtaining

by Martnez-Llorens et al. (2007) was 21.9% for

maximising EPI, 1.29 per fish. Nevertheless, from a

sustainable point of view, the use of 21.9% soybean meal

instead of 14.3% sunflower meal would allow a higher

reduction of fish meal, 171 g kg1

instead of 80 g kg1

.Inclusion of moderate levels of sunflower meal in sea

bream diets did not affect the sensorial characteristics of

the flesh, but the comparison of this result with other

authors is difficult because only Martnez-Llorens et al.

(2007) cited sensory differences with a high soybean

level (50%).

5. Conclusion

The results of the current experiment show that the

optimum dietary sunflower meal level for growth and

nutrient utilisation of sea bream is 1112%, but 1415%

from an economic point of view, and both have no effect

on sensorial analysis.

Acknowledgements

This work was financed by Dibaq S.A. (Spain). Theauthors are grateful to Neil Macowan for revising the

English version.

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