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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
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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.
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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%
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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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