Fish meal replacement with rice protein concentrate in a practical diet for the Pacific white shrimp, Litopenaeus vannamei Boone, 1931

Abstract

Replacement of fish meal (FM) with rice protein concentrate (RPC) as a practical diet for the Pacific white shrimp, Litopenaeus vannamei, was evaluated. Five isonitrogenous (36.6% protein) diets, formulated by replacing 0, 25, 50, 75, and 100% of FM by RPC,
were fed to shrimp (initial weight of 6.99±0.08g) five times daily to satiation for 60days. Relatively high final weight
(FW 17.64–18.25g) and weight gain (WG 10.81–11.39g) were obtained in treatments up to 50% of the plant protein inclusion.
Above this inclusion level, FW (14.93–14.35g) and WG (7.68–7.23g) were reduced. Survival was high (≥95%) and similar for
all diets. There were no significant differences (P>0.05) in tail-muscle composition (moisture, protein, lipid, and ash) among different dietary treatments. Dispensable and
indispensable amino acids of the tail muscle of shrimp fed with 25, 50, and 75% RPC were significantly higher than the FM
(0%) and 100% RPC diets. A decreasing trend in apparent digestibility coefficient (excluding dry matter) for crude protein
(90.52–52.41), ether extract (94.11–80.03), organic matter (87.25–50.16), and gross energy (89.41–55.24) was observed at higher
RPC inclusion rates. The results suggest that RPC meal can be a potential candidate for FM replacement up to 50% of the protein
in shrimp diets.

KeywordsApparent digestibility coefficient–Amino acid profile–Growth–
Litopenaeus
vannamei
–Nutrition–Penaeids–Proximate analysis

Full text

Fish meal replacement with rice protein concentrate
in a practical diet for the Pacific white shrimp,
Litopenaeus vannamei Boone, 1931
Amin Oujifard •Jafar Seyfabadi •Abdolmohammad Abedian Kenari •
Masood Rezaei
Received: 12 September 2010 / Accepted: 3 May 2011 / Published online: 17 May 2011
ÓSpringer Science+Business Media B.V. 2011
Abstract Replacement of fish meal (FM) with rice protein concentrate (RPC) as a
practical diet for the Pacific white shrimp, Litopenaeus vannamei, was evaluated. Five
isonitrogenous (36.6% protein) diets, formulated by replacing 0, 25, 50, 75, and 100% of
FM by RPC, were fed to shrimp (initial weight of 6.99 ±0.08 g) five times daily to
satiation for 60 days. Relatively high final weight (FW 17.64–18.25 g) and weight gain
(WG 10.81–11.39 g) were obtained in treatments up to 50% of the plant protein inclusion.
Above this inclusion level, FW (14.93–14.35 g) and WG (7.68–7.23 g) were reduced.
Survival was high (C95%) and similar for all diets. There were no significant differences
(P[0.05) in tail-muscle composition (moisture, protein, lipid, and ash) among different
dietary treatments. Dispensable and indispensable amino acids of the tail muscle of shrimp
fed with 25, 50, and 75% RPC were significantly higher than the FM (0%) and 100% RPC
diets. A decreasing trend in apparent digestibility coefficient (excluding dry matter) for
crude protein (90.52–52.41), ether extract (94.11–80.03), organic matter (87.25–50.16),
and gross energy (89.41–55.24) was observed at higher RPC inclusion rates. The results
suggest that RPC meal can be a potential candidate for FM replacement up to 50% of the
protein in shrimp diets.
Keywords Apparent digestibility coefficient Amino acid profile Growth Litopenaeus
vannamei Nutrition Penaeids Proximate analysis
Abbreviations
AA Amino acids
ADC Apparent digestibility coefficient
ADC
CP
Apparent digestibility coefficient of crude protein
A. Oujifard A. A. Kenari M. Rezaei
Department of Fisheries, Faculty of Marine Sciences, Tarbiat Modares University, Noor, Mazandaran,
Iran
J. Seyfabadi (&)
Department of Marine Biology, Faculty of Marine Sciences, Tarbiat Modares University,
P.O. Box 46417-76489, Noor, Mazandaran, Iran
e-mail: jseyfabadi@gmail.com
123
Aquacult Int (2012) 20:117–129
DOI 10.1007/s10499-011-9446-8

ADC
DM
Apparent digestibility coefficient of dry matter
ADC
GE
Apparent digestibility coefficient of gross energy
DAA Dispensable amino acids
DE Digestible energy
DP Digestible protein
FCR Feed conversion ratio
FM Fish meal
IAA Indispensable amino acids
NFE Nitrogen-free extracts
PER Protein efficiency ratio
P/E Protein/energy
RPC Rice protein concentrate
Introduction
Protein is the most expensive material in a practical diet for shrimp culture, and fish meal
(FM) constitutes the most commonly used animal protein in the commercially manufac-
tured feeds. The levels of FM inclusion in commercial diets vary from 10 to 50% (Tacon
1993). Almost 68% of the global FM production in 2006 was reportedly consumed for
compound aquaculture feeds (Tacon and Metian 2008). However, increasing demand and
pressure on marine fishery resources are considered as restrictive factors for fish meal
(Tacon and Jackson 1985). In response to this limitation for FM, the potential alternative
sources in aquaculture have recently been considered and a large number of studies have
been focused on various plant protein sources (such as pea, soy beans, rice, wheat gluten,
corn gluten, lupine and canola, etc.) to substitute FM at various levels, depending on the
species, animal size, and feeding habits (Sudaryono et al. 1999; Cruz-Sua
´rez et al. 2001;
Davis et al. 2002; Bautista-Teruel et al. 2003). In this regard, the partial or total substi-
tution of FM with various sources of plant proteins has been accomplished in many
penaeid shrimps with good results in growth performance and shrimp quality (Lim and
Dominy 1990; Eusebio 1991; Sudaryono et al. 1995; Swick et al. 1995; Dersjant-Li 2002;
Forster et al. 2002; Bautista-Teruel et al. 2003; Samocha et al. 2004; Amaya et al. 2007;
Suarez et al. 2009).
In addition to the high price, the availability of protein ingredients is also a problem for
feed producers (Forster et al. 2003). Besides, the use of several sources of plant protein is
limited due to many specific antinutritional factors (Francis et al. 2001) and imbalances in
amino acid composition (Watanabe et al. 1995). Therefore, less-expensive plant proteins
with none or minimum antinutritional factors are seriously being considered as alternative
sources. Among such alternatives, rice protein concentrate (RPC) may prove to be a
valuable protein source due to its high protein content (Palmegiano et al. 2006; Palmegiano
et al. 2007). Besides, RPC is comparable to FM in protein and fat content and is higher
than many other plant protein sources (Palmegiano et al. 2007).
Several studies on RPC assessments as a potential substitution for FM as a source of
protein in fish feeds showed that RPC could partially replace fish meal without any neg-
ative effects on growth parameters (Palmegiano et al. 2006,2007). However, to date, there
have been no published studies on the use of RPC as an alternative for FM in shrimp diets.
Feeds containing less fish meal would benefit shrimp farmers by reducing the production
118 Aquacult Int (2012) 20:117–129
123

cost and, therefore, increase profit margin. Shrimp aquaculture has been considered as the
axis of marine aquaculture in Iran, and efforts in this regard have been oriented toward
increasing production since 1990s; however, efforts have failed mainly due to the cost of
production and disease outbreaks. Iran is a rice-producing country (FAO 2004), and
replacement of FM with less-expensive RPC may contribute to partially meet this purpose.
The objective of the present study was, therefore, to evaluate the effects of partial or total
replacement of dietary FM protein with RPC on the growth, feed conversion ratio, and
survival of juvenile Litopenaeus vannamei. The effect of the different levels of dietary
RPC on apparent digestibility coefficient and tail-muscle composition was also
investigated.
Materials and methods
Shrimp rearing and diet preparation
Juvenile shrimp, obtained from a semi-intensive farm in Bushehr (Iran), were acclimated to
laboratory conditions for 4 days before being randomly distributed into experimental
tanks. The experimental system consisted of 15 indoor substrate-free flat-bottom concrete
tanks (5 m 92m91 m) for rearing. Juvenile shrimp (average body weight
6.99 ±0.08 g) were randomly allocated into these tanks (80 individuals per tank). Sea
water was initially pumped into a 100,000-L concrete settling tank, from which led to a
25,000-L concrete tank equipped with a sand filter, then stored into a 50,000-L concrete
tank before distributing it to the experimental tanks. Continuous aeration was provided by
an electric blower and air-stones.
Five isonitrogenous diets of 36.6% protein level were formulated by replacing 0, 25, 50,
75, and 100% of FM protein with RPC (Table 1). The diet formulation was based on the
lysine requirement (1.6%) for L. vannamei (Fox et al. 1995) and Penaeus monodon’s
requirements for methionine (0.9%), threonin (1.4%), arginine (1.9%), histidine (0.9%),
isoleucine (1.1%), and leucine (1.7%) (Millamena et al. 1996,1997,1998,1999). The
proximate analysis and amino acid composition were determined for the diets (Tables 1,
2). The respective diets were hand-fed to visual satiety (visual observation of first feed
refusal). Uneaten pellets were siphoned from each tank into a bucket lined with 1-mm
2
mesh, dried in air (as a correction to the calculation of daily feed efficiency), and weighed.
Based on this, the total feed intake for each tank was calculated (Hatlen et al. 2005). The
shrimp were fed the experimental diets five times a day at 0800, 1200, 1600, 2000, and
0000 h. Water quality (recorded daily throughout the experimental period) showed that
temperature averaged 27 ±0.47°C, salinity ranged between 44 and 46 ppt, and dissolved
oxygen did not fall below 5.7 mg L
-1
. Total ammonia–nitrogen (range: 0–0.25 mg L
-1
),
nitrite-nitrogen (range: 0–0.04 mg L
-1
) and pH (range: 8.2–8.4) were measured weekly.
The solid wastes were siphoned off the tanks, and water was changed (about 20%) daily
before morning feedings. Fecal collection was done manually. The feces were allowed to
float into a plastic scoop and then siphoned and gently transferred into a collecting vial.
Care was taken to prevent the breaking-up of fecal strands to facilitate collection and to
avoid leaching of nutrients. At the end of the experiment, the growth indexes and survival
rates of the shrimps were calculated. Final body weights were calculated based on total
shrimp biomass.
Aquacult Int (2012) 20:117–129 119
123

Table 1 Ingredient and proximate composition of experimental diets
Ingredient (%) % Replacement meal
RPC0 RPC25 RPC50 RPC75 RPC100
Fish meal
a
45.7 34.3 22.85 11.42 0
Rice protein concentrate
b
0 11.4 22.85 34.27 45.7
Shrimp meal 15 15 15 15 15
Binder (Amet)
c
1.5 1.5 1.5 1.5 1.5
Lecithin 1 1 1 1 1
Cholesterol
d
0.5 0.5 0.5 0.5 0.5
Wheat flour 25.73 25.73 25.73 25.73 25.73
Fish oil
a
0.65 0.99 1.34 1.68 2.02
Soybean oil 0.65 0.99 1.34 1.68 2.02
Mineral premix
e
22222
Vitamin premix
f
22222
Antioxidant
g
0.02 0.02 0.02 0.02 0.02
Antifungal agent
h
0.25 0.25 0.25 0.25 0.25
Dicalcium phosphate 1.5 1.5 1.5 1.5 1.5
Cellulose 3 2.32 1.62 0.93 0.25
Chromic oxide
d
0.5 0.5 0.5 0.5 0.5
Analyzed proximate composition (% dry matter)
Dry matter 94.4 94.5 93.8 92.8 92.6
Crude protein 36.7 36.6 36.6 36.5 36.7
Crude lipid 8.2 8.7 8.5 9.1 9.3
Carbohydrate 32.9 32.8 31.6 31.6 32.3
Ash 16.5 16.3 17.0 15.5 14.2
Fiber 3 3.5 3.8 4.2 4.4
NFE 29.9 29.3 27.8 27.4 27.9
Gross energy (kJ g
-1
diet)
i
17.5 17.7 17.4 17.6 17.9
Digestible energy (kJ g
-1
diet)
j
16 16 16 16 16
a
Fish meal and fish oil derived from Iranian kilka (Clupeonella sp.)
b
Rice protein concentrate (supplied by EUNJIN International Co., Ltd, South Korea): moisture, 10(max);
crude protein, 60%(min); crude fiber, 3%(max); crude ash, 4% (max); crude fat, 7%(min); Ca, 41%; P, 0.75%;
Na, 0.04%; Cl, 0.7%, K, 0.045%
c
Amet Binder (produced in Mehr Afraz Taban Yazd Company: crude protein, 71.98%; crude fiber, 0.9%; ash,
17.8%; moisture, 9.55%)
d
Merck, Germany
e
Mineral mixture (mg kg
-1
mixture): Co, 40; I, 220; Se, 300; Zn, 10000; Fe, 3500; Cu, 4000; Mn, 6000
f
Vitamin added to supply the following (per kg diet): vitamin A, 80000 Iu; vitamin D3, 2000 Iu; vitamin E,
100 mg; vitamin k, 20 mg; thiamin, 60 mg; riboflavin, 60 mg; pyridoxine, 100 mg; pantothenic acid, 150 mg;
niacin, 300 mg; biothin, 2 mg; folic acid, 20 mg; vitamin B12, 0.1 mg; inositol, 300 mg; ascorbic acid,
600 mg; choline chloride, 3,000 mg
g
Antioxidant: Ethoxyquin (Banox E). Adisseo Australia, Carole Park, Qld
h
Antifungal agent: Toxiban premix (Component: Alomino silicat, zeolite, bentonate, propionate ammonium)
i
Calculated on the basis of 23.6, 39.5, and 17.2 kJ g
-1
of protein, fat, and carbohydrate, respectively, (NRC
1993)
j
Calculated on the basis of 23, 35, and 15 kJ g
-1
of protein, fat, and carbohydrate, respectively, (Cousin 1995)
120 Aquacult Int (2012) 20:117–129
123

Evaluation of feed intake and growth parameters
Shrimp production was evaluated at the end of the growth trial considering the following
parameters: feed conversion ratio, protein efficiency ratio, body weight increase (Goy-
tortua-Bores et al. 2006), and daily feed intake (Hatlen et al. 2005).
Weight gain =(final weight -initial weight/initial weight)
FCR: feed conversion ratio =total dry feed intake (g)/wet weight gain (g)
Survival% =(final number of shrimp/initial number of shrimp) 9100
PER: protein efficiency ratio =weight gain in g/protein intake in g
DFI: daily feed intake (% average weight/day) =100 9(total dry feed intake per
shrimp)/[(initial fish weight 9final fish weight)
0.5
]/number of days fed
Sample preparation
At the end of the experiment, all shrimp were chill-killed, washed with tap water, and
stored at -18°C for the determination of final tail-muscle composition. For analyses,
frozen muscle samples from each treatment were thawed at 4°C overnight and then
homogenized with a meat grinder. Each sample consisted of tissues from randomly
selected three individuals from each tank.
Table 2 Amino acids (AA) composition (g 100 g
-1
) of RPC, FM, and experimental diets
AA (g 100 g
-1
) FM RPC % Replacement meal
RPC0 RPC25 RPC50 RPC75 RPC100
Indispensable amino acids (IAA)
Arginine 4.65 5.89 3.32 3.67 3.03 3.11 3.17
Histidine 2.21 1.86 1.3 1.48 1.2 1.07 0.96
Isoleucine 2.93 2.77 2.03 2.21 1.75 1.85 1.68
Leucine 4.56 5.42 2.84 3.11 2.52 2.74 2.45
Lysine 5.07 2.5 3.1 3.2 2.28 2.01 1.65
Methionine 2.19 2.31 1.44 1.68 1.32 1.63 1.4
Phenylalanine 2.6 3.64 1.97 2.27 3.13 2.62 2.06
Threonine 2.41 2.64 1.68 1.81 1.5 1.57 1.47
Valine 3.49 3.52 2.12 2.39 1.94 2.16 2.03
Dispensable amino acids (DAA)
Alanine 4.15 3.95 2.25 2.5 2.04 1.78 1.63
Aspartic acid 4.88 5.92 2.05 1.88 1.67 1.84 1.99
Glutamic acid 9.58 11.21 10.84 10.91 10.07 9.77 11.12
Glycine 3.93 3.13 2.32 2.47 1.92 1.89 1.83
Proline 3 2.93 2.13 2.29 1.76 2.02 2.02
Serine 1.54 3.58 1.38 1.66 1.45 1.61 1.61
Tyrosine 2.4 3.75 1.77 1.93 1.57 1.93 1.84
IAA/DAA 0.87 0.92 0.91 0.90 0.77
Aquacult Int (2012) 20:117–129 121
123

Chemical analysis
Crude protein was determined using Auto Kjeldahl System (Kjeltec Analyzer unit 2300,
Sweden), crude lipid by Soxhlet extraction method (Soxtec 2050 FOSS Model, Switzer-
land), moisture by a dry oven (105°C for 24 h) (ERAEUS instruments), and ash content by
a furnace muffler Naberthern) model: K, Germmany) (550°C for 4 h) (AOAC 1995).
Nitrogen-free extracts (NFE) were calculated following the formula, and NFE plus fiber
was expressed as carbohydrate (Aksnes and Opstvedt 1998):
NFE =100 -(crude protein ?crude lipid ?fiber ?ash ?moisture)
Carbohydrate =NFE ?fiber
The gross energy of the diets and feces was calculated according to the NRC (1993)
procedure, based on 1 g crude protein (P) =23.6 kJ, 1 g crude fat (F) =39.5 kJ, and
1 g carbohydrate (C) =17.2 kJ. Chromic oxide was added to each diet at a concen-
tration of 0.5% as an inert marker for digestibility determinations of dry matter, organic
matter, fat, protein, and energy (Maynard and Loosli 1969). The protocol of digest-
ibility study in shrimp followed the method described by Sudaryono et al. (1996).
Feces were collected daily 1–4 h after feeding for 28 days in the middle of feeding
trial and stored at -20°C. Fecal samples were pooled for each replicate and dried for
the analysis of dry matter, organic matter, fat, and protein content according to the
AOAC (1995) methods. The chromium (Cr) content of all experimental diets and
fecal samples was analyzed by atomic absorption spectrophotometry using the method
of Williams et al. (1962), and apparent nutrient digestibility (AND%) was calculated
as:
(AND%) =100 -100[(%CrFd/%CrFc) 9(%NtFc/%NtFd)]
where, CrFd =chromic oxide in feed, CrFc =chromic oxide in feces, NtFc =nutrient in
feces, and NtFd =nutrient in feed (Maynard and Loosli 1969).
Amino acid composition
Amino acids were determined after hydrolysis of samples in 6 N HCl for 24 h at 110°C.
Then, samples were derivatized with o-phthaldialdehyde (OPA) according to Antoine et al.
(1999). The total amino acids were determined by HPLC (Knauer, Germany) using C18
column (Knauer, Germany) at the flow rate of 1 mL min
-1
with fluorescence detector (RF-
530, Knauer, Germany).
Statistical analysis
The feeding experiment was a completely randomized design with five dietary treat-
ments and three replicates per treatment. All data were analyzed by one-way ANOVA
using SPSS software (release 16.0 for Windows). ANCOVA was used to demonstrate
that there was no effect of initial shrimp weight on the observed parameters. The
Duncan’s multiple comparisons test was used to determine the differences between the
treatment means. Results were considered statistically significant at the level of
P\0.05.
122 Aquacult Int (2012) 20:117–129
123

Results
Growth indices
Results of the feeding trial, summarized in Table 3, indicate that RPC is a suitable partial
substitute for FM in a practical diet for L. vannamei. At the end of the trial, final weight in
shrimp fed the FM (0%) was not significantly different from those fed 25 and 50% RPC
replaced treatments (P[0.05) but was significantly higher than those of shrimp fed with
75 and 100% RPC treatments (P\0.05). Shrimp fed with 75 and 100% RPC had lower
weight gain (%) and higher FCR than other treatments (P\0.05). The shrimp fed with the
FM and 25% RPC feeds showed significantly higher protein efficiency ratio (PER). Shrimp
survival rate was greater than 95% in all treatments.
Shrimp proximate and amino acid composition
No significant differences (P[0.05) were found in tail-muscle composition of the shrimp
fed with various levels of RPC and FM diets (Table 4).
The amount of the total amino acids (AA), indispensable amino acid (IAA), and dis-
pensable amino acid (DAA) profile of tail muscle (except 100% RPC) increased with the
FM replacement (Table 5).
Table 3 Growth performance of juvenile L. vannamei fed with different levels of RPC
Growth index/
treatment
RPC0 RPC25 RPC50 RPC75 RPC100
Initial weight (g) 6.86 ±0.17 6.88 ±0.13 6.83 ±0.28 7.25 ±0.22 7.12 ±0.14
Final weight (g) 18.25 ±0.13
a
17.75 ±0.20
a
17.64 ±0.21
a
14.93 ±0.27
b
14.35 ±0.19
b
Weight gain (g) 11.39 ±0.16
a
10.87 ±0.33
a
10.81 ±0.17
a
7.68 ±0.05
b
7.23 ±0.08
b
Weight gain (%) 166.32 ±5.99
a
158.22 ±7.89
a
159.03 ±8.23
a
106.00 ±2.72
b
101.70 ±1.96
b
PER (%) 2.39 ±0.12
a
2.14 ±0.19
ab
1.98 ±0.08
b
1.30 ±0.03
c
1.28 ±0.05
c
FCR 1.14 ±0.06
a
1.29 ±0.20
a
1.38 ±0.05
a
2.09 ±0.05
b
2.12 ±0.08
b
Survival rate (%) 96.66 ±1.50
a
95.83 ±1.10
a
95.83 ±1.66
a
96.25 ±1.90
a
95.00 ±1.25
a
Daily feed intake
(% body
weight day
-1
)
1.93 ±0.05
a
2.11 ±0.12
ab
2.26 ±0.06
bc
2.58 ±0.11
c
2.53 ±0.11
c
Mean ±SE of three replicates. Number within the same row with different superscripts is significantly
different (P\0.05)
Table 4 Proximate analysis of juvenile shrimp tail muscle fed the experimental diets (% wet matter)
Treatment/chemical
composition (%)
Moisture (%) Protein (%) Lipid (%) Ash (%)
0 74.82 ±0.53 21.08 ±0.50 1.63 ±0.06 1.53 ±0.03
25 74.95 ±0.14 20.63 ±0.25 1.68 ±0.15 1.57 ±0.01
50 74.79 ±0.20 20.60 ±0.26 1.70 ±0.04 1.52 ±0.02
75 75.03 ±0.20 20.63 ±0.23 1.65 ±0.10 1.58 ±0.01
100 75.49 ±0.08 20.16 ±0.21 1.63 ±0.05 1.57 ±0.04
Sample from each treatment was analyzed in triplicate (No significant differences among treatment means)
Aquacult Int (2012) 20:117–129 123
123

Digestibility
As RPC inclusion levels increased, significant decreases in crude protein, ether extract,
organic matter, and gross energy of feed were observed (Table 6). Apparent digestibility
coefficients (ADC) of the dry matter in shrimp fed with FM and 50% RPC were signifi-
cantly higher than 25, 75, and 100%.
Discussion
Replacement of FM with plant protein sources in feed formulation is one of the options
proposed to significantly reduce the production costs of the shrimp (Elkin et al. 2007).
Many studies on the replacement of fish meal with plant protein have been carried out in
recent years, which show positive effects of the replacement on growth performance,
depending on species. For example, Akiyama (1988) showed that size and species dif-
ferences affected the acceptability of plant protein in shrimps, so that L. vannamei con-
sumed diets containing high levels of plant protein better than pink shrimp (Penaeus
duorarum). Therefore, replacement studies are considered species-specific. Our findings
Table 5 Amino acids (AA) content (g 100 g
-1
) in tail muscle of L. vannamei fed with different levels of
RPC
AA (g 100 g
-1
) % Replacement meal
RPC0 RPC25 RPC50 RPC75 RPC100
Indispensable amino acids (IAA)
Arginine 8.04 ±0.05
c
8.41 ±0.30
bc
8.80 ±0.00
ab
8.94 ±0.03
a
8.26 ±0.10
c
Histidine 2.34 ±0.04
b
2.41 ±0.10
b
2.40 ±0.01
b
2.73 ±0.13
a
2.01 ±0.12
c
Isoleucine 3.68 ±0.02
b
3.93 ±0.11
ab
3.92 ±0.07
ab
4.08 ±0.17
a
3.59 ±0.06
b
Leucine 5.71 ±0.06
b
6.39 ±0.18
a
6.37 ±0.15
a
6.56 ±0.20
a
5.63 ±0.07
b
Lysine 6.05 ±0.06
b
6.66 ±0.08
a
7.03 ±0.10
a
6.83 ±0.26
a
5.67 ±0.06
b
Methionine 2.71 ±0.10
abc
3.31 ±0.19
a
2.52 ±0.32
bc
3.13 ±0.14
ab
2.45 ±0.10
c
Phenylalanine 3.65 ±0.01
c
3.93 ±0.09
bc
4.06 ±0.03
ab
4.30 ±0.22
a
3.60 ±0.02
c
Threonine 3.00 ±0.02
b
3.35 ±0.13
ab
3.34 ±0.05
ab
3.48 ±0.08
a
3.10 ±0.16
b
Valine 3.79 ±0.08
a
4.03 ±0.15
a
4.00 ±0.10
a
4.33 ±0.25
a
3.68 ±0.05
a
Dispensable amino acids (DAA)
Alanine 4.41 ±0.01
b
5.41 ±0.18
a
5.03 ±0.12
a
5.12 ±0.21
a
4.43 ±0.15
b
Aspartic acid 7.43 ±0.07
b
8.68 ±0.16
a
8.42 ±0.11
a
8.54 ±0.15
a
7.73 ±0.13
b
Glutamic acid 13.80 ±0.11
c
16.29 ±0.47
a
15.93 ±0.28
ab
15.30 ±0.16
b
14.32 ±0.26
c
Glycine 5.64 ±0.02
a
5.75 ±0.06
a
6.22 ±0.10
a
6.23 ±0.06
a
5.71 ±0.35
a
Proline 5.09 ±0.06
c
5.93 ±0.18
ab
6.05 ±0.30
a
5.28 ±0.06
bc
5.65 ±0.27
abc
Serine 2.50 ±0.01
c
3.12 ±0.10
ab
3.15 ±0.04
ab
3.37 ±0.20
a
2.86 ±0.06
b
Tyrosine 3.14 ±0.18
c
3.53 ±0.15
bc
3.68 ±0.08
ab
4.10 ±0.20
a
3.23 ±0.02
bc
PAA 80.98
b
91.13
a
90.92
a
92.32
a
81.92
b
PIAA 38.97
b
42.42
a
42.44
a
44.38
a
37.99
b
PDAA 42.01
b
48.71
a
48.48
a
47.94
a
43.93
b
Mean ±SE of three replicates. Number within the same row with different superscripts is significantly
different (P\0.05)
124 Aquacult Int (2012) 20:117–129
123

showed that up to 50% of RPC inclusion, as a partial replacement of FM, did not lead to
any adverse effects on the growth performance indexes of L. vannamei (Table 3). Inclusion
levels of 75 and 100% induced a growth reduction of about 18 and 21%, respectively, and
this was confirmed by other growth performance indexes as well. Other studies with
various plant protein sources also demonstrated reduced growth performance with
increased plant protein contents in shrimp (Sudaryono et al. 1995) and fish (Regost et al.
1999; Robaina et al. 1999; Sudaryono et al. 1999; Day and Plascencia Gonza
´lez 2000;
Refestie and Tiekstra 2003; Kaur and Saxena 2005; Palmegiano et al. 2006; Palmegiano
et al. 2007). Weight gain is affected by the quality of protein in the diet (Sudaryono et al.
1995). Since all diets used in our study were isocaloric and isonitrogenous, the replaced
RPC was, therefore, the major factor influencing growth rates in shrimps fed different
diets. No sign of feed rejection and high survival rates in all treatments indicated the
palatability of the diets and the good health condition of the shrimp during the feeding trial
(Table 3).
The growth decrease associated with RPC inclusion higher than 75% in this study
originates from the increased FCR related to the reduced digestibility as indicated by the
lower ADC of dry matter (ADC
DM
), crude protein (ADC
CP
), and gross energy (ADC
GE
)
values. On the other hand, the reduction in PER values could be interpreted by reduced
ADC
CP
recorded in diets RPC75 and RPC100 (Tables 3,6). In addition to reduced
digestibility of nutrients, the reduced performance of diets containing high plant protein
(BETTER TO USE PLANT PROTEIN INSTEAD OF VEGETABLE?) levels may be
explained by the growth inhibiting factors present in rice grain (Juliano 1985) or may be
due to some essential growth factors in fish meal that becomes limiting at low inclusion
levels (Mundheim et al. 2004). In the present study, all diets fed to shrimp had amino acid
Table 6 Apparent digestibility coefficients (ADC) of nutrients of the experimental diets (means ±SE;
n=3)
ADC % Replacement meal
RPC0 RPC25 RPC50 RPC75 RPC100
DM
a
78.67 ±0.72
a
67.73 ±0.83
c
72.03 ±0.18
b
62.85 ±0.76
d
56.24 ±1.19
e
CP
b
90.52 ±0.77
a
80.49 ±0.36
b
80.81 ±1.24
b
71.39 ±1.32
c
52.41 ±0.88
d
EE
c
94.11 ±2.31
a
88.25 ±0.87
b
88.28 ±0.90
b
84.95 ±0.99
b
80.03 ±0.87
c
OM
d
87.25 ±0.56
a
78.36 ±0.90
b
79.91 ±0.72
b
71.12 ±0.50
c
50.16 ±0.76
d
GE
e
89.41 ±1.22
a
80.14 ±1.11
b
82.03 ±1.42
b
73.50 ±1.55
c
55.24 ±1.30
d
DP%
f
33 30 30 26 19
DL%
g
7.7 7.7 7.5 7.7 7.4
GE kJ g
-1h
18 18 18 18 18
DE kJ g
-1i
16 14 14 13 10
In the row, different letters mean statistical difference at (P\0.05)
DM dry matter, CP crude protein, EE ether extract, OM organic matter, GE gross energy, DP digestible
protein, DL digestible lipid, DE digestible energy
a,b,c,d,e
Calculated from AND% =100 -100[(%CrFd/%CrFc) 9(%NtFc/%NtFd)]
f,g
DP, DL% *ADC
CP, EE
of diet 9protein, fat of diet
h
Calculated on the basis of 23.6, 39.5, and 17.2 kJ g
-1
of protein, fat, and carbohydrate, respectively,
(NRC 1993)
i
DE kJ g
-1
*GE 9GE kJ g
-1
Aquacult Int (2012) 20:117–129 125
123

values similar to those reported by Suarez et al. (2009). The RPC source used to replace
FM in the 36.6% protein diet appeared to provide sufficient levels of essential amino acids.
The analysis of tail-muscle composition showed that amino acids profiles of shrimp fed
with 25, 50, and 75% RPC substitution levels were significantly higher than those of
shrimp fed FM and 100% RPC (Table 5). Studies on plant protein substitution in feed for
fish have shown an increase in the activity of enzymes involved in amino acid metabolism
(Moyano et al. 1991; Martin et al. 2003). Go
´mez-Requeni et al. (2003) indicated that the
effects of protein source on amino acid-metabolizing enzymes may be in part due to the
indispensable/dispensable amino acid ratio (IAA/DAA) in the diet. In the present study, the
IAA/DAA ratio in 25, 50, and 75% RPC treatments was higher than FM and 100% RPC
diets (Table 2). This higher IAA/DAA ratio (25, 50, and 75%) in our study could have
increased protein anabolism of shrimp, as it has been found that decreases in IAA/DAA
ratio are associated with increased protein catabolism (Go
´mez-Requeni et al. 2003; Vil-
helmsson et al. 2004). In the present study, RPC substitution up to 75% resulted in higher
amino acid content in the tail muscle than shrimp fed FM. On the other hand, Thompson
et al. (2005) and Aksnes et al. (2006) found no differences in amino acids content in tail
muscle of red claw crayfish (Cherax quadricarinatus) and rainbow trout (Oncorhynchus
mykiss) fillet, respectively, for different levels of plant protein substitution.
Apparent digestibility coefficient (ADC) of a feed depends on its chemical composition
and the digestive characteristics of the target species (Lim and Dominy 1990) as well as
environmental conditions (Brunson et al. 1997). Although RPC may have a good amino
acid (AA) profile for a number of AA, it is low in lysine and has a moderate protein
digestibility that is much lower than fish meal. ADC data clearly indicate that RPC has a
low digestibility and this may have decreased digestible protein allocated for growth at
RPC substitution levels C50% (Table 6). The ADC of the FM diet (RPC0) was signifi-
cantly higher than other treatments (Table 6). This result is in agreement with that of
Palmegiano et al. 2006 who reported reduced ADC with increased RPC content in rainbow
trout. ADC and digestible energy (DE) decreased with increased RPC inclusion. Although
digestible protein decreased with increased RPC inclusion, weight gain apparently
remained stable between 33 and 30% digestible protein (DP) in prepared diets, which
corresponds to the protein requirement of the species (Table 6). In the present study,
optimum DE was considered to be around 14 kJ g
-1
, which is in agreement with a pre-
vious study (Suarez et al. 2009). Considering protein/energy (P/E) ratio in the scope of
utilization of RPC, 2.14 mg protein per kJ (P/E =30/14) is recommended for this species.
Dry matter digestibility in L. vannamei for RPC levels up to 50% (i.e. 70%) was slightly
lower than those reported by Siccardi et al. (2006) but was similar to that reported by
Akiyama et al. (1989). Ether extract and organic matter ADCs for RPC (85 and 79%) were
higher than those reported for P. monodon fed with full fat soy (66%) and Oncorhynchus
mykiss fed with RPC (72%) (Merican and Shim 1995; Palmegiano et al. 2006). The value
of the gross energy ADCs (81%) is also slightly lower than the gross energy digestibility
values for L. vannamei fed with soybean protein concentrate (85%) reported by Suarez
et al. (2009). In addition, protein ADCs for RPC up to 50% inclusion (81%) were lower
than those reported for Litopenaeus vannamei and Penaeus monodon (Suarez et al. 2009;
Akiyama et al. 1989).
Reasons for the decreased crude protein digestibility of RPC (90–52%) observed in this
study were not apparent (Table 6). However, low protein digestibility of feed ingredients
can be caused by numerous factors such as the presence of enzyme inhibitors in the diet,
inappropriate diet formulation, and the presence of protein that is chemically or physically
unavailable (Ash 1985). Akiyama et al. (1992) indicated that protein availability can be
126 Aquacult Int (2012) 20:117–129
123

influenced by the chemical composition of the ingredient, freshness of the processed raw
materials, method of cooking, drying, and storage. Generally, some researchers have
shown increased ADC with higher plant protein levels (Sudaryono et al. 1999; Carter and
Hauler 2000), while some workers have shown otherwise (Palmegiano et al. 2006; Smith
et al. 2006). This conflicting observation for ADC is possibly related to differences in
species examined, size of the animal, ingredient quality, or diet composition (Sudaryono
et al. 1995). In the present study, it would seem that approximately up to 50% fish meal can
be replaced by RPC without altering the growth performance and chemical composition of
L. vannamei’s tail muscle.
Conclusion
Our findings indicated that up to 50% FM can be replaced with RPC as an alternative
protein source in commercial shrimp diets, without affecting growth. This will lead to
optimal utilization of fish meal in diet and reduce the demand for this limited and costly
ingredient.
Acknowledgments The authors would like to thank the Jonob Feridis Aquaculture Center (Bushehr
province, IRAN), particularly Mr. Seyed Muslim Mousavi for providing the facilities and Prof. Gerard
Cuzon (Ifremer BP 7004 Taravao, Tahiti, French Polynesia, France) for his critical review of the manuscript.
This study has been financed by Tarbiat Modares University. We are also grateful to BGMP Co., Ltd. of
South Korea for supplying RPC.
References
Akiyama DM (1988) Soybean meal utilization by marine shrimp. In: AOCS world congress on vegetable
protein utilization in human food and animal feedstuffs, American Soybean Association, Singapore,
2–7 October 1988
Akiyama DM (1989) FSGP Aquaculture Research: the use of soybean meal to replace white fish meal in
commercially processed Penaeus monodon Fabricius feed in Taiwan, ROC. PROC. Aquaculture Feed
Processing and Nutrition Workshop, Thailand and Indonesia, 19 to 25 September 1991, pp 289–299,
American Soybean Asso., Singapore
Akiyama DM, Dominy WG, Lawrence AL (1992) Penaeid shrimp nutrition. In: Fast AW, Lester LJ (eds)
Marine shrimp culture: principles and practices. Developments in aquaculture and fisheries science, vol
23. Elsevier Science Publisher B.V., The Netherlands, pp 535–568
Aksnes A, Opstvedt J (1998) Content of digestible energy in fish feed ingredients determined by the
ingredient-substitution method. Aquaculture 161:45–53
Aksnes A, Britt Hope A, Albrektsen S (2006) Size-fractionated fish hydrolysate as feed ingredient for
rainbow trout (Oncorhynchus mykiss) fed high plant protein diets. II: Flesh quality, absorption,
retention and fillet levels of taurine and anserine. Aquaculture 261:318–326
Amaya EA, Davis DA, Rouse DB (2007) Replacement of fish meal in practical diets for the Pacific white
shrimp (Litopenaeus vannamei) reared under pond conditions. Aquaculture 262:393–401
Antoine FR, Wei CI, Littell RC, Marshall MR (1999) HPLC method for analysis of free amino acids in fish
using o-Phthaldialdehyde precolumn derivatization. J Agric Food Chem 47:5100–5107
Ash R (1985) Protein digestion and absorption. In: Cowey CB, Mackie AM, Bell JG (eds) Nutrition and
feeding in fish. Academic Press Inc., Orlando, Assoc., Singapore, pp 68–93
Association of Official Analytical Chemists (AOAC) (1995) Official methods of analysis of the Association
of Official Analytical Chemists, 16th edn. AOAC, Arlington
Bautista-Teruel MN, Eusebio PS, Welsh TP (2003) Utilization of feed pea, Pisum sativum, meal as a protein
source in practical diets for juvenile tiger shrimp, Penaeus monodon. Aquaculture 225:121–131
Brunson JF, Romaire RP, Reigh RC (1997) Apparent digestibility of selected ingredients in diets for white
shrimp Penaeus setiferus L. Aquac Nutr 3:9–16
Aquacult Int (2012) 20:117–129 127
123

Carter CG, Hauler RC (2000) Fish meal replacement by plant meals in extruded feeds for Atlantic salmon,
Salmo salar L. Aquaculture 185:299–311
Cousin M (1995) Etude de l’utilisation des glucides et du rapport P/E chez 2 espe
`ces de crevettes, P.
vannamei et P. stylirostris. The
`se INA/PG, 210 pp
Cruz-Sua
´rez LE, Marie DM, Salazar MT, McCallum IM, Hickling D (2001) Assessment of differently
processed feed pea Pisum sativum meals and canola meal Brassica sp. in diets for blue shrimp
Litopenaeus stylirostris. Aquaculture 196:87–104
Davis DA, Arnold CR, Mc Callum I (2002) Nutritional value of feed peas (Pisum sativum) in practical diet
formulations for Litopenaeus vannamei. Aquac Nutr 8:87–94
Day OJ, Plascencia Gonza
´lez HG (2000) Soybean protein concentrate as a protein source for turbot,
Scophthalmus maximus L. Aquac Nutr 6:221–228
Dersjant-Li Y (2002) The use of soy protein in aquafeeds. Advances en Nutrition Acuicola VI. Memorias
del VI Simposium Internacional de Nutricion Acuicola. 2002. Cancun, Quintana Roo, Mexico, 3–6
September 2002
Elkin A, Davis DA, Rouse DB (2007) Alternative diets for the Pacific white shrimp Litopenaeus vannamei.
Aquaculture 262:419–425
Eusebio P (1991) Effect of dehulling on the nutritive value of some leguminous seeds as protein sources for
tiger prawn, Peaneus monodon, juveniles. Aquaculture 99:297–308
FAO (2004) http://www.fao.org/docrep/006/J2084e/j2084e06.htm
Forster I, Dominey W, Tacon AGJ (2002) The use of concentrates and other soy products in shrimp feeds.
Advances en Nutricion Acuicola lll. Memorias del VI symposium Intemacional de Nutricion Acuicola.
Cancun, Quintana Roo, Mexico
Forster I, Dominy W, Obaldo L, Tacon AGJ (2003) Rendered meat and bone meals as ingredients of diets
for shrimp Litopenaeus vannamei (Boone, 1931). Aquaculture 219:655–670
Fox JM, Lawrence AL, Li-Chang E (1995) Dietary requirement for lysine by juvenile Penaeus vannamei
using intact and free amino acid sources. Aquaculture 131:279–290
Francis G, Makkar HPS, Becker K (2001) Antinutritional factors present in plant-derived alternate fish feed
ingredients and their effects in fish. Aquaculture 199:197–227
Go
´mez-Requeni P, Mingarro M, Kirchner S, Calduch-Giner JA, Me
´dale F, Corraze G, Panserat S, Martin
SAM, Houlihan HM, Kaushik SJ, Pe
´rez-Sa
´nchez J (2003) Effects of dietary amino acid profile on
growth performance, key metabolic enzymes and somatotropic axis responsiveness of gilthead sea
bream (Sparus aurata). Aquaculture 220:749–767
Goytortua-Bores E, Civera-Cerecedo R, Rocha-Meza S, Green-Yee A (2006) Partial replacement of red crab
(Pleuroncodes planipes) meal for fish meal in practical diets for the white shrimp Litopenaeus van-
namei. Effects on growth and in vivo digestibility. Aquaculture 256:414–422
Hatlen B, Grisdale-Hellen B, Helland SJ (2005) Growth, feed utilization and body composition in two size
groups of Atlantic halibut (Hippoglossus hippoglossus) fed diets differing in protein and carbohydrate
content. Aquaculture 249:401–408
Juliano BO (1985) Rice: chemistry and technology, 2nd edn. Am. Assoc. Cereal Chem., St Paul 774 pp
Kaur VI, Saxena PK (2005) Incorporation of maize gluten in supplementary feed and its impact on growth
and flesh quality of some carps. Aquacult Int 13:555–573
Lim C, Dominy WD (1990) Evaluation of soybean meal as a replacement for marine animal protein in diets
for shrimp (Penaeus vannamei). Aquaculture 87:53–63
Martin SAM, Vilhelmsson O, Me
´dale F, Watt P, Kaushik S, Houlihan DF (2003) Proteomic sensitivity to
dietary manipulations in rainbow trout. Biochim Biophys Acta 1651:17–29
Maynard AL, Loosli KJ (1969) Animal nutrition, 6th edn. McGraw-Hill, New York
Merican ZO, Shim KF (1995) Apparent digestibility of lipid and fatty acids in residual lipids of meals by
adult Penaeus monodon. Aquaculture 133:275–286
Millamena OM, Bautista-Teruel MN, Kanazawa A (1996) Methionine requirement of juvenile tiger shrimp
Penaeus monodon Fabricius. Aquaculture 143:403–410
Millamena OM, Bautista-Teruel MN, Reyes OS, Kanazawa A (1997) Threonine requirement of juvenile
marine shrimp Penaeus monodon. Aquaculture 151:9–14
Millamena OM, Bautista-Teruel MN, Reyes OS, Kanazawa A (1998) Requirements of juvenile marine
shrimp, Penaeus monodon (Fabricius) for lysine and arginine. Aquaculture 164:95–104
Millamena OM, Bautista-Teruel MN, Kanazawa A, Teshima S (1999) Quantitative dietary requirements of
postlarval tiger shrimp, Penaeus monodon, for histidine, isoleucine, leucine, phenylalanine and tryp-
tophan. Aquaculture 179:169–179
Moyano FJ, Gardenete G, de la Higuera M (1991) Nutritive and metabolic utilization of proteins with high
glutamic-acid content by the rainbow-trout (Oncorhynchus mykiss). Comp Biochem Physiol A
100:759–762
128 Aquacult Int (2012) 20:117–129
123

Mundheim H, Aksnes A, Hope B (2004) Growth, feed efficiency and digestibility in salmon (Salmo salar L.)
fed different dietary proportions of vegetable protein sources in combination with two fish meal
qualities. Aquaculture 237:315–331
NRC (Nutrient Requirements of Fish) (1993) Nutrient requirements of warmwater fishes and shellfishes,
revised edition. National Academy Press, Washington, DC, p 114
Palmegiano GB, Dapra
`F, Forneris G, Gai F, Gasco L, Guo K, Peiretti PG, Sicuro B, Zoccarato I (2006) Rice
protein concentrate meal as a potential ingredient in practical diets for rainbow trout (Oncorhynchus
mykiss). Aquaculture 258:357–367
Palmegiano GB, Costanzo MT, Dapra F, Gai F, Galletta MG, Maricchiolo G, Micale V, Peiretti PG,
Genovese L (2007) Rice protein concentrate meal as potential dietary ingredient in practical diets for
blackspot seabream (Pagellus bogaraveo). Journal of Animal Physiology and Animal Nutrition
91:235–239
Refestie S, Tiekstra HAJ (2003) Potato protein concentrate with low content of solanidine glycoalkaloids in
diets for Atlantic salmon (Salmo salar). Aquaculture 216:283–298
Regost C, Arzel J, Kaushik SJ (1999) Partial or total replacement of fish meal by corn gluten meal in diet for
turbot (Psetta maxima). Aquaculture 180:99–117
Robaina L, Corraze G, Aguirre P, Blanc D, Melcion JP, Kaushik S (1999) Digestibility, postprandial
ammonia excretion and selected plasma metabolites in European sea bass (Dicentrarchus labrax) fed
pelleted or extruded diets with or without wheat gluten. Aquaculture 179:45–56
Samocha TM, Davis DA, Saoud IP, De Bault K (2004) Substitution of fish meal by co-extruded soybean
poultry by-product meal in practical diets for the Pacific white shrimp, Litopenaeus vannamei.
Aquaculture 231:197–203
Siccardi AJ III, Lawrence AL, Gatlin DM III, Fox JM, Castille FL, Perez-Velazquez M, Gonza
´lez-Fe
´lix ML
(2006) Digestibilidad aparente de energı
´a, proteı
´na y materia seca de ingredientes utilizados en ali-
mentos balanceados para el camaro
´n blanco del pacı
´fico Litopenaeus vannamei. In: Cruz-Sua
´rez LE,
Ricque-Marie D, Nieto-Lo
´pez MG, Tapia-Salazar M, Villarreal-Cavazos DA, Puello-Cruz AC, Garcı
´a-
Ortega A (eds) Avances enNutricion Acuı
´cola VIII - Memorias del VIII Simposio Internacional de
Nutricio
´n Acuı
´cola. Universidad Auto
´noma de Nuevo Leo
´n, Monterrey, Me
´xico. ISBN: 970-694-331-
5, pp 213–237, 15–17 Noviembre 2006, Mazatla
´n, Sinaloa, Me
´xico
Smith DM, Tabrett S, Irvin S, Barclay M (2006) Lupin- an alternative protein source for use in shrimp feeds.
Avances en Nutricion Acuicola Vlll. Vlll symposium Intemacional de Nutricion Acuicola. Monterrey,
Nuevo Leon, Mexico
Suarez JA, Gaxiola G, Mendoza R, Cadavid S, Garcia G, Alanis G, Suarez A (2009) Substitution of fish
meal with plant protein sources and energy budget for white shrimp Litopenaeus vannamei (Boon,
1931). Aquaculture 289:118–123
Sudaryono A, Tsvetnenko E, Evans LH (1995) Evaluation of potential of lupin meal as an alternative to fish
meal in juvenile Penaeus monodon diets. Aquac Nutr 5:277–285
Sudaryono A, Tsvetnenko E, Evans LH (1996) Digestibility studies on fisheries by-products based diets for
Penaeus monodon. Aquaculture 143:331–340
Sudaryono A, Tsvetnenko E, Hutabarat J, Supriharyono E (1999) Lupin ingredients in shrimp (Penaeus
monodon) diets: influence of lupin species and types of meals. Aquaculture 171:121–133
Swick RA, Akiyama DM, Boonyaratpalin M, Creswell DC (1995) Use of soybean meal and synthetic
methionine in shrimp feed. American Soybean Association, Technical Bulletin, vol AQ 43-1995
Tacon AGJ (1993) Feed ingredients for crustaceans: Natural foods and processed feedstuffs. FAO Fisheries
Circular No. 866, FAO, Rome, p 67
Tacon AGJ, Jackson A (1985) Utilization of conventional and unconventional protein sources in practical
fish feeds. In: Cowey CB, Mackie AMM, Bell JG (eds) Nutrition and feeding in fish. Academic Press,
London, pp 119–145
Tacon AGJ, Metian M (2008) Global overview on the use of fish meal and fish oil in industrially com-
pounded aquafeeds: trends and future prospects. Aquaculture 285:146–158
Thompson KR, Muzinic LA, Engler LS, Webster CD (2005) Evaluation of practical diets containing
different protein levels, with or without fish meal, for juvenile Australian red claw crayfish (Cherax
quadricarinatus). Aquaculture 244:241–249
Vilhelmsson OT, Martin SAM, Me
`dale F, Kaushik SJ, Houlihan DF (2004) Dietary plant-protein substitutes
affects hepatic metabolism in rainbow trout (Oncorhynchus mykiss). Br J Nutr 92:71–80
Watanabe T, Aoki H, Viyakarn V, Maita M, Yamagata Y, Satoh S, Takeuchi T (1995) Combined use of
alternative protein sources as a partial replacement for fish meal in a newly developed soft-dry pellet
for yellowtail. Suisanzoshoku 43:511–520
Williams CH, David DJ, Iismaa O (1962) The determination of chromic oxide in faeces samples by atomic
absorption spectro- photometry. J Agric Sci 59:381–385
Aquacult Int (2012) 20:117–129 129
123