Production of cost-effective nutritionally balanced diets for fish are main
factor affecting intensive aquaculture because of its influence on growth, health
and production cost. Fish Meal (FM) is an important ingredient in aquaculture
diets due to its high protein quality. However, as FM is the most expensive
of all diet ingredients, the use of less expensive animal or plant protein sources
are needed as partial or total replacements for FM. This became an important
research interest in aquaculture nutrition (Yigit et
FM is the major protein source in aqua feeds globally averaged about 6.5 million
metric tonnes (mmt), over the past 20 years. However, the production may fluctuate
year by year. Variability in production is associated with variability in landings
of fish used to make FM (Hardy, 2010). The percentage
of annual global production of FM being utilized in aquafeeds has increased
steadily over the last two decades from approximately 15-65% (Tacon
and Metian, 2008). Over 11% of the FM used in the aquafeeds sector went
into feeds for Carp in 2006. Surprisingly, in feeds for fry and fingerling of
omnivorous species was used about 21% (Hardy, 2010).
Nevertheless, continued growth of aquaculture production is fundamentally unsustainable
if FM remains the primary protein and oil sources used in aquafeed. Sooner or
later, supplies will be insufficient. However, alternatives to FM are available
from other sources, mainly plant (grains/oil seeds) and animal proteins. The
price of fish meal increased significantly from 400 US dollars to over US dollars
1500 per metric ton in 2006. This increased pressure to replace FM with plant
protein ingredients. Therefore, replacement of FM with alternative proteins
with sustainable supplier or less expensive protein sources would be beneficial
in reducing feed costs. Proteins from soybean are widely available economical
protein source with relatively high digestible protein and energy contents (Hertrampf
and Piedad-Pascual, 2000). Use of soybean proteins as a dietary protein
has been examined for many commercial important fish species (Refstie
et al., 2000).
Hazelnut is commercially cultivated in Turkey, the USA, Italy, Spain, China
and Australia. Turkey, the Worlds largest hazelnut producer, produces about
70-80% of the world supply. Hazelnut production in Turkey was about 825.000
tons (in shells) in 2008. Hazelnuts are extensively used in confections, together
with chocolate in truffle and other products and in biscuits and cakes. Excess
hazelnuts are used to produce oil for human consumption. The production of hazelnut
oil and meal reduces the value to one-fifth of its value for domestic sales
as hazelnuts. Hazelnut meal produced after oil extraction has high nutritive
value due to its high protein and low fibre contents (Yalcin
et al., 2005; Ergun et al., 2008).
Various protein sources have evaluated for fish feeds but the results were
inconsistent. Unfortunately, attempts by feed manufacturers and nutritionists
to replace the FM component of practical fish feeds with alternative protein
sources have generally led to reduced feed efficiency and growth (Tacon
and Jackson, 1985; Xie et al., 2001). Poor
palatability, low digestibility, poor utilization of proteins and amino acids,
anti-nutritional factors and other unknown factors are important to consider
in utilization of plant proteins as replacement of FM (Becker
and Makkar, 1999; Xie et al., 2001).
Ornamental fish production is an important component of the aquaculture industry.
The ornamental Carp, Cyprinus carpio var. Koi L. is very popular to fish
hobbyists throughout the World. Commonly known as koi, this fish has a market
for individuals over 4 g and requires only about 3-5 months of grow out to attain
saleable size (Jha et al., 2007). Protein requirement
of koi is reported as 250-450 g kg‾1 of the diet. It is therefore
of interest to replace some of the FM with protein-rich ingredients. Previous
studies with koi have focused on some plant protein sources such as corn gluten
meal, rapeseed meal, peanut cake, potato protein concentrate, cotton seed meal
and soybean meal etc (Xie et al., 2001). The
aim of this study was to investigate the effects of partial or total replacement
of fish meal with hazelnut and soybean meals on growth performance and nutrient
utilization of koi carp juvenile (C. carpio).
MATERIALS AND METHODS
The experiment was conducted at Sinop University, Sinop Faculty of Fisheries, Fresh Water Fish Farming Unit (Sinop, Turkey).
Preparation of experimental diets: Diet ingredients were provided by
a local fish feed manufacturer (SIBAL Inc., Sinop-Turkey). Hazelnut Meal (HM)
was provided by FISKOBIRLIK Inc. (Giresun-Turkey). Five practical diets were
formulated with commercially available ingredients and were produced in the
Fish Nutrition Laboratory of Sinop University in Sinop, Turkey. The diets were
isonitrogenous and isocaloric on a crude protein (350 g kg‾1)
and gross energy (4.20 kcal g‾1) basis.
The experimental diets were formulated by substituting FM protein for Soybean
Meal (SM) and HM protein at levels of 50 and 100% replacement on a crude protein
basis. Ingredients and chemical compositions of the diets are shown in Table
1. The proximate analyses and amino acid contents of protein sources are
shown in Table 2. The amino acid profiles of diets were estimated
according to Kaushik (1995) and shown in Table
3. Total n-3 Highly Unsaturated Fatty Acid (HUFA) contents were calculated
according to the equation given below and ranged from 1.45 g kg‾1
for diet to 2.15 g kg‾1 for the diet containing (Table
Total n-3 HUFA in diet, g kg‾1 = (total fish oil in diet,
g kg‾1) x (% n-3 HUFA in fish oil used). The dry ingredients
and oil were mixed in a food mixer for 15 min. Tap water was then blended into
the mixture to attain a consistency appropriate for passing the mixture through
a meat grinder. After pelleting, the diets were dried to a moisture content
of 7-8% and stored in a deep freeze (-20°C) until use.
Fish and experimental rearing conditions: The feeding experiment was
performed on koi carp juveniles. The juveniles were obtained from the experimental
fish farm at Faculty of Fisheries, Fresh Water Fish Farming Unit in Sinop University.
||Formulation and nutrient composition of the diets used in
|1Vit. Mix.: Rovimix 107 (g kg‾1
mix); Vit. A 8000 IU, Vit D3 800 IU, Vit. E 80 mg, Vit. K3 4.8 mg, Vit.
B1 8 mg, Vit. B2 12 mg, Vit. B6 8 mg, Vit. B12 0.02 mg, Vit. C 80 mg, Niasin
80 mg, Folik asit 2.4 mg, Kalsyum D-Pantothenate 20 mg, Biotin 0.2 mg, Inositol
120 mg. 2Min. Mix.: Remineral B Balik 97 (g kg‾1
mix); Fe 97.5 mg, Cu 18.75 mg, Mn 135 mg, Cb 0.6 mg, Zn 120 mg, I 2.7 mg,
Se 0.225 mg. 3Nitrogen Free Extract (NFE) = Dry matter - (Percentage
of crude protein+Percentage of crude lipid + Percentage of crude ash+Percentage
of crude cellulose). 4Calculated according to 5.65 kcal g‾1
protein, 9.45 kcal g‾1 lipid, 4.1 kcal g‾1
nitrogen free extract; 5According to Guner
et al. (1998)
||Proximate analyses and amino acid profiles of fish meal, soybean
meal, hazelnut meal, Sunflower meal and corn meal
|*Data on amino acids contents of fishmeal and soybean meal
from Halver (1991) of hazelnut meal from Koksal
et al. (2006) of Sunflower meal and corn meal from Bilguven;
NA = Not Available
|| Essential amino acid contents of the experimental diets
|1Calculated from data in Table 2.
2There is no cystine in hazelnut meal
In the experiment, five homogeneous groups consisting of 15 koi (initial mean
body weight: 0.116 g) were randomly distributed in 15 rectangular plastic tanks
(12 l capacity). Fish were fed with diets of control (FM), 50% SM, 50% HM, 100%
SM and 100% HM for 65 days. Each experimental group had three replicates.
Continuous aeration was provided by air pumps. Dissolved oxygen ranged from
8-10 mg L‾1 during experiments period. Fish were fed by hand
ad libitum (visual observation of the first uneaten feed) twice a day
(09.00 and 18.00 h) and daily feed intake was recorded. About 30% of tank water
was replaced by fresh water everyday. The experimental tanks were cleaned daily
to remove uneaten feed and fecal material. Fish were exposed to natural light
regime (14 h light: 10 h dark) for a 65 days period.
Fish were weighed at the start of experiment and beginning of each month and end of the experiment. Before weighing, fish were deprived of feed for a day. The feed consumption was recorded every day. Water temperature was maintained at mean 24°C with water heaters and natural photoperiod was used during the experiment.
Chemical analyses: The chemical composition of the diets was determined
according to AOAC (1984) guidelines as follows: dry matter
after drying at 105°C for 24 h, ash by combustion at 550°C for 12 h,
crude protein (Nx6.25) by the Kjeldahl method after acid digestion and crude
lipid by petroleum ether extraction in a Soxhlet System; nitrogen free extracts
was calculated by difference (NFE = Dry matter - (Crude protein + Crude lipid
+ Crude ash + Crude cellulose).
Calculations: Relative Growth Rate (RGR), Specific Growth Rate (SGW),
Feed Conversion Rate (FCR) and Protein Efficiency Rate (PER) were calculated
as described by Watanabe et al. (1987) and Yigit
et al. (2002).
Statistical analysis: The data on growth, feed conversion ratio and protein efficiency rate of fish were expressed as means and ±standard error. Data from each treatment diet for each sampling period were analysed by one-way ANOVA and significant differences (if present) were ranked with Tukeys multiple comparison test at the 5% level of significance using the MINITAB Release 13.1 Statistical Analysis Software Program for Windows, Version 10.0.1 (Minitab Inc., Chicago, Illinois, USA).
At the end of the 65 days of growth trial, there were no significant differences among the treatments in survival rates. Fish meal protein by different protein sources had no effect on survival rates. All the experimental diets were well accepted by fish. The growth performance and feed utilization values were shown in Table 4. Mean Final Body Weights (FBW) ranged from 0, 28 to 0, 46 g in experiment groups. There were no significantly differences in FBW, Relative Growth Rate (RGR) and Protein Efficiency Ratio (PER) between experiment diet groups. Even though difference was not significant and FBW, RGR and PER in fish fed 50% HM diet better concluded than the other groups. Diet 100% HM gave lowest values of FBW and RGR. Fish fed control, 50% SM, 50% HM and 100% SM diets had similar SGR values while fish fed the 100% HM diet had lower SGR values than those of other diets (p<0.05). The FCR values of fish fed 50% SM and 50% HM diets were significantly different than that of 100% HM (p<0.05). The best FCR values were obtained with 50% HM, 50% SM, 100% SM and control diets, respectively.
|| Growth performance and feed utilization in fish fed with
the experimental diets
|*Values (mean±standard deviation of data for triplicate groups)
with the different superscript along the same row are significantly different
(p<0.05). IBW, initial Body Weight; FBW, Final Body Weight; RGR, Relative
Growth Rate = [(FBW- IBW)/IBW]x100; SGR, Specific Growth Rate (percent increase
in body weight per day) = [(ln FBW-ln IBW)/days]x100; FCR, Feed Conversion
Ratio = feed/weight gain; PER, Protein Efficiency Ratio = weight gain/protein
The present investigation showed the potential of HM and SM meals for inclusion
in granule diets of koi carp juveniles. Several researches reported that FM
in fish diets can be replaced by plant protein sources. Use of plant feedstuffs
as protein sources in fish diet limited for HM in koi juveniles diets. There
has been number of different studies especially on the evaluation of HM and
SM in diets for different fish species. Buyukcarpar and
Kamalak (2007) found that HM can replace up to 35% of protein in FM and
40% of the protein in SM in fingerling mirror carp diets without adverse effects
on growth performance, feed utilization and body composition. Bilgin
et al. (2007) determined the growth performance and feed utilization
in Rainbow trout and reported that hazelnut meal had the potential to substitute
20-30% of soybean meal in extruded feeds. Ergun et al.
(2008) found that turbot diets of SM can be replaced up to 20% of the FM
without reducing the growth performance and nutrient utilization and hazelnut
meal can be incorporated into diet with 20% rate. Sevgili determined that the
inclusion of >10% HM in mirror carp diets resulted in lowering the growth
and feed utilization. The findings in present study agreed with those reported
in other studies. FBW, RGR and SGR values decreased as hazelnut and soybean
meal inclusion rates were increased but acordingly PER among groups and the
fact that fish were fed adlibitum determine that problem of palatability of
diets is not showed. Rodehutscord et al. (1995)
reported that fish meal could totally be replaced by a mixture of wheat glutein
and crystalline amino acids without negative effects on growth in rainbow trout.
The experimental diets supplied the essential fatty acid requirements of koi
carp juveniles. However, control diets contained low n-3 HUFA due to the lower
content of anchovy oil (Table 1). The inadequate fatty acid
content of control diets probably resulted in low growth performance of fish.
Yigit et al. (2006) also stated that low performance
of the poultry by-product meals was related to the insufficient essential amino
acid contents as well as fatty acid levels.
Deficiencies in essential amino acids and negative effects of anti-nutritional
factors can be determined by inclusion of higher levels of some plant protein
sources. In the present study, the low growth performance of koi juvenile fed
with 100% HM diets was largely caused by most of the amino acids. Lysine and
methionine were mostly reported to be growth limiting amino acids (Tacon
and Jackson, 1985). Therefore, lysine and methionine containing of 100%
HM diets were lower growth performance than other diets (Table
Reduced growth performance of juveniles fed with 100% HM, 100% SM and control
diets may be due to their fat contents. Optimal dietary fat levels should be
lower than 12% in the practical diets of cyprinids (Kaushik,
1995). Dietary fat levels of experiment groups were equated. But, control
diets contained low n-3 HUFA than the other diet groups. Although, n-3 HUFA
contents in control diet is <100% HM diet treatment. Control group showed
higher growth performance than 100% HM. Therefore, fatty acids contents may
have not an effect on growth performance. However, low growth performance in
the experiments was related to the amino acid contents of experimental diets.
Some of the amino acid levels exceeded the stated requirements of common carp
(Xie et al., 2001). Even though, the diets were
not fortified with essential amino acids, the imbalances of amino acid composition
between experimental groups were definite (Table 3). Lysine
and methione+cysteines amounts in 100% HM group were 200 and 150% less than
control group, respectively. Lysine and methione + cysteines which are generally
considered the important limiting amino acids for most fish species. Thus, mean
final body weights of fish fed with 100% HM diet were at least 15% lower compared
with the other diet groups (Table 4).
Protein contents of soybean products ranged from 36% to over 70%. Soybeans
like other plant-derived protein sources have anti-nutritional factors that
can reduce the palatability, protein utilization or growth (Hardy,
2000). Trypsin inhibitors decrease the activity of trypsin, a digestive
enzyme that breaks down proteins in the intestine. Trypsine inhibitors were
also reported lowering the protein digestibility in diets of salmon and trout
(Arndt et al., 1999). In this study, results
of the growth performance were not showed that trypsin inhibitors were not affected
protein digestibility in the diets. The result showed increased SM and HM percentages
in koi juvenile diets decreased the growth performances in koi juveniles.
SGR value of koi juveniles fed with 100% HM diet was significantly different
than that of other diet groups (p<0.05). Buyukcarpar
and Kamalak (2007) reported that the PER decreased and FCR increased with
increasing inclusion levels of HM and SM diets. The results may reflect a deficiency
of one or more amino acids in the diets. Similar result, in this study was determined
that FCR was significantly different in experimental diet groups and the best
FCRs were obtained from 50% HM and 50% SM diet groups, respectively (Table
This research indicates that growth performances of koi carp juveniles were negatively affected with 100% HM diet. The results clearly indicated that growth performances were decreased with increasing inclusion level of plant protein sources.
In the present study, koi carp juveniles were tested and the plant proteins were incorporated at relatively high levels. Future experiments should be carried out on koi of different sizes to determine the suitable inclusion levels of various plant proteins that yield the best economic gains.