BAOJ Aquaculture Carvalho EA, BAOJ Aquaculture 2018, 1: 2 1: 006
Research
Apparent Digestibility Evaluation of an Alternate Plant Ingredient, Cupuacu (Theobroma grandiflorum) Seed Cake for Tambaqui (Colossoma macropomum) Carvalho EA1 and Keshavanath P2* Instituto de Ciências e Tecnologia das Águas, Universidade Federal do Oeste do Pará, Av. Mendonça Furtado, 2946, Bairro: Fátima, Santarém, Pará, Brasil
1
Coordenação de Pesquisa em Aqüicultura (CPAQ), Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus- AM, Brasil
2
Abstract
while minimizing the environmental impacts caused by uneaten feed
A reference diet (commercial diet with 32% protein) and a test diet (consisting of 70% reference diet and 30% of cupuacu seed cake) were used with 0.5% chromic oxide (Cr2O3) as an external marker to evaluate the digestibility of Cupuacu (Theobroma grandiflorum) seed cake, employing tambaqui (Colossoma macropomum) juveniles. Fish of average weight 87.2 ± 6.3 g were distributed at 20 each in10 fiberglass tanks with constant water circulation and aeration, adapted for digestibility studies. The two diets were fed to fish in five tanks each. Feces was collected from replicate groups of fish over 50 days, starting from the 11th day of the 60-day experiment, using the fecal collection column attached to the fish tanks. Apparent digestibility coefficients of dry matter (DM), crude protein (CP), ether extract (EE) and nitrogenfree extract (NFE) were determined. Coefficients of DM, CP, EE and NFE were higher for the reference diet, the values being 85%, 89%, 95% and 89%. The respective values were lower at 66%, 71%, 94% and 69% for the test diet. Daily monitored physico-chemical variables of water (dissolved oxygen, pH, temperature and electrical conductivity) as well as those monitored every 15 days (alkalinity, free carbon dioxide, nitrite nitrogen and total ammonia) had no negative impact on the fish. Higher crude fibre and presence of anti-nutrients in cupuacu seed cake appear to be responsible for the lower nutrient digestibility of the test diet.
Keywords:
Cupuacu;
Digestibility;
Colossoma
macropomum;
Alternative Plant Ingredient
Introduction Brazil’s ranking in aquaculture production has improved considerably in recent years and it now contributes over 1% to global production [1]. The continued growth of the aquatic farming industry depends on the development of nutritious feeds that maximize fish growth and health,
BAOJ Aquaculture, an open access journal
and animal waste. Studies on nutritional requirements of aquatic species, aimed at reducing the environmental impact and the cost of food, have thus become indispensable for the development of aquaculture [2]. In intensive fish farming, food represents an important part of the cost, contributing 40 to 60 % of operating costs [3]; it may be even higher depending on the region, the system applied or the species cultivated. In this direction, locally available cheap protein sources play an important role. Fruit wastes are one such source in Brazil, where fruit agribusiness has grown considerably in recent years [4]. Of the total processed fruit, 40% are wastes that need an appropriate targeted use [5]. The Amazonas State produces about 20 million tonnes of cupuacu every year which has multiple uses. It forms the food of tribal people; the pulp is frequently used in desserts, juices and sweets. The seed is processed to produce butter, generating huge quantity of defatted seed cake that can form an alternate protein source in fish diets. *Corresponding Author: Keshavanath P, Coordenação de Pesquisa em Aqüicultura (CPAQ), Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus- AM, Brasil, E-mail:
[email protected] Sub Date: March 29th, 2018, Acc Date: April 11th, 2018, Pub Date: April 12th, 2018. Citation: Carvalho EA and Keshavanath P (2018) Apparent Digestibility Evaluation of an Alternate Plant Ingredient, Cupuacu (Theobroma grandiflorum) Seed Cake for Tambaqui (Colossoma macropomum). BAOJ Aquaculture 1: 006. Copyright: © 2018 Carvalho EA. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Volume 1; Issue 2; 006
Citation: Carvalho EA and Keshavanath P (2018) Apparent Digestibility Evaluation of an Alternate Plant Ingredient, Cupuacu (Theobroma grandiflorum) Seed Cake for Tambaqui (Colossoma macropomum). BAOJ Aquaculture 1: 006.
Page 2 of 6
Tambaqui (Colossoma macropomum) is the most popular freshwater
attached to the lower portion. The tanks received recirculatory well water,
fish cultured in the Amazon region. Results of studies with this species
with daily renewal rate of five times the volume, and constant aeration.
demonstrate the possibility of total replacement of foodstuffs of animal
Each experimental unit was stocked with 20 fish (av. wt. 87.2 ± 6.3 g) that
origin, notably fish meal, by ingredients of plant origin, without affecting
were fed twice daily (09:00 hr and 16:00 hr) to satiation. The two diets
its performance [6-8]. Digestibility of feed ingredients is one of the
were fed to fish in five tanks each.
key factors in the evaluation of prospective novel feed ingredients to be included in aquaculture diets [9]. Since there is no report on the digestibility of cupuacu seed cake by tambaqui, the present study was undertaken, aimed at using this cheap source of plant protein in the diet of tambaqui.
Materials and Methods
Water Quality Monitoring Monitoring of water quality parameters viz. dissolved oxygen (DO), temperature, electrical conductivity (EC) and pH was carried out at 08.00 hr daily during acclimatisation as well as fecal collection period, whereas alkalinity, free carbon dioxide (CO2), nitrite nitrogen (NO2) and total ammonia (NH3) were analyzed every 15 days only during the fecal
This study was conducted at the field laboratory of Coordination of
collection period. A combined digital YSI 85 meter (YSI incorporated
Research in Aquaculture (CPAQ) in the National Institute of Research in
Yellow Springs, Ohio, USA) was used to monitor DO and EC; temperature
the Amazon (INPA), Manaus-AM. The semi-defatted cupuacu seed cake
and pH were measured with a digital YSI 60 meter. Alkalinity, CO2, NO2
was obtained from the Cupuama Company, located in the city of Brown,
and NH3 were estimated following standard procedure [13].
Careiro-AM municipality. The process of seed cake production involves fermentation followed by seed drying, roasting, shelling and pressing for the extraction of cupuacu butter, which is transformed into various ‘cupulate’ products [10]. The dried cake was ground to less than 1 mm particle size and stored at 25°C in an air-tight container.
Test Diets
Fecal Collection Fecal collection was done starting from the 11th day of the 60-day experiment, to allow time for the fish to get acclimatized to the diets. Feces was collected thrice daily-once before the first feed of the day, the second 4 hours after first feeding, and the third before the last meal of the day. Excess water present in the feces collecting units was disposed off.
Two diets were employed - the reprepared commercial feed with 32%
The feces collected daily from the units were kept pooled separately in
protein (reference diet) and the feed prepared incorporating 30% cupuacu
plastic bottles, one for each tank, totaling 10. The bottles were kept stored
seed cake to the commercial diet (test diet). Addition of test ingredient
in a freezer and used for chemical analysis at the end of the experimental
is recommended at 30% to the reference diet in digestibility experiments
period.
[11-12]. Reference diet was prepared by grinding the commercial diet, adding 0.5% of chromic oxide as digestibility marker to the powdered feed and pelleting it again. To obtain the test feed, commercial feed was ground to which cupuacu seed cake was added at the rate of 30% and mixed for homogenization. Then 0.5% of chromic oxide was incorporated and subsequently the feed mixture was pelleted. Both the diets were dried in an oven at 40°C. They were then stored in airtight containers at room
Determination of Digestibility Coefficients The apparent digestibility coefficients (ADC) of DM, CP, EE and NFE from the experimental diets were calculated according to Jobling [14]. A=100100 [(XA/XB) x (YB/YA)], where A=digestibility, XA=concentration of marker in the feed, XB=concentration of marker in the feces, YA= concentration of nutrient in the feed, YB=concentration of the nutrient
temperature (25°C).
in the feces.
Management of Fish
Apparent digestibility coefficient of test ingredient was calculated
Four hundred juveniles of tambaqui were purchased from the commercial farm San Antonio, Rio Preto da Eva-AM. They were acclimated to the experimental conditions in the laboratory for 15 days in two masonry
according to Bureau et al. [11]. ADC TI=ADC TD + [(ADC TD-ADC RD) x (0.7 x RD/0.3 x DI)], where TI=test ingredient, TD=test diet, RD=reference diet, DI=diet ingredient.
tanks (4m3) with water recirculation and constant aeration. During this
Biochemical Analyses
period, they were fed with the commercial feed containing 32% crude
Analyses of the chemical composition of samples of cupuacu seed cake and
protein, twice daily (09:00 hr and 16:00 hr), to apparent satiation. The ten experimental units used for the digestibility study consisted of
the experimental diets were performed at the Fish Nutrition Laboratory of CPAQ-INPA, according to the methodology described by AOAC [15].
fiber glass conical tanks (200 L volume), with a feces collection column
BAOJ Aquaculture, an open access journal
Volume 1; Issue 2; 006
Citation: Carvalho EA and Keshavanath P (2018) Apparent Digestibility Evaluation of an Alternate Plant Ingredient, Cupuacu (Theobroma grandiflorum) Seed Cake for Tambaqui (Colossoma macropomum). BAOJ Aquaculture 1: 006.
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Table 1: Proximate composition of diets and cupuacu seed cake (%) Sample
Moisture
Ash
Ether extract
Crude protein
Crude fibre
NFE
Commercial feed*
6.6
10.5
3.5
32.0
3.8
43.6
Cupuacu (30%) feed
7.1
9.4
5.3
27.8
5.5
44.9
Cupuaccu seed cake
8.0
6.2
9.2
18.1
14.4
44.1
*Nutripeixe TR 32 V, Zoofort Suplementação Animal Ind. e Com to be conducive. Dissolved oxygen in the culture environment should
Determination of Chromic Oxide (Cr2O3) The concentration of chromic oxide in the feed and feces samples was determined by colorimetric method [16]. The calibration curve was calculated from the nitro perchloric samples with known concentrations of chromic oxide digestion. The reading was taken in a spectrophotometer set to 350 nm wavelength. Chromic oxide concentration was determined by the equation y=a + bx, where y=optical concentration and x=chromic oxide concentration in the sample.
be above 4 mg/L, to maintain the comfort of fish and avoid problems in production [1 7 ]. The tissues, cells and molecules of fish are directly affected by vari a tions in temperature, which should be between 25°C and 32°C, the r a nge considered optimum for juvenile tambaqui, so as to obtain rapid growth of this species in captivity [17]. pH is one of the variables that g reatly influence the physiological processes of fish, its ideal range being 6.0 to 8.0. But, there are species that live and grow in the Amazon region where pH of stream water often varies between 3.5
Statistical Analysis
and 4.4 [18]. In nature, jaraqui tolerates large ionic plasticity and survives
Apparent digestibility coefficients of dry matter and nutrients were subjected to square root transformation before being compared by onefactor analysis of variance (ANOVA), followed by the Tukey test (p
