Scientific Article

ISSN 1678-2305 online version

BOLETIM DO INSTITUTO DE PESCA

SIGNOR et al. Bol. Inst. Pesca 2018, 44(3): e338. DOI: 10.20950/1678-2305.2018.338 1/8

FEED MANAGEMENT OF PACU JUVENILES CULTIVATED IN NET

CAGES

ABSTRACT

The aim of this work was to evaluate the feed management (feed percentage and feeding frequency)

of pacu (Piaractus mesopotamicus) juveniles bred in net cages. To evaluate the feed percentage

2,000 juveniles (12.12Â±0.51 g) were randomly distributed in 20 cages of 1 m

3

(0.8 m

3

of useful

volume). The fish were fed four times a day (8:00 a.m.; 11:00 a.m.; 2:00 p.m.; and 5:00 p.m.) with

4, 7, 10, 13, and 16% of feed. To evaluate feeding frequency, another 2,000 juveniles (9.56Â±0.56 g)

were randomly distributed in 20 cages of 0.8 m

3

of useful volume. The fish were fed one, two, three

and four times a day. Due to the feed percentage, significant effects (P<0.05) were observed for

the parameters of weight gain, final length, final biomass, specific growth rate, and apparent feed

conversion. The performance parameters, centesimal composition, and blood biochemistry were

not influenced (P>0.05) by the feeding frequency. Considering the weight gain and apparent feed

conversion of pacu juveniles cultivated in net cages, 8% of feed is recommended regardless of the

feeding frequency adopted.

Key words: intensive aquaculture; feeding frequency; native fishes; blood parameters; feed

percentage.

MANEJO ALIMENTAR DE JUVENIS DE PACU CRIADOS EM TANQUES REDE

RESUMO

O objetivo do presente trabalho foi avaliar o manejo alimentar (porcentagem de arraÃ§oamento

e frequÃªncia alimentar) de juvenis de pacu (Piractus mesopotamicus) criados em tanques rede.

Para avaliar a porcentagem de arraÃ§oamento foram utilizados 2.000 juvenis (12,12Â±0,51 g),

distribuÃdos em 20 tanques rede de 0,8 m

3

de volume Ãºtil, alimentados quatro vezes ao dia

(8, 11, 14 e 17 horas), com 4, 7, 10, 13 e 16% de arraÃ§oamento. Para avaliar a frequÃªncia alimentar,

foram utilizados 2.000 juvenis (9,56Â±0,56 g), distribuÃdos em 20 tanques rede com 0,8 m

3

de

volume Ãºtil, alimentados uma, duas, trÃªs e quatro vezes ao dia. Observou-se efeito significativo

(P<0,05) para os parÃ¢metros de ganho de peso, comprimento final, biomassa final, e conversÃ£o

alimentar aparente, em funÃ§Ã£o do percentual de arraÃ§oamento. NÃ£o foram observadas influÃªncias

(P>0,05) da frequÃªncia alimentar sobre os parÃ¢metros zootÃ©cnicos, composiÃ§Ã£o centesimal e

bioquÃmicos do sangue. Considerando o ganho de peso e conversÃ£o alimentar aparente de juvenis

de pacu criados em tanques rede, recomenda-se 8% de arraÃ§oamento, independentemente da

frequÃªncia alimentar adotada.

Palavras-chave: aquicultura intensiva; frequÃªncia alimentar; peixes nativos; parÃ¢metros

sanguÃneos; porcentagem de arraÃ§oamento.

INTRODUCTION

Determining of the feed percentage and feeding frequency for different species of

fish is fundamental for the production of fish with satisfactory economic return to the

producer. Supplying more feed than is consumed by fish may result in food waste,

negatively influencing water quality (MEURER et al., 2005). The optimum feeding

rate is the one that provides the best apparent feed conversion, together with the best

weight gain of the animals. On the other hand, when the rate is not well defined, it can

cause uneven growth, raise production costs, and impair water quality.

However, the feeding rate varies with the age of the fish and with the temperature

of the water (SANTIAGO et al., 1987; DENG et al., 2003; HAYASHI et al., 2004;

Arcangelo Augusto SIGNOR

1

Flavia Renata Potrich SIGNOR

2

Juliana Alice Losch NERVIS

1

AndrÃ© Luiz WATANABE

3

Adilson REIDEL

1

Wilson Rogerio BOSCOLO

2

1

Instituto Federal do ParanÃ¡ â€“ IFPR, Departamento de

Aquicultura, Av. AraucÃ¡ria, 780, CEP 85860-000, Foz do

IguaÃ§u, PR, Brasil. E-mail: arcangelo.signor@ifpr.edu.br

(corresponding author).

2

Universidade Estadual do Oeste do ParanÃ¡ â€“

UNIOESTE, Campus de Toledo, Rua da Faculdade,

645, CEP 85903-000, Toledo, PR, Brasil.

3

Itaipu Binacional, Av. Tancredo Neves, 6731,

CEP 85856-970, Foz do IguaÃ§u, PR, Brasil.

Received: December 05, 2017

Approved: March 29, 2018

FEED MANAGEMENT OF PACU JUVENILES...

SIGNOR et al. Bol. Inst. Pesca 2018, 44(3): e338. DOI: 10.20950/1678-2305.2018.338 2/8

SANTOS et al., 2013). Moreover, it is necessary to make constant

adjustments in the amount of feed to be offered to the animals

(SALARO et al., 2008), which is a fundamental practice in

intensive production systems (SCORVO FILHO et al., 2010).

The feeding frequency influences the development of the animals

and was studied in different species of fish (LEE et al., 2000a;

LEE et al., 2000b; DWYER et al., 2002; BITTENCOURT et al., 2013;

SOUZA et al., 2014, SANTOS et al., 2015); observing an increase

in weight gain when fed more than once a day. The objective of

the present work was to evaluate the feeding frequency and feed

percentage of juvenile pacu (Piaractus mesopotamicus) raised

in net cages.

METHODS

The trials were conducted at the Fisheries and Ecology of

Native Species Research Station at the Binational Itaipu Reservoir.

The entire experimental procedure was evaluated and approved

by the Committee of Ethics in the Use of Animals of the West

ParanÃ¡ State University, according to certificate NÂº 23/2016 CEUA.

Experimental design - feed percentage - experiment I

To evaluate the feed percentage, 2000 juveniles (12.12Â±0.51 g)

were randomly distributed in 20 net cages with 0.8 m

3

of useful

volume, holding 100 fish per tank. The net cages consisted of

a 15 mm, 1.1 wire, stainless steel screen arranged in lines, respecting

a distance of 1.5 m between the net cages. The fish were fed at

8:00 a.m.; 11:00 a.m.; 2:00 p.m.; and 5:00 p.m., according to feed

offer rates of 4, 7, 10, 13 and 16% of live weight, for a period of

60 days (03/21/2015 to 5/19/2015).

Experimental design - feeding frequency -

experiment II

To evaluate the feeding frequency, 2,000 juveniles were used,

with a mean initial weight of 9.67Â±0.55 g, distributed randomly in

20, 0.8 m

3

net cages (100 fish per tank). The net cages consisted of a

15 mm, 1.1 wire, stainless steel screen arranged in lines, respecting

a distance of 1.5 m between the net cages. The fish were submitted

to different feeding frequencies/schedules (Table 1), for a period

of 114 days (10/21/2015 to 02/11/2016). Biometrics (weighing

and counting) of 100% of the fish were performed biweekly for

the correction of the feed that was provided based on 7% of live

weight. The amount of feed was given according to the frequencies

adopted, once daily (100% of the feed at once), twice daily

(50% at each feeding), three times a day (33, 33% at each feeding),

and four times a day (25% at each feeding).

Extruded commercial feeds of 2 mm and 32% crude protein

were used. The chemical compositions of the feeds are shown

in Table 2.

The water quality variables such as temperature, dissolved oxygen

and pH were monitored daily in the morning using the HORITA

ï›š

U50 multiparameter probe. The averages for Experiment I were

28.4Â±1.09 Â°C, 7.66Â±0.93 mg L

-1

and 7.68Â±0.24 for temperature,

dissolved oxygen and pH, respectively. For Experiment II,

27.10Â±4.77 Â°C, 6.19Â±1.08 mg L

-1

and 6.90Â±0.49 for temperature,

dissolved oxygen and pH, respectively.

Blood collection, hematological and biochemical

analysis - experiments I and II

At the end of the 60-day (Experiment I) and 114-day

(Experiment II) experimental periods, the fish were fasted for

12 hours to empty their digestive tracts, then were anesthetized

with benzocaine (60 mg L

-1

) (GOMES et al., 2001). Two fish

from each tank (experiments I and II) (ten fish per treatment)

were submitted to blood collection (1.5 mL) by caudal puncture

with the aid of a syringe. For each aliquot of blood collected,

the counts of the number of erythrocytes were performed in a

Neubauer chamber (COLLIER, 1944). For the determination of

hemoglobin and hematocrit, the methodology of COLLIER (1944)

and GOLDENFARB et al. (1971) were followed, respectively.

Subsequently, the absolute hematimetric indices (WINTROBE,

1934) were calculated as mean corpuscular volume (MCV),

mean corpuscular hemoglobin (MCH) and mean corpuscular

hemoglobin concentration (MCHC).

For the biochemical analyses in experiment II, the following

parameters were evaluated: serum, for dosage of protein

(WEICHSELBAUM, 1946), triglycerides (TRINDER, 1969;

BUCOLO and DAVID, 1973), cholesterol (TRINDER, 1969;

ALLAIN et al., 1974), and plasma (with fluoride) for glucose

dosing (BERGMEYER, 1986). To determine the analyses, which

were performed with the use of specific Gold Analisa DiagnÃ³stica

ï›š

kits, and the reading was made in a spectrophotometer, according

to the instructions of the manufacturer. The colorimetric enzymatic

Table 1. Feed frequency / feeding time of fish.

Feeding frequency

Feeding times /

quantity of feed provided

8:00 11:00 14:00 17:00

1X/day X - - -

2X/day X - - X

3X/day X X - X

3X/day X - X X

4X/day X X X X

Table 2. Chemical composition of feeds.

Parameters

Experiments I Experiments II

Dry matter (%) 91.77 90.55

Crude protein (%) 31.90 32.06

Lipids (%) 6.18 5.85

Mineral matter (%) 9.29 10.05

Energy (Kcal kg

-1

) 4539.02 4436.11

FEED MANAGEMENT OF PACU JUVENILES...

SIGNOR et al. Bol. Inst. Pesca 2018, 44(3): e338. DOI: 10.20950/1678-2305.2018.338 3/8

method was used for the dosages of cholesterol, triglycerides and

glucose, and the colorimetric-biuret was used for protein analysis.

Zootechnical performance - experiments I and II

All fish were weighed and measured individually. Upon obtaining

the data the following parameters were calculated: weight gain

(WG = final weight - initial weight), final biomass (BioF = final

weight * number of individuals), final length (FL), condition

factor (CF = (final weight / final length

3

) * 100), survival

(SUR = (number of fish at the end / number of fish initial) * 100),

apparent feed conversion (AFC = feed intake / weight gain), and

specific growth rate (SGR = 100 * [(ln average final weight -

ln average initial weight) / time]).

Centesimal composition - experiments I and II

Five fish from each tank (20 fish per treatment) were separated,

euthanized with 250 mL L

-1

of benzocaine (GOMES et al., 2001),

identified, and frozen (-18 Â°C) for further analysis of centesimal

composition. The analysis of centesimal composition followed

the methodology recommended by AOAC (2000). The following

analyses were performed: Dry matter, at 105ÂºC in a greenhouse

(ASL102, Solab, Piracicaba/SP, Brazil) for 8 hours; Mineral

matter, at 550 Â°C by muffle incineration (0318m25T, Quimis,

Diadema / SP, Brazil); Lipids, by Soxhlet extractor (TE-044-5,

Tecnal, Piracicaba/SP, Brazil); Determination of total nitrogen by

the Kjeldahl method (MA036, Marconi, Piracicaba/SP, Brazil),

and nitrogen conversion factor for protein 6.25.

Statistical analyzes - feed percentage - experiment I

All data were submitted to analysis of variance (ANOVA) at

significance levels of 1 and 5%, checking the assumptions of

normality and homogeneity. In the case of statistical differences,

the regression test was applied for the elaboration of models in the

matters of weight gain, final length, final biomass and apparent

feed conversion. A completely randomized experimental design

(CRD) was used, using the statistical program STATISTICA

8.0 (Copyright

Â©

StatSoft). The results were represented by the

mean Â± standard deviation.

Variable behavioral responses test - experiment I

In order to evaluate the behavior of the varying responses to

changes in the feed percentage, the data of weight gain, final

length and final biomass were analyzed, respectively, by quadratic

regression analysis (Table 3), and for the feed conversion data was

analyzed by linear regression (Table 3). To obtain the curves and

identify adjustable parameters, the software OriginPro version 8

SR0 (OriginLab

Â©

) was used. The applicability of the mathematical

models was evaluated by the most appropriate determination

coefficient, R

2

.

Statistical analyses - feeding frequency - Experiment II

All data were submitted to analysis of variance (ANOVA) at

the 5% level of significance, and the normality and homogeneity

assumptions were checked, following statistical program

STATISTIC 8.0 (Copyright

Â©

StatSoft) protocol, GLM. The results

were represented as the mean Â± standard deviation.

RESULTS

Feed percentage - experiment I

Quadratic effects were observed for weight gain (Figure 1A),

final length (Figure 1B) and final biomass (Figure 1C), and

there was a linear effect observed for apparent feed conversion

(Figure 1D).

The influence of the feeding rates on the condition factor, survival

and centesimal composition of the carcass of pacu juveniles were

not observed (P> 0.05) (Table 4).

Regarding hematimetric hematological parameters (Table 5),

no influences were observed (P>0.05) among the different feed

percentages.

Feeding frequency - experiment II

No influence of feeding frequency was observed on performance,

centesimal composition (Table 6), and hematological and

biochemical parameters (Table 7).

Table 3. Mathematical modeling of statistical analysis.

Response

Variables

Regression Parameters*

R

2

Mathematical

Model

A B C

WG (g)**

29.51Â±3.73 6.11Â±0.84 -0.245Â±0.041 0.962 Y = A + B.x + C.x

2

CF (cm)**

11.75Â±0.48 0.42Â±0.11 -0.202Â±0.005 0.877 Y = A + B.x + C.x

2

BioF (g)**

3979.56Â±210.94 666.28Â±47.29 -27.19Â±2.33 0.989 Y = A + B.x + C.x

2

AFC***

0.74Â±0.045 0.31Â±0.004 0 0.999 Y = A + B.x

WG = weight gain; CF = final length; BioF = final biomass; AFC = apparent feed conversion; *Values expressed as mean Â± standard error; **Best mathematical adjustment

by quadratic regression; ***Best mathematical fit by linear regression.