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Effect of feeding rate and frequency on tambaqui (Colossoma macropomum) growth, production and feeding costs during the first growth phase in cages
Aquaculture 264 (2007) 135 – 139 www.elsevier.com/locate/aqua-online
Effect of feeding rate and frequency on tambaqui (Colossoma macropomum) growth, production and feeding costs during the first growth phase in cages Clichenner Rodrigues Silva a , Levy Carvalho Gomes b,⁎, Franmir Rodrigues Brandão a a
Scholarship program, Embrapa Amazônia Ocidental, C.P. 319, 69011-970, Manaus, AM, Brazil b Embrapa Amazônia Ocidental, C.P. 319, 69011-970, Manaus, AM, Brazil
Received 9 October 2006; received in revised form 29 November 2006; accepted 1 December 2006
Abstract Feeding costs contributes up to 60% of the variable costs of cage culture systems. Therefore the objective of our study was to establish an optimal feeding frequency and feeding rate for rearing tambaqui in cages during the first growth phase. A factorial experiment was carried out in twelve 1 m3 fish cages, with two feeding rates (5 and 10% body weight per day — BW/day) and two feeding frequencies (2 and 3 meals/day), over a period of 45 days. At the end of the experiment 20% of fish from each cage were sampled for length and weight measurements. Survival, feed conversion ratio, weight gain, final biomass and feeding costs were calculated. Fish that received 10% BW/day divided in 3 meals/day, presented higher growth rates in weight, length and specific growth rate, when compared to fish fed with other treatments. Fish fed 5% BW/day divided in 3 meals/day presented a lower growth rate. Production parameters evaluated also showed a better performance with fish that received 10% BW/day divided in 3 meals/day. Total cost of feeding was higher for those who received 10% BW/day divided in 3 meals/day, however, the cost of unit produced was similar to other tested treatments. This suggests that the best feeding strategy for tambaqui during the first growth phase in cages is 10% BW/day divided in 3 meals/day. © 2006 Elsevier B.V. All rights reserved. Keywords: Cage culture; Colossoma macropomum; Feeding costs; Feeding optimization; Growth
1. Introduction The rearing of tambaqui (Colossoma macropomum), a native species from the Amazonian basin, has already been tested in cages with promising results with a high production per volume (Merola and Souza, 1988; Chagas et al., 2003; Gomes et al., 2006). Tambaqui ⁎ Corresponding author. Present address: Centro Universitário de Vila Velha, Centro de Biomédicas, Programa de Mestrado Ecologia de Ecossistemas, Vila Velha, Espírito Santo, Brazil. Tel.: +55 27 3239 1179. E-mail address: [email protected] (L.C. Gomes). 0044-8486/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2006.12.007
also presents other advantages for rearing in cages: an easy acquisition of juveniles all year around; high tolerance to low oxygen concentrations; and a high market value (Araujo-Lima and Goulding, 1997). Tambaqui culture in cages is carried out in two phases (Gomes et al., 2004). In first phase juveniles (1– 3 g) are reared to reach 20–40 g, this normally takes from 45–60 days. In the second phase, fish are reared from 20–40 g to reach harvest size (400–600 g), which usually takes 4–6 months. For each phase to be successful it is necessary to establish optimal parameters for growth, production and costs.
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In the initial step to develop a culture system for the first phase for tambaqui in cages, Brandão et al. (2004) established the ideal stocking density (400 fish/m3). But it is also important to establish an appropriate feeding management program, because an inadequate food supply has a direct impact on production costs (Mihelakakis et al., 2002) and water quality (Ng et al., 2000). On the other hand, efficient feeding provides better growth and production (Cho et al., 2003; Eroldogan et al., 2004). Optimum feeding frequency and feeding rate vary depending on fish species, size and rearing system (Cho et al., 2003). Feeding frequency and feeding rate also influence the use of the nutrients in the feed (Mihelakakis et al., 2002). The objectives of this study were to determine the best feeding frequency and rate for tambaqui reared in cages, during the first phase.
Table 2 Production parameters of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day)
2. Materials and methods
Data are means ± SD of three replicates for each treatment. Means with a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ Initial biomass per cage was 213.6 g.
Tambaqui juveniles (2.67 ± 1.13 g; 4.86 ± 1.76 cm; mean ± SD) were obtained from Santo Antônio farm (Rio Preto da Eva, AM, Brazil) and placed in twelve 1 m3 cages, with a 20 mm mesh and covered internally by a multifilament 5 mm mesh. Cages were placed in a six-hectare dam with 80 fish/m3. A factorial experiment was carried out with two feeding rates (5 and 10% body weight per day — BW/ day) and two feeding frequencies (2 and 3 meals/day, at 8:00 and 16:00, and 8:00, 12:00 and 16:00 h, respectiveTable 1 Growth parameters of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day) Feeding rate
Feeding frequency
Total length (cm) ⁎
Weight (g) ⁎
CV (%)
SGR (%/day)
5
2
10.46 ± 0.54c
3
9.47 ± 0.19c
2
11.29 ± 0.32b
3
12.42 ± 0.25a
26.24 ± 2.90b 19.39 ± 1.39c 36.92 ± 2.58b 46.08 ± 3.57a
18.98 ± 0.80a 18.48 ± 4.47a 20.22 ± 5.92a 15.52 ± 2.56a
5.07 ± 0.24c 4.40 ± 0.16d 5.83 ± 0.16b 6.32 ± 0.17a
0.000 0.483 0.001
0.715 0.287 0.383
0.000 0.431 0.001
10
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
0.000 0.683 0.001
Data are means ± SD of three replicates for each treatment. Means within a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ Initial fish size was 4.86 ± 1.76 cm and 2.67 ± 1.13 g (mean ± SD).
Feeding rate
Feeding frequency
Survival (%)
FCR
Weight gain (g)
Final biomass (g) ⁎
5
2
95.42 ± 3.82a 93.33 ± 6.29a 87.92 ± 20.93a 97.92 ± 1.91a
1.10 ± 0.26a 1.30 ± 0.07a 1.94 ± 0.22b 1.48 ± 0.06a
23.57 ± 2.90c 16.72 ± 1.59c 34.25 ± 2.58b 41.41 ± 3.57a
2004 ± 253bc
0.825 0.555 0.375
0.001 0.235 0.011
0.000 0.483 0.001
0.000 0.035 0.001
3 10
2 3
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
1445 ± 77c 2585 ± 581b 4184 ± 317a
ly), with three replications for each treatment, the experiment took 45 days. Fish were fed six times a week with commercial extruded feed containing 34% crude protein. Fish were sampled every 15 days to evaluate growth in weight and length, for this 20% of fish in each cage were captured, anesthetized with 100 mg/L of benzocaine (Gomes et al., 2001) weighed and measured. After each sampling period the amount of feed given was adjusted according to mean weight in each cage. From results of the last sample we calculated growth in weight and length, coefficient of variation of the length [CV = (standard deviation of the length / mean length) ⁎ 100] and specific growth rate [SGR = (ln final mean weight − ln initial mean weight / time) ⁎ 100]. At the end of the experiment production parameters were evaluated by: survival (%), weight gain (WG = final weight − initial weigh), final biomass (FB = final weight × survival) and food conversion rate (FCR = feed consumption / weight gain). To choosing the best result, total cost of feed (R$/cage) and unit cost of feed (R$/kg of fish produced) were also evaluated (US$ 1 = R$ 2.20). Dissolved oxygen and temperature were measured three times a week, at 08:00 h with a digital oxymeter. Every 7 days pH was measured with a digital pH meter, alkalinity and hardness by titration (Boyd, 1982) and total ammonia by endophenol according to APHA (1992). Measurements and water collection were always
C.R. Silva et al. / Aquaculture 264 (2007) 135–139
carried out between the cages in a depth of 1 m. Measurements were not registered inside cages because Brandão et al. (2004) verified that the quality of the water inside is similar to that of the outside. Results were expressed by mean ± SD and analyzed by two-way ANOVA and Tukey test with 5% probability (Zar, 1999). 3. Results Water quality in the dam was: dissolved oxygen (mg/L) 6.97 ± 1.80; temperature (°C) 29.73 ± 0.53; pH 5.86 ± 0.53; total hardness (mg/L) 7.15 ± 0.38; total alkalinity (mg/L) 8.45 ± 0.54 and total ammonia (mg/L) 0.26 ± 0.17. Feeding frequencies tested did not affect growth parameters. Feeding rates, as well as the interaction between feeding rates and feeding frequencies had significant effects on length, weight and SGR. The CV was not affected by feeding rate and frequency (Table 1). Largest growth in length (12.42 ± 0.25 cm), weight (46.08 ± 3.57 g) and SGR (6.32 ± 0.17%/day), was obtained in the treatment fed 10% BW/day divided in 3 meals/day (Table 1). Lowest growth was obtained in treatment fed 5% BW/day divided in 3 meals/day, where length, weight and SGR were respectively, 9.47 ± 0.19 cm, 19.39 ± 1.39 g and 4.40 ± 0.16%/day. CV varied between 15.52 ± 2.56% and 20.22 ± 5.92%. There was no effect of feeding rate and feeding frequency on survival (Table 2). FCR was significantly affected by feeding rate and the interaction between feeding rate and feeding frequency. FCR values was
Table 3 Feeding costs of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day) Feeding rate
Feeding frequency
Total feed cost (R$) ⁎
Feed cost per unit (R$/kg) ⁎
5
2 3 2 3
2.41 ± 0.43a 2.01 ± 0.23a 5.67 ± 0.85b 6.30 ± 0.58b
1.23 ± 0.23a 1.39 ± 0.08a 2.22 ± 0.18b 1.52 ± 0.24a
0.000 0.735 0.135
0.001 0.049 0.006
10
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
Data are means ± SD of three replicates for each treatment. Means with a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ US$ 1 = R$ 2.20.
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significantly higher in fish fed 10% BW/day divided in 2 meals/day, when compared to other treatments (Table 2). Feeding rate and the interaction between feeding rate and feeding frequency influenced weight gain. Feeding rate and feeding frequency, as well as the interaction between the two factors, had an effect on final biomass. Final biomass was greater in fish fed 10% BW/day divided in 3 meals/day (4184 ± 317 g) and smallest when fed 5% BW/day divided in 3 meals/day (1445 ± 77 g). Total feeding cost had a significant relationship to feeding rate, being significantly higher in treatments that received 10% BW/day (Table 3). Total feeding cost was between R$ 5.70–6.30/m3 for treatments that received 10% BW/day, and between R$ 2.01–2.41/m3 for the treatments that received 5% BW/day. Cost of feed per kilogram of fish was influenced by feeding rate and feeding frequency, as well as the interaction between the two factors. Cost was significantly higher for treatment 10% BW/day divided in 2 meals/day. 4. Discussion Dissolved oxygen, temperature and pH were within appropriate ranges for tambaqui farming (Saint-Paul, 1988; Aride et al., 2004). In the Amazon region liming is a unusual procedure in dams as occurred with the one used for this experiment, therefore water alkalinity and hardness were lower than the recommended for fish rearing. However, the water in the Amazonian fish farms usually present acidic pH and lower concentrations of dissolved salts, which probably does not have a negative impact on tambaqui production (Aride et al., 2004; Brandão et al., 2004). Ammonia concentrations were always below the critical levels (1 mg/L) (Boyd, 1982). Therefore we can conclude that the water quality did not have a negative effect on tambaqui cage production during its growth period. The feeding frequency tested did not affect growth parameters; however, feeding rate presented a significant effect on all variables except for CV. It is obvious that the amount of food supplied in each meal is the main limitation factor for growth. Linking feeding rate to feeding frequency has a significant influence on length, weight and SGR. Feeding with 5% BW/day produces a limited growth, mainly if it is divided among 3 meals/ day. On the other hand, fish fed with 10% BW/day grew more, mainly if they had been fed with 3 meals/day. Similar results were observed for cobia (Rachycentron canadum) juvenile, which presented a greater SGR when fed with 7% BW/day, rather than with 3% BW/day (Sun et al., 2006). Juvenile bagri catfish (Mystus nemurus), European sea bass (Dicentrarchus labrax) channel
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catfish (Ictalurus punctatus) and pacu (Piaractus mesopotamicus) also presented greater growth when fed with higher feeding rates rather than smaller (Borghetti and Canzi, 1993; Robinson and Li, 1999; Ng et al., 2000; Eroldogan et al., 2004). Dividing the total feed in 3 meals/day at a rate of 10% BW/day probably increases the nutrient absorption in the feed, as fish have access to nutrients more often during the day. This pattern has been observed in juvenile sunshine bass (Morone chrysops × M. saxatilis), that grew more if fed 2 meals/day, rather than if fed 1 meal/day (Webster et al., 2001), with rainbow trout (Oncorhynchus mykiss) where growth was greater in fish fed 3 meals/day than to fish fed 1 or 2 meals/day (Ruohonen et al., 1998), and in ayu larvae (Plecoglossus altivelis), that grew more when fed 6 meals/day instead of 1 meal/day (Cho et al., 2003). Feeding frequency is strongly influenced by time of gastric evacuation (Riche et al., 2004), Nile tilapia (Oreochromis niloticus) reared in 28 °C, has an appetite 4 h after food was offered, therefore a feeding management that offers meals every 4 h is the best strategy for that species growth. This result also concurs with our data, where feeding frequency of 3 meals/day presented median interval of 4 h between meals during day light and provided better growth for tambaqui when food supplied on each meal was close enough to fish satiety, for example 10% BW/day. Fish survival (87–97%) was similar to that obtained by Brandão et al. (2004), who carried out their study under the same experimental and environmental conditions. Previous studies with tambaqui farming in cages have also obtained high survival rates (Merola and Souza, 1988; Chagas et al., 2003; Gomes et al., 2006), confirming that the species easily adapts to the cage system. The FCR was significantly higher in fish fed with 10% BW/day divided in 2 meals/day. The main reason for this result is the excess of feed, because remaining feed was always observed in this treatment. When fish were fed with 10% BW/day divided in 3 meals/day, FCR was equal to one of treatments that received 5% BW/day, these being similar values to those obtained by Brandão et al. (2004). According to Eroldogan et al. (2004), with low feeding rates fish tend to optimize their digestion to extract more nutrients efficiently, as observed for tambaqui. Fish that received 5% BW/day had a better FCR; however the amount of feed supplied was not enough to satisfy the fish, resulting in low biomass production. Gomes et al. (2006) showed that variable cost dominates total production cost of caged tambaqui (83.6–88.1%) and that feeding costs account for 58% of
variable cost. Similar estimates have also been obtained for some other fish species in which feeding cost were around 30–60% of variable costs (Huguenin, 1997). Therefore from an economical point of view appropriate feeding strategy is fundamental for the success of tambaqui culture in cage. Total cost of feed reflects the total capital necessary for feeding fish during the rearing phase, which is important information for fish farming (Kam et al., 2003). Combining the optimal growth density obtained by Brandão et al. (2004), 400 fish/m3, with total feed cost obtained in treatment 10% BW/day divided in 3 meals/day, the feeding costs is R$ 31.50/m3 (US$ 14.31) to feed tambaqui in the first rearing phase in cage. When feed is offered at 5% BW/day, the total cost of feed is only R$ 12.50/m3 (US$ 5.68), being 2.5 times smaller. However, the production obtained is also significantly smaller, which is not a desirable situation for production systems. When interacting feeding costs with production treatment 10% BW/day divided in 3 meals/day presented the feed cost for each kilogram of fish produced significantly equal to the treatments that received 5% BW/day. The results show that a feeding rate of 10% BW/day divided in 3 meals/day is the more efficient feeding strategy for tambaqui during the first phase in cage, because it provides greater growth and production, with a low cost for feeding. Acknowledgements The authors would like to thank Márcia Pessoa for carrying out water analysis, José Souza for feeding the fish and the student staff from Embrapa for their assistance during the experiment. We also thank Drs. Adriana Chippari-Gomes and Rodrigo Roubach for critical review of the manuscript. This work was supported in part by a grant from the project TANRE/ FINEP/FUCAPI. L. C. Gomes is a research fellowship recipient from CNPq. References APHA, (American Public Health Association, American Water Works Association, Water Environment Federation), 1992. Standard Methods for the Examination of Water and Wastewater, 18th edition. American Public Health Association, New York. 1050 pp. Araujo-Lima, C.R.M., Goulding, M., 1997. So Fruitful Fish: Ecology, Conservation, and Aquaculture of the Amazon's Tambaqui. Columbia University Press, New York. 157 pp. Aride, P.H.R., Roubach, R., Val, A.L., 2004. Water pH in central Amazon and its importance for tambaqui (Colossoma macropomum) culture. World Aquaculture 35 (2), 24–27. Borghetti, J.R., Canzi, C., 1993. The effect of water temperature and feeding rate on the growth rate of pacu (Piaractus mesopotamicus) raised in cages. Aquaculture 114, 93–101.
C.R. Silva et al. / Aquaculture 264 (2007) 135–139 Boyd, C.E., 1982. Water Quality Management for Pond Fish Culture. Elsevier Science Publishers, Amsterdam. 317 pp. Brandão, F.R., Gomes, L.C., Chagas, E.C., Araújo, L.D., 2004. Densidade de estocagem de juvenis de tambaqui durante a recria em tanques-redes. Pesquisa Agropecuária Brasileira 39, 357–362. Chagas, E.C., Lourenço, J.N.P., Gomes, L.C., Val, A.L., 2003. Desempenho e estado de saúde de tambaquis cultivados em tanques-rede sob diferentes densidades de estocagem. In: Urbinati, E.C., Cyrino, J.E.P. (Eds.), Anais do XII Simpósio Brasileiro de Aqüicultura. Aquabio, Jaboticabal, pp. 83–93. Cho, S.H, Lim, Y.S., Lee, J.H, Park, S., 2003. Effect of feeding rate and feeding frequency on survival, growth, and body composition of ayu post-larvae Plecoglossus altivelis. Journal of the World Aquaculture Society 34, 85–91. Eroldogan, O.T., Kumlu, M., Aktas, M., 2004. Optimum feeding rates for European sea bass Dicentrarchus labrax L. reared in seawater and freshwater. Aquaculture 231, 501–515. Gomes, L.C., Chippari-Gomes, A.R., Lopes, N.P., Roubach, R., Araujo-Lima, C.A.R.M., 2001. Efficacy of benzocaine as anesthetic for tambaqui juveniles (Colossoma macropomum). Journal of the World Aquaculture Society 31, 426–431. Gomes, L.C., Brandão, F.R., Chagas, E.C., Ferreira, M.F.B., Lourenço, J.N.P., 2004. Efeito do volume do tanque-rede na produtividade de tambaqui (Colossoma macropomum) durante a recria. Acta Amazônica 34, 111–113. Gomes, L.C., Chagas, E.C., Martins-Junior, H., Roubach, R., Ono, E.A., Lourenço, J.N.P., 2006. Cage culture of tambaqui (Colossoma macropomum) in a central Amazon floodplain lake. Aquaculture 253, 374–384. Huguenin, J., 1997. The design, operations and economics of cage culture systems. Aquacultural Engineering 16, 167–203. Kam, L.E., Leung, P., Ostrowski, A.C., 2003. Economics of offshore aquaculture of pacific threadfin (Polydactylus sexfilis) in Hawaii. Aquaculture 223, 63–87. Merola, N., Souza, J.H., 1988. Cage culture of the Amazon fish tambaqui, Colossoma macropomum, at two stocking densities. Aquaculture 68, 15–21.
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Mihelakakis, A., Tsolkas, C., Yoshimatsu, T., 2002. Optimization of feeding rate for hatchery-produced juvenile gilthead sea bream Sparus aurata. Journal of the World Aquaculture Society 33, 169–175. Ng, W.K., Lu, K.S., Hashim, R., Ali, A., 2000. Effects of feeding rate on growth, feed utilization and body composition of tropical bagrid catfish. Aquaculture International 8, 19–29. Riche, M., Haley, D.I., Oetker, M., Garbrecht, S., Garling, D.L., 2004. Effect of feeding frequency on gastric evacuation and the return of appetite in tilapia Oreochromis niloticus (L.). Aquaculture 234, 657–673. Robinson, E.H., Li, M.H., 1999. Effect of dietary protein concentration and feeding rate on weight gain, feed efficiency, and body composition of pond-raised channel catfish Ictalurus punctatus. Journal of the World Aquaculture Society 30, 311–318. Ruohonen, K., Vielma, J., Grove, D.J., 1998. Effects of feeding frequency on growth and food utilization of rainbow trout (Oncorhynchus mykiss) fed low-fat herring or dry pellets. Aquaculture 165, 111–121. Saint-Paul, U., 1988. Diurnal routine O2 consumption at different O2 concentrations by Colossoma macropomum and Colossoma brachypomum (Teleostei: Serrasalmidae). Comparative Biochemistry and Physiology 89A, 675–682. Sun, L., Chen, H., Huang, L., Wang, Z., 2006. Growth, faecal production, nitrogenous excretion and energy budget of juvenile cobia (Rachycentron canadum) relative to feed type and ration level. Aquaculture 259, 211–221. Webster, C.D., Thompson, K.R., Morgan, A.M., Grigsby, E.J., Dasgupta, S., 2001. Feeding frequency affects growth, not fillet composition, of juvenile sunshine bass Morone chrysops X M. Saxatilis grown in cages. Journal of the World Aquaculture Society 32, 79–88. Zar, J.H., 1999. Biostatiscal Analysis, 4th ed. Prentice Hall, Upper Saddler River. 663 pp.
Effect of feeding rate and frequency on tambaqui (Colossoma macropomum) growth, production and feeding costs during the first growth phase in cages Clichenner Rodrigues Silva a , Levy Carvalho Gomes b,⁎, Franmir Rodrigues Brandão a a
Scholarship program, Embrapa Amazônia Ocidental, C.P. 319, 69011-970, Manaus, AM, Brazil b Embrapa Amazônia Ocidental, C.P. 319, 69011-970, Manaus, AM, Brazil
Received 9 October 2006; received in revised form 29 November 2006; accepted 1 December 2006
Abstract Feeding costs contributes up to 60% of the variable costs of cage culture systems. Therefore the objective of our study was to establish an optimal feeding frequency and feeding rate for rearing tambaqui in cages during the first growth phase. A factorial experiment was carried out in twelve 1 m3 fish cages, with two feeding rates (5 and 10% body weight per day — BW/day) and two feeding frequencies (2 and 3 meals/day), over a period of 45 days. At the end of the experiment 20% of fish from each cage were sampled for length and weight measurements. Survival, feed conversion ratio, weight gain, final biomass and feeding costs were calculated. Fish that received 10% BW/day divided in 3 meals/day, presented higher growth rates in weight, length and specific growth rate, when compared to fish fed with other treatments. Fish fed 5% BW/day divided in 3 meals/day presented a lower growth rate. Production parameters evaluated also showed a better performance with fish that received 10% BW/day divided in 3 meals/day. Total cost of feeding was higher for those who received 10% BW/day divided in 3 meals/day, however, the cost of unit produced was similar to other tested treatments. This suggests that the best feeding strategy for tambaqui during the first growth phase in cages is 10% BW/day divided in 3 meals/day. © 2006 Elsevier B.V. All rights reserved. Keywords: Cage culture; Colossoma macropomum; Feeding costs; Feeding optimization; Growth
1. Introduction The rearing of tambaqui (Colossoma macropomum), a native species from the Amazonian basin, has already been tested in cages with promising results with a high production per volume (Merola and Souza, 1988; Chagas et al., 2003; Gomes et al., 2006). Tambaqui ⁎ Corresponding author. Present address: Centro Universitário de Vila Velha, Centro de Biomédicas, Programa de Mestrado Ecologia de Ecossistemas, Vila Velha, Espírito Santo, Brazil. Tel.: +55 27 3239 1179. E-mail address: [email protected] (L.C. Gomes). 0044-8486/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2006.12.007
also presents other advantages for rearing in cages: an easy acquisition of juveniles all year around; high tolerance to low oxygen concentrations; and a high market value (Araujo-Lima and Goulding, 1997). Tambaqui culture in cages is carried out in two phases (Gomes et al., 2004). In first phase juveniles (1– 3 g) are reared to reach 20–40 g, this normally takes from 45–60 days. In the second phase, fish are reared from 20–40 g to reach harvest size (400–600 g), which usually takes 4–6 months. For each phase to be successful it is necessary to establish optimal parameters for growth, production and costs.
136
C.R. Silva et al. / Aquaculture 264 (2007) 135–139
In the initial step to develop a culture system for the first phase for tambaqui in cages, Brandão et al. (2004) established the ideal stocking density (400 fish/m3). But it is also important to establish an appropriate feeding management program, because an inadequate food supply has a direct impact on production costs (Mihelakakis et al., 2002) and water quality (Ng et al., 2000). On the other hand, efficient feeding provides better growth and production (Cho et al., 2003; Eroldogan et al., 2004). Optimum feeding frequency and feeding rate vary depending on fish species, size and rearing system (Cho et al., 2003). Feeding frequency and feeding rate also influence the use of the nutrients in the feed (Mihelakakis et al., 2002). The objectives of this study were to determine the best feeding frequency and rate for tambaqui reared in cages, during the first phase.
Table 2 Production parameters of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day)
2. Materials and methods
Data are means ± SD of three replicates for each treatment. Means with a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ Initial biomass per cage was 213.6 g.
Tambaqui juveniles (2.67 ± 1.13 g; 4.86 ± 1.76 cm; mean ± SD) were obtained from Santo Antônio farm (Rio Preto da Eva, AM, Brazil) and placed in twelve 1 m3 cages, with a 20 mm mesh and covered internally by a multifilament 5 mm mesh. Cages were placed in a six-hectare dam with 80 fish/m3. A factorial experiment was carried out with two feeding rates (5 and 10% body weight per day — BW/ day) and two feeding frequencies (2 and 3 meals/day, at 8:00 and 16:00, and 8:00, 12:00 and 16:00 h, respectiveTable 1 Growth parameters of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day) Feeding rate
Feeding frequency
Total length (cm) ⁎
Weight (g) ⁎
CV (%)
SGR (%/day)
5
2
10.46 ± 0.54c
3
9.47 ± 0.19c
2
11.29 ± 0.32b
3
12.42 ± 0.25a
26.24 ± 2.90b 19.39 ± 1.39c 36.92 ± 2.58b 46.08 ± 3.57a
18.98 ± 0.80a 18.48 ± 4.47a 20.22 ± 5.92a 15.52 ± 2.56a
5.07 ± 0.24c 4.40 ± 0.16d 5.83 ± 0.16b 6.32 ± 0.17a
0.000 0.483 0.001
0.715 0.287 0.383
0.000 0.431 0.001
10
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
0.000 0.683 0.001
Data are means ± SD of three replicates for each treatment. Means within a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ Initial fish size was 4.86 ± 1.76 cm and 2.67 ± 1.13 g (mean ± SD).
Feeding rate
Feeding frequency
Survival (%)
FCR
Weight gain (g)
Final biomass (g) ⁎
5
2
95.42 ± 3.82a 93.33 ± 6.29a 87.92 ± 20.93a 97.92 ± 1.91a
1.10 ± 0.26a 1.30 ± 0.07a 1.94 ± 0.22b 1.48 ± 0.06a
23.57 ± 2.90c 16.72 ± 1.59c 34.25 ± 2.58b 41.41 ± 3.57a
2004 ± 253bc
0.825 0.555 0.375
0.001 0.235 0.011
0.000 0.483 0.001
0.000 0.035 0.001
3 10
2 3
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
1445 ± 77c 2585 ± 581b 4184 ± 317a
ly), with three replications for each treatment, the experiment took 45 days. Fish were fed six times a week with commercial extruded feed containing 34% crude protein. Fish were sampled every 15 days to evaluate growth in weight and length, for this 20% of fish in each cage were captured, anesthetized with 100 mg/L of benzocaine (Gomes et al., 2001) weighed and measured. After each sampling period the amount of feed given was adjusted according to mean weight in each cage. From results of the last sample we calculated growth in weight and length, coefficient of variation of the length [CV = (standard deviation of the length / mean length) ⁎ 100] and specific growth rate [SGR = (ln final mean weight − ln initial mean weight / time) ⁎ 100]. At the end of the experiment production parameters were evaluated by: survival (%), weight gain (WG = final weight − initial weigh), final biomass (FB = final weight × survival) and food conversion rate (FCR = feed consumption / weight gain). To choosing the best result, total cost of feed (R$/cage) and unit cost of feed (R$/kg of fish produced) were also evaluated (US$ 1 = R$ 2.20). Dissolved oxygen and temperature were measured three times a week, at 08:00 h with a digital oxymeter. Every 7 days pH was measured with a digital pH meter, alkalinity and hardness by titration (Boyd, 1982) and total ammonia by endophenol according to APHA (1992). Measurements and water collection were always
C.R. Silva et al. / Aquaculture 264 (2007) 135–139
carried out between the cages in a depth of 1 m. Measurements were not registered inside cages because Brandão et al. (2004) verified that the quality of the water inside is similar to that of the outside. Results were expressed by mean ± SD and analyzed by two-way ANOVA and Tukey test with 5% probability (Zar, 1999). 3. Results Water quality in the dam was: dissolved oxygen (mg/L) 6.97 ± 1.80; temperature (°C) 29.73 ± 0.53; pH 5.86 ± 0.53; total hardness (mg/L) 7.15 ± 0.38; total alkalinity (mg/L) 8.45 ± 0.54 and total ammonia (mg/L) 0.26 ± 0.17. Feeding frequencies tested did not affect growth parameters. Feeding rates, as well as the interaction between feeding rates and feeding frequencies had significant effects on length, weight and SGR. The CV was not affected by feeding rate and frequency (Table 1). Largest growth in length (12.42 ± 0.25 cm), weight (46.08 ± 3.57 g) and SGR (6.32 ± 0.17%/day), was obtained in the treatment fed 10% BW/day divided in 3 meals/day (Table 1). Lowest growth was obtained in treatment fed 5% BW/day divided in 3 meals/day, where length, weight and SGR were respectively, 9.47 ± 0.19 cm, 19.39 ± 1.39 g and 4.40 ± 0.16%/day. CV varied between 15.52 ± 2.56% and 20.22 ± 5.92%. There was no effect of feeding rate and feeding frequency on survival (Table 2). FCR was significantly affected by feeding rate and the interaction between feeding rate and feeding frequency. FCR values was
Table 3 Feeding costs of tambaqui juveniles (Colossoma macropomum) during first growth phase in cages in different feeding rate (% BW/day) and feeding frequency (meals/day) Feeding rate
Feeding frequency
Total feed cost (R$) ⁎
Feed cost per unit (R$/kg) ⁎
5
2 3 2 3
2.41 ± 0.43a 2.01 ± 0.23a 5.67 ± 0.85b 6.30 ± 0.58b
1.23 ± 0.23a 1.39 ± 0.08a 2.22 ± 0.18b 1.52 ± 0.24a
0.000 0.735 0.135
0.001 0.049 0.006
10
Two-way ANOVA Feeding rate (P) Feeding frequency (P) Interaction (P)
Data are means ± SD of three replicates for each treatment. Means with a column followed by different letters are significantly different (P b 0.05), as determined by two-way ANOVA and Tukey's post-hoc test. ⁎ US$ 1 = R$ 2.20.
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significantly higher in fish fed 10% BW/day divided in 2 meals/day, when compared to other treatments (Table 2). Feeding rate and the interaction between feeding rate and feeding frequency influenced weight gain. Feeding rate and feeding frequency, as well as the interaction between the two factors, had an effect on final biomass. Final biomass was greater in fish fed 10% BW/day divided in 3 meals/day (4184 ± 317 g) and smallest when fed 5% BW/day divided in 3 meals/day (1445 ± 77 g). Total feeding cost had a significant relationship to feeding rate, being significantly higher in treatments that received 10% BW/day (Table 3). Total feeding cost was between R$ 5.70–6.30/m3 for treatments that received 10% BW/day, and between R$ 2.01–2.41/m3 for the treatments that received 5% BW/day. Cost of feed per kilogram of fish was influenced by feeding rate and feeding frequency, as well as the interaction between the two factors. Cost was significantly higher for treatment 10% BW/day divided in 2 meals/day. 4. Discussion Dissolved oxygen, temperature and pH were within appropriate ranges for tambaqui farming (Saint-Paul, 1988; Aride et al., 2004). In the Amazon region liming is a unusual procedure in dams as occurred with the one used for this experiment, therefore water alkalinity and hardness were lower than the recommended for fish rearing. However, the water in the Amazonian fish farms usually present acidic pH and lower concentrations of dissolved salts, which probably does not have a negative impact on tambaqui production (Aride et al., 2004; Brandão et al., 2004). Ammonia concentrations were always below the critical levels (1 mg/L) (Boyd, 1982). Therefore we can conclude that the water quality did not have a negative effect on tambaqui cage production during its growth period. The feeding frequency tested did not affect growth parameters; however, feeding rate presented a significant effect on all variables except for CV. It is obvious that the amount of food supplied in each meal is the main limitation factor for growth. Linking feeding rate to feeding frequency has a significant influence on length, weight and SGR. Feeding with 5% BW/day produces a limited growth, mainly if it is divided among 3 meals/ day. On the other hand, fish fed with 10% BW/day grew more, mainly if they had been fed with 3 meals/day. Similar results were observed for cobia (Rachycentron canadum) juvenile, which presented a greater SGR when fed with 7% BW/day, rather than with 3% BW/day (Sun et al., 2006). Juvenile bagri catfish (Mystus nemurus), European sea bass (Dicentrarchus labrax) channel
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catfish (Ictalurus punctatus) and pacu (Piaractus mesopotamicus) also presented greater growth when fed with higher feeding rates rather than smaller (Borghetti and Canzi, 1993; Robinson and Li, 1999; Ng et al., 2000; Eroldogan et al., 2004). Dividing the total feed in 3 meals/day at a rate of 10% BW/day probably increases the nutrient absorption in the feed, as fish have access to nutrients more often during the day. This pattern has been observed in juvenile sunshine bass (Morone chrysops × M. saxatilis), that grew more if fed 2 meals/day, rather than if fed 1 meal/day (Webster et al., 2001), with rainbow trout (Oncorhynchus mykiss) where growth was greater in fish fed 3 meals/day than to fish fed 1 or 2 meals/day (Ruohonen et al., 1998), and in ayu larvae (Plecoglossus altivelis), that grew more when fed 6 meals/day instead of 1 meal/day (Cho et al., 2003). Feeding frequency is strongly influenced by time of gastric evacuation (Riche et al., 2004), Nile tilapia (Oreochromis niloticus) reared in 28 °C, has an appetite 4 h after food was offered, therefore a feeding management that offers meals every 4 h is the best strategy for that species growth. This result also concurs with our data, where feeding frequency of 3 meals/day presented median interval of 4 h between meals during day light and provided better growth for tambaqui when food supplied on each meal was close enough to fish satiety, for example 10% BW/day. Fish survival (87–97%) was similar to that obtained by Brandão et al. (2004), who carried out their study under the same experimental and environmental conditions. Previous studies with tambaqui farming in cages have also obtained high survival rates (Merola and Souza, 1988; Chagas et al., 2003; Gomes et al., 2006), confirming that the species easily adapts to the cage system. The FCR was significantly higher in fish fed with 10% BW/day divided in 2 meals/day. The main reason for this result is the excess of feed, because remaining feed was always observed in this treatment. When fish were fed with 10% BW/day divided in 3 meals/day, FCR was equal to one of treatments that received 5% BW/day, these being similar values to those obtained by Brandão et al. (2004). According to Eroldogan et al. (2004), with low feeding rates fish tend to optimize their digestion to extract more nutrients efficiently, as observed for tambaqui. Fish that received 5% BW/day had a better FCR; however the amount of feed supplied was not enough to satisfy the fish, resulting in low biomass production. Gomes et al. (2006) showed that variable cost dominates total production cost of caged tambaqui (83.6–88.1%) and that feeding costs account for 58% of
variable cost. Similar estimates have also been obtained for some other fish species in which feeding cost were around 30–60% of variable costs (Huguenin, 1997). Therefore from an economical point of view appropriate feeding strategy is fundamental for the success of tambaqui culture in cage. Total cost of feed reflects the total capital necessary for feeding fish during the rearing phase, which is important information for fish farming (Kam et al., 2003). Combining the optimal growth density obtained by Brandão et al. (2004), 400 fish/m3, with total feed cost obtained in treatment 10% BW/day divided in 3 meals/day, the feeding costs is R$ 31.50/m3 (US$ 14.31) to feed tambaqui in the first rearing phase in cage. When feed is offered at 5% BW/day, the total cost of feed is only R$ 12.50/m3 (US$ 5.68), being 2.5 times smaller. However, the production obtained is also significantly smaller, which is not a desirable situation for production systems. When interacting feeding costs with production treatment 10% BW/day divided in 3 meals/day presented the feed cost for each kilogram of fish produced significantly equal to the treatments that received 5% BW/day. The results show that a feeding rate of 10% BW/day divided in 3 meals/day is the more efficient feeding strategy for tambaqui during the first phase in cage, because it provides greater growth and production, with a low cost for feeding. Acknowledgements The authors would like to thank Márcia Pessoa for carrying out water analysis, José Souza for feeding the fish and the student staff from Embrapa for their assistance during the experiment. We also thank Drs. Adriana Chippari-Gomes and Rodrigo Roubach for critical review of the manuscript. This work was supported in part by a grant from the project TANRE/ FINEP/FUCAPI. L. C. Gomes is a research fellowship recipient from CNPq. References APHA, (American Public Health Association, American Water Works Association, Water Environment Federation), 1992. Standard Methods for the Examination of Water and Wastewater, 18th edition. American Public Health Association, New York. 1050 pp. Araujo-Lima, C.R.M., Goulding, M., 1997. So Fruitful Fish: Ecology, Conservation, and Aquaculture of the Amazon's Tambaqui. Columbia University Press, New York. 157 pp. Aride, P.H.R., Roubach, R., Val, A.L., 2004. Water pH in central Amazon and its importance for tambaqui (Colossoma macropomum) culture. World Aquaculture 35 (2), 24–27. Borghetti, J.R., Canzi, C., 1993. The effect of water temperature and feeding rate on the growth rate of pacu (Piaractus mesopotamicus) raised in cages. Aquaculture 114, 93–101.
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