Muscle delta C-13 change in Nile tilapia (Oreochromis niloticus): Effects of growth and carbon turnover

The contribution of growth and turnover to the muscle delta C-13 change process was investigated using mathematical models which associate delta C-13 change to time of intake of a new diet or increase in body mass. Two groups of Nile tilapia (Oreochromis niloticus) were fed on diets based on C3 (sigma C-13 = - 25.64 +/- 0.06 parts per thousand) or C4 (delta C-13= -16.01 +/- 0.06 parts per thousand) photosynthetic cycle plants to standardize the muscle delta C-13. After establishing the carbon isotopic equilibrium, fish (mean mass 24.12 +/- 6.79 g) then received the other treatment diet until a new carbon isotopic equilibrium could be established, characterizing T1 (C3-C4) and T2 (C4-C3) treatments. No significant differences were observed in fish productive performance. Good fits were obtained for the models that associated the delta C-13 change to time, resulting in carbon half-life values of 23.33 days for T1 and 25.96 days for T2. Based on values found for the muscle delta C-13 change rate from growth (0.0263 day(-1) and 0.0254 day(-1)) and turnover (0.0034 day(-1) and 0.0013 day(-1)), our results indicate that most of the delta C-13 change could be attributed to growth. The application of model that associated the delta C-13 change to body mass increase seems to produce results with no apparent biological explanation. The delta C-13 change rate could directly reflect the daily ration and growth rate, and consequently the isotopic change rates of carbon and other tissue elements can be properly used to assess different factors that may interfere in nutrient utilization and growth. (c) 2006 Published by Elsevier B.V.

Growth of the tambaqui Colossoma macropomum (Cuvier) (Characiformes: Characidae): which is the best model?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chemical modulation on heterogeneous growth in Prochilodus lineatus (Valenciennes, 1847) (Pisces; Characiformes)

No presente trabalho, testou-se o efeito de fatores químicos liberados por coespecíficos sobre o crescimento e sua variabilidade no grupo (crescimento heterogêneo, CHet), numa espécie gregária, o curimbatá, Prochilodus lineatus. O CHet foi avaliado pelo coeficiente de variação do peso dos animais, em dois períodos consecutivos de 21 dias. Os peixes foram agrupados em aquários (4 peixes cada) que receberam água corrente, com vazão constante, de tanques contendo (C) ou não (N) coespecíficos. Quatro condições foram delineadas de acordo com a água que abastecia os aquários: a) água com contato prévio com coespecíficos durante todo o experimento (CC); b) água sem contato prévio com coespecíficos durante todo o experimento (NN); c) água com contato prévio com coespecíficos apenas no primeiro período, 0 a 21 dias (CN); e d) apenas no período de 21 a 42 dias (NC). Ao término dos experimentos, verificou-se que ocorre modulação química sobre a variabilidade de crescimento em P. lineatus: os peixes que receberam água com contato prévio com coespecífico (C) apresentaram exacerbação do CHet. Fato que corrobora a idéia de que o mecanismo predominante da determinação da variação intra-específica do crescimento, em espécies gregárias, está associado à ação de fatores químicos liberados por coespecíficos.

INFLUENCE OF DIETARY-PROTEIN INTAKE AND RECOMBINANT HUMAN SOMATOTROPIN ADMINISTRATION ON GROWTH AND BODY-COMPOSITION OF JUVENILE TAMBACU (A PIARACTUS-MESOPOTAMICUS X COLOSSOMA-MACROPOMUM CROSS)

This experiment was undertaken to study the interaction between level of dietary protein and recombinant human somatotropin (rhGH) administration on performance and body composition of juvenile tambacu (a crossbred Brazilian fish). A total of 72 juvenile tambacu, initially weighing and measuring (mean +/- s.e.m.) 23 +/- 2 g and 9 +/- 0.5 cm, respectively, were randomly divided into 18 groups of 4 fish each. Water temperature was 28 degrees C. Triplicate groups received one of two levels of dietary protein (15 and 30% as fed basis) and one of 3 doses of rhGH (0, 2 and 4 mu g/g) via intraperitoneal injection twice a week for 6 weeks, using a randomized complete block design. Somatotropin was noted to stimulate linear and body weight gain. The higher protein level supported increased growth in weight and length, but there was no interaction between protein level and rhGH dose for either parameter. Protein efficiency ratio and percentage protein deposited showed higher values on diets containing 15% protein. Somatotropin treatment did not significantly affect body composition, but there was a trend towards improved protein retention and reduced carcass lipid. In conclusion, the results of this experiment suggest that rhGH is able to stimulate linear gain in tambacu.

The ultrastructural aspects of vitellogenesis or oocyte secondary growth in Serrasalmus spilopleura (Teleostei, Characiformes, Serrasalminae)

Oocyte secondary growth in S. spiloleura corresponds to the period in which different vesicular structures are formed, including the cortical alveoli and the yolk granules. The oocytes with cortical alveolus formation show vesicular structures with filamentous content in the cortical cytoplasmic region, which are the cortical alveolus precursors. In these oocytes, electron-dense vesicles of heterogenous content are dispersed in the inner cytoplasmic region and their nuclei are irregular, showing many nucleoli of different sizes. The oocytes in vitellogenesis are filled with many vesicles. The cortical alveolus precursors are in the peripheral region, and electron-dense granules are seen near to the nucleus. These fuse and form yolk granules. The oocytes in vitellogenesis show a very irregular nucleus that has nucleoli of different sizes. In the oocytes in final vitellogenesis, the yolk granules are scattered throughout the cytoplasm, displacing the cortical alveoli toward cell periphery. The nucleus is similar to the other stages.

Female germ cell renewal during the annual reproductive cycle in Ostariophysians fish

The objective was to characterize female germ cell renewal during the annual reproductive cycle in two species of ostariophysian fish with distinct reproductive strategies: a siluriform, Pimelodus maculatus, in which oocyte development is group synchronous and the annual reproductive period is short; and a characiform, Serrasalmus maculatus, with asynchronous oocyte development and a prolonged reproductive period. These reproductive strategies result in fish determinate and indeterminate fecundity, respectively. Annual reproductive phases were determined by biometric and histologic analysis of gonads and interpreted according to new proposals for phase classification and stages of oocyte development (with special attention to germinal epithelium activity). Histologically, there were two types of oogonia in the germinal epithelium: single oogonia and those in mitotic proliferation. Oogonial proliferation and their entry into meiosis resulted in formation of cell nests (clusters of cells in the ovarian lamellae). Morphometric analysis was used to estimate germ cell renewal. Based on numbers of single oogonia in the lamellar epithelium, and nests with proliferating oogonia or early prophase oocytes throughout the annual reproductive cycle, oogonial proliferation and entrance into meiosis were more intense during the regenerating phase and developing phase, but decreased sharply (P < 0.05) during the spawning-capable phase. Oogonial proliferation gradually recovered during the regressing phase. We concluded that, independent of species or features of the reproductive cycle, germ cell renewal occurred during the regenerating phase, ensuring availability of eggs for the spawning event. © 2013 Elsevier Inc.

Farelo de canola em dietas para o pacu Piaractus mesopotamicus (Holmberg 1987): efeitos sobre o crescimento e a composição corporal

Avaliaram-se os efeitos da inclusão de farelo de canola em dietas de juvenis de pacu (Piaractus mesopotamicus) sobre parâmetros de crescimento e composição corporal. Um total de 192 alevinos (9 a 15g) foram estocados em 24 tanques de cimento, de 100l de capacidade, durante 103 dias. O farelo de canola foi utilizado em quatro proporções: zero; 9,5%; 19% e 38% da dieta, com ou sem farinha de peixe (12%/dieta), totalizando oito tratamentos. A presença de farinha de peixe não afetou os parâmetros de crescimento avaliados. A inclusão de 38% de farelo de canola na dieta diminuiu o ganho de peso dos peixes, valores médios de 28,74g a 50,70g, e piorou a conversão alimentar aparente, de 1,66 para 2,85. A taxa de eficiência protéica também foi menor nos peixes alimentados com 38% de farelo de canola. As várias proporções de farelo de canola das dietas alteraram os teores de umidade, proteína bruta e lipídios dos peixes. A presença da farinha de peixe, nas dietas, somente influiu no teor de lipídios dos peixes alimentados com dietas contendo 9,5% de farelo de canola. Conclui-se que até 19% de farelo de canola pode ser adicionado às dietas de juvenis de pacu, sem que seu desenvolvimento seja prejudicado.

Effect of Salinity on Larval Rearing of Pacu, Piaractus mesopotamicus, a Freshwater Species

The aim of this study was to evaluate the growth and survival of pacu, Piaractus mesopotamicus, larvae reared in different salinities and to determine the Artemia nauplii life span in freshwater and in saline water. First feeding 5-d-old pacu larvae were reared in freshwater or at 2, 4, 6, 8, 10, 12, and 14 ppt salinities. The larvae were reared in 1.5-L aquaria at a density of 10 larvae/L with three replicates per treatment. After 10 d of rearing, significant differences (P < 0.05) were observed for growth and survival. Larval growth was higher at 2 and 4 ppt, and survival at 2 ppt was 100%. In freshwater and at 4, 6 and 8 ppt, the survival was 91.1, 93.3, 73.3, and 39.9%, respectively. At higher salinities, there was 100% mortality after 2 h (12 and 14 ppt) and 8 h (10 ppt) of exposure. The slightly saline water of at least 2 ppt increased the Artemia nauplii life span compared to the life span in freshwater. Later, in a second trial, 5-d-old pacu larvae were reared in freshwater and at 2 and 4 ppt salinities during the first 5 or 10 d of active feeding, and then the fish were transferred to freshwater. At the end of 15 d, larval growth was lower in freshwater (42 mg) than in treatments 2 and 4 ppt (5963 mg). The abrupt transfer of fish from freshwater to slightly saline water and the return to freshwater did not affect the survival rates (8997%). The larvae were able to adapt to these saline environments and handle abrupt changes in salt concentration. We concluded that salinity concentration of 2 ppt can be used for pacu larval rearing, allowing the Artemia nauplii lifetime to last longer and cause faster fish growth.

Desempenho produtivo, composição corporal e parâmetros fisiológicos de pacu alimentado com níveis crescentes de fibra

O objetivo deste trabalho foi avaliar os efeitos de teores de fibra bruta na dieta sobre o desempenho produtivo, composição centesimal da carcaça e parâmetros fisiológicos de juvenis de pacu. O experimento teve duração de 84 dias, e foram utilizados 360 juvenis de pacu, com peso médio de 23,97±0,59 g, distribuídos aleatóriamente em 30 tanques com 180 L de água, em delineamento inteiramente casualizado, com seis tratamentos (5, 7, 9, 11, 13 e 15% de fibra bruta) e cinco repetições. Dietas com altos teores de fibra (11, 13 e 15%) resultaram em piores taxas de ganho de peso, conversão alimentar e crescimento específico, além de menor eficiência proteica e consumo de ração. A composição da carcaça dos animais foi alterada pelo aumento do teor de fibra das dietas. Os teores de proteína e cinza tiveram aumento com o incremento nos teores de fibra. O metabolismo foi alterado com o emprego de teores crescentes de fibra, o que resultou em pequena elevação do colesterol plasmático. Teores de fibra bruta de até 9% não tiveram efeitos negativos no metabolismo; entretanto, teores acima de 11% reduziram o crescimento dos peixes.

Muscle delta C-13 change in nile tilapia (Oreochromis niloticus) fingerlings fed lants grain-based diets

The effects of grain-based diets from C3 or C4-cycle plants on muscle delta C-13 change process in Nile tilapia (Oreochromis niloticus) fingerlings were investigated. Two groups of sex reversal males Nile tilapia fingerlings were fed with isoproteic (32.0% DP) and isocaloric (3200 kcal DE/kg) diets, differing from each other by their delta C-13. Muscle samples were collected and the carbon isotopic composition was measured. For C4 diet, the formula for the muscle delta C-13 change related to the intake time of a new diet was delta C-13=- 14.88 - 9.2 1 e(-0.0209t) and the half-life (T) of the muscle carbon was 33.2 days. For C3 diet, the formula was delta C-13 = - 25.43 + 8.59e(-0.0533), with T = 13 days. The C3 diet was considered more appropriate based on its palatability and consequent larger food intake than the C4 diet, resulting in an increased muscle delta C-13 change rate. However, for future studies, would be necessary to mix both the C3 and C4 feedstuffs to formulate diets nutritionally appropriated, with contrasting stable isotopes signatures. Tissue delta C-13 change rate is therefore indicated as a promising tool to better understand the biotic and abiotic factors that influence nutrients utilization from the diet and animal growth. (c) 2006 Elsevier B.V. All rights reserved.

Desempenho produtivo de alevinos de tilápia-do-nilo alimentados com levedura e derivados

O objetivo deste trabalho foi avaliar o desempenho produtivo e a composição químico-bromatológica do filé de tilápia-do-nilo alimentada com rações contendo levedura íntegra desidratada, levedura autolisada e parede celular. Rações práticas, isoprotéicas (32% de proteína digestível) e isoenergéticas (3.200 kcal de energia digestível por kg) suplementadas com levedura íntegra (1, 2 e 3%), levedura autolisada (1, 2 e 3%) e parede celular (0,1; 0,2 e 0,3%), e uma controle, sem ingredientes-teste, foram avaliadas. O delineamento experimental foi inteiramente casualizado, com dez tratamentos e quatro repetições. Peixes que receberam rações suplementadas com levedura e derivados apresentaram índice de desempenho produtivo superior ao controle. A suplementação da levedura autolisada proporcionou melhor resposta quanto ao ganho de peso (p<0,05). Não houve diferença na composição químico-bromatológica do filé, quando se compararam os contrastes entre totais de tratamento. A suplementação de levedura e derivados em rações para alevinos de tilápia-do-nilo melhora o desempenho produtivo, sem alterações na composição do filé, e entre os microingredientes avaliados, a levedura autolisada proporciona desempenho superior, quando utilizada entre 1,30 e 1,59%.

Follicular diameter range based on morphological features in Synbranchus marmoratus (Bloch, 1795) (Teleostei, Synbranchiformes, Synbranchidae) from the South-central region of Brazil

The morphological characteristics of Synbranchus marmoratus female germ cells in various development stages were described in details; then measurements of ovarian follicle diameters were taken from primary and secondary growth as during these development stages the oocyte size varied considerably along the fish growth. The results were correlated to total fish length, using the individuals division in six size classes. It was possible to group oocytes by stages according to histological characteristics but not according to morphometric diameter, as there was a wide variation in diameter in each stage and overlap between different maturation stages. These data make available new information on the reproductive biology of Synbranchidae. (c) 2004 Published by Elsevier Ltd.

Composição corporal e índices biométricos do pacu, Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes, Characidae) submetido a ciclos alternados de restrição alimentar e realimentação

The present paper evaluated, through hepatosomatic/mesenteric fat indexes and body composition, the pacu energy utilization when submitted to alternated food restriction/refeeding cycles during the growout period. Juveniles were distributed in three pounds and submitted to different feeding programs: A (ad libitum daily feeding), B (4-week feeding restriction and 9-week refeeding) and C (6-week feeding restrictions and 7-week refeeding), totaling 13 weeks for each cycle (4 experimental cycles). At the end of the periods, fish were sampled to obtain biometrics and biochemical data. The results showed that, during the first two cycles, C treatment obtained the best compensatory growth. Carcass lipid and water contents were inversely related, with body fat decrease. Fishes under B and C treatment during food restriction utilized liver and mesentery energy stores. These parameters were re-established in the refeeding phase, in all cycles.

Relative bioavailability of zinc in supplemental inorganic and organic sources for Nile tilapia Oreochromis niloticus fingerlings

A 90-day feeding experiment was conducted with sex reversed Nile tilapia (Oreochromis niloticus) fingerlings fed purified or practical diets supplemented with different zinc sources to evaluate fish growth performance and zinc and iron retention in fish bones, fillets, liver, skin and eyes. The relative bioavailability value (RBV) of zinc in the supplemental sources tested was also calculated. Fish were fed with isonitrogenous and isoenergetic purified or practical diets supplemented with 150 mg Zn kg -1, as zinc sulphate monohydrate (ZnSO 4), zinc oxide (ZnO) or zinc amino acid complex (Zn-AA). The feeding trial was conducted in 30, 50 L aquaria where four 0.66 ± 0.01 g (mean ± SD) fingerlings were initially stocked. No significant differences were observed for any growth performance variables (P > 0.05). In practical diets, only ZnSO 4 and ZnO presented bone zinc retention similar to that for the standard zinc source. Zinc concentration in the bone of fish fed practical diet supplemented with Zn-AA (171 ± 3.62 μg g -1) was significantly lower than that verified for the practical diets supplemented with the standard zinc source (200 ± 17.7 μg g -1) or with ZnSO 4 (204 ± 19.9 μg g -1). Assuming the concentration of zinc in bones as the response criterion, the supplemental zinc RBV from ZnSO 4 (105%) was higher than the RBV for Zn-AA (95.1%) or ZnO (94.9%). Iron concentration in the bones of animals fed the non-zinc-supplemented purified diet was significantly higher than that observed for purified diet supplemented with Zn-AA (P < 0,05). The results of the present work allowed us to conclude that ZnSO 4 in relation to ZnO or Zn-AA was the supplemental zinc source with higher zinc bioavailability to Nile tilapia. © 2005 Blackwell Publishing Ltd.

Fitase em rações para tilápia-do-nilo na fase de crescimento

This research was carried out to compare the effect of phytase on performance, in the incorporation and excretion phosphorus in Nile tilápia. Four diets were used: one standard (contol), composed by 3,200 DE kcal ED/kg of ration and 30.0% CP and supplemented with phosphorus (4.0% of dicalcium phosphate), considering the treatment control, and others three, without phosphorus supplementation, with different phytase levels (1,000, 1,500, and 2,000 uf/kg), with four replication, per a period of 82 days. Circular tanks of fiber glass, with constant flow and aeration were used. The results demonstrated that the use of phytase in diets for fish production can reduce the levels of inorganic phosphorus in the diets and minimizing the impacts caused by phosphorus in the production system and in the natural environment and also can improve the productivity, increasing the amount of feed to be supplied and, consequently, facilitating the increase of biomass of fish to be used per production area. © 2007 Sociedade Brasileira de Zootecnia.