Morphological aspects of muscle regeneration in the Nile tilapia (Oreochromis niloticus)

The aim of our study was to analyze the morphological events in the skeletal muscle of the Nile tilapia (Oreochromis niloticus) after a traumatic lesion. Thirty-two fish were used, on which a small longitudinal incision was made in the muscle. The fish were sacrificed after 7, 14, 21, and 42 days and muscle samples were collected from the lesion and processed for morphological analysis. Muscle regeneration in the tilapia occurred gradually through the analyzed period, possibly due to the proliferation and differentiation of myosatellite cells, which were more morphologically evident 7 and 14 days after lesion.

Nile tilapia, Oreochromis niloticus, productive performance and carcass characteristics as related to food management

Male juveniles of Nile tilapia, Oreochromis niloticus, were stocked in 12, 300-m 2 ponds at a density of 1.7 fish/m 2 to evaluate the effects of different food management methods (natural foods and diets in pellet, floating or minced form) on fish production and carcass characteristics. Water quality variables monitored during the period were within acceptable levels for the species. Total fish production was significantly different (P < 0.05) and the highest values were obtained with diets in pellet (5,997 kg/ha) and floating (5,441 kg/ha) form. The fish fed diets had higher contents of body fat (1.57 to 1.98%) and visceral fat (12.64 to 25.04%) than fish fed natural food, which had levels between 0.17 and 0%, respectively. Natural food treatment yielded lower fish production and fish with lower body fat, while treatments that yielded higher fish production (rations) higher percentage of visceral fat. © 2004 by The Haworth Press, Inc. All rights reserved.

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.

Apparent absorption of zinc from supplemental inorganic and organic sources to Nile tilapia Oreochromis niloticus juveniles

Nile tilapia Oreochromis niloticus fingerlings were fed with purified or practical diets, supplemented with 150 Ing Zn/kg, from different sources. Dry matter (DM), crude protein (CP), ether extract (EE), and gross energy (GE) apparent digestibility coefficients (ADC), as well as zinc, copper, calcium, and phosphorus apparent absorption coefficients (AAC) were determined by the addition of 0.1% chromic oxide to the diets. The supplemental zinc sources utilized were commercial grade zinc sulfate monohydrate (ZnSO 4), zinc oxide (ZnO) and a zinc amino acid complex (Zn-AA). Analytical grade zinc sulfate heptahydrate was also utilized as a standard reference zinc source. There was a significant difference between purified (74.9%) and practical (41.3%) zinc AAC for the ZnO supplemented diets (P < 0.05). The supplemental zinc sources presented similar AAC when purified diets were utilized. However, ZnSO 4 was the best supplemental zinc source when practical type diets were used. There were no significant differences between supplemental zinc AAC from ZnS0 4 (68.9%), and supplemental zinc AAC from Zn-AA (61.3%) in practical diets, but Zn-AA diet showed a statistically lower zinc AAC when compared with the standard zinc source diet (75.6%). The practical diet supplemented with ZnO had the worst supplemental zinc AAC (41.3%). Dietary copper (74.21%), calcium (70.9%), and phosphorus (71.9%) AAC of the practical diets supplemented with ZnO were statistically lower (P < 0.05) than the respective AAC of the practical ZnSO 4 supplemented diets (83.6%, 84.1%, 87.1%).The ADC of the practical ZnO supplemented diet for DM (76.3%), CP (88.6%), EE (82.4%), and GE (81.6%) were statiscally lower than the respective ADC of the ZnSO 4 practical diet (86.0, 92.7, 93.6, 89.6%, respectively) and those ADC of the Zn-AA practical diet (84.7, 92.7, 93.7, 88.2%, respectively) (P < 0.05). Hence, these results indicate that ZnSO 4 and Zn-AA have equivalent intestinal absorption as supplemental zinc sources for Nile tilapia juveniles and both are superior to ZnO. © Copyright by the World Aquaculture Society 2005.

Energia digestível para larvas de tilápia-do-nilo (oreochromis niloticus) na fase de reversão sexual

This experiment was conducted to evaluate different levels of digestible energy on the performance of Nile tilapia larvae (Oreochromis niloticus) during the sexual reversion phase. Three hundred and seventy-five larvae with initial average length and weight of 21.0±4.0 mg and 1.19±0.72 cm, respectively, were allotted to 25 30L-aquarium. A completely randomized design with five treatments and five replicates was used. The aquarium with 15 larvae was the experimental unit. The diets were formulated to contain levels of 3,300, 3,525, 3,750, 3,975, and 4,200 kcal/kg of digestible energy and to be isoprotein (38.6% digestible protein). The animals were fed ad libitum five times a day. At the end of the experiment, the averages of weight (PF), survival rate (SO), condition factor (FC) and length (CF) were analyzed. Linear reduction of fishes PF and CF, as the dietary digestible energy levels increased, was observed. No differences on fish SO and FC of different treatments were observed. Deleterious effects on performance due to the increasing dietary digestible energy levels were noticed for Nile tilapia larvae during the sexual reversion.

Tocopherol in the lipid stability of tilapia (Oreochromis niloticus) hamburgers

Presence of tocopherol is effective for fish preservation during frozen storage, inhibiting lipid degradation by oxidation. This work evaluated the antioxidant effects of α-tocopherol in diet and postmortem addition on the final quality of hamburgers produced from tilapia fillets kept frozen for zero, 30, 60, and 90 days. Chemical composition varied within the values found for tilapia fish. The increase in α-tocopherol levels reduced the values of thiobarbituric acid reactive substances (TBARS) in the samples at all time intervals. Tocopherol supplementation in diets protected the hamburgers from lipid oxidation more effectively than postmortem addition. © 2007 Elsevier Ltd. All rights reserved.

Metodologia para quantificação de leucóciotos totais em peixe Oreochromis Niloticus

Haematological investigation is an important part of disease diagnosis. The techniques used for mammals are generally applicable for fishes with slight modification. The presence of nucleated erythrocytes and thrombocytes in fish may cause some confusion in the identification of blood cells, mainly in total leukocytes count. This work evaluated two different methods (direct and indirect) of leukocytes counting. Specimens of tilapia were divided randomly into four groups of 48 fish each. Each group was further randomized into three replicate experiments of 16 fish per replicate in 40 L aquarium and maintained for 10 days. Counting of leukocytes in peripheral blood was determined in six fishes per group at the times: 0, 3, 7 and 10 days. The direct method in Neubauer chamber showed a large dispersion of data in regard to the average, the opposite was observed in indirect method determined in blood smears that showed more homogeneity among groups. Due to this factor the indirect method can be considered more accurate than the direct method for counting leukocytes in fishes.

Policultivo do camarão de água doce Macrobrachium amazonicum (Heller, 1862) com a Tilápia do Nilo (Oreochromis niloticus) alimentadas com rações peletizada e farelada

The objective of this work was to evaluate the influence of fresh water shrimp Macrobrachium amazonicum (Heller, 1862) in performance of Nile tilapia (Oreochromis niloticus) cultivated in polyculture system and feeding with ration pelleted and mashed. The work was realized in Centro de Pesquisa em Aqüicultura Ambiental-CPAA/IAP - Toledo/PR during 37 days. Were utilized like experimental unit 16 ponds excavated, covered with concrete but with bottom of soil with dimension the 4 x 3 m and useful volume the 3,5 m 3. Were utilized 30 tilapias e 150 shrimps for experimental unit distributed at an entirely randomized design with 4 treatments and 4 replications, where TF: tilapia feeding with ration mashed; TCF: tilapia and shrimp feeding with ration mashed; TP: tilapia feeding with ration pelleted; TCP: tilapia and shrimp feeding with ration pelleted. The density used were the 2,6 fishes/m 2 with medium initial weight the 5,58 ± 0,10 g and initial length the 5,56 cm, and the density of shrimp was the 13 shrimps/m 2 with initial length the 1,04 cm. The temperature was gauged daily, while the variables dissolved oxygen, pH and electrical conductivity, weekly. The quantity of ration supplied was the 10% of total biomass of fishes, with feed frequency the 4 times a day, being corrected weekly in function of the biometry. During the experimental period the medium values of temperature, dissolved oxygen, pH and electrical conductivity of the ponds water were 23,42 ± 0,83°C, 5,32 ± 0,52 mg/L, 7,02 ± 0,39, e 100,96 ± 1,81 μS/ cm respectively. Won't registering any influence of shrimp during the cultivation and the ration pelleted provide the better conversion alimentary and performance of tilapias.

Valor nutricional do farelo de algodão para alor a tilśpia do nilo (Oreochromis niloticus)

Cottonseed meals (CSM) with different protein levels (35, 39 and 40%) were evaluated to determine their chemical composition and measure apparent digestibility coefficients (ADC) of dry matter, protein, amino acids, energy, lipid and minerals for Nile tilapia. Apparent digestibility coefficients were determined using a reference purified diet containing 0.1% of chromic oxide indicator, and test diets contained 60% of reference diet and 40% of test ingredients. Results showed that apparent digestibility coefficients of cottonseed meals were different (p < 0.05). The apparent digestibility coefficients were: dry matter, 53.45-54.32%; crude protein, 71.56-74.81%; energy, 53.80-58.60%; lipid, 85.37-89.11%; phosphorus, 33.75-34.50%; calcium, 41.21-43.75%; iron, 62.02-79.85%; zinc, 0-67.41%; copper, 13.37-14.27%; essential amino acids, 71.39-79.17%; and non-essential amino acids, 77.08-82.58%. The ADC of protein did not reflect the majority of amino acids ADC showing variation in individual digestibility of amino acids and among cottonseed meals. Cottonseed meal can be used as protein succedaneum in Nile tilapia diets.

Biochemical biomarkers in Nile tilapia (Oreochromis niloticus) after short-term exposure to diesel oil, pure biodiesel and biodiesel blends

Fossil fuels such as diesel are being gradually replaced by biodiesel, a renewable energy source, cheaper and less polluting. However, little is known about the toxic effects of this new energy source on aquatic organisms. Thus, we evaluated biochemical biomarkers related to oxidative stress in Nile tilapia (Oreochromis niloticus) after two and seven exposure days to diesel and pure biodiesel (B100) and blends B5 and B20 at concentrations of 0.01 and 0.1mLL -1. The hepatic ethoxyresorufin-O-deethylase activity was highly induced in all groups, except for those animals exposed to B100. There was an increase in lipid peroxidation in liver and gills in the group exposed to the higher concentration of B5. All treatments caused a significant increase in the levels of 1-hydroxypyrene excreted in the bile after 2 and 7d, except for those fish exposed to B100. The hepatic glutathione-S-transferase increased after 7d in animals exposed to the higher concentration of diesel and in the gill of fish exposed to the higher concentration of pure diesel and B5, but decreased for the two tested concentrations of B100. Superoxide dismutase, catalase and glutathione peroxidase also presented significant changes according to the treatments for all groups, including B100. Biodiesel B20 in the conditions tested had fewer adverse effects than diesel and B5 for the Nile tilapia, and can be suggested as a less harmful fuel in substitution to diesel. However, even B100 could activate biochemical responses in fish, at the experimental conditions tested, indicating that this fuel can also represent a risk to the aquatic biota. © 2011 Elsevier Ltd.

Valores bioquímicos séricos de tilapia del Nilo (Oreochromis niloticus) en cultivo intensivo

The aim of the study was to evaluate the serum biochemical parameters of the Nile tilapia (Oreochromis niloticus), Thai Chitralada lineage, raised under an intensive pisciculture system and captured by the cast net technique. Blood samples from 40 individuals were obtained by caudal venopuncture. Mean body weight was 453 ± 52 g. The serum biochemical parameters evaluated were total protein, albumin, globulins, acid uric, creatinine, urea, calcium, inorganic phosphorus, Ca/P ratio, alkaline phosphatase, and magnesium. In general, the data showed similar parameters in comparison to those established for scale fish, exception of the acid uric.

Thiamin Requirement of Nile Tilapia, Oreochromis niloticus

Juvenile Nile tilapia, Oreochromis niloticus, were fed to apparent satiation twice daily with purified diets containing 0, 1.0, 2.0, 4.0, 8.0, and 16.0 mg/kg and 0, 2.0, 4.0, 8.0, 16.0, and 32.0 mg/kg of thiamin in separate 14- and 8-wk trials (Experiments 1 and 2, respectively). Fish fed the diet devoid of thiamin developed neurological disorders, anorexia, reduced growth, and feed efficiency and increased mortality (Experiment 2 only) within 4-6 and 8-10 wk for Experiments 2 and 1, respectively. Low red blood cell count (RBC) and hematocrit (Ht) were observed in fish fed the thiamin-deficient diet. Serum pyruvate was elevated in fish fed the thiamin unsupplemented diet. Serum lactate was not affected by dietary thiamin levels. Whole body protein was unaffected by dietary levels of thiamin. Body moisture and ash increased whereas body lipid decreased in fish fed the thiamin unsupplemented diets. None of these abnormalities were observed in fish fed the thiamin-supplemented diets. Using the response curves determined by PROC NLMIXED to estimate dietary thiamin levels required for various response variables, a dietary thiamin level of 3.5 mg/kg diet was adequate for optimum growth, feed intake and efficiency, survival, prevention of neurological symptoms, and maintaining normal levels of RBC, Ht, serum pyruvate, and proximate body composition. © 2011.

Histologia e histoquímica do intestino anterior de tilápia do Nilo (Oreochromis niloticus) alimentadas com dietas contendo silagem de peixe

This work was carried out to evaluate the action of the fermented fish silage and fish meal in the histochemical of the middle intestine of O. niloticus. A great epithelium intestinal was present in fishes fed with fish silage, independent of the animal origin protein proportions in diets. It was observed that the variation of the goblet cells secretion glicoproteic intensity is linked directly to the diet supplied to animals. The middle intestine of Oreochromis niloticus showed differences in the neutral mucus glicoproteic, acid glicoproteic and glicoconjugated secretion pattern, depending on the protein origin and the percentage used in the diet, demonstrating that this species can adapt its secretion system for the protection of the digesting apparatus during the absorption of different protein sources.

Determinação da toxicidade do selênio por meio de análises hematológicas em Oreochromis niloticus

Selenium (Se) is described as an essential micronutrient and participates in different biological functions, as the antioxidant defense systems maintenance and regulation. However, when in high concentrations, Se may cause toxic effects as well as hematological changes in fish. The aim of the present study was to determine the toxicity of selenium in the form of sodium selenate (Na 2Se 6+O 4) in Oreochromis niloticus based on hematological parameters, after exposure to different concentrations (0.01, 0.14 and 1.4 mg Se 6+ L -1). The erythrocytic and leukocytic series were examined over 14 days at intervals of 0, 3, 5, 7,10 and 14 days. The erythrocytic series showed significant alterations in the first 7 days, including the control group. Neutrophils and monocytes showed variations in the first 3 days at a concentration of 1.40 mgSe 6+ L -1 characterizing an acute response. The total number of leukocytes was different in relation to time zero on all Se concentrations. The thrombocyte count also differed statistically from time zero and control in the first 3 days at 0.14 mgSe 6+ L -1. These results indicate that different concentrations induce an acute response with diminution of total leukocytes, neutrophilia, monocytosis and thrombocytosis.

Reproduction, food dynamics and exploitation level of Oreochromis niloticus (Perciformes: Cichlidae) from artisanal fisheries in Barra Bonita Reservoir, Brazil

Nile tilapia (Oreochromis niloticus), which is exotic to South America, is the most common species caught in artisanal fisheries at the Barra Bonita Reservoir, Southeastern Brazil. This species is of great socioeconomic importance for the region and keeps active a population of about 500 fishers. In the present study we assess reproduction, food dynamics and level of exploitation of O. niloticus, caught by artisanal fisheries in the Barra Bonita Reservoir. Specimens were collected monthly, from July 2004-June 2005, and a total of 1 715 specimens were analyzed. Each specimen was examined to obtain biological and biometric data: standard length (cm), total weight (g), reproductive data (sex and stage of maturation), and stomach contents (empty, partly full, and full). We also estimated the sex ratio (by macroscopic observation of gonads), reproductive period (by ovarian development and seasonal average of gonadosomatic index in females), and feeding habits (by stomach contents). The possible relationship between abiotic factors and the reproductive period was statistically verified using Spearman's Rank Correlation. The FiSAT (ELEFAN I) package was used to assess growth parameters, mortality rates and to infer exploitation rate from standard length frequencies. The O. niloticus population had a sex ratio of 1.3:1 (M:F). Results indicated that ripe females were captured throughout the year, with a higher frequency during the winter-2004 (with a frequency of 59%, at a mean temperature of 20.5°C), and in spring-2004 (with a frequency of 60.5% at a mean temperature of 21.18°C). The GSI mean values obtained by season were: winter-2004: 1.71; spring-2004: 1.72; summer-2005: 0.80, and autumn-2005: 1.19. The Spearman correlation indicated positive values with respect to pH, dissolved oxygen, electric conductivity, transparency and chlorophyll a, and negative values with respect to temperature, accumulated rainfall and altimetric benchmark. The main food items were phytoplankton and periphytic algae, observed in 99.6% of the analyzed stomachs. The estimated growth and mortality parameters were: L∞=33.60cm, k=0.63/year, longevity= 4.76years, Z=2.81/ year, M=1.20/year and F=1.61/year. The weight-length relationship was Ln Wt=-2.8532+2.8835 Ln Lp. The estimated yield per recruit values were as follows: E=0.570, Emax=0.776, E0.1=0.604 and E0.5=0.349. These results indicate that a well established population of O. niloticus is present at Barra Bonita Reservoir; with an active reproduction throughout the year, more intense during winter and spring, and that O. niloticus is a phytoplanktophagus species. There were no indications that this species is being overfished, we therefore recommend that, due to its exotic condition, no restrictions need to be taken on its fishing activities.