Edgar de Alencar Teixeira

Caracterização genética de seis plantéis comerciais de tilápia (Oreochromis) utilizando marcadores microssatélites

Two hundred and thirty five individuals from six commercial stocks of tilapias (Ceara, Chitralada, Israel, Nilotica, Taiwan and Red) from the Southeastern region of the country were genetically characterized using five microsatellite loci. The results suggest large genetic difference among the stocks, estimated through the fixation allele index (Fst = 0.3263), and a considerable loss of heterozigosity accurs in most of the stocks, according to the population inbreeding coefficient (Fis=0.0486). The Israel and Nilotica stocks were genetically similar (Ig=0.6663), while Chitralada and Taiwan showed less genes in common (Ig=0.2463). The Red stock was the most distinct stock.

Coeficientes de digestibilidade aparente de alimentos energéticos para juvenis de surubim

Neste trabalho, determinou-se o valor nutritivo de quatro alimentos energeticos (fuba de milho, sorgo, farelo de arroz integral e quirera de arroz) para juvenis de surubim. Os coeficientes de digestibilidade aparente da materia seca (MS), proteina bruta (PB) e energia bruta (EB) foram avaliados pela metodologia de substituicao do alimento numa racao-referencia usando-se 0,1% de oxido cromico como indicador externo. Utilizaram-se 240 alevinos com 30 g de peso medio distribuidos em tanques apropriados para coleta de fezes. O delineamento foi inteiramente casualizado com quatro dietas, cada uma com quatro repeticoes. O coeficiente de digestibilidade aparente da materia seca do fuba de milho foi de 62,3%; do farelo de arroz, 59,7%; da quirera de arroz, 40,4%; e do sorgo, 38%. Os coeficientes de digestibilidade da proteina bruta, nesta ordem, foram 87,4; 83,8; 85,3; e 81,1%; e os da energia bruta, 62,4; 66,4; 46,9 e 47,8%. Entre os alimentos avaliados, o que possui maior digestibilidade da materia seca, proteina bruta e energia bruta e o farelo de arroz e o de menor digestibilidade, o sorgo.

Perfil proteico de tilápia nilótica chitralada (Oreochromis niloticus), submetida ao estresse crônico por hipóxia

This study evaluated the secundary response variation to hypoxia stress in a strain of chitralada nilotic tilapia (Oreochromis niloticus) during 18 days, in a recirculation system. The effects were measured by the proteic electrophoretic profile and the difference between the genders. One hundred twenty-six fish were used, 60 males and 66 females, both averaging 800g. The chronic hypoxia stress altered (P<0.05) the relative values of albumin, α+β-globulins, and γ-globulin; modified (P<0.05) the levels of total protein due to an increase in the male group; significantly decreased of the absolute mean values of albumin due to a decrease in the female group; and decreased the g-globulin values in males. The proteic profile, albumin, and γ-globulin were influenced by gender.

Performance and stress resistance of Nile tilapias fed different crude protein levels

The objective of this study was to evaluate the effect of different levels of diet crude protein on the performance and stress resistance rate (Re) of Oreochromis niloticus larvae and fingerlings. In the first experiment, 5, 15 and 25 day-old animals were submitted to 1, 5, 7, 10, 15, 20, 30 and 40 minutes of air exposure on a sieve. In the second experiment, tilapia larvae were fed with 32, 40 and 55% crude protein (CP) diets. Animals after 15 and 30 days of feeding (21 and 36 days of life, respectively) were submitted to the air exposure test for 7 and 10 minutes. Re was estimated based on survival 24 hours after the tests. In the first experiment, it was observed that 5-day-old animals were more resistant than animals with 10 and 20 days of feeding (15 and 25 days of life, respectively), when Re starts to decrease for longer than 7 minutes. In the second experiment, the different diets affected survival, performance and Re, and, in general, the worst results observed were the ones for the animals which received the 55% CP diet. The air exposure tests were efficient to evaluate the effect of diet on the resistance rate of Nile tilapia.

Desempenho produtivo de tambacus alimentados com dietas suplementadas com vitamina E

The objective of this work was to evaluate the effects of tambacu vitamin E dietary supplementation on performance and hematological variables, and determine the relationship of glutathione peroxidase activity with vitamin E and selenium suplementation. Two hundred and fifty juvenile tambacus were used, divided into 25 aquaria. The basal diet was pelleted with 32% of crude protein and 3,300 kcal kg-1 of digestible energy, with 0.40 mg kg-1 Se. Test diets - isoproteic and isocaloric - were composed of the basal diet with increasing vitamin E concentrations (0, 100, 200, 300, 400 mg kg-1), in a completely randomized design, with five treatments and five replications. No significant effect of vitamin E supplementation was observed on total length, mean corpuscular volume, mean corpuscular hemoglobin concentration and total erythrocyte, and on the enzymatic activity of glutathione peroxidase. However, final weight and apparent feed conversion were significantly affected by supplemented treatments. Standard length and weight gain improved using diets supplemented with 400 mg kg-1 of vitamin E. Dietary vitamin E supplementation results in better tambacu performance.

Blood chemistry profile of Surubim hybrid fish (Pseudoplatystoma reticulatum X P. corruscans) raised in different stocking densities

Massive production, such as fish growing in water recirculation system, imposes challenges to animals capable of altering their homeostatic balance, and is able to affect their physiological performance. Therefore, the levels of ions and serum enzymes can be used as indicators of fish health. This study aimed to analyze the blood biochemistry profile of hybrid surubim (P. reticulatum X P. corruscans) submitted to different stocking densities in water recirculation system, in two distinct stages of production, from 150 to 400 g (first trial), and 400 to 1000 g (second trial). In the first trial, the five stocking rates were: 27.5, 47.5, 67.5, 87.5 and 107.5 fish/m3 of water. To obtain these densities, it was used 11, 19, 27, 35 and 43 fish per tank, respectively. In the second trial, five stocking rates were: 10, 20, 30, 40 and 50 fish/m3 of water. To obtain these densities we used 4, 8, 12, 16 and 20 fish per tank, respectively. The concentrations of glucose, cholesterol, triglycerides, urea, creatinine, alkaline phosphatase (ALP), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), calcium, phosphorus, potassium and magnesium were obtained. Only urea concentrations in first trial and ALP and AST concentrations in second trial were influenced by stocking density, presenting a significant difference between groups. Thus, in both trials the hybrid fish studied maintained homeostasis when reared in different stocking densities.

Performance and nutrient utilization in South American juvenile catfish Pseudoplatystoma spp. weighting 89 - 170g, fed at different energy and protein levels

Most studies in nutrition for the South American catfish (surubim) were limited to the initial phase of development. However, it is clear that performance and nutrient utilization can change during the life stages of a fish. Therefore, this study aimed to evaluate the performance and nutrient utilization in juveniles of surubim fed diets varying in protein and energy levels. Two experiments were performed to test different levels of energy and protein in formulated diets. In the first experiment, surubim juveniles (89.2±4.8g) were fed five diets containing different levels of energy (18.0, 18.8, 19.6, 20.5, 21.3 MJ/kg). In the second experiment, juveniles (170.03±3.35g) were fed five diets containing different levels of protein (360, 400, 440, 480 and 520g/kg). The most favorable energy level for weight gain was 20.3 MJ/kg. The increasing energy levels provided a rise in fat and decrease in protein whole-body composition. The protein amount was between 360 to 400g/kg (383g/kg), which was adequate for performance and nutrient assimilation in surubim juveniles.

Eritrograma de híbridos de surubim (Pseudoplatystoma reticulatum X P. coruscans) mantidos em diferentes densidades de estocagem

The blood profile of hybrid fish was studied. Pseudoplatystoma (P. coruscans X P. reticulatum) were submitted to different stocking densities in recirculating water system in two distinct phases of production. Hemoglobin concentration (Hg), packed cell volume (PCV) and mean corpuscular hemoglobin concentration (MCHC) were evaluated. There was no difference between the studied densities. Hemoglobin concentration, PCV and MCHC remained within the normal range for teleost fish.

Produção do híbrido "cachadia" em diferentes densidades de estocagem em sistema de recirculação de água

The aim of this study was to investigate the effect of different stocking densities on cachadia production (Pseudoplatystoma fasciatum x Leiarius marmoratus) in recirculating aquaculture system. In the two first phases for 27 and 40 days using fish with average weight of 31 and 57g, respectively, densities 20, 40, 60, and 80 fish/m3 were tested. In the third and fourth trial, using fish with an average weight of 169 and 399g during 41 and 99 days, respectively, densities 10, 20, 30, and 40 fish/m3 were tested. Survival rate was higher than 92%, without stocking density differences between the treatments. Daily weight gain showed reduction with the increase of the density in the second and fourth trial. However, final biomass presented direct relationship with increase density in all trials. Feed conversion rates ranged 0.8 from 1.3:1 were registered. Cachadia hybrid reached 1.1kg in approximately seven months of rearing indicating promise for intensive production.

Digestibilidade de ingredientes em dietas para juvenis de pacamã (Lophiosilurus alexandri)

The objective of this work was to determine the apparent digestibility coefficient (ADC) of six ingredients, in practical and purified reference diets, and to assess the influence of these reference diets on the digestibility of the ingredients in pacman catfish juveniles. The following ingredients were evaluated: fish meal, meat and bone meal, soybean meal, roasted whole soybean, wheat meal, and corn protenose. There was interaction between the reference diet and the studied ingredients. The purified diet provided higher ADC for crude protein and gross energy. Pacman catfish showed high ADC for protein ingredients of vegetable origin for the two reference diets.