Deposition of bodily chemical components in the carcass of tilapia (oreochromis sp.) strains

The knowledge of how animals deposited chemical components as water, protein, fat and ash in the carcass is importance for the formulation of a balanced diet, allowing maximum performance with a low environmental impact. So, the study was carried out to evaluate the influence of different tilapia strains (Chitralada, Commercial, Red and Universidade Federal de Lavras [UFLA]) on the deposition of bodily chemical components in the carcass. The bodily components analyzed were water, protein, fat and ash. For the determination of the bodily chemical deposition curves by age, the exponential, Brody, logistic, Gompertz and von Bertalanffy models were adjusted. The Commercial and UFLA strains deposited water at a faster speed (P<0.05) compared with the remaining strains. As for protein, the Red strain had a lower estimated maturity weight (49.37 g), and was more precocious (202 days) with regard to maximum deposition in comparison to the other strains (Chitralada, UFLA and Commercial) in which there was an estimated maturity weight of 231.5 g and maximum depositionfor 337 days. There were no differences (P>0.05) for the logistic model parameter between Red, UFLA and Commercial strains for fat, which presented a maximum fat deposition (0.23 g) at 310 days of age. Regarding ash deposition, the Commercial strain presented a higher maximum deposition (0.10 g) at 337 days, occurring later than the other strains that presented maximum deposition (0.033g) at 254 days of age. Thus, it was concluded that the genetic strains evaluated differ in chemical deposition curves of water, protein, fat and ash.

Identities among actin-encoding cDNAs of the Nile tilapia (Oreochromis niloticus) and other eukaryote species revealed by nucleotide and amino acid sequence analyses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

E2 potentializes benzo(a)pyrene-induced hepatic cytochrome P450 enzyme activities in Nile tilapia at high concentrations

In the aquatic environment, biotransformation enzymes are established biomarkers for assessing PAH exposure in fish, but little is known about the effect of 17β-estradiol (E2) on these enzymes during exposure to benzo(a)pyrene (BaP). In this study, Nile tilapia (Oreochromis niloticus) were exposed for 3, 5, and 10 days to BaP (300 μg L(-1)) and E2 (5 μg L(-1)). These substances were applied isolated or mixed. In the mixture experiment, fish were analyzed pre- and postexposure in order to better understand whether preexposure to the hormone masks the responses activated by PAH or vice versa. Phase I enzymes ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-depenthylase (PROD), and benzyloxyresorufin-O-debenzylase (BROD) activities as well as the phase II enzyme glutathione S-transferase (GST) were analyzed. Isolated E2 treatment decreased EROD activity after 3 days, but this enzyme activity returned to control values after 5 and 10 days of exposure. Isolated BaP treatment significantly induced EROD activity after 3 and 5 days, and the activity returned to control levels after ten exposure days. Combined treatment (E2 + Bap) significantly increased EROD activity, both in the pre- and postexposure. This increase was even higher than in the isolated BaP treatment, suggesting a synergism between these two compounds. When E2 and BaP were used singly, they did not change BROD and PROD activities. However, combined treatment (E2 + Bap) significantly increased PROD activity. Isolated BaP treatment increased GST activity after 10 days. However, this response was not observed in the mixture treatment, suggesting that E2 suppressed the GST induction modulated by BaP. The results put together indicated that E2 altered the biotransformation pathway regarding enzymes activated by BaP in Nile tilapia.

Stress responses to chemical alarm cues in Nile tilapia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vitamin A affects haematology, growth and immune response of Nile tilapia (Oreochromis niloticus, L.), but has no protective effect against bacterial challenge or cold-induced stress

Vitamin A (vitA) is an essential nutrient that acts as an endocrine regulator of several metabolic pathways, modulating normal growth and health status of animals. Although the importance of vitA for normal haematology and immune response is well documented for higher vertebrates, there is limited information on the physiological effects of vitA on fish. Therefore, we designed a 130-day feeding trial to evaluate the effect of vitA supplementation on growth, haematology, immune function and resistance to experimental infection with Aeromonas hydrophila and cold-induced stress. A group of 320 Nile tilapia fingerlings 7.49 ± 0.19 g weight (mean ± SD) were randomly stocked into 40 250 L-aquaria and fed practical diets containing graded levels of vitA (0, 0.06, 0.12, 0.24, 0.48, 0.96, 1.92, 3.84 mg retinol (ROH) kg−1 diet. Growth, haematology, plasma protein profile and immune response were significantly affected by vitA supplementation; however, no clear protective effect of vitA supplementation on disease and cold stress resistance were observed in this study. Clinical signs of vitA deficiency were: resting and abnormal swimming behaviour, exophthalmia, haemorrhages at the base of fins and on skin, serous fluids in abdominal cavity, neutropenia, reduction in red blood cell count, haematocrit and haemoglobin evolving to high mortality rates in a short period of time. A dietary level of vitA around 1.2 mg ROH kg−1 may be required to prevent gross deficiency signs and promote proper growth and health status of Nile tilapia. VitA does not seem to have a pronounced effect on leucocyte differentiation, but clearly plays an important role on maintaining normal erythropoiesis.

The ability of Nile tilapia to regulate protein and energy intake evaluated by carbon relative enrichement

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Restructured products from tilapia industry by products: the effects of tapioca starch and washing cycles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estratégia alimentar com ciclos de restrição e realimentação no desempenho produtivo de juvenis de tilápia do Nilo da linhagem GIFT

O objetivo deste estudo foi avaliar a ocorrência de resposta compensatória no desempenho produtivo de juvenis de tilápia do Nilo Oreochromis niloticus, linhagem GIFT, submetidos a diferentes estratégias alimentares. Foram utilizados 135 juvenis de tilápia, distribuídos em nove tanques de polietileno de 100L cada. As estratégias testadas foram: grupo controle (alimentado todo dia), grupo alimentado por cinco dias seguidos de dois dias de restrição de alimento (5A/2R) e grupo alimentado por quatro dias seguidos de três dias de restrição de alimento (4A/3R). Foram avaliados parâmetros físico-químicos da água e de desempenho produtivo. Os resultados foram submetidos à análise de variância, e as médias foram comparadas pelo teste Tukey, a 5% de probabilidade. A qualidade de água, o fator de condição e a conversão alimentar não foram influenciados pela estratégia alimentar. O grupo alimentado com a estratégia 5A/2R apresentou peso final, ganho de peso e taxa de crescimento específico semelhantes ao grupo continuamente alimentado (7,8 e 9,2g; 6,4 e 7,8g e 2,7 e 3,0% dia-1, para peso final, ganho de peso e taxa de crescimento especifico, respectivamente). A estratégia 4A/3R apresentou os piores resultados de desempenho produtivo, e a estratégia 5A/2R pode ser usada na alimentação de juvenis de tilápia do Nilo sem prejuízo ao desempenho produtivo, possibilitando inclusive redução de até 22,5% na quantidade de alimento ofertada.

Amino acid composition of processed fish silage using different raw materials

The objective was to evaluate amino acid composition of silages produced from three raw materials. Commercial marine fish waste, commercial freshwater fish waste, and tilapia filleting residue were used to produce fish silage by acid digestion (20 ml/kg formic acid and 20 ml/kg sulfuric acid) and anaerobic fermentation (50 g/kg Lactobacillus plantarum, 150 g/kg sugar cane molasses). Protein content and amino acid composition were determined for raw materials and silage. Marine fish waste had higher crude protein content (776.7 g/kg) compared to freshwater fish waste (496.2 g/kg) and tilapia filleting residue (429.9 g/kg). All silages lacked up to three amino acids for each product according to FAO standards for essential amino acids. However, considering as the limiting factor only the amino acids below the 30% minimum requirement for fish in general, all products were satisfactory with respect to essential amino acids. Therefore, the results suggest that all products investigated are appropriate for use in balanced fish diets. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Influência do método de filetagem e categorias de peso sobre rendimento de carcaça, filé e pele da tilápia do Nilo (Oreochromis niloticus)

The objective of this study was to evaluate the processing methods (F-1 = to remove skin with pliers and then to cut in fillets; F-2 = cut in fillet and then to remove skin with knife and pliers help) and weight categories (W-1=250-300 g; W-2=301-350 g; W-3 = 351-400 g and W-4 = 401-450 g), on the carcass (CY), fillet (FY) and skin yield of Nile tilapia. Forty-eight fishes were used in a completely randomized design. There was effect for the processing method, being the F-1 mean (56.43 and 36.67 %) higher to the F-2 (53.46 and 32.89%) for CY and FY respectively. For the weight categories, W-1 (56.49 and 37.34%) and W-2 (56.34 and 36.40%) were superior as compared to W-3 (53.27 and 31.98%) and W-4 (53.71 and 33.42%), respectively for CY and FY. Crude skin percentage, clean and of fleshed were higher for F-2, but there was no effect for weight categories. The F-1 processing method promoted the best yield and skin results, and for the weight categories W-1 and W-2 higher yields.

Inclusão de farinha de resíduos da indústria de filetagem de tilápias na alimentação de girinos de rã-touro (Rana Catesbeiana Shaw,1802)

The objective of this experiment was to evaluate the inclusion of meal of tilapia industrial waster in bullfrog tadpoles' diets (Rana Catesbeina Shaw, 1802). Two hundred fifty tadpoles with initial weight and length of 0,18 +/- 0,05g and 2,50 +/- 0,18 centimeters were used, respectively, they were used and distributed in 25 aquariums of 30 liter each in a complete randomized design with five treatments and five repetitions. The tadpoles were fed four times a day with diets containing 0, 5, 10 and 15% of inclusion of tilapia filleting and another diet with 0% of supplemented tilapia filleting with synthetic methionine, being supplied four times a day at ease. The experiment period was 30 days. The diets with tilapia filleting inclusion and methionine supplementation did not have influence in the final weight and length averages, feed survival and conversion of bullfrog tadpoles. It cam be used until 15% of tilapia filleting inclusion in the bullfrog tadpoles food. The synthetic methionine supplementation in diets for bullfrog tadpoles is not necessary in diets with levels over 0,471/4 of the total methionine.

Sexagem histológica e desempenho de Oreochromis niloticus testando diâmetros de ração de acordo com o aparato bucal

Estudou-se o tamanho da boca de larvas de tilápia-do-nilo e testou-se o efeito de diferentes granulometrias da ração sobre o ganho de peso, comprimento e sobrevivência das larvas aos 30 e 60 dias de arraçoamento. Avaliou-se também o método de sexagem por meio de microscopia de luz aos 35 dias de idade. A medida da boca das larvas apresentou valores médios de 918,2±152,9μm aos cinco dias de idade. de acordo com esse dado, testaram-se três granulometrias: 0,25, 0,35 e 0,50mm. Aos 30 e aos 60 dias de arraçoamento, 10% das larvas foram medidas, pesadas e contadas para cálculo da taxa de sobrevivência. O tamanho dos grânulos testados não afetou o desempenho das larvas de tilápia nilótica com alimentação iniciada aos cinco dias pós-eclosão. Quanto à sexagem histológica aos 35 dias de idade, as gônadas apresentaram-se, em sua maioria, indiferenciadas. Recomenda-se que essa análise deva ser realizada de acordo com o tamanho dos animais e não com a idade.

Custos e rentabilidade da produção de juvenis de tilápia-do-nilo em tanques-rede utilizando-se diferentes densidades de estocagem

Neste trabalho foi realizada a análise econômica da produção de juvenis de tilápia-do-nilo em tanques-rede utilizando-se diferentes densidades de estocagem. O experimento foi desenvolvido em área aquícola, em delineamento de blocos casualizados, com quatro densidades de estocagem (100, 200, 300 e 400 peixes m-3), avaliadas com seis repetições, em dois períodos de criação: de março a abril de 2005 (52 dias - peso inicial de 43,08 ± 2,98 g e peso final de 262,14 ± 47,86 g) e de março a abril de 2006 (58 dias - peso inicial de 43,16 ± 5,34 g e peso final 314,24 ± 73,30 g). Foram avaliadas as seguintes variáveis econômicas: custo da ração mais custo do juvenil dividido pela biomassa, em R$ kg-1; porcentagem do custo da ração por quilo de peixe produzido sobre o preço de venda; porcentagem do custo do juvenil por quilo de peixe produzido sobre o preço de venda e; porcentagem dos custos da ração mais do juvenil por quilo de peixe produzido sobre o preço de venda. da menor densidade de estocagem (100) para a maior (400), ocorreu diminuição no ganho de peso diário e elevação do índice de conversão alimentar aparente, mas essa redução não comprometeu a taxa de sobrevivência. Entretanto, o ganho de biomassa aumentou com o adensamento de peixes. As maiores receitas líquidas foram obtidas nas densidades de estocagem de 100 e 200 peixes m-3. Os preços não remuneraram os custos operacionais (efetivo e total) em maiores densidades (300 e 400 peixes m-3). Os melhores resultados para a produção de juvenis de tilápia-do-nilo foram obtidos com densidades de até 200 peixes m-3.