ABSTRACT An experiment was conducted during 60 days with forty pacu males fed diets supplemented with increasing concentrations of ractopamine (0.00, 11.25, 22.50, 33.75, and 45.00 mg kg−1). Eight fish were evaluated for each experimental diet. Performance and survival rate of the fish were measured. At the end of the experiment, blood was collected to determine the levels of cortisol, triacylglycerol, and protein. Moreover, the liver was collected to determine the activities of glucose-6-phosphate dehydrogenase and malic enzymes. The fillets were collected to determine chemical composition, and histologic cuts were analyzed to verify muscle growth and deposition of adipose tissue between muscle fibers. Increasing concentrations of dietary ractopamine did not change feed intake, fillet yield, fillet content of protein and ash, and frequency of relative distribution of muscle fibers. By increasing the dietary ractopamine concentration, the serum cortisol level was elevated. Ractopamine supplementation (45.00 mg kg−1) increased serum levels of triacylglycerol and protein and reduced the activity of hepatic lipogenic enzymes and the survival rate of the fish, probably in response to the high concentration of circulating cortisol. In addition, the higher level of ractopamine supplementation evaluated in this research impaired the weight gain and feed conversion. However, 11.25 mg kg−1 ractopamine reduced the ether extract level determined in the fillet and the fat deposition between muscle fibers, improving the nutritional quality of meat.

O objetivo deste trabalho foi avaliar o efeito do eugenol como anestésico para juvenis de pacamã (Lophiosilurus alexandri). Os animais foram divididos em dois grupos, denominados juvenil I (0,72 g) e juvenil II (7,44 g), e submetidos a seis tratamentos de eugenol (20, 40, 60, 80, 100 e 120 mg L-1), em dez repetições. Durante o experimento, foram realizadas biometrias e cronometragens dos tempos de indução e recuperação. Com o aumento das doses, o tempo de anestesia foi reduzido de 69 para 27 s, em juvenis I, e de 93,8 para 37,3 s em juvenis II. A sobrevivência foi de 100%.

The objective of this work was to evaluate the effect of eugenol as an anesthetic in juvenile pacamã (Lophiosilurus alexandri). The animals were divided into two groups, named juvenile I (0.72 g) and juvenile II (7.44 g), and subjected to six treatments of eugenol (20, 40, 60, 80, 100, and 120 mg L-1) in ten replicates. During the experiment, biometrics and timing of induction and recovery times were measured. With the increasing doses, the anesthesia duration was shortened from 69 to 27 s in juvenile I and from 93.8 to 37.3 s in juvenile II. The survival rate was 100%.

O objetivo deste trabalho foi avaliar parâmetros metabólicos de pacus (Piaractus mesopotamicus) alimentados com dietas com diferentes óleos. O experimento foi conduzido em laboratório, em maio de 2009, durante 28 dias. Foram utilizados 64 pacus com peso inicial de 61 g, mantidos em tanques de 250 L. Os tratamentos foram: dieta controle mais óleo de oliva; dieta controle mais óleo de milho; dieta controle mais óleo de peixe; e dieta controle mais óleo de milho e de peixe. Utilizou-se o delineamento inteiramente casualizado, com quatro repetições, em arranjo fatorial 4x4 (quatro dietas e quatro tempos de coleta: 7, 14, 21 e 28 dias). Foram avaliados: níveis sanguíneos de colesterol e lipoproteínas, composição química muscular, e atividade de glicose-6-fosfato desidrogenase (G6PD) e enzima málica (EM). Os dados foram submetidos à análise de variância, à comparação das médias pelo teste de Tukey, e à análise de regressão. Não houve diferença nos teores musculares de umidade e cinzas, mas foram observadas alterações na deposição lipídica e proteica, conforme os tempos de coleta, em todos os tratamentos. As dietas interferiram nos parâmetros sanguíneos avaliados. A atividade de G6PD é superior à da EM, sendo maior nos animais alimentados com óleo de oliva e milho, o que sugere maior deposição lipídica muscular nestes peixes. Portanto, o metabolismo lipídico do pacu é influenciado pela composição do lipídio da dieta.

The objective of this work was to evaluate the metabolic parameters of pacu (Piaractus mesopotamicus) fed diets with different oils. The experiment was conducted in the laboratory, on May 2009, during 28 days. Sixty four fish with initial weight of 61 g, kept in 250 L tanks, were used. The treatments were: control diet plus olive oil; control diet plus corn oil; control diet plus fish oil; and control diet plus corn oil and fish oil. A completely randomized design was used, with four replicates and a 4x4 factorial arrangement (four diets and four sampling times: 7, 14, 21, and 28 days). The following were evaluated: cholesterol and lipoprotein blood levels, muscle chemical composition, and activity of glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME). The data were subjected to analysis of variance, comparisons of means using the Tukey test, and to regression analysis. There were no differences in muscle levels of moisture or ash, but changes were observed in lipid and protein deposition, depending on collection time, for all treatments. The diets interfered in the evaluated blood parameters. G6PD activity is higher than that of ME, being higher in animals fed with olive and corn oil, suggesting more lipid deposition in the muscles of these fish. Therefore, the lipid metabolism of pacu is influenced by the lipid composition of the diet.

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.

O experimento foi realizado no Centro Nacional de Pesquisa de Peixes Tropicais de Pirassununga, SP, objetivando-se determinar o efeito do processamento da ração sobre os coeficientes de digestibilidade aparente dos ingredientes para o piau (L. elongatus). Foram utilizados 600 machos de piau, distribuídos em seis tanques de 300 L. Os tratamentos aplicados foram: ração farelada, ração peletizada e ração extrusada, formuladas com 32% de PB e 3400 Kcal ED/Kg. O delineamento experimental foi em blocos casualizados, com três tratamentos, três blocos e duas repetições por tratamento. As análises estatísticas foram realizadas pelo SAEG, com as médias comparadas pelo teste SNK (5%). Houve diferenças entre os coeficientes de digestibilidade da proteína bruta e energia para as rações peletizada e extusada (P<0,05). A digestibilidade da matéria seca não diferiu mediante os processamentos avaliados (P>0,05).

The experiment carried out at National Center for Research in Tropical Fish Pirassununga, SP, aiming to determine the effect of the ration processing on the apparent digestibility coefficients of the ingredients for the piau (L. elongatus). A total of 600 males of piau were utilized, allotted into six ponds of 300L. The applied treatments were: grinder processed ration, pelleting ration and extruded ration, utilizing rations with 32% crude protein and 3400 Kcal DE.Kg-1. The experiment was in a randomized blocks design with three treatments, three blocks and two replicates. The data were submitted to variance analysis by the SAEG computational package and the means of the treatments compared by SNK test (5% of significance). The results showed that there were significant differences among the digestibility coefficients of both protein and energy for the pelleted and extrused rations (P<0.05). The results showed no statistical differences for the apparent digestibility coefficient of the dry matter (P>0.05).

Trinta e cinco machos de tilápia com peso médio de 205 g foram mantidos em caixas de 250 litros para avaliar o metabolismo lipídico de tilápias-do-nilo (Oreochromis niloticus). O experimento foi conduzido durante 30 dias, entre os meses de outubro e novembro de 2006. Foram avaliadas cinco dietas, cada uma contendo óleo de oliva, óleo de milho, óleo de soja, óleo de linhaça ou óleo de peixe. Utilizou-se delineamento inteiramente casualizado, com cinco tratamentos e sete repetições. Avaliaram-se a composição química, o perfil lipídico muscular e a atividade hepática de glicose-6-P desidrogenase (G6PD) e enzima málica. Os dados foram submetidos à análise de variância com médias comparadas pelo teste de Scott-Knott (5%). Não houve diferenças significativas para os teores de umidade e cinzas, porém, foram observadas alterações nos teores de lipídios e proteína nos peixes alimentados com as rações contendo óleo de oliva, milho ou soja. O fornecimento de dietas ricas em ácidos graxos poliinsaturados aumentou a composição desses ácidos graxos nos peixes. A atividade da G6PD foi superior à da enzima málica e foi mais alta nos animais alimentados com rações contendo óleos de oliva, milho ou soja, o que evidencia maior deposição lipídica muscular nesses peixes.

A total of 35 males of Nile tilapia, averaging initial weight of 205 g, were maintained in five 250 L metabolism boxes to evaluate the lipid metabolism of Nile tilapias (Oreochromis niloticus). The experiment lasted 30 days, from October to November 2006. The treatments were: control diet plus olive oil; control diet plus corn oil; control diet plus soybean oil; control diet plus linseed oil; control diet plus fish oil. The experiment was in a completely randomized design with five treatments and seven replicates. The evaluated parameters were: fatty acid profile of the muscle tissue and hepatic activity of glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME). The data were submitted to variance analysis and the means of the treatments were compared by Scott-Knott's test (5% of significance). The fish fed on a diet rich in polyunsaturated fatty acids presented increased contents of such fat acids in their lipid muscle composition. The hepatic activity of G6PD was superior to that of ME, being higher in the specimen fed rations containing olive, corn and soybean oil, thus, evidencing the highest lipid muscle deposition of these fish.

Com este experimento objetivou-se verificar os efeitos dos processamentos do milho sobre o desempenho e composição de carcaça de piaba (Leporinus friderici) criada em tanques-rede. Foi conduzido na Usina Hidrelétrica da Companhia Energética de Minas Gerais (CEMIG), município de Itutinga, com duração de 45 dias. Foram utilizados 24 tanques-rede de 1 M³, com 480 alevinos. O delineamento foi em blocos casualizados, com 4 tratamentos (rações formuladas com milho moído, extrusado, laminado e peletizado) e 3 repetições. Os dados foram submetidos à análise de variância e as médias dos tratamentos, comparadas pelo teste Scott & Knott. Os resultados não mostraram diferença significativa para os parâmetros de desempenho (peso final médio, consumo aparente de ração médio, conversão alimentar aparente, ganho de peso total médio, ganho de peso diário médio) (P>0,05), porém, o milho extrusado e o moído aumentaram o teor de proteína (P<0,05) e diminuíram o teor de gordura da carcaça (P<0,05). Conclui-se que o processamento do milho não melhora o desempenho dessa espécie, mas com os milhos moído e extrusado, há uma melhor utilização da proteína para fins estruturais.

The experiment with the objective of verify the effects of the processing (extrusion, rolling and pelleting of corn) on the performance and composition of the Piaba (Leporinus frederici) carcass, was conducted in the Usina Hidreletrica da Companhia Energética de Minas Gerais - CEMIG (Minas Gerais Hydroelectric Station), in the Itutinga- MG , with the lenght of 45 days. The experiment was undertaken in 24 cages of 1M³, 480 fingerlings were utilized, they were distributed into blocks. The four experimental rations were formulated based in corn meal, extruded corn, rolled corn and pelleted corn. The data obtained were submitted to the analysis of variance and the comparison of means of the treatments by the Scott & Knott test. The results showed any statistical difference in the performance parameters. However, the use of extruded corn and corn meal increased protein content (P<0.05) and decreased fat content (P<0.05) of the carcass traits, these results showed, improved protein utilization for structural purposes. In conclusion the corn processing did not improve the performance of the fish and that corn meal and extruded corn increased protein content and reduced fat content in the carcass.

Com este experimento objetivou-se avaliar o rendimento de carcaça de matrinxã (Brycon cephalus) nos diferentes cortes de cabeça, sendo o mesmo conduzido na Estação de Piscicultura da Universidade Federal de Lavras, no mês de maio de 2001. O delineamento foi inteiramente casualizado com 2 tratamentos (corte reto da cabeça e corte oblíquo da cabeça) e 20 repetições. Os peixes foram retirados dos tanques com peso médio de 840 gramas e abatidos por choque térmico em água com gelo. Foram analisados o rendimento de filé, rendimento de tronco limpo e a relação entre o comprimento do filé e o comprimento padrão. Concluiu-se que o corte oblíquo da cabeça proporcionou melhores rendimentos de tronco limpo (65,67%) em relação ao corte reto da cabeça (61,28%). Quanto à relação comprimento do filé e comprimento padrão, o corte oblíquo da cabeça também mostrou resultados superiores quando comparado ao corte reto da cabeça

The objective of this study was to determine the carcass yielding of Brycon cephalus in different cuts of its head. The experiment was conducted in the Fish Farmer at the Federal University of Lavras, in may 2001. The experiment was in a randomized design with two treatments (head rightly cut and head obliquely cut) and twenty replications. The fish were removed from the tank with an average weigh of 840 g and were killed by temperature shock with water and ice. It was concluded that the head obliquely cut rendered the best barrel clean yielding (66%) compared to the head rightly cut (61%). In the same way, the ratio fillet/standard length also showed better results for the oblique cut compared to the right cut