Assessment of methionine plus cystine requirement of tambaqui (Colossoma macropomum) based on zootechnical performance, body composition, erythrogram, and plasmatic and hepatic metabolites.

Tambaqui (Colossoma macropomum) is a species of great cultural and economic importance in aquaculture in the Amazon region. Methionine is considered the first limiting sulfur amino acid in practical fish diets, which encourages investigating its use in diets for tambaqui. This study aimed to verify the digestible methionine plus cystine (Met + Cys) requirement in diets for tambaqui (89.52 ± 0.53 g) for 60 days. The treatments investigated were: 6.50, 7.80, 9.10, 10.40, 11.70, and 13.00 g Met + Cys kg diet-1. The estimated requirement based on final weight, weight gain, feed conversion ratio, and specific growth rate was 9.04, 8.92, 8.91, and 8.58 g Met + Cys kg diet-1, respectively, while on body protein deposition, body fat deposition, body ash deposition, and nitrogen retention efficiency was 9.29, 9.20, 9.19, and 8.72 g Met + Cys kg diet-1, respectively. Linear regression demonstrated that increased digestible Met + Cys in the diet decreased plasma total protein, globulin, and liver total protein levels. Quadratic regression showed that the highest value for liver glycogen was found with a 10.40 g Met + Cys kg diet-1. Another quadratic regression demonstrated a lower hepatic aspartate aminotransferase (AST) enzymatic activity in fish fed between 7.80 and 11.70 g Met + Cys kg diet-1. The different treatments did not influence the erythrogram. In conclusion, when considering an integrative view of the results for growth performance, whole-body deposition, and liver parameters without harming the physiological and metabolic status, we recommended choosing a diet with digestible Met + Cys between 8.58 and 9.29 g kg- 1 for tambaqui.

Efeito de complexo enzimático na dieta para juvenis de pirarucu, Arapaima gigas / Effect of enzymatic complex in the diet of pirarucu, Arapaima gigas juveniles

O pirarucu, Arapaima gigas é um peixe carnívoro nativo da bacia amazônica. Como peixes carnívoros possuem baixa atividade de amilase, enzimas exógenas melhoram a digestibilidade de carboidratos em rações para aquacultura. O objetivo deste estudo foi avaliar a digestibilidade de níveis crescentes de complexo enzimático em dietas para juvenis de pirarucu (65,2 ± 0,4 g). O desenho experimental foi randomizado com quatro tratamentos [dietas contendo 0,25, 0,50, 0,75 e 1 g kg-1 de complexo enzimático adicionado (Allzyme® SSF®, EUA)] e um controle, com três réplicas com densidade de cinco peixes por unidade e 30 dias de duração. A digestibilidade aparente da matéria seca, proteína bruta e energia bruta foi calculada por quantificação de nutrientes e óxido de cromo nas dietas e fezes. A atividade enzimática, o glicogênio hepático e a proteína total foram determinados a partir de amostras do fígado e intestino anterior. A dieta com 1 g kg-1 de complexo enzimático resultou em um aumento da digestibilidade aparente de proteina bruta, energia bruta, matéria seca, glicogênio hepático e proteínas totais no fígado e intestino, mostrando a eficácia do complexo enzimático na dieta dos pirarucus. A acumulação mais alta de matéria seca, energia bruta e extrato etéreo na carcaça indicou o aumento de peso dos peixes tratados com complexo enzimático. A redução da atividade enzimática endógena (protease, lipase e amilase) sugeriu um aumento da eficácia do processo digestivo. Nossos resultados indicam que a inclusão de 1 g kg-1 do complexo enzimático na dietas de juvenis de pirarucu pode ser recomendada para obter maior digestibilidade de nutientes e performance produtiva. (AU)

Corn substitution by mesquite bean flour (Prosopis juliflora) maintains growth and improves protein metabolism of Nile tilapia juveniles (Oreochromis niloticus).

The objective of this study was to evaluate the potential of mesquite bean flour (Prosopis juliflora) as an energy ingredient in extruded diets for juvenile Nile tilapia (Oreochromis niloticus). Two experiments were carried out: the first consisted of a study to evaluate the chemical composition and digestibility of the energy and nutrients of MBF; the second consisted of a growth test, in which juveniles consumed diets containing different proportions of corn substitution by MBF, in which zootechnical, hematological, physiological, and metabolic variables were evaluated. It was observed that MBF has a chemical composition similar to corn, as well as the apparent digestibility of energy and nutrients. The higher sucrose/starch ratio of the ingredient stands out, as well as the difference in digestibility (p < 0.05) between the predominant carbohydrates 87.63 and 99.25% for starch and sucrose, respectively. In the growth assay, no difference was observed between zootechnical variables (p > 0.05), and sucrase and alkaline phosphatase activities were increased (p < 0.05), which was not observed for amylase and lipase (p > 0.05). The hematological variables did not change (p > 0.05). Metabolic variables indicate a reduction in gluconeogenesis from amino acids, as can be seen by the reduction in liver transaminase levels (ALT and AST) and glutamate dehydrogenase (GDH), as well as the greater availability of free amino acids in plasmas (p < 0.05). Thus, it can be said that MBF has a high nutritional value and can totally replace corn in diets for juvenile tilapia and the metabolic findings indicate a potential protein-sparing effect.

Digestibility of spineless cactus meals in extruded diets for Nile tilapia (Oreochromis niloticus): energy, protein, amino acids, and carbohydrates.

The aim of the present study was to determine the apparent digestibility coefficients (ADCs) of gross energy, dry matter, crude protein, amino acids, and different carbohydrate fractions of spineless cactus meals (SCMs) for Nile tilapia juveniles, fed with extruded diets. Fish were fed a reference diet or one of five test diets, each of which included 70% reference diet and 30% corresponding SCM. Fecal collection was performed in modified Guelph method. The ADCs for dry matter, gross energy, and soluble carbohydrates of the "redonda" spineless cactus meal (RSCM) were higher (P < 0.05) than those of either the "IPA 20" spineless cactus meal (ISCM) or "gigante" spineless cactus meal (GSCM), and the ADCs for crude protein of the RSCM and "Orelha de elefante africana" spineless cactus meal (OEASCM) were higher than those of the other cactus meals (P < 0.05). In addition, the ADCs for dry matter, crude protein, and gross energy of the SCMs were similar to wheat middlings. The digestibility of the less soluble fraction of the evaluated carbohydrates, the non-fibrous carbohydrates, varied between 58.32 and 73.04%, indicating efficiency in the digestion and absorption process. The data obtained in this article can be the basis for growth experiments, with the substitution of traditional ingredients for SCMs. The determination of zootechnical, physiological, metabolic, and health variables can indicate the potential for using SCMs in diets for Nile tilapia.

Physical, chemical and sensory evaluation of meat from cobia (rachycentron canadum), desensitized with different voltages of electric shock, stored under refrigeration / Avaliação física, química e sensorial de carne de cobia (rachycentron canadum), desensitizada com diferentes voltagens de choque elétrico, armazenadas em refrigeração

ABSTRACT: Fish quality is conditioned by several factors, among them desensitization methods applied for fish managing and slaughtering. This research used electric shock at different intensities as a desensitization method for cobia (Rachycentron canadum) slaughtering and evaluated its effects over fish quality during refrigerated storage. The experiment was carried out by numbing the fish with electroshock at the intensities of 100, 150 and 200 Volts, and keeping them in refrigerated storage for 21 days. On the cobia, obtained from a commercial fish farm the following physical, chemical and sensorial characteristics as quality variables were evaluated: dielectric properties, rigor index, pH, texture, color, sensorial evaluation of freshness, ATP and degradation catabolites. The experimental design was a 6×3 factorial (6 times of analysis and 3 electroshock intensities). Significant differences (P<0.05) were observed for the analyzed variables, as a consequence of desensitization treatments and of storage time within each treatment. However, the number of variables affected by the treatment was smaller than the number of variables significantly affected by the storage time, and the interaction time×treatment was highly significant within the results reported. The best results for the parameters tested were obtained when the treatment at 150 volts intensity with the majority of analyzed variables held significant differences (P<0.05) among treatments. It was also concluded that cobia can be conserved in refrigerated storage within seven days after slaughtering using electro-narcosis as a method of desensitization.

RESUMO: A qualidade do pescado está condicionada a diversos fatores, entre eles os métodos de insensibilização. Nesta pesquisa foi utilizado o choque elétrico em diferentes intensidades como método de insensibilização do bijupirá (Rachycentron canadum), e avaliados seus efeitos sobre a qualidade dos peixes resfriados. O experimento foi realizado insensibilizando os peixes com eletrochoque de intensidades de 100, 150 e 200 Volts, e armazenados refrigerados durante 21 dias. Os peixes utilizados foram obtidos de uma piscicultura comercial localizada no litoral norte do estado de São Paulo a cerca de 50km, por via marítima, da cidade de Ubatuba-SP. As variáveis de qualidade dos peixes avaliadas foram características físicas, químicas e sensoriais como medidas dielétricas, índice de Rigor Mortir, pH, textura, cor, avaliação sensorial do frescor, ATP e produtos da degradação. O delineamento experimental utilizado foi um fatorial 6X3, seis tempos de análise e três intensidades de choque elétrico. Foram observadas diferenças significativas (P<0,05) para a maioria das variáveis analisadas, tanto para os tratamentos em relação ao tempo, como também para a influência do tempo de armazenamento dentro de cada tratamento. No entanto, o número de variáveis com significância entre os tratamentos foi menor em relação ao número de variáveis em que houve significância para os tempos de conservação, sendo a interação tempoxtratamento a que obteve significância expressiva dentro dos resultados encontrados. Foram observados os melhores resultados para o tratamento com a intensidade em 150 volts para a maioria das variáveis analisadas em que houve diferenças significativas (p<0,05) entre os tratamentos. Concluiu-se também que o bijupirá pode ser conservado em até sete dias após abate em conservação refrigerada utilizando a eletronarcose como método de insensibilização.

Digestive enzymes and metabolic profile of Pseudoplatystoma corruscans (Teleostei: Siluriformes) in response to diet composition.

Digestive enzyme responsiveness to feeding and associated adjustments of metabolism can be used to derive nutritionally effective diet formulations. Juvenile pintado (Pseudoplatystoma corruscans) were fed different diets. After feeding, fish were killed and blood, liver and white muscle were collected to evaluate metabolites. Stomach along with anterior, middle and posterior intestine were sampled for enzyme analysis. Non-specific protease, trypsin, chymotrypsin, amylase and lipase were assayed. Crude protein (CP) did not induce proteolytic activity; highest protease activities were observed in the stomach. Amylase was higher in the stomach in fish feeding on diets containing 13-25% starch. Lipase activity was observed along the gastrointestinal tract, with the highest activities observed in the middle section. The metabolic profile of white muscle was not affected by CP. In contrast, some plasma and liver metabolites were altered concomitant with changes in the digestive enzymes. Amino acid catabolism was increased. Digestion in pintado was responsive to cornstarch, reflected in intermediary metabolism; proteolytic activities of the digestive tract seem to be sufficient to deal with large amounts of dietary protein. As a result, we are able to recommend a balance between protein and energetic compounds, such as lipids and carbohydrates, in the diet to optimize fish growth.

Características hematológicas de teleósteos brasileiros: IV. Variáveis do jundiá Rhamdia quelen ( Pimelodidae) / Haematological characteristics of brazilian teleosts: IV. Parameters of jundiá Rhamdia quelen (Pimelodidae)

As características hematológicas do jundiá Rhamdia quelen Quoy & Gaimard, 1824 (Osteichthyes: Pimelodidae), oriundo de cativeiro foram estudadas. Determinou-se o valor médio da contagem de eritrócitos, taxa de hemoglobina, hematócrito, volume corpuscular médio (VCM), concentraçäo de hemoglobina corpuscular média (CHCM) e distribuiçäo percentual de células sangüíneas de defesa orgânica. As células sangüíneas de defesa orgânica (leucócitos e trombócitos) foram identificadas e caracterizadas morfologicamente. Trombócitos e linfócitos foram as células sangüíneas de defesa orgânica mais freqüente nas extensöes sangüíneas do R. quelen. A análise de regressäo mostrou correlaçäo linear negativa entre o percentual de trombócitos e linfócitos. Os resultados deste estudo fornecem valores sangüíneos normais em R. quelen, em cultivo intensivo, que poderäo servir de comparaçäo com dados dessa espécie em outras situaçöes de cultivo