ABSTRACT. The aim of this study was to investigate the effect of dietary supplementation with Cymbopogon flexuosus essential oil (EO) on productive performance, metabolic parameters and body and fillet composition of adult silver catfish, Rhamdia quelen. Total length, condition factor, weight gain, specific growth rate, hepatosomatic index, visceral fat content and fillet composition were not affected by EO supplementation. Plasma total protein, globulin and triglycerides were reduced by EO supplementation. Supplementation with 1 mL EO kg -1 diet increased carcass yield and protein deposition in the carcass, while reducing gonadosomatic index and fat deposition in the carcass when compared to control group. In addition, 1 mL EO kg -1 diet also improved feed intake when compared to 3 mL EO kg -1 diet. Our results suggest that EO up to 1 mL kg -1 diet can be used in fish feed to improve protein deposition and carcass yield of silver catfish.Keywords: Cymbopogon flexuosus, citral, growth performance, gonads, body composition.A suplementação com óleo essencial de capim-limão microencapsulado melhora a deposição de proteína e o rendimento de carcaça de jundiás (Rhamdia quelen) RESUMO. O objetivo deste estudo foi investigar o efeito da suplementação na dieta com óleo essencial de Cymbopogon flexuosus (EO) sobre o desempenho produtivo, os parâmetros metabólicos e a composição corporal e de filés de jundiás (Rhamdia quelen) adultos. O comprimento total, o fator de condição, o ganho de peso, a taxa de crescimento específico, o índice hepatossomático, o teor de gordura visceral e a composição dos filés não foram afetados pela suplementação com EO. Os níveis plasmáticos de proteína total, globulina e triglicérides foram reduzidos pela suplementação com EO. A suplementação com 1 mL de EO kg -1 de dieta aumentou o rendimento de carcaça e a deposição de proteína na carcaça, mas reduziu o índice gonadossomático e a deposição de gordura em comparação ao grupo controle. Além disso, 1 mL de EO kg -1 de dieta também melhorou o consumo de ração em comparação com 3 mL de EO kg -1 de dieta. Os resultados sugerem que se pode utilizar até 1 mL de EO kg -1 de dieta na alimentação de peixes para melhorar a deposição de proteína e a produtividade de carcaça de jundiás em fase de engorda. Palavras-chave:Cymbopogon flexuosus, citral, desempenho produtivo, gônadas, composição corporal.

RESUMO O objetivo do presente trabalho foi avaliar a inclusão do concentrado proteico da destilação de etanol obtido de arroz (CPA) na alimentação do jundiá. Trezentos e setenta e cinco peixes foram distribuídos em sistema de recirculação de água com 15 caixas (125L). Foram testadas três dietas (37% PB e 3200kcal/kg de energia digestível), sendo uma controle e duas testando a substituição da proteína da farinha de peixe em 25% (CPA-25%) ou 50% (CPA-50%) pelo CPA. Aos 30 dias, foram avaliadas as variáveis de desempenho, composição corporal e índices somáticos. Os animais submetidos ao tratamento CPA-25% apresentaram resposta de crescimento equivalente aos que receberam o tratamento controle, mas superior aos peixes submetidos ao CPA-50%. Não foram observadas diferenças significativas entre os tratamentos para os índices somáticos avaliados. Os animais submetidos às dietas contendo CPA apresentaram maior teor de gordura corporal. Já a deposição de gordura corporal foi superior para os peixes alimentados com CPA-25%, e a deposição de proteína corporal menor para os alimentados com CPA-50%. Os resultados indicam que o CPA pode substituir em até 25% a proteína da farinha de peixe, sem comprometer o crescimento dos jundiás, tendo esse nível de substituição proporcionado, inclusive, uma redução de 8% no custo da dieta.

The aim of this study was to investigate the prebiotic potential of pectin hydrolysates that were extracted from agroindustrial waste (apple pomace—AP and passion fruit peel—PFP) and were added to the diet of silver catfish (Rhamdia quelen). A 49‐day biological assay was conducted, and five test diets were evaluated: one diet was a control diet and the other four diets included pectin hydrolysates (2.5 and 5 g/kg). At 49 experimental days, biometric data and biological material were collected to determine the performance, plasma and liver and histological parameters and to evaluate the intestinal contents. The results were analysed by the normality test, which was followed by an analysis of the variance; the treatment means were compared by an orthogonal contrast analysis at a 5% level of significance. The inclusion of 2.5 g/kg apple pomace hydrolysates resulted in a greater production of butyric acid, increased thickness of the muscular layer and higher goblet cell count in the intestine. The inclusion of 5 g/kg apple pomace hydrolysates led to a greater concentration of liver protein. Further studies are needed to increase the knowledge about the use of these additives in the diet of silver catfish and to establish levels that allow greater gains for the species.

The creation of aquatic organisms it is constantly growing and with this comes the need to meet this demand with the increased production of inputs such as feed for aquaculture. Fish nutrition is mainly characterized by the use of fish meal and oil for the manufacture of rations for their food. Soybean bran is the second most used ingredient as a source of protein in the production of feed for aquaculture. However, these ingredients compete with other feed segments, increasing cost or reducing market availability. Therefore, alternative sources of protein must be studied and developed to meet this demand. In this sense, insects present themselves as sources of high quality protein, in addition to fatty acids, vitamins and minerals. Although there is a problem with large-scale production to meet the demand of the feed market, the ease of breeding certain species of insects is capable of making this reality possible. Thus, insects can be a likely alternative protein source in fish feed, replacing conventional sources. This review aims to evaluate the inclusion of mealworm in the fish diet, in terms of performance and discuss the results obtained.

A 60‐day feeding trial was conducted to evaluate the efficiency of the substitution of fishmeal (FM) with linseed protein concentrate (LPC) in the diet of silver catfish, Rhamdia quelen (6.13 g). Five isonitrogenous and isoenergetic experimental diets were formulated to replace 0, 10, 20, 30, or 40% of FM with LPC, and silver catfish were fed these diets to apparent satiation. LPC had a lower protein content compared to FM, but in vitro results showed higher protein digestibility of LPC as compared to fishmeal. There were no significant differences (p > .05) in growth, digestive somatic index, and intestinal quotient in the groups receiving LPC diets. The activity of the digestive enzymes did not differ among treatments, except for chymotrypsin, which was higher (p < .05) in the 30 and 40% LPC treatment groups. These results show that LPC protein can replace up to 40% of FM in silver catfish diets without adverse effects on growth performance.