This study was performed to determine the dietary methionine requirements and its effects on growth performance, plasma and hepatic metabolites for juvenile silver catfish. The fish (initial weight = 3.26 AE 0.3 g) were distributed in 24 experimental units (35 fish each). Six diets were formulated with increasing levels of methionine (09, 16, 23, 30, 37 and 44 g/kg protein diet). Each diet was distributed randomly to the groups, with four replicates fed twice daily to apparent satiation for 15 weeks.Methionine levels influenced in body composition (moisture and ash), and submit effect on liver metabolism and plasma. The relative weight gain (RWG) and specific growth rate (SGR) increased with highest levels of methionine to 30 g/kg protein in the diet, thereafter maintaining a nearly constant level of 1.9 g/kg cystine in the protein diet. The protein retention coefficient (PRC) also increased with increasing levels of up to 23 g/kg protein diet, thereafter maintaining a constant level of 1.9 g/kg cystine protein diet until beginning to decrease at a level of 44 g/kg protein diet. In conclusion, methionine is an essential amino acid for the growth of juvenile silver catfish and exhibits an efficient capacity when provided as a synthetic amino acid. Based on the RWG and SGR data, the methionine requirement of juvenile silver catfish was estimated at 34.42 and 35.85 g/kg of the CP or 12.74 g/kg and 13.26 g/kg of the diet respectively. K E Y W O R D S amino acid, protein retention coefficient, relative weight gain, sulphur

RESUMO O objetivo deste estudo foi analisar a influência da adição de farinha de resíduos de jundiá (Rhamdia quelen) na dieta de exemplares desta espécie sobre a bioquímica plasmática, parâmetros hepáticos e digestivos. No experimento I (EXP I), compararam-se dietas com 30% de farinha de carne e ossos suína (FCO), farinha de carcaça de jundiás com vísceras (FCJCV), farinha de carcaça de jundiá sem vísceras (FCJSV) e farinha de jundiás inteiros (FJI). No experimento II (EXP II), níveis de inclusão de FCJCV foram testados (0; 3,75; 7,5; 15 e 30%) ABSTRACT The objective of this study was to analyze the influence of the addition of jundiá (Rhamdia quelen) waste meal in the diet of this species, on plasmatic biochemistry, liver and digestive parameters. Experiment I (EXP I) compared diets with 30% of meat and swine bones (FCO), Jundiá carcass meal with viscera (FCJCV), Jundiá carcass meal without viscera (FCJSV) and full Jundiá meal (FJI). In experiment II (EXP II), different FCJCV levels were tested (0, 3.75, 7.5, 15, and 30%

O estudo foi desenvolvido no Laboratório de Piscicultura do Departamento de Zootecnia da Universidade Federal de Santa Maria, com duração de oito semanas, de abril a junho de 2011. O objetivo foi definir o melhor nível de incorporação do resíduo de peixes na alimentação de juvenis de jundiá, em sistema de recirculação d'água, utilizando-se 450 alevinos de jundiás, com peso médio inicial de 7,2±0,27g. Foram testadas cinco diferentes dietas, em três repetições, com níveis diferentes (0; 3,75; 7,5; 15; e 30%) de incorporação de farinha de carcaça de jundiás com vísceras (FCJCV). As dietas continham, aproximadamente, 37% de PB e 3200kcal de EM/kg de dieta. Foram coletados dados de ganho em peso diário, sobrevivência, fator de condição, taxa de crescimento específico, conversão alimentar aparente, rendimento de carcaça, taxa de eficiência proteica e deposição de proteína e lipídio corporal. O maior ganho de peso foi para o nível 30% de inclusão de FCJCV, com peso final de 45,47g e ganho em peso diário de 0,68g/dia. A dieta com nível de 30% de inclusão de FCJCV apresentou melhores valores para taxa de crescimento específico (3,34%/dia), conversão alimentar aparente (1,05: 1), biomassa final 1.105,45g, deposição proteica corporal (64,9mg/dia), taxa de eficiência proteica (1,9) e coeficiente de retenção proteica (1,96%). Concluiu-se que a utilização de farinha de resíduos de processamento de jundiá no nível de 30% de inclusão na dieta foi a que apresentou maior eficiência no desenvolvimento de juvenis de jundiá.

Dietary fatty acids may influence the development of the digestive tract and initial activation of digestive enzymes in fish. The objective of this study was to evaluate the effect of the diet lipid profile on ontogeny and activity of digestive enzymes in silver catfish post larvae fed practical diets. Five diets were tested, replacing broiler liver by soybean protein concentrate (SPC) or fish meal (FM): Standard, 15SPC, 30SPC, 15FM and 30FM. The enzymatic activity of fish was analyzed from 32 Hours after fertilization (Haf). Were analysed acid protease, trypsin, chymotrypsin, lipase, amylase and maltase. The development of the digestive system was analyzed from first feeding up to 28 days by histological techniques. The enzymatic activity presented peaks for the post-larvae fed with the 15SPC diet and fish fed with diet 15FM showed best growth. The development of the digestive system did not suffer damage from the diets offered. Post-larvae fed the 30SPC diet showed reduced development of the digestive tract. The diet 15FM provide good lipid profile for silver catfish post larvae.

No abstract