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The objective of this study was to evaluate the effect of diets containing different inclusion levels (0%, 7%, 14%, 21% and 28%) of soybean meal fermented by Lactobacillus acidophilus (SMFL) on the zootechnical performance and intestinal health of South American catfish juveniles (Rhamdia quelen). The experimental design was completely randomized with five treatments and four replications and lasted 56 days. Five isoproteic (39% crude protein) and isoenergetic (4300 kcal of gross energy kg−1) diets were formulated where SMFL was included in replacement of fish meal. Two hundred forty South American catfish juveniles (3.0 ± 0.5 g) were distributed in 20 tanks (70 L) connected in a recirculation aquaculture system. At the end of the experiment, the inclusion of SMFL up to 21% in replacement of fish meal did not affect the zootechnical performance and also decreased the concentration of Vibrionaceae bacteria present in the intestine compared to the control group. The amount of total lactic and heterotrophic bacteria, the enzymatic activity and the intestinal morphometry did not differ between dietary treatments. The results demonstrate that fermentation with Lactobacillus acidophilus enables greater inclusion of soybean protein in South American catfish diets and promotes the control of intestinal pathogenic bacteria.

The objective of this study was to evaluate the effect of the inclusion of the soluble fraction of sardine protein hydrolysate on the stability of diets and the excretion of ammonia in South American catfish. Seven experimental diets were prepared with soluble fractions of sardine muscle and viscera hydrolysates. The stability of the pellets in the water was determined at different time intervals (5 min, 10 min, 20 min, 30 min, 1 h and 1.5 h). Total ammonia was determined every five hours. Significant difference was detected for diet stability only at 5 minutes, where the feed containing 20% muscle soluble hydrolysate demonstrated a higher leaching rate when compared to the control diet. Starting at 10 hours of observation, the ammonia concentration was higher in the control when compared to the other treatments. The sardine waste protein hydrolysate demonstrated to be a promising alternative protein source for South American catfish. The inclusion of up to 10% of the soluble fraction of the sardine muscle and viscera hydrolysates had no effect on the stability of diets; however, the ammonia excretion was reduced exhibiting eco-friendly diets with lower environmental impact.Key words: water quality, jundiá, leaching, ammonia, Rhamdia quelen, Sardinella brasiliensis FRAÇÃO SOLÚVEL DE HIDROLISADO PROTEICO DE SARDINHA NA ALIMENTAÇÃO DO JUNDIÁ RESUMOO objetivo deste trabalho foi avaliar o efeito da inclusão da fração solúvel do hidrolisado proteico de sardinha sobre a estabilidade das dietas e a excreção de amônia de juvenis de jundiá. Foram elaboradas sete dietas experimentais com as frações solúveis dos hidrolisados de músculo e vísceras de sardinha. A determinação da estabilidade do pellet na água foi medida em intervalos de tempo diferentes (5 min, 10 min, 20 min, 30 min, 1 h e 1,5 h). A determinação de amônia total foi realizada a cada cinco horas. Como resultado do teste de estabilidade foi detectado diferença significativa somente no período de 5 minutos, onde a dieta contendo 20% de hidrolisado solúvel de musculo teve maior taxa de lixiviação em comparação com a dieta controle. A partir de 10 horas de observação, a concentração de amônia foi maior no controle em relação aos outros tratamentos. O hidrolisado proteico de resíduo de sardinha tem grande potencial para ser utilizado nas rações do jundiá. A inclusão de até 10% da fração solúvel de hidrolisados de músculo e de vísceras de sardinha não afeta a estabilidade das dietas, porém reduz a excreção de amônia, minimizando o impacto ambiental.

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This study evaluated the effects of different dietary inclusion levels of fermented soybean meal (FSM) as replacement for fish meal and their effects on the productive performance and intestinal condition of goldfish (Carassius auratus) produced in biofloc (BFT) system. Five isoproteic (39.5% crude protein) and isoenergetic diets (4250 kcal kg −1 of crude energy) were formulated with FSM inclusion levels of 0%, 7%, 14%, 21% and 28% (0, 11, 22, 32 and 43 fish meal replacement). A total of 400 goldfish (0.25 ± 0.02 g) were weighed and distributed in 20 glass aquariums (15 L). Fish were fed twice daily for 56 days. The diet with FSM inclusion level of 28% reduced the weight gain and the specific growth rate and increased the feed conversion of the goldfish. Diets with FSM inclusion levels of 21% and 28% increased the α-amylase activity in the fish intestine. The diet with FSM inclusion level of 21% increased total height of the intestinal villi of the goldfish. In conclusion, the inclusion of up to 21% of FSM can replace fishmeal without affecting the growth of goldfish juveniles reared in BFT system. Fish fed 21% of FSM showed evidence of improvement in the intestinal health.