This study aimed to evaluate increasing levels (0, 4, 8 and 12%) of acid silage viscera of surubim catfish as an alternative protein source on growth performance and apparent digestibility coefficients (ADC) for Nile tilapia. Weight gain (WG), feed intake (FI), feed conversion ratio (FCR), and protein efficiency ratio (PER) were evaluated. The digestibility for dry matter (DM), crude protein (CP), ether extract (EE), gross energy (GE) and availability of phosphorus (P) were also assessed. The experimental design was completely randomized with four treatments and four repetitions. The results indicated no difference (p > 0.05) for growth performance parameters. The ADC of CP of treatment containing 8% of silage was lower (p < 0.05) when compared to the others. On the other hand, for the GE, the same level provided a higher ADC (p < 0.05). In conclusion, acid silage viscera of surubim catfish can be included in diets for Nile tilapia up to 12%, with no negative effects on growth performance and digestibility as well as to reduce feed cost.

Resumo -O objetivo deste trabalho foi avaliar o efeito da secagem da parte aérea da mandioca, ao sol e à sombra, sobre a composição bromatológica e o coeficiente de digestibilidade aparente (CDA) de nutrientes, energia e aminoácidos para tilápia-do-nilo (Oreochromis niloticus). Não houve diferença entre os métodos de secagem para a composição bromatológica. O CDA da proteína bruta apresentou maior digestibilidade para a parte aérea seca à sombra. A secagem da parte aérea da mandioca à sombra permite maior conservação do conteúdo proteico e melhor digestibilidade aparente da fração proteica e aminoacídica para a tilápia-do-nilo.Termos para indexação: Manihot esculenta, Oreochromis niloticus, alimento alternativo, aminoácidos, secagem. Chemical composition and apparent digestibility of dried aerial part of cassava in Nile tilapia feedingAbstract -The objective of this work was to evaluate the effect of sun and shade drying of the aerial part of cassava on the chemical composition and apparent digestibility coefficient (ADC) of nutrients, energy, and aminoacids for Nile tilapia (Oreochromis niloticus). There was no difference between the drying methods for chemical composition. The ADC of crude protein showed higher digestibility for the shade dried aerial part. Shade drying of the aerial part of cassava allows higher conservation of the protein content and better apparent digestibility of the protein and amino acid fraction for Nile tilapia.

This study evaluated the apparent digestibility coefficient (ADC) of crambe meal (CM) and its potential to partially replace soybean meal (SM) protein in Nile tilapia diets. The ADC for dry matter, crude protein, ether extract, energy, amino acids, calcium and phosphorus of CM were assessed in fish (n=80; 65.30 ± 5.32 g). Subsequently, an 80-day feeding trial was conducted with Nile tilapia (n=140; 6.04 ± 0.25 g) randomly distributed in 20 experimental cages (70 L; seven fish cage-1) allocated in five circular tanks (1000 L) in recirculation water system, to evaluate the effects of replacement of SM by CM (0, 6, 12, 18 and 24% in isonitrogenous and isoenergetic diets) on growth, blood parameters, fillet yield and proximal composition. The CM shows good digestibility of protein (0.824) and amino acids (0.844) by Nile tilapia and its inclusion in the diet does not affect carcass and fillet yield or proximal composition. Fish fed diets with 24.0% of the SM replaced by CM showed the worst weight gain and feed conversion rate. The protein efficiency ratio decreased in fish fed diets with 12.0, 18.0 and 24.0% of the SM replaced by CM. Hemoglobin, mean corpuscular hemoglobin concentration, total plasma protein, glucose and alanine aminotransferase enzyme activity trend to increase at highest levels of CM in the diet. In conclusion, CM has potential to replace SM in Nile tilapia diets, due to high digestibility of protein and amino acids. However, anti-nutritional factors present in untreated CM interfere on the growth and nutrient utilization of Nile tilapia.

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