The objective of this study was to determine the crude protein requirements for juvenile jundiara fish, a hybrid of Pseudoplatystoma fasciatum X Leiarius marmoratus. A total of 240 juveniles of the hybrid, with an initial mean weight of 8.4 ± 1.41 g, were distributed in 15 fiberglass tanks (170 L) in a closed water recirculation and constant aeration system, with a density of 16 fish/tank. The experimental design was completely randomized with five treatments and three replications. The treatments consisted of diets with 32, 34, 36, 38 and 40% crude protein. Seventy days into the experiment the final fish weight and feed intake were measured. Two specimens from each experimental unit were collected for evaluation of carcass chemical composition, nutritional efficiency and blood parameters. The increase in crude protein content promoted the significant, increasing linear effect for mean weight gain, mean feed intake and specific growth rate, and decreasing effect for feed conversion. Significant differences were also observed in carcass chemical composition, nutritional efficiency, total plasma protein, glucose, cholesterol, triglycerides and lipase enzymatic activity. Thus, the increase in crude protein levels of up to 40% in jundiara diets promotes improvement in the productive performance of juvenile jundiara.
The objectives of this work were to determine the apparent digestibility coefficients (ADC) of dry matter (DM), crude protein (CP) and gross energy (GE) of coconut biscuit residues (CBR), sweet biscuits (SBR) and noodles (NR) for Nile tilapia and evaluate the performance of fingerlings fed with diets containing the residues with the highest nutritional value. In the digestibility study, 72 juveniles (with an average weight of 70.5 ± 2.7 g) were organized in a completely randomized design with three treatments and three replications (12 fish per replication). ADC was determined using an indirect method in which 0.10% chromium oxide (Cr 2 O 3 ) acted as an indicator. To evaluate performance, 225 fingerlings (with an average weight of 3.4 ± 0.5 g) were distributed across 15 tanks (150 L), creating a completely randomized design with five treatments and three replications. The test diets contained 0, 4, 8, 12 or 16% CBR. ADCDM, ADCCP and ADCGE for each of the different residues were, respectively: 85, 88 and 86% for CBR; 32, 51 and 46% for SBR; 24, 31 and 26% for NR. The inclusion of CBR significantly affected final weight of the fish, specific growth rate and protein retention rate, as well as the carcass composition values for dry matter, mineral matter, gross energy and ethereal extract. CBR presents better digestibility than the other tested residues and it can be used as a substitute for maize meal in quantities up to 11.62%, thus improving fish performance. Key words: Alternative food. Digestibility. Noodle residue. Oreochromis niloticus. Performance. ResumoObjetivou-se determinar os coeficientes de digestibilidade aparente da matéria seca (CDAMS), proteína bruta (CDAPB) e energia bruta (CDAEB) dos resíduos de biscoito de coco (RBC), biscoito doce (RBD) e macarrão (RM) para a tilápia-do-nilo e avaliar o desempenho destes alevinos alimentados com dietas contendo o resíduo com o maior valor nutritivo. No estudo de digestibilidade 72 juvenis (70,5±2,7g) foram distribuídos em um delineamento inteiramente casualizado com três tratamentos e três repetições (12 peixes por repetição). A determinação dos CDA foi realizada pelo método indireto, com a utilização de 0,10% de óxido crômico (Cr 2 O 3 ) como indicador. Para avaliação do desempenho 225 alevinos (3,4±0,5g) foram distribuídos em 15 tanques (150 L), compondo um delineamento inteiramente
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