Suchergebnisse

Supplying the nutritional needs of animals in an economical way is essential to the success of any type of production. The forage palm is a cactaceae well-adapted to semiarid regions and commonly used in the feeding of ruminants. However, studies assessing its use in fishes are scarce. We aimed to evaluate the digestibility of bran from five different forage palm cultivars (Opuntia fícus) in juvenile Nile tilapia and the development of juveniles when receiving increasing levels of the cultivar with the best apparent digestibility coefficient of crude protein (ADCCP) (75.2%). We used 90 masculinized juvenile Nile tilapia (with an average weight of 6.02 ± 0.65 g) in the digestibility experiment to determine the apparent digestibility coefficients of dry matter (ADCDM), crude energy (ADCCP), and crude protein of the cultivars (Orelha de onça, Miúda, Gigante, Comum, and IPA 20). The experimental design was completely randomized (CRD) with five treatments and three repetitions. In the development experiment, 300 masculinized juvenile Nile tilapia (with average weight of 1.39 ± 0.12 g) received feed with different inclusion levels (0, 72, 144, and 216 g Kg-1) of IPA 20 palm bran in a CRD with four treatments and five repetitions. We observed significant differences (P < 0.05) for ADCDM and ADCCP between the treatments. The cultivars that presented the highest ADCDM were IPA 20 (41.75%), Orelha de onça (36.41%), and Gigante (32.59%). For ADCCP, the best cultivar was IPA 20 with 75.2%, followed by Orelha de onça (61.5%), and Miúda (56.1%). As for the performance, the inclusion of IPA 20 palm bran at a rate of 113 g/kg-1 provided the best values in terms of weight gain and final weight in juvenile Nile tilapia.

<p>The productive performance and the variable cost of production were evaluated for different feeding strategies for tilapia during the production cycle. A sample of 2,000 juvenile tilapia was distributed (23.55 ± 2.38 g) into five treatments and with four repetitions as follows: C (feed consumption to apparent satiety), R20 (beginning feed restriction when fish reached an average weight of 20 g), R200 (beginning feed restriction when fish reached an average weight of 200 g), R400 (beginning feed restriction when fish reached an average weight of 400 g) and R600 (beginning feed restriction when fish reached an average weight of 600 g). The fish were given extruded commercial feed containing 34% crude protein until they reached a weight of 200 g, at which time they received feed containing 32% crude protein. Monthly biometrics were performed in order to determine the food restriction starting point, which was one day of restriction followed by six feeding days. The following parameters were evaluated: water quality, productive performance variables, the variable costs of production and excreted nitrogen. The results were subjected to analysis of variance, and the means were compared using Tukey's test (5% significance). No statistical differences were observed in final weight, weight gain, feed consumption, feed conversion or survival. The fish from the R20 treatment had the lowest variable cost of production (g fish-1) and the lowest nitrogen excretion into the water. This suggests that feed restriction from the early stages of life does not compromise the productive performance and contributes to reducing the variable costs and the quantity of nitrogen excreted into the environment. Thus, a one-day per week feed restriction strategy can be applied from the earliest stages of life without compromising the productive performance or body composition of Nile tilapia. This strategy can also reduce variable costs of production by means of reducing relative labour and feed costs. </p>

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 (Cr2O3) 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.

Knowledge on the nutritional value of feed ingredient is an important step in the formulation of diets in order to maximize animal productivity. Thus a study was conducted to determine the apparent digestibility coefficients (ADC) of dry matter (ADCDM), crude protein (ADCCP), gross energy (ADCGE) and amino acids (ADCAA) of conventional feed ingredients for juvenile silver mojarra (13.0 ± 3.23 g). The study was conducted in the laboratory for nutrition and feeding of fish (AQUANUT), using 80 silver mojarra collected in nature, which were kept in digestibility aquaria for a period of 21 days. The following ingredients were evaluated: fish meal, soybean meal, corn meal, corn gluten meal, rice bran, wheat bran and starch, which substituted 30% of a reference pelletized diet with 325.00 g kg-1 crude protein and 3,692 Kcal kg-1 gross energy. Additionally 1.0 g kg-1 chrome oxide was added to each diet as a marker. The excreta were obtained using three repetitions for each tested ingredient, which were dried for further analyses. The soybean meal showed the best ADCDM value (67.45%), followed by the other ingredients. There was no significant difference between the soybean meal (95.16%), fish meal (92.97%) and the corn meal (91.90%) for the best ADCCP coefficients. The ADCGE for soybean meal and maize meal were 65.23% and 60.31%, respectively, followed by fish meal (51.85%). The results demonstrate that silver mojarra can digest animal protein as well as that of vegetal origin. Silver mojarra can also efficiently digest and absorb some of the main amino acids of fish, such as lysine, methionine and threonine, from the same studied ingredients.