Diets For Juvenile Tilapia Research Articles

Effects of the extrusion process on the physical properties of micro pellets and the growth performance of juvenile Nile tilapia

The present study aimed to evaluate the effect of different extrusion processes on the physical properties of micro pellets and how the alterations affect the growth performance of juvenile Nile tilapia. Four experimental diets were produced with the same formulation, but with different extrusion processes: CE: cold extrusion (18 ºC); HE: hot extrusion (100 ºC); D1: double extrusion, first a hot extrusion (100 ºC) of all the ingredients followed by cold extrusion (18 ºC); D2: double extrusion, first a hot extrusion (100 ºC) of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion (18 ºC). Juvenile tilapia (0.83 ± 0.01 g; 3.68 ± 0.19 cm) were distributed in 20 experimental units (60 L; n=5; 20 fish per unit) in a completely randomized design for four weeks. The micro pellets of the experimental HE diet presented a positive expansion rate (2.86 ± 0.45 %) and a lower bulk density (465.9 ± 3.45 g/L). The D1 and D2 micro pellets presented higher bulk density (671.0 ± 2.98 and 612.8 ± 4.99 g/L, respectively). All the micro pellets showed high durability (>95 %). The D2 micro pellets showed low water resistance (24.4 ± 3.51 %), resulting in a high leaching rate of nutrients (>68 %). The HE and D1 micro pellets showed a higher absorption rate in water (3.65 ± 0.29 and 3.66 ± 0.21 g water/g, respectively). The water solubility index of the micro pellets was not influenced by the different extrusion processes (P > 0.05), nor were survival and feed consumption. The fish fed with the HE diet showed greater weight gain (3.84 ± 0.44 g), and the lowest weight gain was in the fish fed with the CE diet (3.05 ± 0.39 g) (P < 0.05). Feed conversion was lower in fish fed the HE (1.06) and D1 (1.11) diets (P < 0.05). Fish fed the HE diet had the highest values for relative growth rate (9.08 ± 0.62 %/d), protein retention (30.6 ± 2.61 %) and protein efficiency (2.26 ± 0.22 %) (P < 0.05). Fish fed the CE diet had the lowest values for relative growth rate (7.82 ± 0.51 %/d), protein retention (21.4 ± 2.72 %) and protein efficiency (1.55 ± 0.23 %) (P < 0.05), though the values are in line with those in the literature. In conclusion, hot extrusion resulted in micro pellets with better physical properties and fish with higher growth performance. Double extrusion, first a hot extrusion of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion is not recommended due to high levels of nutrient leaching. Cold extrusion and double extrusion, first a hot extrusion of all the ingredients followed by cold extrusion processing can be considered for producing micro diets for juvenile tilapia, especially when less investment in the extrusion process is desired.

Corn substitution by mesquite bean flour (Prosopis juliflora) maintains growth and improves protein metabolism of Nile tilapia juveniles (Oreochromis niloticus).

The objective of this study was to evaluate the potential of mesquite bean flour (Prosopis juliflora) as an energy ingredient in extruded diets for juvenile Nile tilapia (Oreochromis niloticus). Two experiments were carried out: the first consisted of a study to evaluate the chemical composition and digestibility of the energy and nutrients of MBF; the second consisted of a growth test, in which juveniles consumed diets containing different proportions of corn substitution by MBF, in which zootechnical, hematological, physiological, and metabolic variables were evaluated. It was observed that MBF has a chemical composition similar to corn, as well as the apparent digestibility of energy and nutrients. The higher sucrose/starch ratio of the ingredient stands out, as well as the difference in digestibility (p < 0.05) between the predominant carbohydrates 87.63 and 99.25% for starch and sucrose, respectively. In the growth assay, no difference was observed between zootechnical variables (p > 0.05), and sucrase and alkaline phosphatase activities were increased (p < 0.05), which was not observed for amylase and lipase (p > 0.05). The hematological variables did not change (p > 0.05). Metabolic variables indicate a reduction in gluconeogenesis from amino acids, as can be seen by the reduction in liver transaminase levels (ALT and AST) and glutamate dehydrogenase (GDH), as well as the greater availability of free amino acids in plasmas (p < 0.05). Thus, it can be said that MBF has a high nutritional value and can totally replace corn in diets for juvenile tilapia and the metabolic findings indicate a potential protein-sparing effect.

Replacement of fish oil with camelina (Camelina sativa) oil in diets for juvenile tilapia (var. GIFT Oreochromis niloticus) and its effect on growth, feed utilization and muscle lipid composition

Camelina oil (CO) is a potential replacement for fish oil (FO) in aquaculture feeds. CO is high in α-linolenic acid (18:3n-3 or ALA) (35%), with an omega-3/omega-6 (n-3/n-6) ratio near 2. In order to test the effect of CO on the overall performance of tilapia (Oreochromis niloticus var. GIFT), feed utilization, lipid composition and capacity to synthesize the long-chain fatty acids eicosapentaenoic acid (20:5n-3 or EPA) and docosahexaenoic acid (22:6n-3 or DHA) from ALA, were tested in an 8-week feeding trial with juvenile tilapia. The average fish weight at the start was 28 ± 6 g and they were grown in a biofloc system. Four dietary treatments were formulated, two containing either fish oil (TFO) or camelina oil (TCO), and two more where FO was replaced by CO at low (Low-CO) and mid (Mid-CO) levels. A commercial diet (COM) was used as a reference diet. Compound-specific stable isotope analysis (CSIA) and stable isotope mixing models with R software (SIAR) were used to calculate the contribution of ALA to EPA and DHA synthesis. At the end of the experiment, replacing FO by CO had no effect on growth (139 ± 22 g fish−1) or total lipid in the muscle (2.2–2.9 g). However, the tilapia fed TCO had significantly more phospholipid in muscle compared to tilapia fed TFO. Also, a higher content of linoleic acid (18:2n-6 or LOA) and ALA was revealed. ALA content in muscle followed the ALA content in diets; by contrast, EPA and DHA decreased significantly as the level of dietary CO increased. Despite the variation in fatty acids, n-3 PUFA and the n-3/n-6 ratio in muscle tissue did not show differences among experimental diets. CSIA revealed that the δ13C isotopic signature of DHA in tilapia muscle after feeding TCO and biofloc was slightly but significantly enriched in (Budge et al., 2008)C. However, CO feeding resulted in a significantly depleted isotopic signal for docosapentaenoic acid (22:5n-3 or DPA) compared to FO. SIAR indicated that 28% of DHA, 36% of EPA, and 40% of DPA was synthesized from camelina oil ALA.

Optimizing diets to decrease environmental impact of Nile tilapia (Oreochromis niloticus) production

Aquaculture is one of the most thriving animal production sectors, and Nile tilapia (Oreochromis niloticus) farming represents 8% of total finfish culture. However, the industry sustainability depends on the development of cost-effective and environmental friendly feeds. This study aimed to reduce dietary protein levels in diets for juvenile tilapia and to minimize diet environmental impact while maximizing biological efficiency. A growth trial was performed using five isoenergetic plant protein-based diets with decreasing levels of crude protein: 360, 340, 320, 300 and 280 g/kg diet (D360, D340, D320, D300 and D280, respectively). Dietary protein utilization was assessed by metabolic trials using a radiolabelled amino acid mixture. Tilapia in all treatments showed similar growth performance and feed intake. Feed conversion ratio was significantly higher in fish fed the D280 than the D360 diet, while no differences were found for other treatments. Protein retention was significantly higher in tilapia fed the D300 than the D360 diet. Amino acid catabolism increased in fish fed the D360 diet, though without significant differences in muscle amino acid retention. This study demonstrates that dietary protein levels can be reduced to 300 g/kg diet without hindering tilapia growth and feed conversion ratio, while reducing environmental nitrogen losses.

O extrato de maracujá sobre a morfometria de hepatócitos da tilápia do Nilo

Avaliaram-se os efeitos do extrato de maracujá veiculado na dieta (0, 50, 100 e 200mg kg-1) sobre o consumo de alimento, o ganho em peso e os níveis de glicose e cortisol plasmático de juvenis de tilápias do Nilo (87,0±6,6g). Ao final do experimento (28 dias), os peixes foram eutanasiados para remoção do fígado, visando à avaliação da área citoplasmática, contagem de células e verificação dos estoques de glicogênio hepático. Os dados foram submetidos à ANOVA unidirecional, comparando-se as médias pelo Teste de Tukey (P&lt;0,05), com posterior estudo de regressão, buscando estabelecer as curvas das áreas citoplasmáticas, em função das diferentes doses do extrato. A inclusão do extrato na dieta não afetou o consumo de alimento e o crescimento e todos os peixes apresentaram aumento da glicose e redução do cortisol plasmático, porém sem diferenças entre os tratamentos. As curvas de regressão indicaram aumento quadrático da área citoplasmática com a elevação da doses do extrato, principalmente para 100mg kg-1, resultando em uma curva dose-resposta em forma de "U" invertido. O aumento da área do citoplasma decorreu de um acúmulo de glicogênio hepático, conforme comprovado pela prova da amilase salivar. Concluiu-se que o extrato de maracujá pode ser fornecido na dieta de juvenis de tilápia, sem prejudicar o consumo alimentar e o crescimento dos animais e que o produto altera a morfometria dos hepatócitos, sugerindo a atividade de flavonóides sobre o metabolismo de carboidratos.

Effect of potential probiotic bacteria on growth and survival of tilapiaOreochromis niloticusL., cultured in the laboratory under high density and suboptimum temperature

This study examined the eiect of potential probiotic bacteria on growth and survival of the tilapia Oreochromis niloticus, under high density and suboptimum temperature. Presumptive Bacillus and lactic acid bacteria (LAB) were isolated from tilapia and from their culture system and were characterized for haemolytic and enzymatic activity, and antagonism against Vibrio. Selected strains were included in the diet of juvenile tilapia and evaluated during a 134day assay. The experiment was conducted with four treatments: (1) ¢sh fed with commercial feed plus Dry Oil s ; (2) ¢sh fed with commercial feed plus LAB; (3) ¢sh with bacilli in water; (4) ¢sh with a mixture of treatments 2 and 3. Tilapias in all treatments, including bacteria, grew signi¢cantly better than ¢sh fed with commercial feed plus Dry Oil s (control group). Survival was similar in all treatments. The physicochemical parameters of the culture system were maintained within the optimal ranges for the species, with the exception of temperature (19.9^24.821C). Animals fed diet supplemented with bacilli and LAB had good survival and the best growth performance, suggesting that bacteria are appropriate growth-stimulating additives in tilapia cultivation.

The Effect of Different Levels of Krill Meal Supplementation of Soybean-based Diets on Feed Intake, Digestibility, and Chemical Composition of Juvenile Nile Tilapia Oreochromis niloticus, L

— The main objective of this study was to determine the effect of different levels of krill meal (KM) as a feed attractant in juvenile Nile tilapia fed soybean (SBM) diets on growth performance, feed utilization, and body composition. Fish of an initial average weight 0.8 × 0.01g were stocked in 18 glass aquaria (80 L each) at a rate of 25 fish per aquarium. Fish meal (FM 20% of the diet) was used as the sole source of animal protein in the control (Diet 1). Diets 2 to 6 had (SBM) protein with various levels of krill meal (0.0,1.5,3.0,4.5, and 6.0%, diets 2-6 respectively). Test diets were fed to satiation to triplicate groups of Nile tilapia four times daily for 20 wk. Fish fed krill meal supplemented diets had significantly (P < 0.05) better growth performance compared with fish fed the unsupplemented and FM control diets. The krill meal increased growth of Nile tilapia by 31.9% compared to control diets (average Anal wet weight, 14.15 × 0.95 g and 10.72 × 0.2 g, respectively). Moreover, weight gains were not significantly different for fish fed diets with different levels of krill meal. Feed utilization parameters such as feed intake, feed conversion ratio, protein efficiency ratio differed significantly for fish fed krill meal diets compared with control. Digestibility of nutrient and energy of diets increased with increasing levels of krii meal. The incorporation of krill meal in diets significantly affected the protein, fat, ash, and energy of whole body composition. These results suggest that supplementation of krill meal at 1.5% in the diets of Nile tilapia as attractant or stimulant may lead to increased feed intake, growth performance, and feed utilization. Soybean meal can completely replace fishmeal in diets for juvenile tilapia.

Evaluation of pea protein isolate as alternative protein source in diets for juvenile tilapia (Oreochromis niloticus)

To evaluate isolated pea protein as feed ingredient for tilapia (Oreochromis niloticus) juveniles, triplicate groups were fed with four isonitrogenous [crude protein: 421.1–427.5 g kg−1 in dry matter (d.m.)] and isoenergetic (gross energy: 20.46–21.06 MJ kg−1 d.m.) diets with varying protein sources for 8 weeks. Fish meal-based protein content of diets was substituted with 0% (diet 100/0=control group), 30% (diet 70/30), 45% (diet 55/45) and 60% (diet 40/60) isolated pea protein. Tilapia juveniles with an initial body weight of 2.23–2.27 g were fed in average at a level of 5% of their body weight per day. Highest individual weight gain (WG: 21.39 g) and specific growth rate (SGR: 4.21% day−1) and best feed conversion ratio (FCR: 0.90) were observed in tilapia fed diet 100/0, followed by fish-fed diet 70/30 (WG: 19.09 g; SGR: 4.03% day−1; FCR: 0.98), diet 55/45 (WG: 16.69 g; SGR: 3.80% day−1; FCR: 1.06) and diet 40/60 (WG: 16.18 g; SGR: 3.74% day−1; FCR: 1.06). Although fish fed diet 100/0 showed the best performance, inclusion of 30% protein derived from pea protein isolate resulted in a growth performance (in terms of WG and SGR) that did not differ significantly from diet 100/0 in contrast to fish fed diet 55/45 and 40/60. Crude ash content in the final body composition of the experimental fish decreased with increasing dietary pea protein content, while crude protein and lipid content remained equal between the groups. Significant decreasing growth performance and body ash incorporation of tilapia at higher inclusion levels seem to be mainly related to the dietary amino acid profile and phytic acid contents.