Search

Recent studies have evidenced exogenous enzymes as nutritional tool to elaborate low-polluting aquafeeds. This study aimed to evaluate effects of enzyme complex (EC) on apparent digestibility coefficients (ADC) of energy and nutrients, including amino acids, as well nitrogen (N) and phosphorus (P) loss in pre-growout Nile tilapia (Oreochromis niloticus). Diets without EC (Control) or with EC supplemented at 225 (EC225) or 450 mg/kg diet (EC450) and fed to Nile tilapia (n = 135, 150 ± 20 g) distributed in an entirely randomized design of three treatments and three replicates of 15 fish each. Fish fed diet EC450 showed higher digestibility of energy, protein, amino acids and mineral, and increased digestible energy (DE; +221.25 kcal/kg diet), digestible protein (DP; +10.54 g/kg diet) contents of diets, whereas reduced N (−23.82%) and P (−18.46%) loss relative to fish fed diet control. This study evidenced that EC at 450 mg/kg diet optimizes the ADC of multiple nutrients, including amino acids, and identified its potential to enhance the nutritive value of feeds and elaborate sustainable feeds for Nile tilapia. RESUMO Estudos recentes têm evidenciado enzimas exógenas como ferramenta nutricional para elaboração de dietas aquáticas pouco poluentes. Este estudo teve como objetivo avaliar os efeitos de um complexo enzimático (CE) nos coeficientes de digestibilidade aparente (CDA) de energia e nutrientes, incluindo aminoácidos, bem como perda de nitrogênio (N) e fósforo (P) em tilápia-do-nilo, Oreochromis niloticus em crescimento. Dietas sem CE (Controle) ou com EC suplementado em 225 (CE225) ou 450 mg/kg dieta (CE450) foram fornecidas para tilápias do Nilo (n = 135, 150 ± 20 g) distribuídas em um desenho inteiramente aleatório de três tratamentos e três repetições de 15 peixes cada. Peixes alimentados com a dieta EC450 apresentaram maior digestibilidade da energia, proteína, aminoácidos e minerais, e aumento nos conteúdos de energia digestível (ED; +221,25 kcal/kg dieta) e proteína digestível (PD; +10,54 g/kg dieta) das dietas, enquanto houve redução na perda de N (−23,82%) e P (−18,46%) em relação aos peixes alimentados com a dieta de controle. Este estudo evidenciou que o CE a 450 mg/kg de dieta otimiza o CDA de múltiplos nutrientes, incluindo aminoácidos e identificou seu potencial para melhorar o valor nutritivo dos alimentos, assim como elaborar dietas sustentáveis para tilápias do Nilo.

This study investigates the hypothesis that dietary supplementation of threonine above the current recommendation for protein synthesis stimulates gill mucus cell production in juvenile Nile tilapia, Oreochromis niloticus. During our experiment, six isonitrogenous and isocaloric extruded diets were elaborated with graded threonine levels [8 (control), 12, 16, 20, 24, and 28 g kg−1]. Fish (n = 216; 10.78 ± 0.03 g) were randomly assigned to triplicate groups of 12 fish and hand-fed six times a day until apparent satiety. Maximum body weight gain and feed efficiency ratio occurred in fish fed up to 17.71 and 13.73 g kg−1 diet of threonine, respectively. However, gill mucus cell counts were significantly higher in fish fed up to 20 g kg−1 diet of threonine, than that fed diet control (8 g kg−1 diet threonine). The relative expressions of MyoD and MyoG genes were upregulated in fish fed threonine at 16 g kg−1. Second-order polynomial regression analysis of protein retention efficiency gain against dietary threonine levels estimates that the dietary threonine requirement for juvenile Nile tilapia is 16.30 g kg−1 diet (4.89 g 100 g−1 protein). In contrast, a higher threonine level of 20 g kg−1 diet (6.00 g100 g−1 protein) optimizes gill mucus cell counts. This study provides insight into threonine as functional amino acid in tilapia aquaculture.

This research was conducted to determine optimal dietary histidine requirement of grow-out Nile tilapia, Oreochromis niloticus, based on muscle development, expression of muscle-growth-related genes, and blood parameters. Fish (n = 288, initial body weight of 64.17±0.53 g) were fed extruded diets with graded levels of histidine (4.23, 5.44, 7.17, 8.91, and 11.57 g kg−1), containing approximately 289 g kg−1 crude protein and 3565 kcal kg−1 digestible energy. The study followed a completely randomized design with five treatments and four replicates each, for 65 days. There was a quadratic effect of dietary histidine on final body weight, feed conversion, and net protein utilization, and the best values were optimized at 8.09, 7.88, and 7.33 g kg−1, respectively. Feed intake, hepatosomatic index, survival, body composition, and blood parameters of total protein, glucose, triglycerides, cholesterol, hematocrit, and hemoglobin were not affected by dietary treatments. Predominance of hypertrophic growth and higher mRNA levels of myogenin and MyoD were observed in fish fed histidine from 5.44 to 11.57 g kg−1 compared with fish fed histidine at 4.23 g kg−1. The mRNA expression of myostatin was not affected by dietary treatments. The dietary requirement of histidine for grow-out Nile tilapia was determined at 8.09 g kg−1, considering growth performance, muscle development, and gene expression responses.

This study aimed to determine the length-weight relationship and mathematical models to predict dressed and fillet weight and yield and fillet composition of wild traíra, Hoplias malabaricus (Bloch, 1794). A total of 80 marketable-sized fish from 292.28 to 2879.57 g and 32.06 to 61.19 cm were used. The length:weight ratio was estimated using the equation: W = a × L b, in which W is body weight (g) and L is length (cm). The models of dressed and fillet weight and yield and body were elaborated using first-order ( y ^ i = β 0 + β 1 x i ) or second-order ( y ^ i = β 0 + β 1 x i + β 1 x i 2 ) linear regression analyses. The value of slope b in the length:weight ratio was 3.3732 and intercept was 0.0029. The prediction equations obtained for dressed weight, fillet weight, dressed yield, fillet yield, fillet gross energy, moisture, crude protein, crude lipid, and ash were, respectively: y ^ = 0.3244 + 0.9373 W, y ^ = 0.7651 + 0.4181 W, y ^ = 939.8015 + 0.0019 W, y ^ = 420.55170 + 0.0064 W, y ^ = 997.9600 + 0.0630 W, y ^ = 810.6500 − 0.0085 W, y ^ = 184.080 − 0.0111 W, y ^ = 3.1131 + 0.0049 W, and y ^ = 10.6110 + 0.0009 W, in which W is the body weight of fish (g). We demonstrated the possibility of elaborating realistic expressions to describe degutted weight, fillet weight, and fillet composition. However, lower mathematical adjustment was observed to estimate realistic prediction of dressed and fillet yield.

The dietary total and available requirement of tryptophan of Nile tilapia fingerlings was determined using linear regression analysis. Six hundred fish (3.4 ± 0.0 g) were fed diets containing 296.4 g/kg of crude protein and 14.1 MJ/kg of digestible energy. Five extruded diets containing 2.5, 3.0, 3.4, 3.8 and 4.2 g/kg of total tryptophan were evaluated. Fish were fed four times a day during 45 days. Final body weight, weight gain, feed intake, feed conversion ratio and net protein utilization of fish fed Trp 3.4 and Trp 3.8 diets were improved compared to fish fed Trp 2.5 and Trp 4.2 diets. No significant differences in survival rate, whole‐body moisture and ash were observed. Whole‐body amino acid profile of fish fed different diets did not differ statistically (p > .05). Fish fed Trp 3.0 and Trp 3.4 diets showed higher tryptophan retention compared to fish fed Trp 2.5 and Trp 4.2 diets. Excepting blood glucose, no effects of dietary tryptophan on haematological parameters were observed. The dietary total tryptophan requirement of Nile tilapia fingerlings based on weight gain was estimated to be 3.4 g/kg (11.0 g/kg of dietary crude protein) or 3.0 g/kg of available tryptophan (11.0 g/kg of dietary digestible protein).

Made available in DSpace on 2022-04-29T08:29:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-15 Recent research has provided new mechanistic insights that amino acids (AA) coordinate protein synthesis by expressing the evolutionarily conserved target of rapamycin complex 1 (mTORC1) signaling pathway genes. An 8-week feeding trial was conducted to evaluate the impacts of experimental diets (420 g kg−1 crude protein; 15 MJ g kg−1) with protein-bound AA (Control), crystalline amino acids (CAA) supplemented at 60 g kg−1 and CAA at 120 g kg−1 on growth performance, AA retention, and mTORC1 signaling pathway (mTOR, mLST8, and Raptor) genes in Nile tilapia, Oreochromis niloticus fingerling (n = 360; 4.3 ± 0.1). At the end of feeding trial, the time-course postprandial plasmatic lysine and methionine were determined by collecting blood samples of fish immediately after feeding and at 60, 120, 240, 480 and 960 min. Each diet was randomly distributed into eight replicates groups of 12 fish and hand-fed, six times a day until apparent satiety for eight weeks. Compared with fish fed CA120 diet, body weight gain (BWG), feed intake (FI), feed efficiency (FE), protein retention efficiency (PRE) and retention of six essential and five non-essential AA parameters were improved in fish fed Control and CA60 diets. Furthermore, fish fed CA60 diet showed significantly lower whole-body lipids and higher crude protein than those fed other diets, whereas humidity and ash were not affected by dietary treatments. Plasmatic lysine and methionine linearly increased in fish fed Control diet. However, time-course plasmatic lysine and methionine were affected along with quadratic effect, and plasmatic lysine and methionine peaked at 461 and 496 min in fish fed CA60 diet, being reduced at 364 and 405 min in fish fed CA120 diet, respectively. The mechanistic insights of well-balanced AA coordinating protein synthesis in fish fed Control and CA60 diets was identified through a similar response on relative gene expression of mLST8 and mTOR genes, but higher than that in fish fed CA120 diet. Overall, this study validated CAA up to 60 g kg−1 without adverse effects on fish growth performance. However, a high CAA level at 120 g kg−1 depressed growth performance and may be considered to produce industrial-scale feeds for precision tilapia feeding. Statement of relevance: This study revealed new mechanistic insights that amino acids regulate protein synthesis through genomic approaches by regulating relative gene expression of mTORC1 signaling pathway. The data is relevant to the formulation of well-balanced amino acids precision tilapia feeding. PPZ/UEPG – Animal Science Post Graduation Program State University of Ponta Grossa Ichthus Unlimited Department of Morphology Institute of Bioscience of Botucatu São Paulo State University Graduate Program in Environment and Regional Development University of Western São Paulo CIIMAR Interdisciplinary Center for Marine and Environmental Research Department of Biology Faculty of Sciences Porto University Department of Animal Science State University of Ponta Grossa Department of Morphology Institute of Bioscience of Botucatu São Paulo State University

Recent evidence has shown that the advantage of top-spray enzymes is to surmount the problem caused by high temperature during extrusion and drying processes and ensure high residual content of exogenous enzymes in extruded aquafeeds. This experiment aimed to investigate the effects of the liquid blend of xylanase and β-glucanase (XB) on the apparent digestibility coefficient (ADC) of dry matter (DM), gross energy (GE), and nutrients including amino acids (AA), as well impacts on digestible energy (DE) and nitrogen retention (Nr) in low and high-fiber diets fed to growing Nile tilapia, Oreochromis niloticus. Fish (n = 192) were randomly assigned to 4 treatments in a 2 × 2 factorial design with 2 levels of fiber (low or high), either not supplemented (Control) or supplemented with XB (0.2 g/kg, contained analyzed 1130 TXU/kg of 1,4-β-xylanase and 512 TGU/kg of 1,4-β-glucanase). The chromium oxide was used as an indigestible marker. Data were obtained during 2 subsequent runs of feces collection of 10 days, run 1 (initial body weight of 60 g ± 3.4 g), and run 2 (initial body weight of 72 ± 3.7 g). Each diet was tested using 4 replicates with 2 replicates run. The low-fiber diet with XB exhibited significantly higher ADC of GE than other diets. However, the high-fiber diet containing XB revealed higher ADC of GE than that without XB addition. Compared to control, XB addition improved the ADC of dry matter (DM), crude protein (CP), calcium (Ca), and phosphorus (P). Relative to control, DE and Nr were notably higher in the XB-added diet by 0.41 MJ/kg and 0.21 g/kg diet, respectively. The high-fiber diet containing XB showed equivalent ADC of Thr than the low-fiber diet without XB inclusion. The high-fiber diet with XB exhibited comparable ADC of Thr than the low-fiber diet without XB addition. The low-fiber diet showed increased ADC of all essential AA, except Lys and Met. However, compared to control, XB addition improved the ADCs of branched-chain AA, Lys, and Thr. Overall, liquid XB at 0.2 g/kg onto extruded pellets optimized digestibility, increased digestible energy, and retained N contents, mainly in the high-fiber diet. This study identified the potential of liquid XB to be used on an industrial-scale by application onto extruded pellets for precision Nile tilapia feeding.

Recent studies provide new mechanistic insights that isoleucine (ILE) regulates protein synthesis through genomic approaches. An 8-week feeding trial was performed to determine dietary ILE requirement based on growth performance, body composition, amino acid (AA) retention, and mRNA levels of myogenic regulatory factors (MRFs), including myogenic differentiation (MyoD), myogenin (MyoG), and myostatin (Mst) as negative regulatory of myogenesis, and mammalian target of rapamycin (mTOR) genes in fingerling Nile tilapia, Oreochromis niloticus. Fish (n = 288; 2.46 ± 0.10 g; mean ± SD) were randomly distributed into six treatments with four replicate groups of 12 fish. Fish were fed diets with graded levels of analyzed ILE at 9.08 (ILE1), 12.13 (ILE2), 15.11 (ILE3), 18.02 (ILE4), 21.15(ILE5), and 24.06 g kg−1 diet (ILE6). Fish were hand-fed, six times a day, until apparent satiety. At the end of the feeding trial, incremental levels of dietary ILE significantly affected body weight gain (BWG), feed efficiency ratio (FER), protein retention efficiency (PRE), and essential and non-essential AA retention. Also, the relative expression of MyoD and MyoG genes in the white skeletal muscle and mTOR gene in the liver was up-regulated in fish fed diet ILE3 (P > 0.05). Optimal branched-chain amino acid (BCAA) ratio (Ile:Leu:Val) was found at 1:1.3:0.9. Based on one-slope broken line model of BWG, the optimal dietary ILE requirement for fingerling Nile tilapia was estimated at 13.67 g kg−1. The results indicate that appropriate dietary ILE level at 5.0% dietary protein could improve protein synthesis and positively regulates muscle growth-related and mTOR genes in fast-growing Nile tilapia.

The objective of this study was to determine the dietary tryptophan (Trp) requirements to optimize growth performance of juvenile Nile tilapia. A hundred and eighty fish (38.2 ± 0.09 g) were fed to extruded isonitrogenous (28% crude protein) and isoenergetic (14.5 MJ/kg digestible energy) diets, containing graded levels of dietary Trp (1.8, 2.3, 2.7, 3.2, and 3.7 g/kg). Fish were hand fed to triplicate groups of 12 fish, three times a day to apparent satiety for 45 days. The relationship between body weight gain, feed conversion ratio, protein efficiency ratio, and fish uniformity against dietary Trp levels could be expressed as a second-order polynomial regression analysis, where the best Trp levels were estimated to be 2.9, 3.1, 3.1, and 2.9 g/kg, respectively. No effects of dietary Trp on hepatosomatic index, visceral fat, survival, or body composition were observed. Whole body retentions of arginine, phenylalanine, and lysine were highest in fish fed 3.0, 3.1, and 3.1 g/kg Trp, respectively. The dietary Trp requirement of juvenile Nile tilapia was estimated to be 2.9 g/kg for maximum weight gain of fish.

A 100-day feeding trial was carried out to determine the dietary histidine requirement of Nile tilapia juveniles based on growth performance, muscle development, expression of muscle-growth-related genes, biochemical and hematological responses. Nile tilapia juveniles (4.84 ± 0.04 g) were fed six extruded practical isonitrogenous (265.7 g of crude protein kg − 1 ) and isoenergetic (17.3 MJ of gross energy kg − 1 ) diets containing graded levels of histidine (4.2, 5.4, 7.1, 8.9, 9.8 and 11.5 g kg − 1 dry diet). The feeding trial was conducted in a flow-through system (1.5 L min − 1 ) at 28 °C water temperature, and triplicate groups of fish were hand-fed each diet four times a day until apparent satiation. Final weight, weight gain, feed conversion ratio, protein efficiency ratio and net protein utilization were optimized in fish fed 8.9 g of histidine kg − 1 . Whole-body protein content was enhanced in fish fed 7.1 and 9.8 g of histidine kg−1 compared to fish fed 11.5 g of histidine kg − 1 . Active hypertrophic growth process was observed in fish fed 8.9 g of histidine kg − 1 , as confirmed by lower frequency of occurrence of muscle fibers 50 µm diameter, compared to fish fed 5.4 g of histidine kg − 1 . Fish fed 9.8 g of histidine kg − 1 showed the highest expression level of MyoD . However, myogenin expression was higher in fish fed 9.8 and 11.5 g of histidine kg − 1 compared to fish fed 4.2 to 7.1 g of histidine kg − 1 . Myostatin expression was similar among fish from all treatments. Biochemical and haematological responses were not affected in fish fed graded levels of histidine. Based on second-order regression analysis, the dietary histidine requirement for maximum WG of Nile tilapia juveniles was estimated to be 8.2 g kg − 1 , corresponding to 3.1% of crude protein. Statement of Relevance Histidine is a limiting amino acid in Nile tilapia diets.

The dietary lysine requirement has not been established for finishing Nile tilapia despite being considered the first limiting essential amino acid in many cereal grain ingredients. A feeding trial was designed to determine the dietary lysine requirement using 600 fish (274.9 ± 3.3 g) distributed into 15, 1.2 m 3 net cages in a completely randomized design with five treatments and three replicates. Five extruded isoproteic (251.2 g of crude protein kg − 1 ) and isoenergetic diets (13.1 MJ of digestible energy kg − 1 ) containing 11.1, 12.5, 13.9, 15.1 and 16.4 g lysine kg − 1 were prepared. Fish were hand fed four times a day until apparent satiety. Fish fed 15.1 g lysine kg − 1 exhibited improved final body weight and daily weight gain compared to fish fed 11.1 g lysine kg − 1 . Fillet weight and fillet yield of finishing Nile tilapia were significantly affected by dietary lysine levels and optimized at 15.1 g lysine kg − 1 compared to fish fed the other treatments. Whole-body and fillet compositions of fish were unresponsive to dietary lysine levels. Whole-body lysine, tryptophan, alanine, aspartic acid and tyrosine retention was significantly affected by dietary lysine levels. Although the recruitment of new fibers by hyperplasia continues in adult Nile tilapia, the predominance of muscle growth was by hypertrophy as observed in fish from all treatments. Based on second-order regression analysis, the dietary lysine requirement for maximum fillet yield of finishing Nile tilapia was estimated at 14.6 g kg − 1 , corresponding to 5.8% of dietary protein. Statement of relevance First mention of lysine requirements of large Nile tilapia

Threonine is the third-limiting essential amino acid in diets based on cereal ingredients. A 4-week trial was conducted to determine the threonine requirement of large Nile tilapia based on fish growth, feed efficiency, body composition, protein and amino acid retention. Six hundred fish (563.3 ± 15.1 g) were distributed into twenty 1.2-m3 cages. Five diets containing 288 g kg−1 of crude protein, 12.7 MJ kg−1 of digestible energy and 8.9, 10.5, 12.2, 13.7 and 15.4 g kg−1 of threonine were elaborated. Fish were hand-fed five times a day to extruded diets. Significantly, differences in growth performance and amino acids retention among the treatments were observed. Fish fed 10.5 g kg−1 of threonine showed higher daily weight gain, gutted weight and fillet weight (P

Meat and bone meal (MBM) is an excellent source of amino acids (AAs) for fish but its proximate composition varies according to its origin and processing. Apparent digestibility coefficients (ADC) of dry matter, crude protein, and gross energy, and apparent availability coefficients (AAC) of essential and nonessential AAs (EAA and NEAA, respectively) in MBM containing various levels of crude protein (MBM-340, 370, 400, 430, and 460 g/kg) were determined for juvenile Nile tilapia (Oreochromis niloticus, 32.7 ± 4.5 g). A reference diet containing 351.9 g/kg crude protein and 4541.1 kcal/kg of gross energy and test diets containing a 70:30 mixture of the reference diet and MBM were used with 5 g/kg Cr2O3 as an external indicator. ADC of dry matter, gross energy, and crude protein in MBM samples were 42.9–76.2%, 71.6–89.1%, and 49.4–86.9%, respectively. MBM-400, 430, and 460 showed higher dry matter, gross energy, and crude protein ADC than that by MBM-340 and 370. All AAs in MBM-460 showed AAC of EAA > 90%, while the value for MBM-430 was >85%, except arginine (82.1%) and lysine (84.8%). High ADC of energy, crude protein, and AAC in MBM-430 and 460 indicate good potential as quantitative AA sources. Besides the low AA quality of MBM-340, 370, and 400, their utilization is limited by low digestible energy and high ash, which should be considered in the production of least-cost, well-balanced, and sustainable diets for tilapia.

The effect of graded levels of dietary available phosphorus (AP) on large Nile tilapia (145.87 ± 9.51 g) performance, feed efficiency, body composition and mineral retention in vertebrae was evaluated. All male fish were distributed into three replicates in fiberglass aquaria (800 L each; 12 fish per tank) for 87 days and hand fed to pelletized diets three times a day until apparent satiation. Diets with approximately 302 g kg−1 of digestible protein and 15.2 kJ g−1 of digestible energy with graded levels of dibasic phosphate yield AP levels of 2.39, 4.17, 6.12 and 8.91 g kg−1. At the end of the trial, feed intake, hepatosomatic index, fillet yield, whole body moisture and crude protein of fish fed 2.39–8.91 g kg−1 of AP diets were not significantly different. The supplementation of 6.12 and 8.91 g kg−1 of AP resulted in significantly increased weight gain, whole body ash and calcium. Whole body crude lipids significantly decreased with increasing AP from 6.12 to 8.91 g kg−1. However, concentration of zinc in the vertebrae was not affected by dietary treatments. The magnesium contents of the fish vertebrae were lower in fish fed lower dietary AP level. No effects of the dietary AP on apparent digestibility coefficients of energy and nutrients were observed. The study indicated that the dietary AP level of at least 6.12 g kg−1 satisfies the needs for growth performance, body composition and bone mineralization of large Nile tilapia.

This study was conducted out to determine the dietary digestible lysine requirements of Nile tilapia from 87 to 226 g. Fish (n = 170; average initial weight = 86.62 ± 4.89 g) were distributed 15 1000-L cages, in a completely randomized design with five treatments and three replicates, and fed extruded diets containing 0.88; 1.12; 1.36; 1.59 and 1.83% of digestible lysine, balanced to keep the arginine to lysine ratio as 1.43:1. There was no effect of the dietary lysine levels on whole body moisture and ash. By Linear Response Plateau analysis of lysine levels on daily gain, feed conversion, protein efficiency ratio and rate of protein deposition was estimated requirement of 1.31, 1.03, 1.16 and 1.31 % of lysine, respectively. A quadratic effect of lysine levels on whole body fat deposition ratio and whole body ether extract composition were observed, and the lowest values were estimated with 1.16% and 1.43% of dietary lysine, respectively. An increase of the dietary lysine levels resulted in linear increase on the fillet yield. The digestible lysine requirements of Nile tilapia (87 to 226 g) is 1.31%, in diets balanced for arginine to lysine ratio.Este estudo foi realizado com o objetivo de determinar a exigência de lisina digestível em dietas para alevinos de tilápia-do-Nilo de 87 a 226 g. Os peixes (n=300; peso inicial médio = 86,62 ± 4,89 g) foram distribuídos em 15 tanques-rede de 1000 L cada, em delineamento inteiramente casualizado com cinco tratamentos e três repetições e alimentados com dietas extrusadas contendo 0,88; 1,12; 1,36; 1,59 e 1,83% de lisina digestível, balanceadas para relação arginina:lisina em 1,43:1. Não foi observado efeito dos níveis de lisina na dieta sobre os teores de umidade e proteína corporal. Pela análise Linear Response Plateau dos níveis de lisina sobre o ganho de peso diário, conversão alimentar, taxa de eficiência proteica e taxa de deposição de proteína, estimou-se exigência de 1,31; 1,03; 1,16 e 1,31% de lisina digestível, respectivamente. Foi observado efeito quadrático dos níveis de lisina sobre a taxa de deposição de gordura e teor de extrato etéreo corporal, em que os menores valores dessas variáveis foram estimados com 1,16% e 1,43% de lisina, respectivamente. Com o incremento nos teores de lisina na dieta ocorreu aumento linear no rendimento de filé e nível de proteína corporal. Concluiu-se que a tilápia-do-Nilo (87 a 226 g) exige 1,31% de lisina digestível, em dietas balanceadas para a relação arginina:lisina.

This study was conducted to determine the digestible lysine requirements of Nile tilapia fingerlings. Fish (n = 300; average initial weight = 1.44 g) were distributed 15 300-L aquariums, in a completely randomized design with five treatments and three replicates, and fed extruded diets containing 11.3, 13.7, 16.1, 18.4 or 20.8 g/kg of digestible lysine. The arginine:lysine ratio was maintained at 1.3:1. All fish were fed diets containing 281 g/kg of digestible protein and 3,372 kcal digestible energy/kg, hand-fed until apparent satiation. There was no effect of the dietary lysine levels on survival rate, or protein and ash body rates. With increasing levels of lysine in the diet, a quadratic effect on weight gain, feed conversion, protein efficiency ratio, protein deposition rate, deposition rate of fat, body moisture and body lipids was observed, where the best values of the variables were estimated at 15.96, 16.4, 14.35, 15.21, 15.87, 15.21 and 16.29 g/kg of lysine, respectively. The digestible lysine requirement of Nile tilapia fingerlings is 15.21 g/kg (5.41 g/100 g of digestible protein), in diets balanced for the arginine:lysine ratio.

The optimal dietary supply of amino acids to tilapia has been studied for many years. Nevertheless, a general agreement on the amino acid requirement for tilapias has not been established. In order to optimize efficiency and reduce surplus nitrogen, values of digestibility of each amino acid of feed must be considered. Due to variations in the amino acid requirement due to new tilapia strains introduction, continuous research on amino acid requirements is necessary to elaborate economical and environmental sustainability diets, also improving fish growth, efficiency and fillet yield. The concept of ideal protein in tilapia diets was introduced more than ten years ago, and new researches have shown the importance of protein and amino acids on fish performance and health, when tilapias are submitted to constant challenging from internal and external factors. Inovacoes sobre o uso de aminoacidos industriais em dietas para a tilapia-do-nilo RESUMO - O suprimento adequado de aminoacidos dieteticos para tilapias tem sido estudado por muitos anos. No entanto, ainda nao foi estabelecida uma concordância geral sobre a exigencia de aminoacidos para tilapias. A fim de otimizar a eficiencia e reduzir o excesso de nitrogenio, as dietas devem ser elaboradas considerando-se os valores de digestibilidade de cada aminoacido dos alimentos. Devido as variacoes nas exigencias de aminoacidos pela introducao novas linhagens de tilapias, a investigacao continua sobre exigencias de aminoacidos e necessaria para a elaboracao de dietas ambiental e economicamente sustentaveis que melhorem tambem o crescimento dos peixes, a eficiencia alimentar e o rendimento de file. O conceito de proteina ideal em dietas de tilapias foi introduzido ha mais de dez anos, e novas pesquisas tem mostrado a importância da proteina e aminoacidos no desempenho e na saude dos peixes submetidos a desafios frente a fatores internos e externos. Palavras-chave: aminoacidos, desempenho, digestibilidade, proteina ideal, peixes, qualidade da carne

Colliroja, Astyanax fasciatus, is a new aquaculture species, and information on its dietary essential amino acid requirements is lacking. The whole body composition of 120 farmed fish (16.2 ± 8.8 g) was determined to estimate the dietary essential amino acid requirement based on the ideal protein concept ((each essential amino acid/lysine) x100), and the findings were correlated to the whole body essential amino acid content of Nile tilapia Oreochromis niloticus. The dietary essential amino acids, including cysteine and tyrosine, accounted for 5.46, 4.62, 1.16, 3.28, 5.63, 2.01, 2.59, 2.84, 4.66, 3.39, 0.65, and 3.51% of the total protein for lysine, arginine, histidine, isoleucine, leucine, methionine, methionine+tyrosine, phenylalanine, phenylalanine+tyrosine, threonine, tryptophan, and valine, respectively. There were positive linear and high correlations (r = 0.971) between the whole body amino acid profiles of colliroja and Nile tilapia. Thus, the whole body amino acid profile of colliroja might be used to estimate accurately the essential amino acid requirement. Colirroja, Astyanax fasciatus, es una nueva especie de la acuicultura y no hay información sobre sus requerimentos de aminoácidos esenciales en la dieta. Se determinó la composición corporal de 120 peces de cultivo (16,2 ± 8,8 g) para estimar los requirimientos nutricionales de aminoácidos essenciales en la dieta, incluyendo cistina y tirosina, basada en el concepto de proteína ideal ((cada aminoácido essencial/lisina) x 100) y los resultados se correlacionaron con el perfil corporal de la tilapia del Nilo Oreochromis niloticus. El perfil dietético de aminoácidos essenciales explica el 5,46, 4,62, 1,16, 3,28, 5,63, 2,01, 2,59, 2,.84, 4,66, 3,39, 0.65 y 3,51% de la proteína, respectivamente para lisina, arginina, histidina, isoleucina, leucina, metionina, metionina+cistina, fenilalanina, fenilalanina+tirosina, treonina, triptófano y valina. Hubo una alta correlación lineal positiva (r = 0,971) entre el perfil corporal de aminoácidos de colirroja y el de tilapia del Nilo. Por lo tanto, el perfil corporal de los aminoácidos basado en el concepto de proteína ideal podría ser utilizado para estimar con precisión el requisito de aminoácidos essenciales de colirroja.

The objective of the present study was to develop models for predicting live weight from the length-weight relationship and body composition of Nile tilapia. A total of 3,000 juvenile fish (initial weight = 28.6±4.16 g and standard length = 13.8±0.16 cm) were distributed into three circular cages (12 m3 each). The fish were hand-fed extruded diets containing 332 g kg-1 of crude protein and 3,230 kcal kg-1 of digestible energy, until apparent satiety, twice daily, for 100 days. Twelve fish were collected from each cage every 20 days for measurements of body weight and length, and proximate composition analysis; statistical analysis was conducted using linear regression. The value of the slope b and the intercept for the length-weight relationship were 3.0604 and 0.0203, respectively. The prediction equations obtained for body moisture (MO), crude protein (CP), crude lipid (CL), and ash against body weight (BW) in g/100 g of fish were as follows: MO = 70.0090 - 0.0071BW; CP = 13.7550 + 0.0037BW; CL = 9.2636 + 0.0057BW; and ash = 4.2392 - 0.0024BW. It is possible to develop equations to predict body weight and composition, which can be used to control the production of Nile tilapia and improve its commercial value.

Este estudo foi realizado com o objetivo de determinar a exigência de lisina digestível para juvenis de tilápia-do-nilo. Noventa e seis peixes revertidos sexualmente e com peso vivo inicial de 5,72 ± 0,10 g foram alimentados por 42 dias com quatro rações (29.51% de PB e 3.235 kcal de energia digestível/kg) contendo diferentes níveis de L-lisina HCl (0,1; 0,3; 0,5 e 0,7%, correspondendo a rações com 1,04; 1,27; 1,51 e 1,741% de lisina digestível, respectivamente). Os peixes foram distribuídos em 16 tanques com capacidade de 1.000 L cada um, em um delineamento inteiramente casualizado, com quatro tratamentos, três repetições e seis peixes por unidade experimental. Não foi observado efeito dos níveis de lisina sobre o índice hepato-somático, a gordura visceral, a sobrevivência e os teores de água e extrato etéreo na carcaça. A análise de Linear Response Plateau do ganho de peso e da conversão alimentar versus níveis de lisina digestível demonstrou estimativa de exigência de 1,56 e 1,44% de lisina digestível, respectivamente. Foi observado efeito quadrático sobre o rendimento de carcaça, que aumentou até o nível de 1,61% de lisina digestível. Considerando o desempenho, recomenda-se que dietas para juvenis de tilápia-do-nilo devem conter 1,44% de lisina digestível (5,23% da proteína da dieta). This trial was carried out to determine the digestible lysine requirements of Nile tilapia juveniles. Ninety- six reverted fishes averaging initial weight of 5.72 ± 0.10 g were fed four diets (29.51% of crude protein and 3,235 kcal/kg of digestible energy) containing increasing levels of L-lysine HCl (0.1, 0.3, 0.5, and 0.7%), during 42 days. The following treatments were evaluated: dietary lysine levels of 1.04; 1.27; 1.51 and 1.741%. Fishes were allotted to 1000-L 16 tanks, as a completely randomized design with four treatments, three replicates and eight fishes per experimental unit. No treatment effects on hepatosomatic index, visceral fat, survival rate and water ether extract in the carcass were observed. The Linear Response Plateau analysis of weight gain and feed:gain ratio versus digestible lysine level yielded an estimated digestible lysine requirement of 1.56 and 1.44% for Nile tilapia juveniles, respectively. Quadratic effect of treatments on carcass yield that increased up to 1.61% of digestible lysine was observed. Considering the performance, it is recommended diets containing up to 1.44% of digestible lysine (5.23% of protein) for Nile tilapia juveniles.

This study ascertains the length-weight relationship and predicts body composition equations in cultivated Astyanax aff. fasciatus. A total of 300 fish were distributed in five groups according to body weight: 1.19 ± 0.18, 3.7 ± 0.70, 7.55 ± 0.97, 12.28 ± 2.32 and 22.16 ± 2.64 g. The length-weight relationship was elaborated using linear (y i = b0 + b1x i) or second-order (y i = b0 + b1x i + b1x i²) regression analysis. The value of the b slope in the length-weight relationship was 3.6971 and the intercept was 0.0031. The prediction equations obtained for body moisture, crude protein, crude lipid and ash were, y = 71.680 - 0.404BW, y = 17.140 - 0.095BW, y = 8.432 +0.364BW and y = 3.720 - 0.032BW, respectively, where BW is the body weight of fish (g). The use of prediction equations to describe body composition as a tool to support fish production and commercialization is suggested.

Este estudo foi realizado para se avaliar a redução dos níveis de proteína em dietas para tilápia-do-nilo (5 a 125 g), adotando-se o conceito de proteína ideal. Cento e sessenta peixes (4,40 ± 0,9 g) foram distribuídos em um delineamento inteiramente casualizado, com quatro tratamentos [25,5; 27; 28,5 e 30% (controle) de proteína digestível], três repetições e dez animais por unidade experimental. Os aminoácidos sintéticos foram suplementados para se manter as proporções de aminoácidos de acordo com o conceito de proteína ideal. Os aminoácidos lisina, metionina e treonina foram suplementados para se obter os níveis de aminoácidos da dieta controle. As dietas foram fornecidas à vontade, durante 83 dias. Não foram observados efeitos dos níveis de proteína sobre o ganho de peso, a conversão alimentar, o índice hepatossomático, o peso da gordura visceral, a taxa de sobrevivência, os níveis de proteína na carcaça e o diâmetro da fibra intermediária. O aumento nos níveis de proteína resultou em redução linear na taxa de eficiência protéica e de retenção do nitrogênio e aumento linear na excreção de nitrogênio. Foi observado efeito quadrático sobre o rendimento de carcaça e o teor de extrato etéreo na carcaça; os melhores valores foram obtidos com 28,40 e 27,31% de proteína na dieta, respectivamente. Concluiu-se que é possível a redução do nível de proteína de 30 para 27,5% em dietas para juvenis de tilápia do Nilo, sem efeitos negativos sobre o crescimento, rendimento de carcaça e a composição química dos filés. No entanto, a redução do nível de proteína de 30 para 25,5% acarreta redução no diâmetro das fibras musculares vermelha e branca. This trial was carried out to evaluate the effects of ideal protein concept on reduction of dietary protein content for Nile tilapia (5 to 125 g). A hundred and sixty juvenile fishes (4.40 ± 0.9 g) were assigned to a randomized experimental design with four treatments [25.5, 27, 28.5 and 30% (control) of digestible protein], three replicates and ten fish by experimental unit. Crystalline amino acids were added to maintain amino acid levels according to the ideal protein concept. The amino acids (lysine, methionine and threonine) were supplemented at levels to simulate amino acid levels of the reference diet. Diets were fed ad libitum during 83 days. No significant effects of protein levels on weight gain, feed:gain ratio, hepatossomatic, visceral fat, survival rate, carcass protein and intermediate fiber diameter were observed. The protein efficiency rate and nitrogen retention decreased linearly and excreted nitrogen increased linearly as the dietary digestible protein levels increased. Quadratic effect for carcass yield and carcass ether extract content was observed, with the best values at 28.40 and 27.31% dietary protein, respectively. It was concluded that is possible to reduce the dietary protein from 30 to 27.5% for juvenile Nile tilapia, with no change on growth, carcass yield and fillet chemical composition. However, the reduction of white and red fibers diameter was observed when dietary protein decreased from 30 to 27.5%.

O presente estudo foi realizado com o objetivo de determinar a abundância natural do isótopo estável de carbono (13C) de alguns componentes alimentares e determinar sua contribuição no crescimento de juvenis de pintado, em condições laboratoriais. Foram utilizados 150 peixes com peso vivo médio de 1,39 g, que permaneceram em dois tanques-rede com volume útil unitário de 125L, durante 60 dias. A cada 10 dias foram coletadas amostras de água para análise de fitoplâncton e zooplâncton. Cladocera foi o item dominante na análise de conteúdo estomacal, seguido de Chironomidae e Copepoda. Foi coletada amostra de peixes ao início e final do experimento para determinação do sinal isotópico. Foram obtidos valores médios de -20,94; -15,36 e -18,81 δ 13C‰ para o fitoplâncton, Cladocera e Chironomidae, respectivamente. Cladocera foi a principal fonte de carbono e contribuiu com uma média de 89,24% do carbono na alimentação dessa espécie, enquanto que Chironomidae contribuiu com 10,76%. O δ 13C demonstrou ser efetivo como marcador de carbono (C) ao longo da cadeia alimentar, uma vez que o consumidor reflete isotopicamente sua dieta.The aim of this study is to determine the natural abundance of carbon stable isotope (13C) of some food components and determine its contribution to the pintado juvenile growth, in laboratory conditions. 150 fishes were used with average weight of 1.39 g, and stocked in two net ponds with 125L each, during 60 days. Every 10 days a water sample was collected to analyse phytoplakton and zooplankton. Clacocera was dominant in the analysis of the stomach contents, following Chironomidae and Copepoda. A fish sample was collected in the beginning, and at the end of the experiment to analyses the isotopic signal. An average value of -20.94; -15.36 and -18.81 δ 13C‰ was obtained for phytoplankton, Cladocera and Chironomidae, respectively. Cladocera was the main carbon source and contribution with carbon average 89.24% in feeding this species, while the Chironomid contribution was 10.76%. The δ 13C was effective as carbon tracer in food chain, because the consumer reflects its diet isotopicly.

O presente estudo teve por objetivo determinar os efeitos da inclusão de farelo de canola (FC) em substituição à proteína do farelo de soja (FS) na alimentação do piavuçú, Leporinus macrocephalus (Garavello & Britski) (Characiformes, Anastomidae), na fase inicial. Foram utilizados 100 alevinos (8,51 ± 0,07g), distribuídos em blocos casualizados com quatro tratamentos, cinco repetições, sendo que cada unidade experimental era constituída por cinco peixes. Foram elaboradas quatro rações isocalóricas (3.000kcal ED/kg) e isoprotéicas (30% de PB com base em milho, farelo de soja e farinha de peixe, contendo 0%, 19%,12%; 38%,24% e 57,36% de FC). A análise de variância não apresentou efeitos dos níveis de inclusão de FC sobre as variáveis de consumo, sobrevivência, rendimento e composição química da carcaça, gordura visceral e índice hepatossomático. Foi observado efeito quadrático dos níveis de inclusão sobre a porcentagem de ganho de peso, ocorrendo o ponto máximo no nível de 19,11% de inclusão de FC. Com o aumento nos níveis de FC, foi observado piora linear sobre a conversão alimentar e taxa de eficiência protéica. A inclusão de 11,19% de FC resultou em melhor desempenho e rendimento de carcaça.This research aimed to investigate the effects of canola bran (CB) inclusion, replacing the soybean bran crude protein in piavuçu diet, Leporinus macrocephalus (Garavello & Britski) (Characiformes, Anastomidae), in initial phase. One hundred fingerlings (8.51 ± 0.07g) were assigned to a completely randomized block design with five replications, totalizing 25 fishes per treatment. Four isocaloric (3,000kcal ED/kg) and isoproteic (30% CP) diets were formulated, based on corn, soybean bran and fish flour, containing 0%; 19.12%; 38.24% and 57.36% CB. Variance analysis showed no effect of CB inclusion on feed intake survival, carcass yield and composition, visceral fat and hepato somatic index. Quadratic effect of CM inclusion was observed (11,19%) on weight gain. Feed gain ratio and protein efficiency ratio were negatively influenced by CB inclusion. The inclusion of 11.19% CB resulted in better performance and carcass yield.