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This study investigated the effect of different levels of digestible protein (DP) on blood metabolites, hepatic enzyme activity of glycolysis and amino acid metabolism, energy reserves, and the production characteristics of pacu (Piaractus mesopotamicus) during the finishing growth phase. Six semi purified and isoenergetic diets, containing 16.3, 20.1, 23.8, 27.2, 31.5, and 34.8% of balanced DP, provided with essential amino acid balance, were hand-fed to pacu (1100.0 ± 10.3 g, initial weight) three times daily for 7 weeks. The experiment consisted of six treatments, with three randomly arranged replicates (tanks) per treatment. The data obtained from this experiment were analyzed by one-way analysis of variance (ANOVA), and significant differences (p < 0.05) between treatments were determined using Tukey's test. Blood metabolites, except serum ammonia and the hepatic enzymes activities of glycolysis and amino acid metabolism, except hexokinase activity were affected (p < 0.05) by balanced DP. The energy reserve indices, except hepatic total lipid content, were also found associated (p < 0.05) with balanced DP. The test diets significantly (p < 0.05) affected growth performance parameters. Higher dietary proteins led to a greater energy uptake by fish from the protein in feed. Overall, fish fed the intermediate level (23.8%) of balanced DP with digestible energy of 17.95 MJ kg-1 showed better production traits and physio-biochemical health markers. This information could help nutritionists and farmers to develop nutritionally balanced and economically and environmentally sustainable aquafeed for promoting healthy and sustainable production of pacu in intensive culture systems.

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The objective of this study was to evaluate laying hens from 8 to 102 weeks old, regarding their changes in performance, body composition, and egg components produced in three scenarios of nutrition. Three treatments designed to contain different levels of balanced protein (BP) were randomly assigned to the experimental units, performing ten replicates per treatment with 20 birds each. A standard feed was formulated to meet hen requirements and the ideal ratio between essential amino acids. Then, two experimental feeds were formulated to contain 20% above or below the dietary BP used in the standard feed. The responses evaluated were cumulated feed intake (g), daily feed intake (g/day), body weight (g), body composition (g of protein, fat, and ash), hen-housed egg production (%/hen-housed), egg production (%), egg weight (g), egg mass (g), and egg components (percentages of yolk, albumen, and eggshell). The dietary BP influenced the body composition, egg production, egg weight, and egg mass of white laying hens. The increase in dietary BP was related to an increase in body contents and egg weight, whereas hens consuming the low dietary balanced protein presented a lower body weight, leaner, and produced smaller eggs.

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OBJECTIVE: This study aimed to evaluate the effect of the ad libitum and restricted feeding regimen on fasting heat production (FHP) and body composition. METHODS: Twelve Hubbard broilers breeders were selected with the same body weight and submitted in two feeding regimes: Restricted (T1) with feed intake of 150 g/bird/d and ad libitum (T2). The birds were randomly distributed on the treatments in two runs with three replications per treatment (per run). The birds were adapted to the feed regimens for ten days. After that, they were allocated in the open-circuit chambers and kept for three days for adaptation. On the last day, oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured by 30 h under fasting. The respiratory quotient (RQ) was calculated as the VCO2/VO2 ratio, and the heat production (HP) was obtained using the Brower equation (1985). The FHP was estimated throughout the plateau of HP 12 hours after the feed deprivation. The body composition was analyzed by dual-energy X-ray absorptiometry scanning at the end of each period. Data were analyzed for one-way analysis of variance using the Minitab software. RESULTS: The daily feed intake was 30 g higher to T2 (p<0.01) than the T1. Also, the birds of the T2 had significatively (p<0.05) more oxygen consumption (+3.1 L/kg0.75/d) and CO2 production (+2.2 L/kg0.75/d). That resulted in a higher FHP 359±14 kJ/kg0.75/d for T2 than T1 296±17.23 kJ/kg0.75/d. In contrast, the RQ was not different between treatments, with an average of 0.77 for the fasting condition. In addition, protein and fat composition were not affected by the treatment, while a tendency (p<0.1) was shown to higher bone mineral content on the T1. CONCLUSION: The birds under ad libitum feeding had a higher maintenance energy requirement but their body composition was not affected compared to restricted feeding.

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The objective with this study was to determine the lysine maintenance requirements (LMR) of male and female broilers as animal models. A total of 252 birds were used for nitrogen balance trials during three periods (I: 6-21, II: 22-37, and III: 38-53 days). Six lysine levels were used (2.76, 5.88, 8.99, 12.1, 15.2, and 18.3 g kg−1) with six replications. A control group also included, totalizing seven treatments for males and females for each assay. The experimental period was 15 days. The response variables included nitrogen intake (NI) and excretion (NEX), and their difference was assumed to be deposited as nitrogen. An exponential regression between NEX and lysine intake (LI) was fitted, and LMR was estimated when LI = 0. The daily values for LMR were 9.29, 33.4, and 40.2 mg BW0.67 kg−1 for males and 9.36, 30.0, and 39.4 mg BW0.67 kg−1 for females. The final value for both sexes were 10.1 (period I), 31.5 (period II), and 39.8 mg BW0.67 kg−1 (period III). Expressed as body protein weight at maturity (BPm), the LMR were 172 and 148 (period I), 216 and 207 (period II), and 189 and 180 mg BPm0.73 kg−1 (period III) for males and females, respectively. The results provided ranges of LMR values recommended in previous studies, validating this procedure. The procedure to estimate the requirements presented here provides new insights into the model of amino acid requirement estimations.(AU)

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Current study evaluates the macrophyte biomass of water hyacinth, Eichhornia crassipes, in diet food to improve the growth and survival of angelfish, Pterophyllum scalare. The liquid (extract) and ground modes are employed. Specific growth rate, weight gain, feed intake and final body weight in basal diet and macrophyte extract biomass diets were similar (p > 0.05). Fish survival was high in all dietary treatments (> 90%), while survival percentage of 100% was reported in ground macrophyte biomass treatment. Ground macrophyte biomass may be included in the diet of P. scalare up to 5%. The inclusion of E. crassipes in the diet of P. scalare proved similar or better results than basal diet. The macrophyte proved to be a food strategy in angelfish diets that may be implemented in the species’s diet at 32% levels of crude protein. The latter, easily found in tropical regions, affects directly the species’s growth and survival rates.

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Current study evaluates the macrophyte biomass of water hyacinth, Eichhornia crassipes, in diet food to improve the growth and survival of angelfish, Pterophyllum scalare. The liquid (extract) and ground modes are employed. Specific growth rate, weight gain, feed intake and final body weight in basal diet and macrophyte extract biomass diets were similar (p > 0.05). Fish survival was high in all dietary treatments (> 90%), while survival percentage of 100% was reported in ground macrophyte biomass treatment. Ground macrophyte biomass may be included in the diet of P. scalare up to 5%. The inclusion of E. crassipes in the diet of P. scalare proved similar or better results than basal diet. The macrophyte proved to be a food strategy in angelfish diets that may be implemented in the speciess diet at 32% levels of crude protein. The latter, easily found in tropical regions, affects directly the speciess growth and survival rates.(AU)

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For the production and commercialization of ornamental fish species, it is indispensable to collect biometric data that facilitate the selection of animals for trade and genetic improvement of the stock. However, during the handling process, fish receive more stress if proper anesthetics are not used. Thus, application of appropriate anesthetics is an important tool for minimizing stress in animals. The objective of this study was to determine the effective concentrations of benzocaine, eugenol, and menthol for achieving anesthesia in Freshwater Angelfish Pterophyllum scalare and to develop induction and recovery response curves for different concentrations of these anesthetics. In total, 75 fish were exposed to five concentrations of the three anesthetics in a completely randomized design: benzocaine at 60, 85, 110, 135, and 160 mg/L; eugenol at 40, 80, 120, 160, and 200 mg/L; and menthol at 50, 75, 150, 200, and 250 mg/L. Each concentration (5 fish/concentration) consisted of five replicates, with each replicate represented by a single fish. The results indicated that the tested substances met the criteria of anesthetic efficiency. The effective concentrations of benzocaine, eugenol, and menthol for the anesthesia of Freshwater Angelfish were identified as 89.25, 90.6, and 92.1 mg/L, respectively.

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This study aimed to estimate the utilization efficiency and optimal intake of digestible protein to maximize weight gain and feed conversion in Nile tilapia juveniles at different development stages. Four trials, each lasting 45 days, were performed using sexually inverted Nile tilapia juveniles with an initial average weight of 2.01 g (phase A), 14.26 g (phase B), 59.96 g (phase C), and 149.11 g (phase D). The experimental design was completely randomized with five treatments and four replicates. The levels of digestible protein ranged from 175 to 425 g kg-1 (phase A), 163 to 390 g kg-1 (phase B), 150 to 360 g kg-1 (phase C), and 138 to 330 g kg-1 (phase D). The maximum responses in terms of weight gain were obtained with protein intakes (digestible protein) of 88, 328, 713, and 855 mg fish-1 day-1, respectively, for phases A, B, C, and D. The maximum feed conversion ratio was obtained with protein intakes of 78, 272, 697, and 793 mg fish-1 day-1, respectively, for phases A, B, C, and D. The protein utilization efficiency was 52, 51, 51, and 50% for phases A, B, C, and D, respectively.

Objetivou-se estimar a eficiência de utilização e a ingestão ótima de proteína digestível para maximizar o ganho de peso e a conversão alimentar de juvenis de tilápia do Nilo em diferentes fases de crescimento. Cada um dos quatro ensaios durou 45 dias, utilizando-se juvenis revertidos sexualmente com peso médio inicial de 2,01g (fase A), 14,26 g (fase B), 59,96 g (fase C) e 149,11 g (fase D). O delineamento adotado foi o inteiramente ao acaso, com cinco tratamentos e quatro repetições. Os níveis de proteína digestível variaram de 175 a 425 g kg-1 (fase A), de 163 a 390 g kg-1 (fase B), de 150 a 360 g kg-1 (fase C) e de 138 a 330 g kg-1 (fase D). As máximas respostas para ganho de peso foram estimadas com ingestões de proteína de 88, 328, 713 e 855 mg peixe-1 dia-1 nas fases A, B, C e D, respectivamente. Para maximizar a conversão alimentar estimaram-se ingestões de proteína de 78, 272, 697 e 793 mg peixe-1 dia-1 para as fases A, B, C e D, respectivamente. As eficiências de utilização da proteína encontradas para as fases A, B, C e D, foram 52, 51, 51 e 50%, respectivamente.

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This study aimed to estimate the utilization efficiency and optimal intake of digestible protein to maximize weight gain and feed conversion in Nile tilapia juveniles at different development stages. Four trials, each lasting 45 days, were performed using sexually inverted Nile tilapia juveniles with an initial average weight of 2.01 g (phase A), 14.26 g (phase B), 59.96 g (phase C), and 149.11 g (phase D). The experimental design was completely randomized with five treatments and four replicates. The levels of digestible protein ranged from 175 to 425 g kg-1 (phase A), 163 to 390 g kg-1 (phase B), 150 to 360 g kg-1 (phase C), and 138 to 330 g kg-1 (phase D). The maximum responses in terms of weight gain were obtained with protein intakes (digestible protein) of 88, 328, 713, and 855 mg fish-1 day-1, respectively, for phases A, B, C, and D. The maximum feed conversion ratio was obtained with protein intakes of 78, 272, 697, and 793 mg fish-1 day-1, respectively, for phases A, B, C, and D. The protein utilization efficiency was 52, 51, 51, and 50% for phases A, B, C, and D, respectively.(AU)

Objetivou-se estimar a eficiência de utilização e a ingestão ótima de proteína digestível para maximizar o ganho de peso e a conversão alimentar de juvenis de tilápia do Nilo em diferentes fases de crescimento. Cada um dos quatro ensaios durou 45 dias, utilizando-se juvenis revertidos sexualmente com peso médio inicial de 2,01g (fase A), 14,26 g (fase B), 59,96 g (fase C) e 149,11 g (fase D). O delineamento adotado foi o inteiramente ao acaso, com cinco tratamentos e quatro repetições. Os níveis de proteína digestível variaram de 175 a 425 g kg-1 (fase A), de 163 a 390 g kg-1 (fase B), de 150 a 360 g kg-1 (fase C) e de 138 a 330 g kg-1 (fase D). As máximas respostas para ganho de peso foram estimadas com ingestões de proteína de 88, 328, 713 e 855 mg peixe-1 dia-1 nas fases A, B, C e D, respectivamente. Para maximizar a conversão alimentar estimaram-se ingestões de proteína de 78, 272, 697 e 793 mg peixe-1 dia-1 para as fases A, B, C e D, respectivamente. As eficiências de utilização da proteína encontradas para as fases A, B, C e D, foram 52, 51, 51 e 50%, respectivamente.(AU)

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In the present review, the ongoing researches about selenium research in fish nutrition have been comprehensively discussed. Selenium research is getting popularity in fish nutrition as it is required for the normal growth and proper physiological and biochemical functions in fish. Its deficiency or surplus amounts create severe problems in fish. It is available as inorganic form, organic form, and nano form. In fish, most of the previous research is about the selenium requirements for fish by using only one selenium source mainly the inorganic one. Selenium shows maximum biological activity and bioavailability when it is supplied in proper form. However, to differentiate the more bioavailable and less toxic form of selenium, sufficient information is needed about the comparative bioavailability of different selenium forms in different fish species. In fish, important data about the new forms of selenoproteins is still scarce. Therefore, it is necessary to focus on the determination and elucidation of the new selenoproteins in fish through the utilization of recent approaches of molecular biology and proteomics. The adaptation of these new approaches will replace the old fashioned methodologies regarding the selenium research in fish nutrition. Moreover, the use of molecular biology and proteomics-based new approaches in combination with selenium research will help in optimizing the area of fish nutrition and will improve the feed intake, growth performance, and more importantly the flesh quality which has a promising importance in the consumer market.

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