Adjusted Thr: Lys Ratio Improved the Performance and Efficiency of Japanese Quail

Two hundred and forty Japanese quail aged 125 days were randomly allocated to five treatment groups based on laying (%) and quail's weight (90.71 ± 1.8% egg/day × 100 and 178.05 ± 9.38 g, respectively), each of which included six replicates of eight quails. The diets were formulated based on corn, soybean meal, and industrial amino acids. An optimal diet achieves 100% of amino acids required by the quail requirements, except for threonine. Five treatments were made: 20% less amino acid; 10% less amino acid; optimal diet; 10% more amino acid; and 20% more amino acids than those in the optimal diet. The increase in amino acid levels in a fixed Lys: amino acid ratio led to histological alterations in the liver and uterine epithelium, reduction in blood lipid peroxidation, lower hepatic HSP70 gene expression, and the performance of laying Japanese quail. The optimal diet based on the NRC with an adjusted Thr: Lys 78 ratio (Lys 1.0%) improved the performance and efficiency of Japanese quail from 125 to 230 days of age.(AU)

Calcium Requirement and Vitamin D Supplementation in Meat-Type Quail at First Stage of Growth

Currently, feed formulations for quail are based on foreign data or data from other species; this undermines productivity with the use of excessive or deficient levels of some nutrients. Therefore, this study aimed to determine the nutritional requirement levels of calcium (Ca) and supplementation vitamin D in meat-type quail from 1 to 14 d of age. The experiment was a 4 × 4 factorial arrangement of treatments (levels of Ca: 0.42, 0.58, 0.74 and 0.90% and levels of vitamin D: 1,000, 2,000, 3,000 and 4,000 IU) with 3 replicate pens and 43 quails per pen. Weight gain increased quadratically with increased levels of Ca and vitamin D; this variable yielded estimated levels of 0.73% Ca and 2,883 IU vitamin D. There was no Ca x vitamin D interaction effect on bone variables. Bone Ca, bone phosphorus, bone ash, femoral bone strength, tibial bone strength and the femoral Seedor index increased quadratically with an increase in Ca levels. These variables yielded estimated values of 0.78, 0.71, 0.78, 0.77, 0.83, and 0.71% Ca, respectively. It is concluded that the requirements of Ca and vitamin D for the maximum weight gain of meat-type quails, in the period from one to 14 days of age, were 0.73% Ca (p=0.001) and 2,883 IU vitamin D (p=0.02), respectively.(AU)

Calcium Requirement and Vitamin D Supplementation in Meat-Type Quail at First Stage of Growth

Currently, feed formulations for quail are based on foreign data or data from other species; this undermines productivity with the use of excessive or deficient levels of some nutrients. Therefore, this study aimed to determine the nutritional requirement levels of calcium (Ca) and supplementation vitamin D in meat-type quail from 1 to 14 d of age. The experiment was a 4 × 4 factorial arrangement of treatments (levels of Ca: 0.42, 0.58, 0.74 and 0.90% and levels of vitamin D: 1,000, 2,000, 3,000 and 4,000 IU) with 3 replicate pens and 43 quails per pen. Weight gain increased quadratically with increased levels of Ca and vitamin D; this variable yielded estimated levels of 0.73% Ca and 2,883 IU vitamin D. There was no Ca x vitamin D interaction effect on bone variables. Bone Ca, bone phosphorus, bone ash, femoral bone strength, tibial bone strength and the femoral Seedor index increased quadratically with an increase in Ca levels. These variables yielded estimated values of 0.78, 0.71, 0.78, 0.77, 0.83, and 0.71% Ca, respectively. It is concluded that the requirements of Ca and vitamin D for the maximum weight gain of meat-type quails, in the period from one to 14 days of age, were 0.73% Ca (p=0.001) and 2,883 IU vitamin D (p=0.02), respectively.

Metabolizable energy levels in diets with a fixed nutrient: calorie ratio for free-range broilers / Níveis de energia metabolizável com manutenção da relação nutriente: caloria em dietas para frangos de corte tipo caipira

The present study proposes to examine the effect of dietary levels of metabolizable energy, under a fixed nutrient:calorie ratio, on the production performance; body fat and protein deposition; and carcass characteristics of free-range broilers from 1 to 84 days of age. Nine hundred unsexed chicks were allocated to six treatments in a completely randomized design with six replicates of 25 birds each. Treatments consisted of diets with varying levels of metabolizable energy (2700, 2800, 2900, 3000, 3100 and 3200 Kcal ME/kg of diet) and a fixed proportion of nutrients relative to the energy level according to the nutritional requirements for each rearing phase. Body weight, weight gain, feed intake, feed conversion, production viability, metabolizable energy intake, protein intake, lysine intake, body fat deposition, body protein deposition and carcass characteristics were evaluated. Data were subjected to analysis of variance and, later, to regression analysis. Increasing levels of metabolizable energy, coupled with a fixed nutrient:calorie ratio, reduced feed intake, increased body weight and weight gain, improved feed conversion and did not affect carcass characteristics. In conclusion, adjusting the nutrient supply according to the dietary energy level improves production performance by improving feed conversion, ensuring adequate nutrient intake and preserving fat and protein deposition in the carcass when the metabolizable energy level is raised up to 3200 Kcal/kg in all rearing stages.(AU)

O objetivo do presente estudo foi avaliar os níveis de energia metabolizável, sob uma relação nutriente:caloria fixa, no desempenho produtivo; deposição de gordura e proteína corporal e características de carcaça de frangos de corte tipo caipiras. Foram utilizados novecentos pintainhos não sexados, distribuidos em seis tratamentos em delineamento inteiramente casualizado com seis repetições de 25 aves cada. Os tratamentos consistiram em dietas com diferentes níveis de energia metabolizável (2700, 2800, 2900, 3000, 3100 e 3200 Kcal EM / kg de dieta) e uma proporção fixa de nutrientes em relação ao nível de energia de acordo com as necessidades nutricionais de cada fase de criação. Foram avaliados o peso corporal, ganho de peso, consumo de ração, conversão alimentar, viabilidade criatória, consumo de energia metabolizável, consumo de proteína, consumo de lisina, deposição de gordura corporal, deposição de proteína corporal e características de carcaça. Os dados foram submetidos à análise de variância e posteriormente à análise de regressão. O aumento dos níveis de energia metabolizável juntamente com a manutenção da relação nutriente:caloria reduziu o consumo de ração, aumentou o peso corporal e o ganho de peso, melhorou a conversão alimentar e não afetou as características da carcaça. Em conclusão, o ajuste da oferta de nutrientes de acordo com o nível de energia da dieta melhora o desempenho da produção, melhorando a conversão alimentar, garantindo a ingestão adequada de nutrientes e preservando a deposição de gordura e proteína na carcaça quando o nível de energia metabolizável é elevado até 3200 Kcal/kg em todas as fases de criação.(AU)

Energy and protein requirements for Nellore steers estimated with the deuterium oxide marker

The aim of this study was determine the energy and protein requirements for maintenance and gain of Nellore steers. Thirty six Nellore steers with an average weight and age of 359±13 kg and 20 months at the beginning of the trial were individually fed for 56. The steers were fed the same diet (76.43% TDN and 13.62% CP) in three levels of dry matter (DM) intake, ad libitum, 75 g DM/kg BW0.75 and 60 g DM/kg BW0.75. The initial and final body composition was estimated with the marker deuterium oxide that allowed repeated water estimate in the same animal. Deuterium in blood samples was analyzed by mass spectrometry. The effects of intake levels, comparison of intercept and slope among feeding level, and equations were evaluated by the analysis of variance, adopting P<0.05 as a significant level. The net energy for maintenance was 75 kcal/kg EBW 0.75 or 70 kcal/kg BW 0.75. The net energy for gain for steers with 350 to 450 kg weight was 5.1 to 6.1Mcal. The efficiency of energy utilization for maintenance, km, was 0.7492 and for weight gain, kg, was 0.3404. The metabolizable protein requirement for maintenance was 4.32 * BW0.75and the net protein for gain was estimated with the equation NPg= (254.68*EBWG) – (29.38*RE). The technique of deuterium oxide marker used to estimate energy and protein requirement for maintenance and weight gain at Nellore steers confirm the hypothesis presented in NRC, that NEmis lower than the requirement for taurine cattle. On the other hand, the reverse was true for the NP requirement for maintenance and for weight gain. We consider that indirect method using D2O for estimate body composition in zebu cattle was suitable to determine nutrient requirements.

Energy and protein requirements for Nellore steers estimated with the deuterium oxide marker

The aim of this study was determine the energy and protein requirements for maintenance and gain of Nellore steers. Thirty six Nellore steers with an average weight and age of 359±13 kg and 20 months at the beginning of the trial were individually fed for 56. The steers were fed the same diet (76.43% TDN and 13.62% CP) in three levels of dry matter (DM) intake, ad libitum, 75 g DM/kg BW0.75 and 60 g DM/kg BW0.75. The initial and final body composition was estimated with the marker deuterium oxide that allowed repeated water estimate in the same animal. Deuterium in blood samples was analyzed by mass spectrometry. The effects of intake levels, comparison of intercept and slope among feeding level, and equations were evaluated by the analysis of variance, adopting P<0.05 as a significant level. The net energy for maintenance was 75 kcal/kg EBW 0.75 or 70 kcal/kg BW 0.75. The net energy for gain for steers with 350 to 450 kg weight was 5.1 to 6.1Mcal. The efficiency of energy utilization for maintenance, km, was 0.7492 and for weight gain, kg, was 0.3404. The metabolizable protein requirement for maintenance was 4.32 * BW0.75and the net protein for gain was estimated with the equation NPg= (254.68*EBWG) (29.38*RE). The technique of deuterium oxide marker used to estimate energy and protein requirement for maintenance and weight gain at Nellore steers confirm the hypothesis presented in NRC, that NEmis lower than the requirement for taurine cattle. On the other hand, the reverse was true for the NP requirement for maintenance and for weight gain. We consider that indirect method using D2O for estimate body composition in zebu cattle was suitable to determine nutrient requirements.(AU)

Choline and digestible methionine + cystine supplementation for quail in the laying phase / Suplementação de colina e metionina + cistina digestível para codornas em fase de postura

The aim of this study was to evaluate the effect of levels of choline and digestible methionine + cystine in diets for quail in the laying phase. A total of 280 Japanese laying quail were assigned to one of eight treatments in a completely randomized design in a 4 × 2 factorial arrangement consisting of dietary supplementation with four levels of choline (0.0, 0.042, 0.084 and 0.126%) and two levels of digestible methionine + cystine (0.857 and 0.685%), with five replicates and seven birds per plot. The experimental period was 84 days, represented by four 21-day evaluation cycles in which quail performance and egg quality were evaluated. There was no interaction effect between the factors for any of the studied variables, except quail weight. The highest tested levels of methionine + cystine and choline supplementation improved egg weight, feed conversion egg mass-1 and yolk percentage. By contrast, albumen percentage decreased linearly as choline inclusion in the diet was elevated. The choline supplementation levels induced a quadratic response from eggshell percentage, whose optimum result was estimated at the choline level of 0.05% in the diet. Egg specific gravity decreased linearly as choline supplementation was increased. The indicated level of digestible methionine + cystine in the diet of Japanese quail in the laying phase is 0.857%, while choline should be supplemented at 0.126%.

O objetivo deste estudo foi avaliar o efeito dos níveis de colina e metionina + cistina digestível em dietas para codornas em fase de postura. Um total de 280 codornas japonesas foi submetido a oito tratamentos, em delineamento inteiramente casualizado, em esquema fatorial 4 × 2, composto por suplementação alimentar com quatro níveis de colina (0,0; 0,042; 0,084 e 0,126%) e dois níveis de metionina + cistina digestível (0,857 e 0,685%), com cinco repetições e sete aves por parcela. O período experimental foi de 84 dias, representado por quatro ciclos de avaliação de 21 dias, em que foram avaliados o desempenho das codornas e a qualidade dos ovos. Não houve efeito de interação entre os fatores para nenhuma das variáveis estudadas, exceto o peso das codornas. Os níveis mais altos testados de suplementação com metionina + cistina e colina melhoraram o peso dos ovos, a conversão alimentar em massa de ovos e a porcentagem de gema. Por outro lado, a porcentagem de albumina diminuiu linearmente à medida que a inclusão de colina na dieta foi elevada. Os níveis de suplementação de colina induziram uma resposta quadrática da porcentagem de casca de ovo, cujo resultado ideal foi estimado no nível de colina de 0,05% na dieta. A gravidade específica do ovo diminuiu linearmente à medida que a suplementação de colina foi aumentada. O nível indicado de metionina + cistina digestível na dieta de codornas japonesas na fase de postura é de 0,857%, enquanto a colina deve ser suplementada em 0,126%.

Choline and digestible methionine + cystine supplementation for quail in the laying phase / Suplementação de colina e metionina + cistina digestível para codornas em fase de postura

The aim of this study was to evaluate the effect of levels of choline and digestible methionine + cystine in diets for quail in the laying phase. A total of 280 Japanese laying quail were assigned to one of eight treatments in a completely randomized design in a 4 × 2 factorial arrangement consisting of dietary supplementation with four levels of choline (0.0, 0.042, 0.084 and 0.126%) and two levels of digestible methionine + cystine (0.857 and 0.685%), with five replicates and seven birds per plot. The experimental period was 84 days, represented by four 21-day evaluation cycles in which quail performance and egg quality were evaluated. There was no interaction effect between the factors for any of the studied variables, except quail weight. The highest tested levels of methionine + cystine and choline supplementation improved egg weight, feed conversion egg mass-1 and yolk percentage. By contrast, albumen percentage decreased linearly as choline inclusion in the diet was elevated. The choline supplementation levels induced a quadratic response from eggshell percentage, whose optimum result was estimated at the choline level of 0.05% in the diet. Egg specific gravity decreased linearly as choline supplementation was increased. The indicated level of digestible methionine + cystine in the diet of Japanese quail in the laying phase is 0.857%, while choline should be supplemented at 0.126%.(AU)

O objetivo deste estudo foi avaliar o efeito dos níveis de colina e metionina + cistina digestível em dietas para codornas em fase de postura. Um total de 280 codornas japonesas foi submetido a oito tratamentos, em delineamento inteiramente casualizado, em esquema fatorial 4 × 2, composto por suplementação alimentar com quatro níveis de colina (0,0; 0,042; 0,084 e 0,126%) e dois níveis de metionina + cistina digestível (0,857 e 0,685%), com cinco repetições e sete aves por parcela. O período experimental foi de 84 dias, representado por quatro ciclos de avaliação de 21 dias, em que foram avaliados o desempenho das codornas e a qualidade dos ovos. Não houve efeito de interação entre os fatores para nenhuma das variáveis estudadas, exceto o peso das codornas. Os níveis mais altos testados de suplementação com metionina + cistina e colina melhoraram o peso dos ovos, a conversão alimentar em massa de ovos e a porcentagem de gema. Por outro lado, a porcentagem de albumina diminuiu linearmente à medida que a inclusão de colina na dieta foi elevada. Os níveis de suplementação de colina induziram uma resposta quadrática da porcentagem de casca de ovo, cujo resultado ideal foi estimado no nível de colina de 0,05% na dieta. A gravidade específica do ovo diminuiu linearmente à medida que a suplementação de colina foi aumentada. O nível indicado de metionina + cistina digestível na dieta de codornas japonesas na fase de postura é de 0,857%, enquanto a colina deve ser suplementada em 0,126%.(AU)

Exigência de lisina digestível de frangos de corte machos de 22 a 42 dias de idade / Digestible lysine levels of male broilers from 22 to 42 days of age

O objetivo deste estudo foi determinar a exigência de lisina digestível para frangos de corte machos sob as características de desempenho, composição corporal e rendimento de carcaça dos animais, de 22 a 42 dias de idade. As dietas diferiram quanto aos níveis de lisina digestível, mantendo-se a relação dos demais aminoácidos com a lisina. Foram utilizados seis níveis de lisina digestível: 0,88%; 0,96%; 1,05%; 1,13%; 1,22%; e 1,30%. Distribuídos em 36 unidades experimentais de 36 aves cada, 1296 animais da linhagem Cobb - 500® tiveram as seguintes características de desempenho avaliadas: consumo de ração (CR), peso corporal (PC), ganho de peso (GP), conversão alimentar (CA), viabilidade criatória (VC) e índice de eficiência produtiva (IEP). Aos 42 dias de idade, foram selecionadas ao acaso cinco aves para avaliação do rendimento de carcaça, e duas para avaliação da composição corporal. A CA, o IEP e o rendimento de peito foram influenciados, sendo sua exigência de 1,30%, sugerindo que níveis maiores de lisina digestível que as recomendações utilizadas como base neste estudo (1,13%) trouxeram benefícios aos animais sobre essas características.(AU)

The objective of the present study was to evaluate the optimal levels of digestible lysine in the diet of male broilers, evaluating performance characteristics, body composition, and carcass yield of the animals in the final phase (22 to 42 days old). The diets differed in digestible lysine content, maintaining the relation among the other amino acids and lysine in accordance with the ideal protein concept. The six levels of digestible lysine in the diet were: 0.88%; 0.96%; 1.05%; 1.13%; 1.22%, and 1.30%. A total of 1296 animals were employed, distributed in 36 experimental units of 36 birds each. The determined performance characteristics corresponded to feed intake (FI), body weight (BW), weight gain (WG), feed conversion (FC), viability (VB), and productive efficiency index (PEI). At 42 days of age seven birds per experimental unit were selected at random, five for the estimation of yield and total carcass and commercial cut weight, and two for the evaluation of body composition. FC, animal breast yield and PEI weres influenced with requirements of 1.30%. With respect to nationally known recommendations regarding digestible lysine (1.13%), higher levels of the amino acid in the diet have brought benefits regarding the characteristics above.(AU)

Exigência de lisina digestível de frangos de corte machos de 22 a 42 dias de idade / Digestible lysine levels of male broilers from 22 to 42 days of age

O objetivo deste estudo foi determinar a exigência de lisina digestível para frangos de corte machos sob as características de desempenho, composição corporal e rendimento de carcaça dos animais, de 22 a 42 dias de idade. As dietas diferiram quanto aos níveis de lisina digestível, mantendo-se a relação dos demais aminoácidos com a lisina. Foram utilizados seis níveis de lisina digestível: 0,88%; 0,96%; 1,05%; 1,13%; 1,22%; e 1,30%. Distribuídos em 36 unidades experimentais de 36 aves cada, 1296 animais da linhagem Cobb - 500® tiveram as seguintes características de desempenho avaliadas: consumo de ração (CR), peso corporal (PC), ganho de peso (GP), conversão alimentar (CA), viabilidade criatória (VC) e índice de eficiência produtiva (IEP). Aos 42 dias de idade, foram selecionadas ao acaso cinco aves para avaliação do rendimento de carcaça, e duas para avaliação da composição corporal. A CA, o IEP e o rendimento de peito foram influenciados, sendo sua exigência de 1,30%, sugerindo que níveis maiores de lisina digestível que as recomendações utilizadas como base neste estudo (1,13%) trouxeram benefícios aos animais sobre essas características.(AU)

The objective of the present study was to evaluate the optimal levels of digestible lysine in the diet of male broilers, evaluating performance characteristics, body composition, and carcass yield of the animals in the final phase (22 to 42 days old). The diets differed in digestible lysine content, maintaining the relation among the other amino acids and lysine in accordance with the ideal protein concept. The six levels of digestible lysine in the diet were: 0.88%; 0.96%; 1.05%; 1.13%; 1.22%, and 1.30%. A total of 1296 animals were employed, distributed in 36 experimental units of 36 birds each. The determined performance characteristics corresponded to feed intake (FI), body weight (BW), weight gain (WG), feed conversion (FC), viability (VB), and productive efficiency index (PEI). At 42 days of age seven birds per experimental unit were selected at random, five for the estimation of yield and total carcass and commercial cut weight, and two for the evaluation of body composition. FC, animal breast yield and PEI weres influenced with requirements of 1.30%. With respect to nationally known recommendations regarding digestible lysine (1.13%), higher levels of the amino acid in the diet have brought benefits regarding the characteristics above.(AU)

Metabolizable energy levels in diets with high lysine for growing and finishing pigs / Níveis de energia metabolizável em rações com alta lisina para suínos em crescimento e terminação

The objective of this experiment was to evaluate the effects of metabolizable energy (ME) levels in diets with high digestible lysine concentration on performance, carcass traits, and meat quality of barrows from 95 to 158 days of age. Eighty commercial hybrid barrows (50 ± 1.82 kg) selected for lean meat deposition, were assigned to four dietary treatments (3,150, 3,235, 3,320, and 3,400 kcal EM kg <->1) in a randomized design with 10 replicate pens per treatment and two pigs per pen. From 95 to 116 days of age, we observed no effects of ME on final body weight (FBW), average daily gain (ADG), metabolizable energy intake (MEI), and feed conversion (F: G). Average daily feed intake (ADFI) decreased linearly with increasing ME levels (Ŷ = 5.79961 - 0.00096790X - r² = 0.89). From 95 to 137 days of age, no effects of ME were observed on final body weight (FBW), average daily gain (ADG), metabolizable energy intake (MEI), and feed conversion (F: G). Average daily feed intake (ADFI) decreased linearly with increasing ME (Ŷ= 6.1176 - 0.001X - r²= 0.97). From 95 to 158 days, of age no effects of ME were observed on FBW and ADG. Dietary ME influenced the ADFI and F: G, which decreased linearly with increasing ME concentrations (Ŷ= 8.12951 - 0.00149X - r²= 0.99; Ŷ= 6.0914 - 0.001X - r² = 0.75, respectively). There was a linear increase in loin eye area (LEA) with increasing ME (Ŷ = - 29.851 + 0.0207 X - r² = 0.87). Backfat thickness, pH, and temperature, measured at different times after slaughter (0 min, 45 min, 3 h, and 24 h), were not affected by dietary ME. The level of ME also did not affect the meat quality parameters Color L*, Color a*, Color b*, Warner-Bratzler shear force, thaw water losses, cooking water losses, sum of water losses, intramuscular fat content, and TBARS. Diets with 3,400 kcal kg <->1 ME, corresponding to 2.75, 2.57, and 2.31 g digestible lysine/Mcal of ME for pigs from 95 to 116, 116 to 137, and 95 to 158 days of age, respectively, resulted...(AU)

Objetivou-se com este experimento avaliar os efeitos de níveis de energia metabolizável (EM) em rações com alta lisina no desempenho, nas características de carcaça e na qualidade de carne de suínos machos castrados, dos 95 aos 158 dias de idade. Foram utilizados 80 suínos (Agroceres PIC), machos castrados, com peso inicial de 50 ± 1,82 kg. Os animais foram distribuídos em delineamento inteiramente casualizado, com quatro tratamentos (3150 kcal EM kg <->1, 3235 kcal EM kg <->1, 3320 kcal EM kg <->1, 3400 kcal EM kg <->1), dez repetições e dois animais por unidade experimental, representada pela baia. No período de 95 a 116 dias de idade, não foram observados efeitos dos níveis de EM sobre os parâmetros de desempenho: peso médio final (PMF), ganho de peso médio diário (GPD), consumo de energia metabolizável (CEM) e conversão alimentar (CA). O consumo de ração médio diário (CDR) reduziu de forma linear com o aumento dos níveis de EM da ração (Ŷ= 5,79961 - 0,00096790 X - r²= 0,89). No período de 95 a 137 dias de idade, não foram observados efeitos dos níveis de EM sobre os parâmetros de desempenho: peso médio final (PMF), ganho de peso médio diário (GPD), consumo de energia metabolizável (CEM) e conversão alimentar (CA). O consumo de ração médio diário (CDR) reduziu de forma linear com o aumento dos níveis de EM da ração (Ŷ= 6,1176 - 0,001X - r²= 0,97). No período de 95 a 158 dias de idade, não foram observados efeitos dos níveis de EM sobre o PMF e o GPD dos suínos. O CDR e a CA dos animais reduziram de forma linear com o aumento dos níveis de EM da ração (Ŷ= 8,12951 - 0,00149X - r² = 0,99 e Ŷ= 6,0914 - 0,001X - r² = 0,75; respectivamente). Verificou-se aumento linear da área de olho de lombo com o aumento do nível de EM das rações, (Ŷ = -29851 + 0,0207X - r² = 0.87). A espessura de toucinho, o pH e a temperatura medida em diferentes tempos após o abate (0 min, 45 min, 3 horas e 24 horas) não foram influenciados pelos níveis de EM da ração. Não foi observado efeito dos...(AU)

Effects of nutritional levels on performance, carcass characteristics and nutrient digestibility of sexed broilers

The objective of this study was to evaluate the effects of dietary nutrient levels on performance, carcass yield, commercial cuts, digestibility and economical viability of broilers from 1 to 42 days of age. During the experiment, 180 COBB 500™ chicks were housed in metal batteries and subjected to a completely randomized design in a 2x3 factorial arrangement, of two sexes and three diets (male, female and mixed), totaling 6 treatments and 6 repetitions of 5 birds each. Data were subjected to statistical analysis and the means were compared using the Tukey test, at 5% probability. The results indicate the effect of sex on performance and commercial cuts, except for breast and thigh fillets, in which males and females showed similar results when given the mixed diet. The influence of the nutritional levels on performance, digestibility and commercial cuts was observed, in which the female diet showed the highest results for feed intake, body weight and weight gain, in addition to greater retention of protein and crude energy. For drumstick and abdominal fat yield, the highest values were obtained using the mixed diet and the female diet, and the lowest values were obtained using the male diet. Regarding economic viability, the female diet showed the highest return per unit of Real (R$) spent on feed. Therefore, these data prove that the female diet had a positive effect when provided to both sexes, and it may be a promising alternative for its application at the production level.(AU)

Effects of nutritional levels on performance, carcass characteristics and nutrient digestibility of sexed broilers

The objective of this study was to evaluate the effects of dietary nutrient levels on performance, carcass yield, commercial cuts, digestibility and economical viability of broilers from 1 to 42 days of age. During the experiment, 180 COBB 500™ chicks were housed in metal batteries and subjected to a completely randomized design in a 2x3 factorial arrangement, of two sexes and three diets (male, female and mixed), totaling 6 treatments and 6 repetitions of 5 birds each. Data were subjected to statistical analysis and the means were compared using the Tukey test, at 5% probability. The results indicate the effect of sex on performance and commercial cuts, except for breast and thigh fillets, in which males and females showed similar results when given the mixed diet. The influence of the nutritional levels on performance, digestibility and commercial cuts was observed, in which the female diet showed the highest results for feed intake, body weight and weight gain, in addition to greater retention of protein and crude energy. For drumstick and abdominal fat yield, the highest values were obtained using the mixed diet and the female diet, and the lowest values were obtained using the male diet. Regarding economic viability, the female diet showed the highest return per unit of Real (R$) spent on feed. Therefore, these data prove that the female diet had a positive effect when provided to both sexes, and it may be a promising alternative for its application at the production level.

Net energy for 60 to 120 kg pigs fed low crude protein diets / Energia líquida em rações com redução de proteína bruta para suínos dos 60 aos 120 kg

Two experiments were conducted to determine the effects of dietary net energy content (NE) on performance and carcass traits of finishing barrows fed low crude protein (CP) diets. Pigs (60.0 ± 2.41 kg, Exp. 1; 90.0 ± 2.96 kg, Exp. 2) were allotted in randomized design to four dietary treatments. Exp. 1 had nine pens treatment-1 and Exp. 2 had eight pens treatment-1, with two pigs in all pens. The treatments were as follows: 179 g kg-1 CP and 2589 kcal NE kg-1, 134 g kg-1 CP and 2631 kcal NE kg-1, 134 g kg-1 CP and 2589 kcal NE kg-1, and 134 g kg-1 and 2589 kcal NE kg-1 (pair-feeding to 179 g kg-1 CP and 2589 kcal NE kg-1) in Exp. 1 and 166 g kg-1 and 2604 kcal NE kg-1, 123 g kg-1 CP and 2645 kcal NE kg-1, 123 g kg-1 CP and 2604 kcal NE kg-1, and 12.34% CP and 2604 kcal NE kg-1 (pair feeding to 166 g kg-1 CP and 2604 kcal NE kg-1) in Exp. 2. In Exp. 1, there was no effect of CP or NE on any performance and carcass traits evaluated. In Exp. 2, the greatest result of average daily gain was obtained with 123 g kg-1 CP and 2645 kcal NE kg-1. There was no effect of CP or NE on any other performance and carcass traits evaluated. For 60 to 90 kg barrows, reducing the CP of the diet from 179 g kg-1 to 134 g kg-1, adjusting or not adjusting the NE content of the diets with 134 g kg-1 CP does not compromise performance or carcass traits. For 90 to 110 kg barrows, reducing the CP of the...

Dois experimentos foram conduzidos para avaliar níveis de energia líquida (EL) da ração sobre o desempenho e características de carcaça de suínos alimentados com dietas com redução de proteína bruta (PB). Os suínos (60,0 ± 2,41 kg, Exp. 1; 90,0 ± 2,96 kg, Exp. 2) foram distribuídos em delineamento inteiramente casualizado em quatro tratamentos. O Exp. 1 teve nove repetições/tratamento e o Exp. 2, teve oito repetições/tratamento. Todas repetições tiveram dois animais por unidade experimental. Os tratamentos foram: 179 g kg-1 PB e 2589 kcal EL kg-1; 134 g kg-1 PB e 2621 kcal EL kg-1; 134 g kg-1 PB e 2589 kcal EL kg-1 e 134 g kg-1 PB e 2589 kcal EL kg-1 (alimentação pareada a 179 g kg-1 PB e 2589 kcal EL kg-1) no Exp. 1 e 166 g kg-1 PB e 2604 kcal EL kg-1; 123 g kg-1 PB e 2645 kcal EL kg-1; 123 g kg-1 PB e 2604 kcal EL kg-1 e 123 g kg-1 PB e 2604 kcal NE kg-1 (alimentação pareada a 166 g kg-1 PB e 2604 kcal EL kg-1) no Exp. 2. No Exp. 1, não houve efeito da PB ou EL nas variáveis de desempenho e de carcaça. No Exp. 2, o melhor resultado do ganho médio diário foi obtido com a dieta contendo 123 g kg-1 PB e 2645 kcal EL kg-1, comparado com 166 g kg-1 PB e 2604 kcal EL kg-1. Não houve efeito da PB ou da EL em nenhuma outra variável de desempenho e de carcaça. Para suínos dos 60 aos 90 kg, a redução da PB de 179 g kg-1 para 134 g kg-1, mantendo-se ou não o nível de EL da ração, não...

Description of amino acid and fatty acid content during initial development of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae), a carnivorous freshwater catfish

Samples of eggs, newly hatched larvae (NHL), and larvae at the end of the lecithotrophic period (eight days after hatching) (LPL) of Lophiosilurus alexandri were collected to determine the amino acid and fatty acid profiles. Crude protein did not change throughout initial development and the concentration of lipids was highest in NHL. The content of the indispensable amino acids (IAA) isoleucine, leucine, and valine decreased in LPL, while in eggs and NHL they remained high and similar in value. The dispensable amino acids (DAA), such as aspartic acid, tyrosine, and glycine, increased in LPL, while alanine decreased. The percentage of neutral lipids increased in LPL. The saturated fatty acid content decreased during ontogeny, while monounsaturated fatty acids decreased only in LPL. The polyunsaturated fatty acid content was highest in LP. Polar fatty acids were found in higher percentages in eggs and NHL, but lower in LPL. Saturated fatty acid content decreased during ontogenetic development, while that of monounsaturated fatty acids decreased only in LPL. Polyunsaturated fatty acid content was highest in LPL. Protein content was maintained during ontogenetic development, while amino acid classes experienced changes. Lophiosilurus alexandri preferentially uses saturated and monosaturated fatty acids as an energy source during its early development.(AU)

Amostras de ovos, larvas recém-eclodidas (NHL) e larvas no final do período lecitotrófico (oito dias após a incubação) (LPL) de Lophiosilurus alexandri foram coletadas para determinar os perfis de aminoácidos e ácidos graxos. A proteína bruta não alterou durante o desenvolvimento inicial e a concentração de lipídios foi maior na NHL. O conteúdo dos aminoácidos indispensáveis (IAA) isoleucina, leucina e valina diminuíram em LPL, enquanto nos ovos e NHL eles permaneceram com valores elevados e semelhantes entre si. Os aminoácidos dispensáveis (DAA), como ácido aspártico, tirosina e glicina, aumentaram em LPL, enquanto a alanina diminuiu. A porcentagem de lipídios neutros aumentou em LPL. O teor de ácidos graxos saturados diminuiu durante a ontogenia, enquanto os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. Os ácidos graxos polares foram encontrados em porcentagens mais altas em ovos e NHL, e menores em LPL. O teor de ácidos graxos saturados reduziu durante o desenvolvimento ontogenético, enquanto que os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. O conteúdo de proteínas foi mantido durante o desenvolvimento ontogenético, enquanto as classes de aminoácidos sofreram mudanças. Lophiosilurus alexandri usa preferencialmente ácidos graxos saturados e monossaturados como fonte de energia durante o desenvolvimento inicial.(AU)

Description of amino acid and fatty acid content during initial development of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae), a carnivorous freshwater catfish

Samples of eggs, newly hatched larvae (NHL), and larvae at the end of the lecithotrophic period (eight days after hatching) (LPL) of Lophiosilurus alexandri were collected to determine the amino acid and fatty acid profiles. Crude protein did not change throughout initial development and the concentration of lipids was highest in NHL. The content of the indispensable amino acids (IAA) isoleucine, leucine, and valine decreased in LPL, while in eggs and NHL they remained high and similar in value. The dispensable amino acids (DAA), such as aspartic acid, tyrosine, and glycine, increased in LPL, while alanine decreased. The percentage of neutral lipids increased in LPL. The saturated fatty acid content decreased during ontogeny, while monounsaturated fatty acids decreased only in LPL. The polyunsaturated fatty acid content was highest in LP. Polar fatty acids were found in higher percentages in eggs and NHL, but lower in LPL. Saturated fatty acid content decreased during ontogenetic development, while that of monounsaturated fatty acids decreased only in LPL. Polyunsaturated fatty acid content was highest in LPL. Protein content was maintained during ontogenetic development, while amino acid classes experienced changes. Lophiosilurus alexandri preferentially uses saturated and monosaturated fatty acids as an energy source during its early development.(AU)

Amostras de ovos, larvas recém-eclodidas (NHL) e larvas no final do período lecitotrófico (oito dias após a incubação) (LPL) de Lophiosilurus alexandri foram coletadas para determinar os perfis de aminoácidos e ácidos graxos. A proteína bruta não alterou durante o desenvolvimento inicial e a concentração de lipídios foi maior na NHL. O conteúdo dos aminoácidos indispensáveis (IAA) isoleucina, leucina e valina diminuíram em LPL, enquanto nos ovos e NHL eles permaneceram com valores elevados e semelhantes entre si. Os aminoácidos dispensáveis (DAA), como ácido aspártico, tirosina e glicina, aumentaram em LPL, enquanto a alanina diminuiu. A porcentagem de lipídios neutros aumentou em LPL. O teor de ácidos graxos saturados diminuiu durante a ontogenia, enquanto os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. Os ácidos graxos polares foram encontrados em porcentagens mais altas em ovos e NHL, e menores em LPL. O teor de ácidos graxos saturados reduziu durante o desenvolvimento ontogenético, enquanto que os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. O conteúdo de proteínas foi mantido durante o desenvolvimento ontogenético, enquanto as classes de aminoácidos sofreram mudanças. Lophiosilurus alexandri usa preferencialmente ácidos graxos saturados e monossaturados como fonte de energia durante o desenvolvimento inicial.(AU)

Net energy for 60 to 120 kg pigs fed low crude protein diets / Energia líquida em rações com redução de proteína bruta para suínos dos 60 aos 120 kg

Two experiments were conducted to determine the effects of dietary net energy content (NE) on performance and carcass traits of finishing barrows fed low crude protein (CP) diets. Pigs (60.0 ± 2.41 kg, Exp. 1; 90.0 ± 2.96 kg, Exp. 2) were allotted in randomized design to four dietary treatments. Exp. 1 had nine pens treatment-1 and Exp. 2 had eight pens treatment-1, with two pigs in all pens. The treatments were as follows: 179 g kg-1 CP and 2589 kcal NE kg-1, 134 g kg-1 CP and 2631 kcal NE kg-1, 134 g kg-1 CP and 2589 kcal NE kg-1, and 134 g kg-1 and 2589 kcal NE kg-1 (pair-feeding to 179 g kg-1 CP and 2589 kcal NE kg-1) in Exp. 1 and 166 g kg-1 and 2604 kcal NE kg-1, 123 g kg-1 CP and 2645 kcal NE kg-1, 123 g kg-1 CP and 2604 kcal NE kg-1, and 12.34% CP and 2604 kcal NE kg-1 (pair feeding to 166 g kg-1 CP and 2604 kcal NE kg-1) in Exp. 2. In Exp. 1, there was no effect of CP or NE on any performance and carcass traits evaluated. In Exp. 2, the greatest result of average daily gain was obtained with 123 g kg-1 CP and 2645 kcal NE kg-1. There was no effect of CP or NE on any other performance and carcass traits evaluated. For 60 to 90 kg barrows, reducing the CP of the diet from 179 g kg-1 to 134 g kg-1, adjusting or not adjusting the NE content of the diets with 134 g kg-1 CP does not compromise performance or carcass traits. For 90 to 110 kg barrows, reducing the CP of the...(AU)

Dois experimentos foram conduzidos para avaliar níveis de energia líquida (EL) da ração sobre o desempenho e características de carcaça de suínos alimentados com dietas com redução de proteína bruta (PB). Os suínos (60,0 ± 2,41 kg, Exp. 1; 90,0 ± 2,96 kg, Exp. 2) foram distribuídos em delineamento inteiramente casualizado em quatro tratamentos. O Exp. 1 teve nove repetições/tratamento e o Exp. 2, teve oito repetições/tratamento. Todas repetições tiveram dois animais por unidade experimental. Os tratamentos foram: 179 g kg-1 PB e 2589 kcal EL kg-1; 134 g kg-1 PB e 2621 kcal EL kg-1; 134 g kg-1 PB e 2589 kcal EL kg-1 e 134 g kg-1 PB e 2589 kcal EL kg-1 (alimentação pareada a 179 g kg-1 PB e 2589 kcal EL kg-1) no Exp. 1 e 166 g kg-1 PB e 2604 kcal EL kg-1; 123 g kg-1 PB e 2645 kcal EL kg-1; 123 g kg-1 PB e 2604 kcal EL kg-1 e 123 g kg-1 PB e 2604 kcal NE kg-1 (alimentação pareada a 166 g kg-1 PB e 2604 kcal EL kg-1) no Exp. 2. No Exp. 1, não houve efeito da PB ou EL nas variáveis de desempenho e de carcaça. No Exp. 2, o melhor resultado do ganho médio diário foi obtido com a dieta contendo 123 g kg-1 PB e 2645 kcal EL kg-1, comparado com 166 g kg-1 PB e 2604 kcal EL kg-1. Não houve efeito da PB ou da EL em nenhuma outra variável de desempenho e de carcaça. Para suínos dos 60 aos 90 kg, a redução da PB de 179 g kg-1 para 134 g kg-1, mantendo-se ou não o nível de EL da ração, não...(AU)

Evaluation of the standardized ileal digestible lysine requirement of nursery pigs from 28 to 63 d of age in a three-phase feeding program / Avaliação da exigência de lisina digestível de leitões na fase de creche dos 28 a 63 dias de idade em programa de alimentação trifásico

The objective of this study was to determine the standardized ileal digestible lysine (SID Lys)requirement of nursery pigs from 28 to 63 d of age fed a multi-phase feeding (PF) program and itspossible adaptation to SID Lys-deficient diets. Ninety-six commercial hybrid piglets (Topigs Norsvin,46 castrated males and 50 females) that had been weaned at 28 d of age with an initial body weight of8.82 ± 0.28 kg were distributed in a randomized block design composed of four treatments, with eightreplicates per treatment and three animals per replicate. The treatments were as follows: PF1, SID Lyslevels of 1.05, 0.95, and 0.85%; PF 2, SID Lys levels of 1.15, 1.05, and 0.95%; PF 3, SID Lys levelsof 1.25, 1.15, and 1.05%; and PF 4, SID Lys levels of 1.35, 1.25, and 1.15% from 28 to 35, 36 to 49,and 50 to 63 d of age, respectively. From 28 to 63 d of age, the average daily feed intake (ADFI) andaverage daily gain (ADG) were not affected by the SID Lys levels tested; however, final body weight(fBW) was affected, with PF1 having the lowest fBW. The SID Lys levels tested had a significant effecton the feed conversion ratio (FCR), which varied linearly from 28 to 35 d of age. In the period from 28to 63 d of age, pigs fed PF4 had the highest FCR results. The protein deposition ratio (PDR) was alsoaffected by the SID Lys levels tested, with PF3 and PF4 having the highest PDR results. Therefore, theoptimal SID Lys requirement for nursery pigs from 28 to 35 d of age that provided better performanceresults was 1.25%, corresponding to a daily Lys intake of 4.13 g/d. PF3 provided the best performanceand PDR results for piglets from 28 to 63 days of age.

O objetivo deste estudo foi determinar a exigência de lisina digestível (LD) de leitões na fase de creche dos 28 aos 63 dias de idade alimentados com plano nutricional (PN) multifásico e sua possível adaptação às dietas deficientes em LD. Para este propósito, um total de noventa e seis leitões híbridos comerciais (Topigs Norsvin), quarenta e seis machos castrados e cinquenta fêmeas, desmamados aos28 dias de idade, com peso corporal inicial de 8,82 ± 0,28 kg, foram distribuídos em um delineamentoem blocos ao acaso composto por quatro tratamentos (Trt), com oito repetições por Trt, e três animaispor repetição. Os Trts foram: PN1. Níveis de LD de 1,05; 0,95; e 0,85%, PN2. Níveis de LD de 1,15;1,05; e 0,95%, PN3. Níveis de LD de 1,25; 1,15; e 1,05%, e PN4. Níveis de LD de 1,35; 1,25; e 1,15%,respectivamente, para as fases compreendidas de 28 a 35, 36 a 49, e 50 a 63 dias de idade. De 28 a63 dias de idade, a ingestão diária média de alimento (IDMA) e o ganho médio diário (GMD) nãoforam afetados pelos níveis testados de LD o peso corporal final (PCF) dos leitões foi afetado, PN1apresentando o menor PCF. Os níveis de LD testados apresentaram um efeito significativo sobre aconversão alimentar (CA), que variou linearmente de 28 a 35 dias de idade. No período de 28 a 63 dias deidade, os leitões alimentados com PN4 apresentaram os maiores resultados de CA. A taxa de deposiçãode proteína (TDP) também foi afetada pelos níveis de LD testados, com PN3 e PN4 apresentando osmaiores resultados para TDP. Portanto, a exigência de LD para leitões na fase de creche dos 28 aos 35dias de idade que proporcionou os melhores resultados de desempenho foi de 1,25%, correspondendoao consumo diário de lisina de 4,13 g. PN3 forneceu os melhores resultados de desempenho e TDP paraleitões dos 28 aos 63 dias de idade.

Evaluation of the standardized ileal digestible lysine requirement of nursery pigs from 28 to 63 d of age in a three-phase feeding program / Avaliação da exigência de lisina digestível de leitões na fase de creche dos 28 a 63 dias de idade em programa de alimentação trifásico

The objective of this study was to determine the standardized ileal digestible lysine (SID Lys)requirement of nursery pigs from 28 to 63 d of age fed a multi-phase feeding (PF) program and itspossible adaptation to SID Lys-deficient diets. Ninety-six commercial hybrid piglets (Topigs Norsvin,46 castrated males and 50 females) that had been weaned at 28 d of age with an initial body weight of8.82 ± 0.28 kg were distributed in a randomized block design composed of four treatments, with eightreplicates per treatment and three animals per replicate. The treatments were as follows: PF1, SID Lyslevels of 1.05, 0.95, and 0.85%; PF 2, SID Lys levels of 1.15, 1.05, and 0.95%; PF 3, SID Lys levelsof 1.25, 1.15, and 1.05%; and PF 4, SID Lys levels of 1.35, 1.25, and 1.15% from 28 to 35, 36 to 49,and 50 to 63 d of age, respectively. From 28 to 63 d of age, the average daily feed intake (ADFI) andaverage daily gain (ADG) were not affected by the SID Lys levels tested; however, final body weight(fBW) was affected, with PF1 having the lowest fBW. The SID Lys levels tested had a significant effecton the feed conversion ratio (FCR), which varied linearly from 28 to 35 d of age. In the period from 28to 63 d of age, pigs fed PF4 had the highest FCR results. The protein deposition ratio (PDR) was alsoaffected by the SID Lys levels tested, with PF3 and PF4 having the highest PDR results. Therefore, theoptimal SID Lys requirement for nursery pigs from 28 to 35 d of age that provided better performanceresults was 1.25%, corresponding to a daily Lys intake of 4.13 g/d. PF3 provided the best performanceand PDR results for piglets from 28 to 63 days of age.(AU)

O objetivo deste estudo foi determinar a exigência de lisina digestível (LD) de leitões na fase de creche dos 28 aos 63 dias de idade alimentados com plano nutricional (PN) multifásico e sua possível adaptação às dietas deficientes em LD. Para este propósito, um total de noventa e seis leitões híbridos comerciais (Topigs Norsvin), quarenta e seis machos castrados e cinquenta fêmeas, desmamados aos28 dias de idade, com peso corporal inicial de 8,82 ± 0,28 kg, foram distribuídos em um delineamentoem blocos ao acaso composto por quatro tratamentos (Trt), com oito repetições por Trt, e três animaispor repetição. Os Trts foram: PN1. Níveis de LD de 1,05; 0,95; e 0,85%, PN2. Níveis de LD de 1,15;1,05; e 0,95%, PN3. Níveis de LD de 1,25; 1,15; e 1,05%, e PN4. Níveis de LD de 1,35; 1,25; e 1,15%,respectivamente, para as fases compreendidas de 28 a 35, 36 a 49, e 50 a 63 dias de idade. De 28 a63 dias de idade, a ingestão diária média de alimento (IDMA) e o ganho médio diário (GMD) nãoforam afetados pelos níveis testados de LD o peso corporal final (PCF) dos leitões foi afetado, PN1apresentando o menor PCF. Os níveis de LD testados apresentaram um efeito significativo sobre aconversão alimentar (CA), que variou linearmente de 28 a 35 dias de idade. No período de 28 a 63 dias deidade, os leitões alimentados com PN4 apresentaram os maiores resultados de CA. A taxa de deposiçãode proteína (TDP) também foi afetada pelos níveis de LD testados, com PN3 e PN4 apresentando osmaiores resultados para TDP. Portanto, a exigência de LD para leitões na fase de creche dos 28 aos 35dias de idade que proporcionou os melhores resultados de desempenho foi de 1,25%, correspondendoao consumo diário de lisina de 4,13 g. PN3 forneceu os melhores resultados de desempenho e TDP paraleitões dos 28 aos 63 dias de idade.(AU)

Phosphorus requirements of tambaqui juveniles / Exigência de fósforo para juvenis de tambaqui

The aim of this study was to determine the requirement of digestible phosphorus in diets for juvenile tambaqui (Colossoma macropomum). 300 juveniles (26.4 ± 0.68 g) were used in a completely randomized design, consisting of six treatments with five replicates and 10 fish per experimental unit. The treatments consisted of six isoprotein, isonitrogenous, and isocalcium rations, with different levels of digestible phosphorus: 0.27; 0.46; 0.67; 0.91; 1.04; and 1.14%. The fish were kept in 30 polyethylene tanks (500 L) with a closed water circulation system and fed six meals per day for 49 days. Parameters of performance and feed efficiency, daily protein, and fat, ash, and phosphorus deposition rates were evaluated. The elevation of digestible phosphorus provided a quadratic increase in feed consumption to a level of 0.92%, linear increase in the consumption of digestible phosphorus, and quadratic reduction in the efficiency of digestible phosphorus for weight gain. The linear response plateau model was the best fit for weight gain and specific growth rate, estimated at 0.55% and 0.56% digestible phosphorus, respectively. The feed conversion and protein efficiency for weight gain improved quadratically up to an estimated level of 0.84% of digestible phosphorus. Body fat deposition improved quadratically up to an estimated level of 0.90% of digestible phosphorus. The linear response plateau model was the best fit for body deposition of protein, ash, and phosphorus, estimated at 0.55%, 0.46%, and 0.59% of digestible phosphorus, respectively. To optimize weight gain, the recommended level of digestible phosphorus in diets for juvenile tambaqui is 0.55%, which corresponds to an estimated level of 0.87% of total phosphorus.(AU)

Objetivou-se determinar a exigência de fósforo digestível em rações para juvenis de tambaqui (Colossoma macropomum). Utilizou-se 300 juvenis (26,4±0,68 g) em delineamento inteiramente casualizado, composto por seis tratamentos, cinco repetições e dez peixes por parcela. Os tratamentos constituíram-se de seis rações isoproteicas, isoenergéticas e isocálcicas, com diferentes níveis de fósforo digestível (0,27; 0,46; 0,67; 0,91; 1,04; e 1,14%). Os peixes foram mantidos em 30 caixas de polietileno de 500 L em sistema fechado de circulação de água e alimentados em seis refeições diárias durante 49 dias. Avaliaram-se parâmetros de desempenho e eficiência alimentar, taxas de deposição diária de proteína, gordura, cinzas e fósforo corporais. A elevação dos níveis de fósforo digestível proporcionou aumento de forma quadrática no consumo de ração até o nível de 0,92%, aumento linear no consumo de fósforo digestível, e redução de forma quadrática na eficiência de fósforo digestível para o ganho de peso dos peixes. Para o ganho de peso e taxa de crescimento específico dos peixes, o modelo Linear Response Plateau foi o que melhor se ajustou aos dados, estimando em 0,55% e 0,56% o nível de fósforo digestível a partir dos quais ocorreram os platôs. A conversão alimentar e a eficiência proteica para o ganho de peso melhoraram de forma quadrática até o nível estimado de 0,84% de fósforo digestível, respectivamente. A deposição gordura corporal de forma quadrática até o nível estimado de 0,90% de fósforo digestível. Para as deposições corporais de proteína e cinzas e fósforo, o modelo Linear Response Plateau foi o que melhor se ajustou aos dados, estimando em 0,55%, 0,46%, 0,59% o nível de fósforo digestível a partir dos quais ocorreram os respectivos platôs. Concluiu-se que a recomendação dos níveis de fósforo digestível em rações para juvenis de tambaqui é de 0,55%, por otimizar o ganho de peso, que corresponde ao nível estimado de 0,87% de fósforo total.(AU)