ABSTRACT 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.

RESUMO Objetivou-se determinar a composição aminoacídica e os valores de proteína digestível de diferentes leveduras de cana-de-açúcar, bem como gerar equações de predição dos coeficientes de digestibilidade aparente da matéria seca (CDAMS) e proteína bruta (CDAPB), com base na composição química da levedura e idade dos frangos de corte. Quatro ensaios de digestilidade ileal foram realizados com 690 frangos de corte, divididos nas fases pré-inicial, inicial, crescimento e final. As aves foram alojadas em gaiolas de metabolismo e distribuídas num delineamento inteiramente casualizado constituído de cinco tratamentos e seis repetições de: oito, seis, cinco e quatro, respectivamente, para cada fase experimental. Os tratamentos foram: uma ração referência e quatro rações testes com a substituição de 30% da ração referência por quatro diferentes leveduras. As leveduras dois e quatro apresentaram maiores percentagem de aminoácidos. Entretanto, a levedura dois apresentou os maiores percentuais de CDAMS, CDAPB e de proteína digestível, estes sendo: 83,64; 81,22 e 14,66% na fase pré-inicial, 78,09; 78,28; 14,13% na inicial, 76,74; 74,75 e 13,49% na fase de crescimento e 72,98; 71,21 e 12,85% na fase final, respectivamente. Houve redução média de 0,424% no CDAMS e 0,428% no CDAPB, para cada dia de envelhecimento das aves. A partir da composição das leveduras e idade dos frangos, foram geradas as seguintes equações de predição: CDAMS = 77,4 - 0,424*(idade) - 7,51*(MS) -45,01*(EE) e - 0,424* (idade) + 3,02*(PB) + 126,93*(EE) - 0,03*(DGM) e CDAPB = 606,9 - 0,428*(idade) - 5,8*(MS) - 0,01*(DGM) e - 0,426*(idade) + 2,68(PB) + 139,7*(EE) - 0,03*(DGM).

ABSTRACT The aim of this study was to determine the amino acid composition and digestible protein values of different sugarcane yeasts, as well as to generate prediction equations for the apparent digestibility coefficient of dry matter (ADCDM) and crude protein (ADCCP), based on the chemical composition of the yeast and the age of the broilers. Four ileal digestion trials were carried out with 690 broilers, divided into the pre-starter, starter, growth and final phases. The birds were housed in metabolic cages and distributed in a completely randomised design, consisting of five treatments and six replications of eight, six, five and four birds respectively in each experimental phase. The treatments consisted of one reference feed and four test feeds, substituting 30% of the reference feed with four different yeasts. Yeasts two and four showed a higher percentage of amino acids. However, yeast two had the highest percentages of ADCDM, ADCCP and digestible protein: 83.64, 81.22 and 14.66% in the pre-starter phase; 78.09, 78.28 and 14.13% in the starter phase; 76.74, 74.75 and 13.49% in the growth phase; and 72.98, 71.21 and 12.85% in the final phase respectively. There was an average reduction of 0.424% in ADCDM and 0.428% in ADCCP for each day the birds aged. The following prediction equations were generated from the composition of the yeasts and age of the chickens: ADCDM = 77.4 - 0.424*(age) - 7.51*(DM) - 45.01*(EE) and - 0.424*(age) + 3.02*(CP) + 126.93*(EE) - 0.03*(GMD) and ADCCP = 606.9-0.428*(age) -5.8*(DM) - 0.01*(GMD) and -0.426*(age) + 2.68(CP) + 139.7*(EE) - 0.03*(GMD).

ABSTRACT The objective of this study was to describe the growth of freshwater angelfish (Pterophyllum scalare) using the Gompertz model, determining the relative growth and allometric coefficients of body components in relation to body weight and protein weight. Six hundred animals were grown until 233 days of age. Data on chemical composition (water, lipid, protein, and ash) and weight measurements were obtained each 30 days. The Gompertz growth equation was used to analyze chemical allometry and to estimate growth parameters. The relationship between chemical components and body protein was estimated. Protein and body weight increased proportionally, with ash being the earliest nutrient (209.2 days), while lipid deposition occurred later. Linear regression analysis showed an inverse relationship between lipids and body water. This study provided a useful equation to predict the growth, chemical body composition, and rate of nutrient deposition across the life stages of freshwater angelfish. The rates of nutrient deposition as a function of body weight are important to understand the growth process of freshwater angelfish. Thus, mature weight was estimated in 26.14 g. The allometric relationships of body components and deposition rates indicated that protein and body weight are highly correlated across the life stages of freshwater angelfish. The Gompertz equation is a useful tool to describe the growth and body composition of freshwater angelfish.

RESUMO Objetivou-se avaliar o efeito do nível de substituição do gérmen integral de milho (GIM) sobre os valores energéticos obtidos pelos métodos de Matterson e da regressão. Foram utilizadas 120 aves com 45 semanas de idade, da linhagem Embrapa 051. O ensaio foi delineado inteiramente ao acaso, com cinco tratamentos e seis repetições de 4 aves. Os tratamentos foram compostos pela ração referência (RR) e quatro níveis de substituição da RR (10, 20, 30 e 40% pelo GIM). Foi utilizado o método de coleta total de excretas. As variáveis analisadas foram: energia metabolizável aparente (EMA), aparente corrigida para o balanço de nitrogênio (EMAn), tempo (TP) e taxa de passagem (TxP) do GIM. A relação entre as variáveis e os níveis de GIM foi estudada por análise de regressão. O tempo e a taxa de passagem foram afetados linearmente pelo nível de substituição do GIM. Os valores de EMA e EMAn foram reduzidos com o aumento do nível de substituição até 31,4 e 32,2% de GIM, respectivamente. O método da regressão proporcionou melhores estimativas para EMA e EMAn do GIM. Os valores de EMA e EMAn do GIM para aves de postura foram 5,161 e 5,066 kcal g-1, respectivamente.

ABSTRACT The aim of this study was to evaluate the effect of the substitution level of corn germ meal (CGM) on energy values obtained with Matterson's method and regression analysis. One hundred twenty laying hens from Embrapa 051 strain with 45 weeks of age, were used. The trial design was completely randomised, with five treatments and six replications of four birds. The treatments consisted of the reference feed (RF) and four other diets with dietary substitution levels of RF by CGM (10, 20, 30 and 40%). The method of total excreta collection was used. The variables analysed were: apparent metabolizable energy (AME), AME corrected for nitrogen balance (AMEn), time (T) and passage rate (PR) of the CGM. The relationship between the variables and levels of CGM was studied with regression analysis. The time and passage rate were linearly affected by the level of substitution of the CGM; with increases in the level of substitution. The values for AME and AMEn were reduced by 31.4% and 32.2% CGM respectively. The regression method provides better estimates for AME and AMEn of the CGM. In laying hens the CGM values for AME and AMEn were 5.161 and 5.066 kcal g-1, respectively.

RESUMO O intuito desta pesquisa foi analisar o ajuste da função Gompertz fixando, ou não alguns parâmetros para descrever o crescimento corporal e dos principais constituintes químicos corporais de frangas de postura em crescimento. Foram coletados semanalmente os dados de peso corporal e os componentes químicos da carcaça depenada e penas de 1.200 pintainhas de quatro linhagens de postura: Hisex marrom, Hisex branca, Hy Line marrom e Hy Line branca W36, até a 18ª semana de idade. As variáveis foram submetidas a dois ajustes, fixando-se ou não alguns parâmetros da função Gompertz. Foram calculados os parâmetros de um modelo alométrico para os componentes químicos. Lipídeo e proteína foram os componentes da carcaça depenada com maior variação nas últimas semanas. Por outro lado, a composição química da pena apresentou pouca variação. Os parâmetros da função Gompertz assumiram valores de acordo com o ajuste empregado, sobretudo para proteína e gordura da carcaça depenada. O ajuste da função Gompertz, fixando os dois parâmetros, permitiu coerência e significado biológico. Os coeficientes alométricos indicaram que à medida que aumentou o peso proteico, aumentou a proporção de gordura e reduziu a proporção de água e cinzas no corpo. O ajuste do modelo, fixando os parâmetros, possibilita coerência com significado biológico, sem perder a precisão nas estimativas.

ABSTRACT The purpose of this research was analyze the fit of Gompertz function with or without fixing some of the parameters to describe body growth and major bodily chemical constituents of growing pullets. Weekly, data of body weight and chemical components of body free of feathers and feathers were collected from 1,200 chicks of four laying strains (Hisex Brown, Hisex White, Hy Line Brown and Hy Line White W36) until 18 weeks of age. The variables were subjected to two adjustments fixing, or not, some parameters of Gompertz function. The allometric model parameters were calculated for the chemical components. The lipid and protein composition of the body free of feathers were the components with the biggest change in the last weeks. Moreover, the chemical composition of the feather showed small variation. The parameters of the Gompertz function assumed values according to the employed adjustment, especially for protein and fat of the body free of feathers carcass. The adjustment of the Gompertz function by fixing the two parameters allowed coherence and biological significance. The allometric coefficients indicate that as the protein weight increased, the proportion of fat increased and the proportion of water and ashes in the body decreased. The fit of the model allows setting the parameters with consistency and biological significance without losing accuracy in the estimates.

A utilização de procedimento linear-platô para descrever a resposta de um indivíduo a ingestão de um nutriente na população tem sustentação teórica, uma vez que cada indivíduo tem seu máximo potencial de produção determinado geneticamente, e qualquer aumento no consumo de nutriente limitante acima de manutenção resulta numa resposta linear na massa de ovo até atingir o potencial genético e, portanto, atendendo a exigência do indivíduo. No entanto, por causa da distribuição do peso corporal e da massa de ovos na população, a resposta média da população é curvilínea, a qual anula a possibilidade de definir uma "exigência" para o nutriente limitante, e, ao invés disso, leva à possibilidade de definir uma ingestão ótima econômica do nutriente. O Reading Model descreve a resposta da população à ingestão do nutriente limitante, integrando as respostas dos indivíduos que constituem a população. A resposta da população é obtida invertendo um modelo fatorial simples, usando parâmetros para descrever o peso corporal, máximo potencial de produção e as respectivas distribuições (normal) e covariância. Reading Model descreve a resposta da população à ingestão do nutriente limitante, integrando as respostas dos indivíduos que constituem a população. A resposta da população é obtida invertendo um modelo fatorial simples, usando parâmetros para descrever o peso corporal, máximo potencial de produção e as respectivas distribuições (normal) e covariância. A resposta média da população é representada por um modelo linear-platô com uma forma sigmoidal. O Reading Model tem sido amplamente utilizado para estimar a ingestão ótima econômica de aminoácidos para poedeiras comerciais, com diferenças no peso corporal e massa de ovo

The use of a linear-plateau procedure to describe the response of an individual in the population has theoretical support, since the maximum potential performance of each individual is genetically determined, and any increment in intake of the limiting nutrient above maintenance will result in a linear response in output until this genetic potential, and hence requirement, is reached. However, because of the distribution of body weights and maximum potential outputs in the population, the mean response of the population is curvilinear, which negates the possibility of defining a 'requirement' for the limiting nutrient, and instead leads to the possibility of defining an optimum economic intake of the nutrient.. The Reading model describes the response of a flock to a limiting nutrient by integrating the responses of the individuals making up the population. The response of the population is obtained by inverting a simple factorial model using parameters to describe the mean body weight and maximum output of the flock, their distributions (normal) and covariance. The average response of the population is represented by a linear plateau model with a sigmoidal shape. This model has been widely used to predict the optimum economic intake of amino acids for commercial laying flocks varying in body weight and potential egg output

The objective of this study was to measure the response of Dekalb White laying hens to different intakes of digestible methionine + cystine (met+cys) to optimise their performance. Two hundred eighty-eight Dekalb White laying hens, ranging in age from 33 to 48 weeks, were used in the study. The birds were randomly allocated into eight treatment (levels of met+cys and the control treatment) groups with six replicates of six hens per unit. The experimental diets consisted of seven increasing levels of met+cys (1.37, 2.75, 4.14, 5.51, 6.89, 7.92 and 8.95 g kg−1) and were prepared using a dilution technique. A control treatment was used to confirm that the limiting response was due to met+cys intake. Egg production, feed intake, egg weight, egg mass and feed conversion per mass were measured. The data were analysed with repeated measures and regression analyses using Broken Line and Quadratic models, as well as using the combination of both models. The different met+cys intakes influenced the studied variables; all the variables except feed conversion per mass were significantly different between the periods and levels. The digestible met+cys intakes based on the association of the Broken Line and Quadratic models to optimise the birds' response to egg mass are 671 mg/bird d for 33 to 36 weeks, 728 mg/bird d for 37 to 40 weeks, 743 mg/bird d for 41 to 44 weeks, and 770 mg/bird d for 45 to 48 weeks.

O conhecimento do crescimento dos animais é importante para a atividade zootécnica ser mais precisa e sustentável. O objetivo do estudo foi descrever o crescimento em peso vivo, dos tecidos hepático e adiposo, da coxa e o consumo alimentar acumulado da rã-touro na engorda, através de ajuste de modelos não lineares. Foram utilizados 2.375 imagos de rã-touro com peso inicial de 7,03±0,16g, os quais foram alojados em cinco baias de engorda com 12 m². Foram realizadas 10 amostragens, a cada 14 dias, para obtenção das variáveis estudadas. Os dados amostrados foram utilizados para estimar os parâmetros dos modelos de Gompertz e Logístico em função do tempo. Os valores estimados de peso (Pm) e consumo à maturidade (Cm) e tempo em que a taxa de crescimento é máxima (t*) dos parâmetros avaliados foram mais próximos do esperado no modelo Logístico. Os valores de Pm para peso vivo, tecido hepático e adiposo, coxas e Cm para consumo alimentar foram 343,7 g; 15,7g; 19.6g; 96,03 e 369,3g, respectivamente, com t* aos 109, 98, 105, 109 e 107 dias, respectivamente. Portanto, o modelo Logístico foi a melhor ferramenta para estimar o crescimento e o consumo alimentar da rã-touro na fase de engorda.

Knowledge of the growth of animals is important so that zootechnical activity can be more accurate and sustainable. The objective of this study was to describe the live weight, development of liver tissue and fat body, leg growth, and cumulative food intake of bullfrogs during the fattening phase using nonlinear models. A total of 2,375 bullfrog froglets with an initial weight of 7.03 ± 0.16 g were housed in five fattening pens (12 m²). Ten samplings were performed at intervals of 14 days to obtain the variables studied. These data were used to estimate the parameters of Gompertz and logistic models as a function of time. The estimated values of weight (Wm) and food intake (FIm) at maturity and time when the growth rate is maximum (t*) were closer to expected values when the logistic model was used. The Wm values for live weight and liver, adipose and leg weights and the FIm value for food intake were 343.7, 15.7, 19.6, 96.03 and 369.3 g, respectively, with t* at 109, 98, 105, 109 and 107 days. Therefore, the logistic model was the best model to estimate the growth and food intake of bullfrogs during the fattening phase.

An outstanding feature of poultry production that provides animal protein yield for human feeding is its short production cycle. This characteristic has a linear relationship with waste production. Increasing the inclusion of this residue in diets in the near future is desirable in step with the growth of poultry production since it offers a better environmental and nutritional alternative to current methods. We evaluated the effects on the performance and carcass characteristics of broiler chickens produced by the inclusion of poultry offal meal (POM) in their feed. Treatments consisted of a control diet (corn, Zea mays and soybean, Glycine max) and four diets with inclusion of 30, 60, 90 and 120 g kg-1 of POM. The diets were formulated based on the level of digestible amino acid once categorized as isocalcic, isophosphoric, isosodic, isoenergetic and isonutritive for protein, methionine+cystine, lysine and threonine. The feed's electrolytes were corrected so that each diet had the same electrolytic balance. The variables analyzed were feed intake, weight gain, feed conversion ratio, body weight, carcass yield, chicken cut yield and abdominal fat. Feed intake was not affected by the quantities of POM added. The weight gain, feed conversion, carcass yield and noble cuts presented quadratic responses to the treatments. Abdominal fat increased linearly. The performance of the poultry, and carcass characteristics were maximized by the inclusion of 53 and 65 g kg-1, respectively, of POM in the diet, and the inclusion of 120 g kg-1 of POM provided greater disposition of abdominal fat.

O objetivo deste estudo foi desenvolver um procedimento baseado na função Gompertz para determinar a eficiência de utilização do aminoácido. O procedimento foi aplicado para determinar a eficiência de utilização da lisina, metionina+cistina e treonina da dieta de frangas de postura em crescimento, e com base nas eficiências foram estimadas as exigências para fase de crescimento das aves. A função Gompertz foi ajustada aos dados de consumo de ração, peso corporal, peso proteico do corpo depenado e peso de penas de quatro linhagens de aves de postura na fase de crescimento. As taxas de consumo e deposição diária de proteína (DP) foram calculadas. A deposição do aminoácido foi obtida multiplicando a DP pela concentração do aminoácido nas penas e corpo depenado. Os resultados obtidos demonstraram que as eficiências de utilização dos aminoácidos diminuíram com a maturidade e, inversamente, houve um aumento proporcional da exigência por kg de ganho de peso. O procedimento baseado na função Gompertz para determinar a eficiência de utilização do aminoácido mostrou ser adequado para avaliar a eficiência de utilização do aminoácido e pode ser uma ferramenta útil para diagnosticar a eficácia do manejo nutricional auxiliando na tomada de decisões sobre o manejo nutricional.

The aim of this study was to develop a procedure based on Gompertz function to determine the efficiency of utilization of amino acid. The procedure was applied to determine the efficiency of utilization of dietary lysine, methionine+cystine and threonine by growing pullets and based on the efficiencies were estimated the requirements for the growth phase of birds. The Gompertz function was fitted to the data of feed intake, body weight, feather-free body protein weight and feather protein weight of four strains of laying hens in the growth phase. The rates of consumption and daily protein deposition (PD) were calculated. The amino acid deposition was obtained by multiplying the PD by the amino acid concentration in feather protein and feather-free body protein. The results showed that the efficiency of utilization of amino acid decreased with maturity and, conversely, there was a proportional increase of the requirement per kg of weight gain. The procedure based on the Gompertz function to determine the efficiency of utilization of amino acid proved to be suitable to evaluate the efficiency of utilization of amino acid and can be a useful tool to diagnose the effectiveness of the nutritional management, aiding in decision-making on the nutritional management.

Broiler strains available in the poultry industry present different requirements for dietary lysine due to their different growth potentials as a result of their genetic makeup. This study aimed to determine the model parameters for maximum nitrogen retention (NRmaxT), the nitrogen maintenance requirement (NMR) and the efficiency of lysine utilization (bc-1) to reevaluate the lysine (Lys) requirements of male and female broilers. Nitrogen balance trials were performed during three periods (I: 6-21 days, II: 22-37 days, and III: 38-53 days). Seven treatments were used for males and females; the treatments consisted of seven diets with protein levels ranging from 61 to 364 g kg-1 dry matter, with Lys being limiting in the dietary nitrogen (4.91 g of Lys in 16 g of N). Nitrogen intake (NI), excretion (NEX), deposition (ND, ND=NI-NEX) and retention (NR, NR=ND+NMR) values were obtained. The NMR was represented by the exponential relationship between NEX and NI. The NRmax T and bc-1 were estimated by the exponential fit between ND and NI. The NRmax T, bc-1, and NMR values were combined in a model to estimate Lys intake by simulating different percentages of the NRmaxT. The Lys intake estimates were 581, 1,538, and 2,171 mg day-1 for males and 512, 1,340, and 1674 mg day-1 for females during periods I, II, and III, respectively. Due to the flexibility of the model, it is possible to calculate the Lys intake for percentages of NR in the range of practical performance data.

Objetivou-se com esta pesquisa descrever o potencial de retenção de nitrogênio por duas técnicas: abate comparativo e balanço de nitrogênio. Também se objetivou comparar os modelos ajustados para cada técnica e estimar as exigências de mantença para frangas de postura. Os ensaios foram realizados no período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, utilizando 168 frangas. Os ensaios tiveram sete tratamentos e oito repetições. Os tratamentos consistiram de níveis de proteína variando de 75 a 435gkg-1 de matéria seca. As variáveis coletadas pelo abate comparativo foram nitrogênio ingerido e depositado e, pela técnica do balanço de nitrogênio, ingestão e excreção de nitrogênio. O intercepto da relação exponencial entre nitrogênio excretado e ingerido foi considerado a exigência de mantença. Os modelos ajustados foram comparados pelo teste da razão de máxima verossimilhança. As técnicas comparadas descreveram de forma diferente a exigência de mantença de nitrogênio. Para o abate comparativo, a exigência de mantença foi estimada em 342, 372 e 543mg/kgPC0,67 e para o balanço de nitrogênio foi de 342, 225 e 284mg/kgPC0,67, para os período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, respectivamente.

The objectives of this study were to describe the potential for nitrogen retention by two techniques: comparative slaughter and nitrogen balance; compare the adjusted models for each technique and estimate the maintenance requirement for pullets. Assays were performed during 14 to 28, 56-70 and 98 to 112 days of age, using 168 pullets. The design was completely randomized with seven treatments and eight replications. Treatments consisted of protein levels ranging from 75 to 435gkg-1 of dry matter. The variables were collected by comparative slaughter and nitrogen ingested and deposited in nitrogen balance technique intake and nitrogen excretion. The intercept of the exponential relationship between ingested and excreted nitrogen was considered a requirement for maintenance. The adjusted models were compared by using the maximum likelihood ratio. The techniques described differently compared the requirement for maintenance of nitrogen. For comparative slaughter requiring maintenance was estimated at 342, 372 and 543mg/kgPC0,67 and for nitrogen balance was 342, 225 and 284mg/kgPC0,67 for the period of 14 to 28, 56-70 and 98 to 112 days of age, respectively.

Objetivou-se descrever o máximo potencial de deposição de nitrogênio e estimar a ingestão de metionina+cistina pela técnica do balanço de nitrogênio e abate comparativo. Foram realizados ensaios no período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, utilizando 168 frangas Dekalb White, distribuídas em sete tratamentos e oito repetições. Os tratamentos consistiram de níveis de proteína na dieta, variando de 75 a 435 g kg-1 de matéria seca, em que a metionina+cistina foi o primeiro aminoácido limitante. As variáveis coletadas pelo abate comparativo foram nitrogênio ingerido e depositado e, nos ensaios de balanço de nitrogênio, coletaram-se ingestão e excreção de nitrogênio. Por meio da relação exponencial entre ingestão e deposição de nitrogênio, determinou-se a máxima deposição de nitrogênio. As técnicas foram comparadas pelo teste da razão de máxima verossimilhança. As técnicas descrevem de forma diferente o máximo potencial de deposição pela ave, mas são similares na estimativa da exigência de metionina+cistina. Com base em 60% do máximo potencial, as ingestões de metionina+cistina digestível foram estimadas em 163, 243 e 343 mg dia-1 para os período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, respectivamente.

This study aimed to describe the maximum potential of nitrogen deposition and to estimate the intake of methionine+cystine by nitrogen balance and comparative slaughter. Assays were performed in the periodsof 14 to 28, 56 to 70 and 98 to 112 days of age, using 168 Dekalb White pullets, distributed in seven treatments and eight replications. Treatments consisted of protein levels in the diets ranging from 75 to 435 g kg-1 dry matter in which methionine+cystine was the first limiting amino acid. The variables collected by comparative slaughter were nitrogen intake and deposition and, in nitrogen balance trials were collected nitrogen intake and excretion. With the exponential relationship between nitrogen intake and deposition was determined the maximum nitrogen deposition. The techniques were compared by the test of maximum likelihood ratio. The techniques described differently the maximum potential for deposition by the bird, but were similar in the estimation of methionine+cystine. Based on 60% of the maximum potential the intakes of digestible methionine+cystine were estimated at 163, 243 and 343mg day-1 for the period of 14 to 28, 56 to70 and 98 to 112 days of age, respectively.

Objetivou-se com esta pesquisa avaliar o efeito da idade sobre os coeficientes de digestibilidade ileal aparente dos nutrientes, da energia bruta e os valores de energia digestível do gérmen integral de milho para frangos de corte. Quatro ensaios de digestibilidade foram realizados com 280 aves de corte (Cobb 500) distribuídas em um delineamento experimental inteiramente casualizado, com quatro tratamentos e cinco repetições. Os tratamentos avaliados consistiram das diferentes idades das aves: 10, 20, 30 e 40 dias. A quantidade de aves utilizadas nos ensaios foram: dez, oito, seis e quatro em cada unidade experimental, nas diferentes idades avaliadas, respectivamente. Os resultados foram analisados considerando-se como variável dependente a digestibilidade ileal aparente da matéria seca, da proteína bruta, do extrato etéreo e da energia bruta, matéria seca digestível, proteína bruta digestível, extrato etéreo digestível e energia digestível e como variável independente as idades (10, 20, 30 e 40 dias). Os resultados obtidos para as variáveis analisadas revelaram que a idade da ave exerceu influência apenas nos coeficientes de digestibilidade ileal da matéria seca e da energia bruta. A energia digestível do gérmen integral de milho aumentou cerca de 13 kcal kg-1 dia-1 até a idade avaliada (40 dias).

The objective of this research study was to evaluate the effect of age on the apparent ileal digestibility coefficient of nutrients, gross energy and digestible energy of corn germ meal for broilers. Four digestibility trials were conducted using 280 broilers (Cobb 500) distributed in a completely randomized design with two treatments and five replications, repeated at four ages (10, 20, 30 and 40 days). The number of birds used in the tests was 10, 8, 6 and 4 birds per experimental unit at the different ages. The results were analyzed considering as dependent variable the apparent ileal digestibility of dry matter, crude protein, ether extract and gross energy, digestible dry matter, digestible crude protein, lipid and digestible energy; and ages (10, 20, 30 and 40 days) as the independent variable. The results for the variables showed that bird age exerted influence only in the ileal digestibility of dry matter and gross energy. The digestible energy of corn germ meal increased by about 13 kcal kg-1 day-1 up to the evaluated age (40 days).

Objetivou-se determinar a composição química e os valores nergéticos dos resíduos de goiaba e de tomate para frangos de corte em diferentes idades. Os resíduos foram coletados em meses distintos e, posteriormente, determinada a composição química por meio de ensaios de metabolismo utilizando a metodologia da coleta total de excretas. Utilizaram-se 270 pintos de corte da linhagem COBB, sendo 150 no período de 1 a 8 dias e 120 no período de 10 a 17 dias de idade. Nos ensaios utilizou-se o delineamento inteiramente casualizado e três tratamentos com cinco repetições de 10 e 8 aves nas respectivas idades. Os tratamentos consistiram de três dietas: uma dieta referência, uma com 30% de farelo de tomate e outra com 20% de farelo de goiaba, ambas substituindo parte da ração referência. Os valores de composição química dos resíduos da goiaba e do tomate variaram quanto à época de coleta. Os resíduos apresentaram composição satisfatória para alimentação de aves, porém com altos teores de fibra bruta. Os valores de energia metabolizável o coeficiente de metabolizabilidade da energia bruta do resíduo da goiaba não sofreram influência da idade das aves. Para o resíduo de tomate os valores de energia metabolizável aparente e coeficiente de metabolização variaram entre as idades. Os valores de energia metabolizável aparente corrigida para pintos de corte de 1 a 8 e de 10 a 17 dias de idade foram de 1.331 e 1.358 kcal/kg para o resíduo de goiaba e de 2.351 e 2.465 kcal/kg para o resíduo de tomate.

The chemical composition and energy value of guava and tomato wastes for broilers at different ages were determined in this research. The metabolism assays were carried out by using the methodology of total excreta collection to calculate the chemical composition of wastes collected in different months. A total of 270 COBB broiler chicks was used: 150 in the period from 1 to 8 days of age (phase 1) and 120 chicks were used in the period from 10 to 17 days of age (phase 2). The trials were analyzed as completely randomized design with three treatments with five replications of 10 and 8 birds at the respective ages. The treatments consisted of different diets: one reference diet, one with 30% tomato meal and another with 20% guava meal, both partially replacing the reference diet. The values of the chemical composition of guava and tomato wastes varied according to the collection season. The chemical composition indicated that the wastes can be used in poultry feed, but with high crude fiber contents. The values of apparent metabolizable energy and nitrogen-corrected apparent metabolizable energy and of gross energy metabolizability coefficient of guava waste was not affected by the birds age, different from the result observed for tomato waste, whose digestibility coefficients and apparent metabolizable energy values varied among growing phases. The apparent metabolizable energy values (AME) for broilers form 1 to 8 and from 10 to 17 days of age were 1,331 and 1,358 kcal/kg for guava waste and from 2,351 to 2,465 kcal/kg for tomato waste.