Resumo Objetivou-se determinar a exigência de metionina + cistina total para frangas na fase inicial e verificar seu efeito sobre a fase de postura. Na primeira fase experimental, 720 aves (50% Lohmann LSL e 50% Lohmann Brown) com uma semana de idade foram distribuídas em delineamento experimental inteiramente casualizado, em esquema fatorial 5 x 2 (níveis de met + cis e linhagens), com quatro repetições e 18 aves por repetição. Os níveis de met + cis total estudados foram 0,536; 0,616; 0,696; 0,776; e 0,856 %. Ao atingirem 22 semanas de idade, iniciou-se a segunda fase experimental, sendo utilizadas 240 aves (50% Lohmann LSL e 50% Lohmann Brown) provenientes da primeira fase experimental. A ração fornecida às aves nesta fase foi igual para todos os tratamentos. Na fase de produção avaliaram-se os efeitos residuais das dietas fornecidas no período inicial sobre os parâmetros produtivos. As exigências de metionina + cistina recomendadas para aves leves e semipesadas, no período de 1 a 6 semanas de idade, são de 0,778% de met + cis total (correspondendo a 0,700% de met + cis digestível) e 0,739% de met + cis total (correspondendo a 0,665% de met + cis digestível), respectivamente.

Abstract An experiment was carried out to evaluate the requirement of methionine +cystine for growing pullets at starter phase (1 to 6 weeks old) and its effect on the laying phase. In the first experiment, 720 birds (50% Lohmann LSL and 50% Lohmann Brown) at one week of age were distributed on a completely randomized design, 5 x 2 factorial arrangement (levels of met + cys and strain), with four replications and 18 birds each. The levels of total methionine + cystine studied were 0.536; 0.616; 0.696; 0.776; and 0.856 %. At 22 weeks of age, 240 birds were used for the second experimental phase. The diets given to birds at this phase was the same for all the treatments. In the production phase, the residual effects of the experimental diets provided during the initial phase on the production parameters were evaluated. The level of methionine + cystine recommended for white-egg and brown-egg pullets in the period from 1 to 6 weeks of age are 0.778 % of total methionine + cystine (0.700% met + cis digestible) and 0.739% of total methionine + cystine (0.665% of digestible methionine + cystine), respectively.

RESUMO O objetivo deste trabalho foi determinar a composição química e os valores de energia metabolizável aparente (EMA) e metabolizável aparente corrigida pelo balanço de nitrogênio, EMAn, de alguns alimentos para frangos de corte. Foram utilizados 432 pintos de corte macho, de 14 a 24 dias de idade, distribuídos em delineamento inteiramente casualizado com 12 tratamentos (11 alimentos e uma dieta referência), seis repetições e seis aves por unidade experimental. A metodologia utilizada foi da coleta total de excretas. Foram objetos de estudo: Duas farinhas de vísceras (FV), duas farinhas de penas e sangue (FPS), duas farinhas de carnes e ossos (FCO), soja integral tostada (SIT), farelo de soja (FS), quirera de milho (QM), farelo de trigo (FT) e milheto (M). Os valores de proteína bruta e extrato etéreo (%), EMA e EMAn (kcal/kg) foram, respectivamente: 58,84; 12,64; 3705 e 3340 para a FV 1; 57,64; 11,66; 3565 e 3241 para a FV 2; 80,58; 6,79; 3070 e 2740 para a FPS 1; 82,27; 6,38; 3060 e 2703 para a FPS 2; 48,06; 9,60; 1574 e 1283 para a FCO 1; 41,21; 9,08; 1353 e 1088 para a FCO 2; 36,45; 20,78; 3192 e 2989 para a SIT; 46,22; 1,72; 2648 e 2336 para o FS; 8,51; 3,61; 3354 e 3265 para a QM; 17,11; 3,14; 1948 e 1788 para o FT e 12,01; 4,09; 3072 e 2948 para o M. As diferenças observadas na composição química e energética evidenciam a necessidade de pesquisas para atualizar os valores nutricionais dos alimentos.

ABSTRACT The aim of this work was to determine the chemical composition and values for apparent metabolisable energy (AME), and apparent metabolizable energy corrected for nitrogen (AMEn), in broiler feeds. In the experiment, 432 male broiler chicks, 14 to 24 days old were used, distributed in a completely randomised design with 12 treatments (11 feeds and a reference diet), six replications and six birds per experimental unit. The method employed was the total collection of excreta. The feeds under study were: Two of viscera meal (VM), two feather and blood meal (FBM), two meat and bone meal (MBM), roasted whole soybean (RWS), soybean meal (SM), ground corn (GC), wheat bran (WB) and millet (M). The values for crude protein and ether extract (%), AME and AMEn (kcal/kg) were respectively: 58.84, 12.64, 3705 and 3340 for VM1; 57.64, 11.66, 3565 and 3241 for VM 2; 80.58, 6.79, 3070 2740 for FBM 1; 82.27, 6.38, 3060 2703 for FBM 2; 48.06, 9.60, 1574 and 1283 for MBM 1; 41.21, 9.08, 1353 and 1088 for MBM 2; 36.45, 20.78, 3192 and 2989 for RWS; 46.22, 1.72, 2648 and 2336 for SM; 8.51, 3.61, 3354 and 3265 for GC; 17.11, 3.14, 1948 and 1788 and for WB; and 12.01, 4.09, 3072 and 2948 for M. The differences found in chemical and energy composition highlight the need for research to revise the nutritional values of feed.

RESUMO: Este estudo foi realizado para determinar a relação ideal de treonina:lisina digestíveis em rações com baixo nível de proteína bruta para galinhas poedeiras leves de 24 a 40 semanas de idade. Utilizaram-se 240 poedeiras Hy Line W-36 distribuídas em delineamento inteiramente casualizado, com cinco relações treonina:lisina digestíveis (60; 67; 74; 81 e 88%), oito repetições e seis aves por unidade experimental. As relações treonina:lisina digestíveis não influenciaram o consumo de ração e de lisina; peso médio dos ovos e seus componentes; ganho de peso e peso corporal final das aves, mas houve efeito linear para o consumo de treonina. O modelo Linear Response Plateau (LRP) foi o que melhor representou a distribuição dos dados para taxa de postura; massa de ovos; eficiência de utilização da lisina por massa; conversão alimentar por massa e por dúzia de ovos; e balanço de nitrogênio. Os platôs ocorrem nos níveis de treonina de 0.61; 0.580; 0.614; 0.599; 0.599 e 0.643%, que corresponde às relações treonina:lisina digestíveis de 80; 75; 80; 78; 78 e 83%, respectivamente. A relação ideal de treonina:lisina digestíveis em rações para galinhas poedeiras leves de 24 a 40 semanas de idade é de 80%.

ABSTRACT: This trial was performed to determine the dietary digestible threonine-to-lysine (dig. Thr-to-Lys) ideal ratio for laying hens fed with low-protein diets from 24 to 40 weeks of age. At 24 weeks of age, two hundred forty Hy Line W-36 laying hens were randomly assigned to five treatments, represented by five dig Thr-to-Lys ratios (60; 67; 74; 81 and 88%), with eight replicates each one with six hens per experimental unit. Digestible Thr-to-Lys did not affect laying hen performance and egg quality, except for digestible Threonine intake, which showed linear increase as dig. Thr-to-Lys ratios increased. Linear broken-line model was chosen to analyze data according to lack of fit. According to linear broken-linen estimates, digestible Threonine ideal levels for optimum egg production, egg mass, feed efficiency of lysine utilization for egg mass, feed conversion per egg mass and dozens of eggs and nitrogen balance were 0.610; 0.580; 0.614; 0.599; 0.599 and 0.643%, which correspond respectively to dig Thr-to-Lys ratios of 80; 75; 80; 78; 78 and 83%. The digestible threonine-to-lysine ideal ratio for laying hens from 24 to 40 weeks of age is 80%.

RESUMO Este estudo foi realizado para determinar a relação ideal de treonina:lisina digestíveis para poedeiras leves no período de 42 a 58 semanas de idade. Foram utilizadas 240 poedeiras Hy Line W-36 com 42 semanas de idade durante 16 semanas. Os tratamentos foram distribuídos em delineamento inteiramente casualizado, com oito repetições e seis aves por unidade experimental. As dietas experimentais foram formuladas com cinco níveis de treonina digestível (0,461; 0,515; 0,569; 0,622 e 0,676%) proporcionando as cinco relações treonina:lisina digestíveis (60; 67; 74; 81 e 88%) estudadas. As variáveis analisadas foram: produção de ovos; consumo de ração, de lisina e de treonina; massa e peso médio dos ovos; eficiências de utilização da lisina por massa e ovos produzidos; conversões alimentares por massa e dúzia de ovos; pesos médios de: gema, albúmen e de casca; ganho de peso; peso corporal final das aves; e balanço de nitrogênio. As relações treonina:lisina digestíveis na dieta não influenciaram as variáveis analisadas, exceto o consumo de treonina que apresentou efeito linear. A relação ideal de treonina:lisina digestíveis na dieta para galinhas poedeiras leves de 42 a 58 semanas de idade é de 60%, que corresponde ao nível de 0,461% de treonina digestível na dieta e ao consumo diário de treonina digestível de 446mg/ave.

SUMMARY This study was conducted to determine the ideal ratio of digestible threonine: lysine in diets for laying hens at 42 to 58 weeks of age. Two hundred forty Hy Line W-36 laying hens were used at 42 weeks of age for 16 weeks. The treatments were distributed in a completely randomized design with eight replicates and six birds each. The experimental diets were formulated with five levels of digestible threonine (0.461; 0.515; 0.569; 0.622 and 0.676%) providing the five ratio of digestible threonine: lysine (60; 67; 74; 81 and 88%) studied. The variables analyzed were: egg production; feed intake; lysine intake; threonine intake; mass egg; average egg weight; lysine use efficiencies by mass and produced eggs; feed conversion per mass and dozen eggs; Average weights yolk, albumen and shell; weight gain and final body weights of birds; and nitrogen balance. The digestible threonine: lysine ratio in the diet did not influence the analyzed variables except consumption of threonine which showed a linear effect. The ideal ratio of digestible threonine: lysine in diets for white laying hens at 42 to 58 weeks of age is 60%, which corresponds to the level of 0.461% of digestible threonine in the diet and daily intake of digestible threonine 446mg/bird.

Resumo Objetivou-se determinar a exigência nutricional de cálcio e a melhor relação cálcio:fósforo em rações para poedeiras leves de 24 a 40 semanas de idade. Foram utilizadas 324 aves Hy-Line W-36, distribuídas em delineamento inteiramente casualizado, esquema fatorial 3x3, sendo três níveis de cálcio (3,9; 4,2 e 4,5 %) e três relações cálcio/fósforo (9,3; 10,53 e 12,12/1), totalizando nove tratamentos, seis repetições e seis aves por unidade experimental. Avaliou-se o desempenho produtivo, a qualidade do ovo, as características ósseas, o balanço de cálcio e fósforo e a mortalidade. Não houve interação (P>0,05) entre os níveis de cálcio e as relações cálcio/fósforo para nenhuma das variáveis, porém os níveis de cálcio promoveram efeito (P<0,05) sobre o peso e porcentagem da casca, cálcio na casca, ovos perdidos, consumo de cálcio e fósforo, cálcio e fósforo na excreta, cálcio e fósforo retido. A relação cálcio/fósforo influenciou significativamente (P<0,05) o consumo de ração, ganho de peso, conversão alimentar, consumo de cálcio e fósforo, fósforo na excreta e fósforo retido. Rações contendo 4,5% de cálcio e relação cálcio:fósforo de 12,12:1, correspondendo ao consumo de cálcio de 3,71 g/ave/dia e de fósforo de 306 mg/ave/dia, garantem desempenho satisfatório em rações para poedeiras leves no período de 24 a 40 semanas.

Abstract The objective of this study was to determine the nutritional requirement for calcium and the best calcium:phosphorus ratio in the diet for laying hens from 24 to 40 weeks of age. 324 Hy-Line W-36 birds were distributed in a completely randomized design in 3x3 factorial scheme, consisting of three levels of calcium (3.9, 4.2, and 4.5%) and three calcium:phosphorus ratios (9.3, 10.53, and 12.12:1) totaling nine treatments, six replicates and six birds each. We evaluated performance, egg quality, bone characteristics, balance of calcium and phosphorus, and mortality. There was no interaction (P> 0.05) between calcium levels and calcium:phosphorus ratio for the variables, but levels of calcium affected (P <0.05) weight and shell percentage, calcium in the shell, lost eggs, consumption of calcium and phosphorus, calcium and phosphorus excretion, and retained calcium and phosphorus. The calcium:phosphorus ratio affected significantly (P <0.05) feed intake, weight gain, feed conversion per dozen eggs, egg mass, calcium and phosphorus intake, phosphorus excretion, and retained phosphorus. Diets containing 4.5% calcium and the calcium:phosphorus ratio of 12,12:1, corresponding to a calcium intake of 3.71 g/hen/day and phosphorus of 306 mg/bird /day, guarantee satisfactory performance in diets for laying hens from 24 to 40 weeks.

Resumo Para determinar a relação ideal triptofano digestível:lisina digestível em dietas para poedeiras de 42 a 58 semanas de idade, 240 poedeiras Hy-Line W-36 com 42 semanas de idade foram distribuídas em delineamento inteiramente ao acaso com cinco tratamentos, oito repetições e seis aves por unidade experimental. Com 42 semanas de idade as aves foram submetidas aos tratamentos experimentais, que consistiram de dietas com quantidades iguais de nutrientes, exceto para o nível de triptofano digestível. Os níveis de triptofano digestível nas dietas experimentais foram 0,149; 0,160; 0,171; 0,182 e 0.193%, gerando relações triptofano digestível:lisina digestível de 21,5; 23,1; 24,6; 26,2 e 27,8%. O nível de lisina digestível nas dietas foi sub-ótimo (0,694%). As mesmas relações entre a lisina e outros aminoácidos foram mantidas em todas as dietas experimentais. A relação ideal triptofano digestpivel:lisina digestível foi estimada por meio dos parâmetros estudados utilizando análise de variância e análise de regressão polinomial (α = 0.05). A relação triptofano digestível:lisina digestível nas dietas influenciaram quadraticamente a produção de ovos, massa de ovos, conversão alimentar e a eficiência de utilização de lisina digestível para massa de ovos. No entanto, não houve efeito (P> 0,05) sobre o peso dos ovos, conversão alimentar por dúzia de ovos, eficiência de utilização de lisina digestível para número de ovos produzidos, porcentagem dos componentes dos ovos e ganho de peso. A relação ideal triptofano digestível:lisina digestível estimada para esses parâmetros variaram de 23,6 a 24,3%. A relação triptofano digestível:lisina digestível recomendada em dietas para poedeiras de 42 a 58 semanas de idade é 24,3%.

SUMMARY To determine the ideal digestible tryptophan-to-digestible lysine ratio in diets for laying hens of 42 to 58 weeks of age, 240 Hy-Line W-36 hens at 42 weeks of age were distributed in a completely randomized design with five treatments, eight replicates and six birds per experimental unit. At 42 weeks of age, the birds were subjected to experimental treatments that consisted of diets with equal amounts of nutrients, except for the digestible tryptophan level. The digestible tryptophan levels in the experimental diets were 0.149, 0.160, 0.171, 0.182 and 0.193%, generating digestible tryptophan-to-digestible lysine ratios of 21.5, 23.1, 24.6, 26.2 and 27.8%. The digestible lysine level in the diets was sub-optimal (0.694%). The same ratios between lysine and the other amino acids were maintained in all experimental diets. The ideal digestible tryptophan-to-digestible lysine ratio was estimated through the studied parameters using analysis of variance and polynomial regression analysis (α = 0.05). The digestible tryptophan-to-digestible lysine ratio in diets quadratically affected egg production, egg mass, feed conversion per egg mass and use efficiency of digestible lysine for egg mass. However, there were no effect (P>0.05) on egg weight, feed conversion per dozen eggs, use efficiency of digestible lysine for number of eggs produced, percentage of egg components and weight gain. The digestible tryptophan-to-digestible lysine ratio estimated for theses parameters ranged from 23.6 to 24.3%. The digestible tryptophan-to-digestible lysine ratio recommended in diets for laying hens of 42 to 58 weeks of age is 24.3%.

O objetivo com este trabalho foi determinar a exigência nutricional de lisina digestível para galinhas poedeiras leves em idade avançada. Foram utilizadas 288 galinhas poedeiras Hy Line W-36 com 60 semanas de idade, distribuídas em delineamento inteiramente casualizado, com seis níveis de lisina digestível (6,0; 6,6; 7,2; 7,8; 8,4 e 9,0g kg-1), oito repetições e seis aves por unidade experimental. Os níveis de lisina digestível na ração influenciaram de forma linear o consumo de lisina e a eficiência de utilização da lisina. Para a produção e massa de ovos, os platôs ocorreram a partir dos níveis de 6,57g kg-1 e de 7,10g kg-1 de lisina digestível, respectivamente. Houve efeito quadrático dos níveis de lisina sobre o peso de gema, com o nível estimado em 7,6g kg-1de lisina digestível. A exigência de lisina digestível de galinhas poedeiras leves no período de 60 a 76 semanas de idade é de 7,10g kg-1 de ração, correspondendo ao consumo diário de 690mg ave-1 de lisina digestível.

The objective of this research was to determine the nutritional requirement of digestible lysine for white laying hens in old age. Two hundred eighty-eight Hy Line W-36 laying hens at 60 weeks of age were distributed in a completely randomized design, with six levels of digestible lysine (6.0; 6.6; 7.2; 7.8; 8.4 and 9.0g kg-1) and eight replications with six birds per experimental unit. There was linear effect of lysine levels on lysine intake and efficiency of utilization of lysine. For the production and egg mass, the levels of digestible lysine in the diet from which the plateaus occurred were of 6.57g kg-1 and 7.10g kg-1, respectively. There was quadratic effect of lysine levels on yolk weight, with the estimated level of 7.6g kg-1 of digestible lysine. The digestible lysine requirement of white laying hens from 60 to 76 weeks of age is 7.10g kg-1 in diet, corresponding to daily intake of 690mg bird-1 of digestible lysine.

Two-hundred sixteen white laying hens were used to assess the ideal ratio of digestible threonine:lysine in diets for laying hens at 24 to 40 weeks of age. Birds were assigned to a randomized block design, with six treatments, six replicates per treatment and six birds per experimental unit. The cage was used as the blocking criterion. Experimental diets contained different digestible threonine:digestible lysine ratios (65, 70, 75, 80, 85 and 90%) with 142 g/kg of crude protein. Experimental diets were formulated to be isonitrogenous and isocaloric with different contents of L-glutamic acid. Feed intake (g/hen/d), egg production (%), egg weight (g), egg mass (g/hen/d), feed conversion ratio (kg/dozen and kg/kg egg), eggshell weight (g), albumen weight (g), yolk weight (g) and body weight gain (g) were assessed. The maximum egg production was observed at 78% digestible threonine:digestible lysine ratio, while the best values of feed conversion ratio (kg/dozen egg) and feed conversion ratio (kg/kg of egg) were observed at 77.6% and 75%, respectively. Feed intake, egg mass and egg contents (yolk, albumen and eggshell) were not affected by treatments. The estimated digestible threonine:digestible lysine ratio of Hy-Line W36 laying hens at 24 to 40 weeks of age is 78%, corresponding to 5.70 g/kg of dietary digestible threonine.

Two hundred fifty-two Hy-Line W36 laying hens were allotted in a randomized block design with 6 treatments, 7 replicates and 6 hens per experimental unit in order to determine the ideal digestible isoleucine: digestible lysine (Ile:Lys) ratio for laying hens aged 24-40 weeks. Experimental diets contained 5.92, 6.33, 6.73, 7.14, 7.54 and 7.95 g/kg of digestible isoleucine, resulting in different Ile:Lys ratios (0.73:1, 0.78:1, 0.83:1, 0.88:1, 0.93:1 and 0.98:1). Experimental diets were isonitrogenous, with different dietary contents of glutamic acid, and made isocaloric by adjusting the levels of cornstarch. All essential amino acids were provided proportionally to digestible lysine. Feed intake, egg production, egg weight, egg mass, feed conversion ratio per egg mass, feed conversion ratio per dozen eggs, albumen, yolk and eggshell content were assessed. Feed intake, egg production, egg mass and feed conversion ratio were influenced by Ile: Lys ratios quadratically. The egg weight was not affected by Ile: Lys ratio. No differences were observed in the egg quality according to Ile: Lys ratios. The data indicates that the optimum digestible isoleucine: digestible lysine ratio for laying hens aged 24-40 week is 0.84:1, corresponding to the consumption of 681 mg of isoleucine and 811 mg of lysine/hen day-1.

This study was conducted to verify the effects of dietary crude protein reduction on growth and carcass performance of 22-42-day-old broilers reared under different temperatures. Treatments were set up in a five by two factorial arrangement, with five crude protein levels (220, 210, 200, 190 and 184 g/kg) and two temperatures (21.6 and 32.2 ºC). Diets were isocaloric and essential amino acid-to-lysine ratio was maintained constant in all treatments. There was no interaction between crude protein reduction and environmental temperature for any of the parameters evaluated. Crude protein had no influence on feed intake. Nevertheless, weight gain and feed conversion ratio were linearly influenced by crude protein reduction. Worse performance was also observed in birds exposed to heat stress as compared with birds kept under thermoneutral temperature. There was no effect of crude protein reduction on breast and legs. Birds kept under heat stress had lower breast yield and higher leg yield as compared with broilers reared at 21.6 ºC. Any crude protein reduction in the range of 220 to 184 g/kg for 22 to 42-day-old broilers has a negative effect on their performance. Heat stress worsens broiler performance and breast yield.

The objective of this study was to estimate the digestible lysine requirement of Japanese quails in the egg-laying phase. A total of 336 female Japanese quails (Coturnix coturnix japonica) of average initial age of 207 days were distributed in a completely randomized experimental design, composed of 6 treatments (lysine levels) with 7 replicates and 8 birds per experimental unit, with duration of 84 days. Experimental diets were formulated from a basal diet, with corn and soybean meal, with 2.800 kcal ME/kg and 203.70 g/kg crude protein, showing levels of 9.50; 10.00; 10.50; 11.00; 11.50; and 12.00 g/kg digestible lysine; diets remained isoprotein and isocaloric. The following variables were studied: feed intake (FI); lysine intake (LI); egg production per bird per day (EPBD); egg production per bird housed (EPBH); production of marketable eggs (PME); egg weight (EW); egg mass (EM); utilization efficiency of lysine for egg mass production (UELEM); feed conversion per mass (FCEM); feed conversion per dozen eggs (FCDZ); bird availability (BA); percentages of yolk (Y), albumen (A) and shell (S); specific egg weight (SW); nitrogen ingested (NI); nitrogen excreted (NE); and nitrogen balance (NB). Significant effect was only observed for LI, EW, EM, UELEM, FCEM, Y, A and SW. The digestible lysine level estimated in diets for laying Japanese quails is 11.20 g digestible lysine/kg diet, corresponding to an average daily intake of 272.23 mg lysine.

Muitos indicadores podem ser utilizados em ensaios de digestibilidade para suínos, mas precisam ser avaliados antes de serem utilizados. O experimento foi realizado com o objetivo de determinar os coeficientes de digestibilidade ileal aparentes (CDIA) e estandardizados (CDIE) dos aminoácidos da farinha de carne e ossos, para suínos, utilizando diferentes indicadores. Oito suínos, machos castrados, foram submetidos à cirurgia para aimplantação de cânulas T simples, no íleo distal. Quatro animais receberam uma dieta isenta de proteína e outros quatro uma dieta contendo farinha de carne e ossos como única fonte protéica na dieta. Os tratamentos consistiram em avaliar o óxido crómico, cinza insolúvel em ácido naturalmente contido na dieta, celulose e lignina como indicadores para determinar os CDIA e CDIE dos aminoácidos da farinha de carne e ossos. Os dados foram submetidos a análise de variância e as médias foram comparadas pelo teste de Tukey, ao nível de 5% de significância. Os CDIA, obtidos usando o óxido crômico como indicador externo, foram menores (P<0,05) em relação aos obtidos utilizando cinza insolúvel em ácido, lignina e celulose como indicadores, observando-se diferenças para todos os aminoácidos avaliados. O CDIE de todos os aminoácidos estudados foram menores (P<0,05) quando o óxido crômico foi utilizado para a determinação do fator de indigestibilidade. Conclui-se que o óxido de cromo utilizado como indicador externo, para determinar os coeficientes de digestibilidade ileal aparente e standarizado dos aminoácidos da farinha de carne e ossos, é mais apropriado do que a lignina, celulose e a cinza insolúvel em ácido naturalmente encontrada na dieta.

Many markers can be used in digestibility assays for swine, but needs to be evaluated before its use. An assay was carried out with the objective of measuring the coefficients of ileal apparent (CIAD) and standardized digestibility (CISD) of amino acids in meat and bone meal for swine using different markers. Eight crossbred barrows were equipped with T-cannulas in the distal ileum. Four animals received a free protein diet and another four received a diet containing meat and bone meal as the only protein source in the diet. The treatments consisted in evaluating the chromic oxide, acid-insoluble ash naturally occurring in the diet, cellulose and lignin as markers to determine the apparent and standardized digestibility of the amino acids contained in the meat and bone meal. All data were submitted to analysis of variance and means were compared using the Tukey test, with a significance of 5%. The CIAD, obtained using chromic oxide as external marker, were lower (P<0.05) than those obtained when acid insoluble ash, lignin and cellulose were used as markers, observing differences for all the amino acids evaluated. Similarly, the CISD from all the studied amino acids were lower (P<0.05) when the chromic oxide was used for determining the indigestibility factor. It is concluded that chromic oxide used as a external marker, to determine the coefficients of apparent and standardized ileal digestibility of the amino acids of the meat and bone meal, is most appropriate than the acid insoluble ash naturally occurring in diets, lignin and cellulose.

The experiment was conducted to determine the nutritional requirement of calcium and the best calcium:available phosphorus ratio for commercial layers at the post-laying peak. A total of 324 Hy-Line W-36 laying hens were utilized in the period from 42 to 58 weeks of age, distributed in a completely randomized design in a 3 × 3 factorial arrangement, composed of three levels of calcium (39, 42 and 45 g/kg) and three calcium:phosphorus ratios (12.12:1; 10.53:1; and 9.30:1), totaling nine treatments with six replications and six birds per experimental unit. There was no significant effect from the calcium levels × calcium:phosphorus ratio interaction for any of the variables studied. The calcium levels and the calcium:phosphorus ratios did not affect the variables performance or egg and bone quality. At the evaluation of the calcium:phosphorus balance, as the levels of calcium of the diet were raised, the intake of calcium and phosphorus and the contents of mineral matter and calcium in the excreta increased linearly, and the retention of calcium by birds decreased linearly. With the reduction of the calcium:phosphorus ratios of the diet, intake, retention and excretion of phosphorus by layers increased. Diets containing calcium at 39 g/kg and a calcium:phosphorus ratio of 12.12:1, corresponding to an increase in calcium of 3.51 g/bird/day and available phosphorus of 289 mg/bird/day, meet the requirements of calcium and available phosphorus of white egg layers in the period from 42 to 58 weeks of age.

Four trials were conducted to determine the requirements of available phosphorus (aP) of female broiler chicks from 1 to 10 (exp.1), 11 to 21 (exp.2), 22 to 33 (exp.3), and from 34 to 46 (exp.4) days of age, keeping the calcium:available phosphorus ratio equal to 2:1. In each trial, 480 Cobb broilers were randomly allotted in a completely randomized design with 6 treatments, 8 replicates and 10 birds per pen. The levels of aP ranged from 2.0 to 5.5 g/kg (Exp. 1), 1.9 to 5.4g/kg (exp. 2), 1.8 to 5.3 g/kg (exp. 3) and 1.7 to 5.2 g/kg of diet (exp. 4), in increments of 0.7 g/kg. The experimental diets were formulated using corn and soybean meal and the available phosphorus was considered 33% of total phosphorus. The characteristics evaluated were body weight gain, feed intake, feed conversion ratio and bone parameters. For female broiler chicks from 1 to 10; 11 to 21; 22 to 33; and from 34 to 46 days of age, the levels of available phosphorus and calcium recommended are 4.59 and 9.18; 3.88 and 7.76; 3.58 and 7.16; and 2.56 and 5.12 g/kg of diet, respectively.

Four experiments were conducted to study the requirements of available phosphorus (aP) for commercial male broilers of 1-10 day of age (exp.1), 11-21 days of age (exp. 2), 22-33 day of age (exp. 3) and 34-46 days of age (exp. 4), at a constant calcium:aP ratio. A complete randomized design was used in each experiment. The experimental diets were fed ad libitum to 8 replicate groups of ten broilers in each. The increments in the levels of aP ranged from 2.0 to 5.5 g/kg (exp. 1), 1.9 to 5.4 g/kg (exp. 2), 1.8 to 5.3 g/kg (exp. 3) and 1.7 to 5.2 g/kg (exp. 4), in 0.7 g/kg. The parameters evaluated were body weight gain, feed intake, feed conversion ratio and bone parameters. The level of aP in the diet influenced the performance of broilers of 1-10 and 11-21 days of age, but did not affect the performance of broilers at 22-33 and 34-46 days of age. Feed intake was not affected. The requirements of aP and Ca for male broilers from 1-10, 11-21, 22-33 and 34-46 days of age are 4.82 and 9.64 g/kg, 4.10 and 8.20 g/kg, 3.95 and 7.90 g/kg and 3.19 g.kg and 6.38 g/kg, respectively. The results indicate that low levels aP were required because the requirements of the mineral reduced as birds aged. Provided there is no excess of dietary levels of Ca, using a Ca:aP ratio of 2:1 may reduce the dietary levels of aP.