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 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%.

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.

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.

The objective of this study was to evaluate the effect of digestible lysine levels in diets with or without supplementation of industrial amino acids on performance, carcass characteristics and nitrogen excretion in broilers of 22 to 42 days of age. Birds were distributed in a completely randomized experimental design in a 4 × 2 factorial arrangement, with four digestible lysine levels (9.0, 10.0, 11.0 and 12.0 g/kg) and two methods to obtain the lysine levels (variation in the proportion of corn and soybean meal, without supplementation; or supplementation of industrial amino acids), eight replicates and 20 birds per replicate. There was an interaction effect on the performance characteristics and on the weights and yields of prime cuts. In both diets, feed conversion improved linearly as the lysine levels were increased. Feed intake; weight gain; carcass, thigh and drumstick weights; and boneless breast yield increased and abdominal fat reduced linearly as the lysine levels were increased in the unsupplemented diet. The lysine levels of the supplemented diets linearly reduced the yield of drumstick and quadratically reduced the yields of bone-in and boneless breast up to the estimated levels of 10.4 and 10.7 g/kg, respectively. Diets without supplementation increased the excretion and retention of nitrogen. The levels of 9.0 and 12.0 g/kg digestible lysine obtained with supplementation of industrial amino acids and without it, respectively, provide the best performance and yield of prime cuts in the birds. Diets in which the digestible lysine levels are obtained without supplementation provide better performance responses and carcass characteristics compared with supplemented diets.

This study was conducted to evaluate the effects of digestible lysine levels in diets with and without supplementation of industrial amino acids on performance and fat deposition in the carcass of broilers in the starter phase. One thousand four hundred and forty chickens with initial weight of 168.1±5.0 g were distributed in a completely randomized experimental design, in a 5 × 2 factorial arrangement, composed of five digestible lysine levels (10.0, 11.0, 12.0, 13.0 and 14.0 g/kg) and two types of diet (diet with different proportions of corn and soybean meal and diet supplemented with industrial amino acids to obtain the digestible lysine levels), with eight replications and 18 birds per replication. There was interaction effect only on weight gain and fat deposition in the birds. The lysine levels reduced feed intake linearly in both diets, but caused a linear increase in lysine intake. The lysine levels quadratically affected weight gain and feed conversion, which improved up to the estimated levels of 13.0 and 12.8 g/kg lysine, respectively, when the corn:soybean meal ratio of the diet changed. In the diets supplemented with amino acids, the lysine levels increased weight gain and improved feed conversion linearly. Regardless of the type of diet, protein deposition increased linearly, whereas fat deposition reduced also linearly, as the lysine levels in the diets were increased. The levels of 13.0 and 14.0 g/kg digestible lysine provide, respectively, the best performance in birds fed a diet in which the proportion of corn and soybean meal varies and a diet supplemented with industrial amino acids, in the period from 8 to 21 days of age.

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.