RESUMO O ácido linoleico conjugado (CLA) compreende o grupo de isômeros posicionais e geométricos do ácido linoleico. Na dieta de matrizes, aumenta a proporção de ácidos graxos saturados dos ovos e pode ser uma importante ferramenta para o estudo dos efeitos da suplementação materna de CLA sobre o metabolismo lipídico da progênie. Objetivou-se avaliar o efeito da inclusão de CLA na dieta de matrizes de frango de corte sobre o perfil de ácidos graxos da gema, a qualidade dos ovos e a incubação. Dois lotes comerciais de matrizes Cobb500®, com 58 semanas de idade, foram suplementados com 0% ou 0,025% de CLA (trans-10, cis-12). Após 26 dias, 300 ovos por tratamento foram coletados, dois quais 30 foram utilizados para as análises de qualidade e perfil de ácidos graxos da gema, enquanto os ovos restantes foram submetidos à incubação. A qualidade das aves foi avaliada à eclosão, e o peso e conteúdo do saco vitelínico residual foram avaliados à eclosão. Ovos não eclodidos foram submetidos a análise residual. A suplementação das matrizes não influenciou os parâmetros de incubação e peso dos pintos à eclosão. Contudo, modificou o perfil de ácidos graxos da gema e do saco vitelínico, levando ao acúmulo de CLA no saco vitelínico após a eclosão. Conclui-se que a suplementação de 0,025% de CLA na dieta de matrizes não altera parâmetros de incubação e o peso da progênie à eclosão, mas modifica os perfis de ômega-6 e ácidos palmitoleico, linoleico e araquidônico tanto na gema quando no saco vitelínico residual. (CLA Objetivouse Objetivou se Cobb500 Cobb Cobb500® 5 idade 0 0025 025 0,025 trans10, trans10 trans 10, 10 (trans-10 cis12. cis12 cis 12 . cis-12) 2 dias coletados 3 eclosão Contudo Concluise Conclui ômega6 ômega 6 ômega- palmitoleico Cobb50 002 02 0,02 trans1 1 (trans-1 cis1 cis-12 Cobb5 00 0,0 (trans- cis-1 0, (trans cis-

ABSTRACT Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of linoleic acid. Hens fed a diet supplemented with CLA exhibit increased levels of saturated fatty acids, which may influence the quality characteristics of eggs and the offspring lipid metabolism. The present study, aimed to evaluate the effect of the dietary inclusion of CLA for broiler breeders on the residual yolk sac fatty acid profile, egg quality, and hatchability. Two 58-week-old Cobb500® broiler breeder commercial flocks were fed diets supplemented with 0% or 0.025% CLA (trans-10, cis-12). After 26 days, 300 eggs from each treatment group were collected, and among these eggs, 30 were subjected to egg quality assessment and egg yolk fatty acid profile analysis. The remaining 270 eggs were subjected to incubation analysis. The quality of the chicks was evaluated at hatch. The residual yolk sac content and weight at hatch were also evaluated. Unhatched eggs were subjected to residual analysis. The supplementation of the breeders’ diet with 0.025% CLA did not influence the incubation parameters and the weight of the chicks at hatch. However, the egg yolk and residual yolk sac fatty acid profile were altered and CLA accumulation was increased in the residual yolk sac at hatch in this treatment group. In conclusion, CLA supplementation in the diet of breeders did not influence the incubation parameters and the weight of the chicks, although it did alter the profiles of omega-6, palmitoleic, linoleic, and arachidonic acids in both egg yolk and residual yolk sac. (CLA metabolism study hatchability 58weekold weekold 58 week old Cobb500 Cobb 0 0025 025 0.025 trans10, trans10 trans 10, 10 (trans-10 cis12. cis12 cis 12 . cis-12) 2 days collected 3 analysis 27 However conclusion omega6, omega6 omega 6, 6 omega-6 palmitoleic 5 Cobb50 002 02 0.02 trans1 1 (trans-1 cis1 cis-12 omega- Cobb5 00 0.0 (trans- cis-1 0. (trans cis-

ABSTRACT. Two experiments were carried out to evaluate the effects of protease addition to the diet of broilers at a higher level (1× or 2×) than the nutritional value proposed for the enzyme. The first experiment, 1280 day-old chicks (Cobb500®) were randomly allocated (randomized block design, 2×2+1 factorial arrangement), five treatments, eight replicates containing 32 birds/replicate. Treatments consisted: control diet without protease (CD); CD + 1× nutritional value of the enzyme (CDM1); CD + 2× nutritional value of the enzyme (CDM2); CDM1 + protease; and CDM2 + protease. The experimental period was 42 days. The mean weight (AFW), feed intake (FI), weight gain (WG), feed conversion, and carcass yield were evaluated. Significant differences were observed for AFW, WG, FI, abdominal fat yield, and feet percentage in the carcass. In the second experiment, 120 Cobb500® chicks at 14 days of age were allotted in a completely randomized design, 2×2+1 factorial arrangement, five treatments, six replicates with four birds/replicate. The treatments were consistent with the first experiment. Significant improvements in the nitrogen balance were observed for the broilers that received protease. The use of the enzyme tested is recommended with the recommended nutritional matrix, improving the zootechnical indices of broilers. ABSTRACT 1 (1 2 experiment 128 dayold day old Cobb500 Cobb (Cobb500® design 221 2×2+ arrangement , arrangement) 3 birdsreplicate birds replicate birds/replicate consisted (CD) CDM (CDM1) (CDM2) 4 AFW (AFW) FI (FI) WG (WG) conversion evaluated 12 matrix ( Cobb50 (Cobb500 22 2×2 (CD (CDM1 (CDM2 (AFW (FI (WG Cobb5 (Cobb50 (CDM (Cobb5 (Cobb

RESUMO: A qualidade da casca está diretamente ligada à boa aceitabilidade do produto pelos consumidores, enquanto a indústria se preocupa com as perdas econômicas. Períodos prolongados de postura, doenças, nutrição, idade da ave e genética podem influenciar a qualidade dos ovos. Objetivou-se avaliar a influência do ambiente, idade da ave e período de armazenamento nas características físicas da casca de ovos de poedeiras comerciais. Foram utilizados 288 ovos de poedeiras Hy-line, distribuídos em um delineamento inteiramente casualizado em fatorial triplo 3x2x4, sendo os fatores: três idades (31, 62 e 88 semanas), temperatura de armazenamento (ambiente e refrigerado), e quatro períodos de armazenamento (um, 10, 20 e 30 dias), totalizando 24 tratamentos, com quatro repetições de três ovos. Avaliou-se a resistência, percentual e espessura da casca. Foram observadas diferenças, uma vez que os ovos armazenados em temperatura ambiente apresentaram diminuição na resistência de casca. Ovos de poedeiras em idade avançada (88 semanas) apresentaram pior resistência de casca em relação às demais idades, enquanto ovos provenientes de poedeiras jovens (31 semanas) apresentaram maior espessura de casca. A idade avançada da poedeira reduziu a qualidade de casca dos ovos, independentemente do ambiente de armazenamento. Ainda, os ovos armazenados em geladeira apresentaram melhor qualidade e integridade da casca em comparação com os armazenados ao ambiente.

ABSTRACT: Eggshell quality is directly linked to the good acceptability of the product by consumers, whereas the industry is concerned with economic losses. Prolonged periods of laying, diseases, nutrition, bird age and genetics can influence egg quality. This study aimed to examine the influence of the environment, bird age and storage period on the physical characteristics of the shell of eggs from commercial laying hens. The experiment involved 288 eggs from Hy-line hens, which were distributed in a completely randomized design with a triple 3×2×4 factorial arrangement represented by three ages (31, 62 or 88 weeks), two storage temperatures (ambient or refrigerated), and four storage periods (one, 10, 20 or 30 days), totaling 24 treatments. Four replications were used with three eggs each. Eggshell strength, percentage and thickness were measured. Differences were observed, with the eggs stored at room temperature exhibiting lower shell strength. Laying eggs at an advanced age (88 weeks) resulted in decreased eggshell strength as compared with the other ages, whereas the eggs from young layers (31 weeks) had a thicker shell. The advancing age of the laying hens reduced eggshell quality, regardless of the storage environment. Nonetheless, the eggs stored in the refrigerator showed better eggshell quality and integrity than those stored at ambient temperature.

RESUMO Objetivou-se avaliar o processamento térmico de rações pré-iniciais sobre o desempenho, morfometria dos órgãos do sistema digestório e metabolizabilidade dos nutrientes das rações de pintos de corte. Foram utilizados 180 pintos de corte, distribuídos em delineamento inteiramente casualizado, com dois tratamentos, seis repetições de 15 aves cada. Os tratamentos consistiram em ração peletizada (70°C) e ração extrusada (150°C). O ensaio de metabolizabilidade foi realizado de quatro a sete dias de idade, enquanto o desempenho e morfometria dos órgãos do sistema digestório foram avaliados aos sete e 21 dias de idade. Os dados foram submetidos à análise de variância. Aos sete dias de idade, os pintos que consumiram ração extrusada apresentaram menor consumo de ração, menor desenvolvimento dos órgãos do trato digestório, pior metabolizabilidade do nitrogênio, matéria seca, além de menor energia metabolizável em relação a ração peletizada. Do mesmo modo, aos 21 dias de idade, os pintos que consumiram ração pré-inicial extrusada apresentaram pior desempenho em relação a ração peletizada. Conclui-se que ração extrusada a 150°C para pintos de corte na fase pré-inicial, resulta em menor metabolizabilidade dos nutrientes e menor desenvolvimento dos órgãos do sistema digestório aos sete dias de idade e pior desempenho aos 21 dias.

ABSTRACT The objective of this study was to evaluate the thermal processing of pre-initial diets on performance, morphometry of the organs of the digestive system and nutrient digestibility in broiler chicks. The test sample consisted of 180 broiler chicks distributed in a completely randomized design, with two treatments, six replications of 15 birds each. The treatments consisted of pelleted feed (70°C) and extruded feed (150°C). The metabolism test was realized from 4 to 7 days of age, while the performance and morphometry of the organs of the digestive system were evaluated at 7 and 21 days of age. The data were submitted to analysis of variance. At seven days of age, chicks that consumed extruded feed had lower feed intake, less development of digestive tract organs, lower nitrogen absorption rate, dry matter, in addition to less metabolizable energy compared to pelleted feed. Likewise, at 21 days of age, chicks that consumed extruded pre-starter feed performed worse than pelleted feed. The conclusion is thus reached that feed extruded at 150 ° C for broiler chicks in the pre-initial phase, results in lower nutrient digestibility and an inferior development of the organs of the digestive system at 7 days of age and worse performance at 21 days.

RESUMO Objetivou-se verificar o efeito do óleo de sucupira em dietas para frangos de corte sobre o desenvolvimento intestinal, metabolizabilidade da matéria seca e do nitrogênio e desempenho de frangos de corte. Um total de 350 frangos de corte Cobb500® de um dia de idade, machos, foram distribuídos em sete tratamentos com cinco repetições, totalizando 35 unidades experimentais com 10 aves cada. Os tratamentos consistiram em dieta controle negativo, quatro dietas com diferentes níveis de óleo de sucupira (100; 500; 900 e 1.300 mg/kg), dieta com mananoligossacarídeo e dieta controle positivo com antibiótico. A inclusão de 900 e 1.300 mg de óleo de sucupira prejudicou o desenvolvimento intestinal e a metabolizabilidade dos nutrientes (P <0,05). A inclusão de 100 ou 500 mg de óleo de sucupira na ração para frangos de corte foi semelhante aos tratamentos controle negativo, MOS e antibiótico para as variáveis de desempenho (todas as fases estudadas) e também para a metabolizabilidade dos nutrientes (P <0,05). Pode-se concluir que níveis elevados de óleo de sucupira não são recomendados na dieta de frangos de corte.

ABSTRACT The objective of the present study was to ascertain the effect of sucupira oil in diets of broilers on gut development, dry matter and nitrogen metabolizability and broilers performance. A total of 350 one-d-old, male, Cobb500® broiler were allotted in seven treatments with five replicates, totaling 35 experimental units with 10 birds each. The dietary treatments consisted of a negative control diet, four diets with different levels of sucupira oil (100; 500; 900 and 1,300 mg/kg), diet with mannanoligosaccharide and control diet with antibiotic. The inclusion of 900 and 1,300 mg of sucupira oil impaired gut development and metabolizability of nutrients (P<0.05). The inclusion of 100 or 500 mg of sucupira oil in broiler feed was similar to negative control, MOS and antibiotic treatments for performance variables (all phases studied) and also for nutrient metabolizability (P<0.05). It can be concluded that high levels of sucupira oil is not recommended in broilers diet.

ABSTRACT Two experiments were carried out to evaluate the effects of digestible valine supplementation in pre-starter and starter diets on the productivity, nutrient metabolizability coefficient (NMC), and immune response of broilers from breeders of different ages. Experiments I and II were conducted with broilers in the pre-starter (1 to 7 days of age) and starter (8 to 21 days of age) phases, respectively. Broilers were fed diets that differed in their digestible valine content. In each trial, 400 male Cobb 500® chicks were randomly housed in a 2 × 4 factorial arrangement with eight treatments and five replicates of 10 birds each. The main effects were breeder age (37 vs. 52 weeks) and the digestible valine level in pre-starter (9.2, 10.2, 11.2, and 12.2 g/kg) and starter (8.3, 9.3, 10.3, and 11.3 g/kg) diets. Productive performance, intestinal histology, and immune response of broilers were evaluated. Supplementation with 11.2 g/kg valine in pre-starter diets improved NMC and increased villus height and villus:crypt ratio in the duodenum, jejunum development, and lymphocyte proliferation in the spleen of broilers at seven days of age, without improving performance (body weight gain, feed intake, and feed conversion ratio). In the starter phase, valine supplementation reduced feed intake but did not affect NMC, intestinal development, or immune response. The present results suggest that the same level of digestible valine should be used in the diet of broilers born to breeders of different ages, and the use of 9.2 and 8.3 g/kg digestible valine in pre-starter and starter diets, respectively, is sufficient to ensure satisfactory broiler performance. However, to improve the duodenum and jejunum development and immune response of broilers in the pre-starter phase, higher digestible valine levels are required.

ABSTRACT An experiment was conducted aiming to evaluate the effect of different levels of crude protein, based on the ideal protein concept and two rearing systems, on productive performance of brown laying hens. A total of 400 Hisex Brown laying hens between 30 and 45 weeks of age were distributed in a completely randomized design and a 2×4 factorial arrangement, with main effects including two rearing systems (cage and floor) and levels of crude protein (140, 150, 160, and 180 g kg−1), totalizing eight treatments. Five replicates with 10 birds each were used per experimental unit. The following parameters were evaluated: egg production, feed intake, body weight gain, feed conversion ratio, and quality traits such as dirty, cracked, or broken eggs. No interaction effect was observed between dietary protein levels and rearing systems for body weight gain, feed intake, egg production, egg weight, and feed conversion ratio. Feed intake and egg production were higher in the floor rearing system. Feed conversion ratio (kg/dz) was improved in birds reared in the cage system. The rate of cracked and broken eggs was higher in the cage system. The layers reared in the floor system produced a higher percentage of dirty eggs. The dietary protein level did not affect the evaluated parameters. Thus, we conclude that a floor rearing system is an option for layers, and the dietary protein level can be reduced up to 140 g kg−1 for Hisex Brown hens from 30 to 45 weeks of age.

ABSTRACT The objective of this study was the evaluation of egg quality of 30 to 45-week-old brown layers, raised in cages or on floor, supplemented with amino acids, using the ideal protein concept with levels of 14, 15, 16, and 18% crude protein. A total of 400 birds (Hy-sex Brown) were used, distributed into two breeding systems (conventional cage or floor). The evaluated variables were the yolk relative weight, yolk height, albumen relative weight, albumen height, specific gravity, eggshell thickness, and eggshell weight. Treatments consisted of reduced levels of crude protein and were provided to both groups equally. We adopted a completely randomized design, in a factorial scheme, composed of two breeding systems and four levels of crude protein, totaling eight treatments. Five replicates per treatment and 10 birds per experimental unit were used. The breeding system on floor was configured as an option in the breeding of brown layers, of Hy-sex Brown commercial lineage, in the period between the 30th and the 45th week of age, since it presents results equivalent to the ones obtained in the breeding system in cages, having the egg quality as parameter. The system of production on floor is configured as an option in the farming of brown layers, of the commercial lineage Hy-sex Brown.

RESUMO. Objetivou-se avaliar a suplementação do extrato de Lafoensia pacari padronizado em taninos na ração de poedeiras sobre o desempenho, a qualidade interna e externa de ovos e metabolizabilidade dos nutrientes da ração. Utilizaram-se 168 poedeiras Isa Brown com 24 semanas de idade, peso médio 2,6 kg e taxa de postura média 87% durante quatro períodos de 28 dias cada. Os tratamentos constituíram de rações com antibiótico melhorador de desempenho Halquinol, prebiótico Mananoligossacarídeo (MOS) e três níveis de extrato de pacari - 1.000, 2.000 e 3.000 mg kg-1 de ração. O delineamento experimental foi inteiramente casualizado com seis tratamentos e sete repetições com quatro aves cada. O extrato de pacari padronizado em teor de taninos apresentou porcentagem de albúmen e peso do ovo semelhante ao antibiótico (p < 0,04). A suplementação com o extrato melhorou a qualidade da casca, verificada pela gravidade específica (p < 0,03) e promoveu metabolizabilidade do extrato etéreo semelhante ao antibiótico e MOS (p < 0,04), sendo indicado como aditivo fitogênico.

ABSTRACT. It was intended to evaluate the supplementation of Lafoensia pacari standardized in tannins extract in the diet of laying hens on the performance, internal and external quality of eggs and metabolism of the feed nutrients. A total of 168 Isa Brown laying hens, aged 24 weeks, with the mean weight of 2.6 kg and the mean posture rate of 87% were used during 4 periods of 28 days each. The treatments consisted of Halquinol performance-enhancing antibiotic, Mannanoligosaccharide (MOS) prebiotic and three levels of pacari extract - 1,000, 2,000 and 3,000 mg kg-1of feed. The experimental design was completely randomized, with six treatments and seven replicates of four hens each. The pacari standardized in tannin extract presented a percentage of albumen and an egg weight similar to the antibiotic (p < 0.04). The supplementation with the extract improved the shell quality, verified by the specific gravity (p < 0.03) and promoted the metabolizability of ether extract similar to antibiotic and MOS (p < 0.04), allowing its indication as a phytogenic additive.

Resumo: Objetivou-se avaliar o efeito da idade da matriz e da variação da temperatura de incubação sobre a qualidade do pinto neonato. O delineamento foi inteiramente casualizado em esquema fatorial 3x2 (três idades x duas temperaturas de incubação). Foram incubados 720 ovos, provenientes de matrizes com diferentes idades (30, 42 ou 64 semanas). A temperatura da máquina de incubar para os grupos controle foi mantida constante (37,5 ºC) e para os tratamentos com estresse por calor foi aplicada uma temperatura de 39,0 ºC por 6h durante o período de 10 a 18 dias de incubação. Cinco pintos por tratamento foram sacrificados para coletas de órgãos e realizada a histomorfometria intestinal, de baço e bursa. Os dados foram submetidos a análise de variância e foi utilizado o teste de Tukey (5%). A área dos folículos da bursa foi maior nos pintos oriundos de matrizes mais velhas quando os ovos foram incubados em temperatura ideal. A temperatura de 39,0 ºC estimulou o desenvolvimento intestinal. A variação na temperatura de incubação prejudicou a qualidade de pintos, sobretudo para pintos originados de matrizes jovens. Pintos oriundos de matrizes velhas apresentaram melhor resposta imune e desenvolvimento intestinal, independentemente da variação da temperatura de incubação.

Abstract: This study was carried out to evaluate the effect of breeder age and hatching temperature variations on chick quality. The experiment was a completely randomized design in a 3x2 factorial arrangement (three breeder ages and two hatching temperatures). We used 720 eggs from three breeder ages (30, 42, or 64 weeks). The hatching temperature for control group was 37.5 ºC during all the hatching period and for the elevated temperature group, it was 39.0 ºC during 6h between 10 and 18 days of incubation. Five chicks per treatment were euthanized by cervical dislocation for bursal and spleen morphological measurements. The data were analyzed using ANOVA and the differences among means were compared by Tukey test (5%). Chicks from older flock had larger follicular area of bursa de Fabricius when hatched under normal temperature. The higher hatching temperature induced intestinal development because chicks hatched under high temperature had bigger crypt depth. Changes in hatching machine temperature affected young flock chick quality. Chicks from older flocks had better immune response.

The experiment evaluated the influence of isolated or associated phytogenic additives (PA) and organic acids (OA) on nutrient digestibility, performance and carcass characteristics of broiler chickens. Two experiments were conducted in a completely randomized design with a 2 × 2 + 1 factorial arrangement of treatments (with or without PA × with or without OA + antibiotic performance enhancer and anticoccidial). In the first experiment, two metabolic tests were conducted to determine the metabolizability coefficients of the nutrients of starter and growth diets. In the second experiment, 2520 one-day-old chicks were housed in 40 experimental units to evaluate the performance and carcass characteristics. The phytogenic additives and organic acids, isolated or associated, improve the nutrient digestibility of the diet and replace the growth- promoting antibiotics. The use of organic acids isolated or associated with phytogenic additives in broiler diets improves broiler performance in comparison with free antibiotic performance enhancer at 42 days of age. Isolated or associated phytogenic additives and organic acids provided better carcass characteristics.

The objective of this experiment was to evaluate the effect of two digestible lysine levels and four digestible arginine levels on laying hens from 24 to 48 weeks of age. Three hundred and twenty Lohmann LSL laying hens were allotted in a completely randomized design in a 2 × 4 factorial arrangement, with two levels of digestible lysine (700 and 900 mg/kg of diet) and four digestible arginine levels (700, 800, 900 and 1000 mg/kg of diet). Results indicated requirement of 884 and 830 mg of digestible arginine/kg of diet, considering an average feed intake of 95 g/hen/day and an average hen weight of 1.5 kg, aiming at lesser feed intake and better nutritional balance of nitrogen, respectively. High digestible lysine levels in the diet require higher digestible arginine supplementation for a better performance of hens.

Neste experimento foram avaliados os efeitos de níveis de lisina digestível no desempenho, no balanço de nitrogênio e na digestibilidade de extrato etéreo em poedeiras Lohmann LSL entre 16 e 25 semanas de idade. Foram avaliados quatro níveis de lisina digestível (0,6; 0,7; 0,8 e 0,9% da ração) utilizando-se 160 poedeiras durante o período de 16 até 25 semanas de idade. As dietas foram isonutritivas, com 17% de PB e 2.800 (pré-postura) e 2.750 kcal (pré-pico) EM/kg. O delineamento inteiramente casualizado foi adotado com quatro níveis de lisina digestível avaliados em quatro repetições. Os níveis de lisina digestível não influenciaram o ganho de peso, os consumos de ração e de proteína e energia, a idade ao primeiro ovo, a produção e o peso dos ovos, os índices de conversão alimentar, a massa do ovo e os balanços de nitrogênio e extrato etéreo. Houve aumento linear positivo do consumo de lisina de acordo com os níveis dietéticos de lisina digestível. Os níveis de lisina utilizados não interferem no desempenho nem no balanço de nutrientes. Sugere-se o uso de 0,6% de lisina por quilograma de ração.

In this experiment, the effects of digestible lysine levels on performance, nitrogen balance and fat digestibility in Lohmann LSL hens 16 to 25 weeks of age were evaluated. Four levels of digestible lysine (0.6, 0.7, 0.8 and 0.9% in ration) were assessed by utilizing 160 16-year-old laying hens 16 to 25 weeks of age. The diets were isonutritive with 17% CP and 2800 (pre laying) and 2750 (pre peak) kcal/kg. A completely randomized design was used with four lysine levels assessed in four replicates. The lysine levels did not influence weight gain, feed intake, protein and energy intake, age at first egg laying, egg production, egg weight, feed conversion indexes, egg mass, nitrogen balance or crude fat. There was positive linear increase on lysine intake according to the dietary levels of digestible lysine. Lysine levels do not influence the performance or the nutrients balance, and 0.6% of lysine per kilogram of feed is recommended.

Objetivou-se determinar os melhores níveis de lisina digestível para poedeiras em produção. Avaliaram-se o desempenho, o consumo de nutrientes, o metabolismo, a qualidade de ovos, os parâmetros sanguíneos e o desenvolvimento do aparelho reprodutor de 160 poedeiras Hy-Line W-36 com 25 semanas de idade. As aves foram distribuídas em delineamento inteiramente casualizado, com quatro níveis de lisina digestível (600, 700, 800 ou 900 mg de lisina/kg de ração) e quatro repetições, utilizando-se o esquema de parcelas subdivididas na avaliação do balanço de nitrogênio, dos parâmetros sanguíneos e do aparelho reprodutor. Os níveis de lisina da dieta influenciaram os consumos de alimento, proteína e energia, cujo ponto de máximo foi observado no nível de 720 mg de lisina. Para produção de ovos, o melhor nível foi 800 mg de lisina; para conversão alimentar, 900 mg; e, para balanço de nitrogênio, 700 mg. A digestibilidade de extrato etéreo, a qualidade dos ovos, o desenvolvimento do aparelho reprodutor e os parâmetros sanguíneos não foram influenciados pelos níveis de lisina digestível da dieta. Recomendam-se níveis de 700 a 800 mg de lisina digestível para metabolismo e desempenho e 600 mg para qualidade dos ovos e melhor desenvolvimento do aparelho reprodutor.

In this experiment it was aimed to determine the best levels of digestible lysine for laying hens in production period. Performance, nutrients intake, metabolism, egg quality, blood parameters and development of reproductive tract for 160 Hy-Line W-36 hens at 25 weeks of age. Hens were distributed in a completely randomized design with four levels of digestible lysine (600, 700, 800 or 900 mg of Lys/kg) and four replicates by using a split spot scheme was used at evaluation of nitrogen balance, blood parameters and reproductive tract. Lysine levels in the diet affected food, protein and energy intakes whose maximum point was noted at the level of 720 mg of Lysine. For egg production, food conversion, and nitrogen balance, the best levels of lysine was 800 mg, 900 mg, and 700 mg, respectively. The digestibility of ethereal extract, egg quality, development of reproductive tract and blood parameters were not affected by levels of digestible lysine in the diet. It is suggested 700 and 800 mg of digestible lysine for metabolism and performance, respectively, and 600 mg for egg quality and better development of the reproductive trait.