The objective of this study was to evaluate the effect of the supplementation of xylanase in diets with reduced energy level on the apparent metabolizable energy corrected for nitrogen, determined with laying hens at 14, 36, 60 and 80 weeks of age. Four digestibility trials were conducted, using 80 Hy-line W36 laying hens aged 14, 36, 60 and 80 weeks of age. Birds were distributed in a completely randomized design in 2 × 2 factorial arrangement (energy level × inclusion of xylanase), totaling four treatments with 10 replicates of two birds each. Treatments were: positive control (balanced diet for their age); positive control + xylanase; negative control (diet with reduction of 100 kcal/kg in the level of metabolizable energy); and negative control + xylanase. Xylanase, produced by microorganism Trichoderma reesei, was added to the diets at 100 g/t (16,000 BXU/kg) for diets fed at 14 weeks and 75 g/t for diets of 36, 60 and 80 weeks (12,000 BXU/kg). The data obtained were subjected to analysis of variance at 5% probability. Supplementation of xylanase promoted higher values for AME (apparent metabolizable energy) and AMEn (apparent metabolizable energy corrected for nitrogen) determined with 80-week-old laying hens, subjected to diet with energy level according to the nutritional requirements for their age. Supplementation of xylanase increases the matabolizability coefficient of the dietary crude protein and improves the nitrogen retention of laying hens at 14 weeks. In addition, xylanase associated with adequate levels of dietary energy promotes higher values for AME and AMEn determined with laying hens at 80 weeks of age.

Avaliaram-se os efeitos dos níveis lisina digestível e zinco quelato combinados na dieta de galinhas poedeiras sobre a qualidade do ovo. Foram usadas 720 aves de 48 a 60 semanas de idade, distribuídas em delineamento inteiramente casualizado em arranjo fatorial 3 × 5 com três níveis de zinco e cinco níveis de lisina aplicados a seis repetições em unidades experimentais de oito aves por parcela. Os níveis foram: 137, 309 e 655 ppm de zinco e 0,482; 0,527; 0,582; 0,644; 0,732% de lisina digestível. Não se constatou interação de lisina digestível e zinco para as principais variáveis das frações e composição do ovo. O nível de zinco reduziu o peso do ovo e isso sugere menor eficiência na absorção de nutrientes. Na maior concentração dietética de zinco, o acréscimo de lisina digestível coincidiu com aumento linear no peso da casca. Por outro lado, o acréscimo de zinco, independentemente do nível de lisina na dieta, culminou na redução do peso do ovo e da porcentagem da matéria mineral na gema limitando a eficiência de deposição mineral nessa fração do ovo. A concentração de zinco que promoveu os melhores resultados foi a de 137 ppm, uma vez que quantidades mais elevadas limitaram o uso de lisina digestível, com efeitos prejudiciais à composição e qualidade do ovo. As exigências de lisina digestível foram de 0,639% da 48ª à 52ª semana; 0,679% da 52ª à 56ª semana; e 0,635% da 56ª à 60ª semana. No período total entre a 48ª e 60ª semana, o nível 0,638% de lisina, ou a ingestão diária de 707 mg desse aminoácido, atende às necessidades para qualidade de ovo de galinhas poedeiras semipesadas.

It was evaluated the effects of levels of digestible lysine and chelate zinc combined in the diet for laying on the egg quality. It was used 720 birds, from 48 to 60 weeks of age, distributed in a completely randomized design in a 3 × 5 factorial scheme with three levels of zinc and five levels of lysine, applied into six replicates in the experimental units of eight birds per plot. The levels were: 137, 309 and 655 ppm zinc and 0.482, 0.527, 0.582, 0.644 and 0.732% digestible lysine. It was not observed any interaction among digestible lysine and zinc for the primary variables of fractions and egg composition. Levels of zinc reduced egg weight, suggesting the lowest efficiency in nutrient intake. At the highest dietary concentration of zinc, the addition of digestible lysine coincided with a linear increase in shell weight. However, zinc addition, regardless of lysine level in the diet, resulted in the reduction of egg weight and of the percentage of mineral matter in the yolk, limiting the efficiency of mineral deposition in this fraction of the egg. Concentration of zinc that produced the best results was 137 ppm inasmuch as higher quantities limit the use of digestible lysine, with effects harming composition and egg quality. The study indicates the following requirement for digestible lysine: 0.639% from the 48th to the 52nd week, 0.679% from the 52nd to 56th week, and 0.635% from the 56th to the 60th week. Considering the total period from 48th to the 60th week, the level 0.638% of lysine or the daily intake of 707 mg of the amino acid met the requirement for egg quality of semi-heavy layers used in this study.

Objetivou-se avaliar a produção de ovos em galinhas Isa Brown alimentadas com dietas com diferentes níveis de lisina digestível e zinco quelato. Utilizaram-se 720 poedeiras marrons, em dois períodos de avaliação, de 24 a 36 e de 48 a 60 semanas de idade. As dietas foram avaliadas em delineamento inteiramente casualizado, em esquema fatorial 5 × 3, composto de 5 níveis de lisina digestível (0,482; 0,527; 0,582; 0,644 e 0,732%) e 3 de zinco quelato (20, 40 e 80 ppm), de modo que cada combinação foi testada em 6 repetições de 8 aves por unidade experimental. Na fase de 24 a 36 semanas de idade, houve influência da interação de lisina digestível e zinco no consumo médio diário de ração e na porcentagem de postura. Na fase de 48 a 60 semanas, a interação foi evidenciada somente no consumo médio diário de ração. O aumento da concentração de lisina digestível favoreceu o consumo de ração em todos os níveis de zinco. Em ambas as fases, a menor concentração de zinco atende às necessidades de produção das aves. O valor médio estimado de lisina digestível ideal foi de 0,732% para a fase de 24 a 36 semanas e de 0,578% para a fase de 48 a 60 semanas de idade.

This work aimed at evaluating egg production in Isa Brown hens fed diets with different levels of digestible lysine and chelate zinc. It was used 720 brown laying hens, in two evaluation periods, from 24 to 36 and from 48 to 60 weeks of age. The diets were evaluated in a completely randomized design in a 5 × 3 factorial scheme composed of five levels of digestible lysine (0.482; 0.527; 0.582; 0.644 and 0.732%) and three levels of chelate zinc (20, 40 and 80 ppm), so each combination was tested in 6 repetitions of 8 birds per experimental unit. In the phase from 24 to 36 weeks of age, there was an influence of digestible lysine and zinc on average feed intake of the ration and on laying percentage. During the phase from 48 to 60 weeks of age, the interaction was evidenced only on the average feed intake. The increase of digestible lysine concentration favored feed intake at all zinc levels. In both phases, the lowest zinc concentration meets poultry production needs. The estimated average value of ideal digestible lysine was 0.732% for the phase from 24 to 36 weeks of age and 0.578% for phase from 48 to 60 weeks of age.