No abstract

The effects of enzyme combinations in diets for commercial laying hens need further clarification. The goal of this study was to determine if the type of protease used in diets supplemented with phytase affects performance, nutrient intake, egg quality or intestinal mucosa morphometry of laying hens during peak egg production. Seven hundred and eighty hens (25-week-old Hy-Line W36 hens) were assigned to a completely randomized design composed of five treatments/diets with 12 replicates of 13 birds each. The five treatments were: 1) positive control: diet formulated according to the Hy-Line nutritional recommendations, without proteases , 2) negative control A: positive control diet reduced in energy, protein and amino acids according to protease A matrix, without protease supplementation, 3) negative control B: positive control diet reduced in energy, protein and amino acids according to protease B matrix, without protease supplementation, 4) negative control A plus protease A, 5) negative control B plus protease B. There was no effect of the treatments (P > 0.05) on egg production, egg mass or feed conversion; however, the nutritional restriction imposed by the negative controls reduced egg weight (negative control A, P=0.02), albumen height (P < 0.01) and the Haugh unit (P < 0.01). Protease supplementation reduced the calculated intake of protein and amino acids compared to the positive control; nevertheless, protease A was able to maintain egg weight, albumen height and the Haugh unit at the same levels as that obtained with the positive control hens. The intestinal mucosa responded to treatment only at the jejunum (P < 0.01), but the negative controls did not modify villus height or crypt depth compared to the positive control. However, crypt depth of protease B hens was higher than that of the positive control hens. In conclusion, when included in diets supplemented with phytase, the type of protease affects performance, nutrient intake, egg quality and intestinal mucosa morphometry of laying hens during peak egg production. Key words: Amino acid. Egg production. Egg quality. Enzyme. Nutritional restriction. ResumoOs efeitos da utilização em conjunto de enzimas exógenas para aves de postura precisam ser mais explorados na literatura. No intuito de determinar se o tipo de protease, em dietas suplementadas com fitase, interfere no desempenho, qualidade do ovo, ingestão de nutrientes e morfometria da mucosa intestinal de galinhas em pico de postura, 780 galinhas Hy-Line W36 de 25 semanas foram distribuídas em um delineamento inteiramente casualizado composto por cinco tratamentos/dietas com 12 repetições de 13 aves cada. Os cinco tratamentos foram: 1) controle positivo: dieta formulada de acordo com as recomendações nutricionais da Hy-Line, sem proteases, 2) controle negativo A: dieta controle positivo reduzida em energia, proteína e aminoácidos conforme a matriz nutricional da protease A, sem proteases, 3) controle negativo B: dieta controle positivo reduzida em energia, proteína e aminoácidos confor...

machos da linhagem Cobb, criados em sistema intensivo com fornecimento das dietas a partir da fase inicial até a terminação, com abate aos 42 dias. O delineamento foi inteiramente casualizado (DIC) com cinco tratamentos e sete repetições (5 x 7), sendo cada parcela experimental constituída por três aves.Os tratamentos foram os seguintes: T1 -ração basal sem adição de glicerina; T2 -30 g/kg de adição de glicerina; T3 -60 g/kg de adição de glicerina; T4 -90 g/kg de adição de glicerina e T5 -120 g/kg de adição de glicerina. Os resultados mostraram efeito dos níveis de glicerina sobre os parâmetros de carcaça (Peso ao abate, Rendimento de carcaça e do Peito, Peso das Pernas e Asas). Para a cor da carne do peito, ocorreu aumento dos teores de vermelho e alteração no ângulo de tonalidade da cor. Não foram observadas alterações em relação à perda de peso por cozimento, pH final e maciez em ambos os cortes. A glicerina bruta não promoveu alteração nos valores de composição nutricional na carne de frango independente do nível de utilização e do corte.De forma geral, a glicerina bruta na alimentação de frangos apesar de afetar os parâmetros de carcaça, destaca-se como um ingrediente de potencial uso devido às reduzidas alterações observado em relação à qualidade de carne.

The physiological responses of xylose-grown Debaryomyces hansenii were studied under different nutritive stress conditions using continuous cultivation at a constant dilution rate of 0.055 h 3I . Metabolic steady-state data were obtained for xylose, ammonium, potassium, phosphate and oxygen limitation. For xylose and potassium limitation, fully oxidative metabolism occurred leading to the production of biomass and CO P as the only metabolic products. However, potassium-limiting cultivation was the most severe nutritional stress of all tested, exhibiting the highest xylose and O P specific consumption rates along with the lowest biomass yield, 0.22 g g 3I xylose. It is suggested that carbon was mainly channelled to meet the cellular energy requirements for potassium uptake. For the other limiting nutritional conditions increasing amounts of extracellular xylitol were found for ammonium, phosphate and oxygen limitation. Although xylitol excretion is not significant for ammonium limitation, the same is not true for phosphate limitation where the xylitol productivity reached 0.10 g l 3I h 3I , about half of that found under oxygen-limiting conditions, 0.21 g l 3I h 3I . This work is the first evidence that xylitol production by D. hansenii might not only be a consequence of a redox imbalance usually attained under semi-aerobic conditions, but additional physiological mechanisms must be involved, especially under phosphate limitation. Cell yields changed drastically as a function of the limiting nutrient, being 0.22, 0.29, and 0.39 g g 3I xylose for potassium, oxygen and phosphate limitation, respectively, and are a good indicator of the severity of nutritive stress. z

The physiological responses of xylose‐grown Debaryomyces hansenii were studied under different nutritive stress conditions using continuous cultivation at a constant dilution rate of 0.055 h−1. Metabolic steady‐state data were obtained for xylose, ammonium, potassium, phosphate and oxygen limitation. For xylose and potassium limitation, fully oxidative metabolism occurred leading to the production of biomass and CO2 as the only metabolic products. However, potassium‐limiting cultivation was the most severe nutritional stress of all tested, exhibiting the highest xylose and O2 specific consumption rates along with the lowest biomass yield, 0.22 g g−1 xylose. It is suggested that carbon was mainly channelled to meet the cellular energy requirements for potassium uptake. For the other limiting nutritional conditions increasing amounts of extracellular xylitol were found for ammonium, phosphate and oxygen limitation. Although xylitol excretion is not significant for ammonium limitation, the same is not true for phosphate limitation where the xylitol productivity reached 0.10 g l−1 h−1, about half of that found under oxygen‐limiting conditions, 0.21 g l−1 h−1. This work is the first evidence that xylitol production by D. hansenii might not only be a consequence of a redox imbalance usually attained under semi‐aerobic conditions, but additional physiological mechanisms must be involved, especially under phosphate limitation. Cell yields changed drastically as a function of the limiting nutrient, being 0.22, 0.29, and 0.39 g g−1 xylose for potassium, oxygen and phosphate limitation, respectively, and are a good indicator of the severity of nutritive stress.