Effects of amino acid levels during rearing on Cobb 500 slow-feathering broiler breeders: 1. Growth and development.

Adequate pullet nutrition is essential to reach BW and suitable body composition for reproduction. An experiment was conducted to determine the effects of 4 dietary amino acid (AA) levels on BW, flock uniformity, body conformation, organ, leg, and feathering development of broiler breeder pullets during the rearing phase from 5 to 24 wk. A total of 1,360 Cobb-500 slow-feathering (SF) pullets were randomly placed in 16-floor pens with 85 females per pen. Diets with corn, soybean meal, and wheat-midds were formulated without protein restriction maintaining minimum ratios between essential AA and Lys on a digestible (dig) ideal basis. Treatments consisted of 4 dietary AA levels with 80% (low-AA), 90% (moderate-AA), 100% (standard-AA), and 110% (high-AA) of the Cobb-Vantress recommendations guided by dig Lys using balanced protein. Up to 4 wk, all pullets were fed a common starter crumble diet. Grower and developer mash diets were fed to pullets from 5 to 15 wk and from 16 to 24 wk, respectively. Pullets fed standard-AA and high-AA diets were heavier (P < 0.001) than those fed low-AA diets at 10, 15, and 20 wk of age. High-AA diets resulted in better (P = 0.040) flock uniformity at 10 wk. Pullets fed a high-AA diet had the highest (P = 0.041) relative breast weight at 20 wk of age and the lowest (P = 0.044) deposits of abdominal fat at 15 wk of age. Fleshing increased (P < 0.05) as AA content rise in the diet, while the relative shank length (P < 0.001) and the number of wing juvenile feathers (P = 0.004) decreased. Pullets fed the lowest dietary AA level had the longest (P = 0.007) small intestine relative to BW at 10 wk of age, but a smaller (P = 0.001) liver than those fed moderate and standard-AA diets at 20 wk of age. Dietary AA levels have important effects on pullet BW, fleshing, and organ development during rearing with potential reproductive performance impacts.

Utilização da vitamina D3 e seus metabólitos na alimentação de frangos de corte sobre parâmetros imunológicos e morfometria intestinal / Use of vitamin D3 and its metabolites in broiler feed on immunological parameters and intestinal morphometry

Os efeitos da suplementação da vitamina D3 e de seus diferentes metabólitos foram avaliados na resposta imune e na morfometria intestinal de frangos de corte. Foram utilizados 952 frangos de corte de um dia de idade, distribuídos em um delineamento inteiramente casualizado, com quatro tratamentos, sete repetições e 34 aves por unidade experimental. Os tratamentos foram constituídos por quatros diferentes fontes de vitamina D3: colecalciferol (D3), 25-hidroxicolecalciferol (25(OH)D3),1,25dihidroxicolecalciferol (1,25(OH)2D3) e 1α-hidroxicolecalciferol (1α(OH)D3). As diferentes fontes foram incluídas na dieta, fornecendo 2000 e 1600 UI de vitamina D, nas fases pré-inicial, inicial e de crescimento, respectivamente. O peso relativo do intestino delgado diferiu entre os tratamentos aos 7, 21 e 42 dias e o peso relativo do fígado somente aos 42 dias de idade. Os demais órgãos e parâmetros imunológicos avaliados (peso dos órgãos linfóides, reação de hipersensibilidade cutânea basofílica, avaliação da atividade de macrófagos, dosagem de nitrito e perfil heterofilo: linfócito foram similares entre os animais alimentados com os diferentes metabólitos. Houve efeito (P<0,05) dos diferentes metabólitos da vitamina D3 sobre o comprimento dos vilos de jejuno e íleo aos sete dias, diferindo entre os animais alimentados com 1,25(OH)2D3 e 1α(OH)D3 para jejuno e 1,25(OH)2D3 e vitamina D3 para íleo (P<0,05). Para as demais fases não foi observado influência (P>0,05) dos tratamentos. Os parâmetros imunológicos não foram afetados pelos diferentes metabólitos de vitamina D. Os diferentes metabólitos de vitamina D afetaram positivamente a morfometria intestinal na altura de vilo na fase inicial, sendo os melhores resultados obtido pelos animais alimentados com 1,25(OH)2D3, contudo os parâmetros imunológicos foram similares entre os metabólitos estudados.

The aim of this experiment was to evaluate the effect of different vitamin D metabolites on immune response and intestine morphometry of broiler chickens. We used 952 1-day-old chicks, male Cobb, distributed into a completely randomized design with four treatments, seven replications and 34 birds each. There were evaluated four different metabolites of vitamin D: D3, 25(OH)D3, 1,25(OH)2D3 and 1α(OH)D3, providing 2000 and 1600 IU/kg feed of vitamin D in initial and growth period, respectively. The different metabolites of vitamin D did not affect the relative weight of the organs except for the weight of the intestine and liver at 21 and 42 days. There was a significant effect (P<0.05) of the different metabolites of D3 vitamin on the villi length of jejunum and ileum at 7 days, between animals fed with 1,25(OH)2D3 and 1α(OH)D3 to the jejunum and 1,25(OH)2D3 and vitamin D3 to the ileum (P<0.05). There were no differences (P>0.05) for weight of lymphoid organs, cutaneous basophil hypersensitivity reaction, macrophage activity assessment, measurement of nitric oxide and heterophil profile: lymphocyte. The different sources of vitamin D affect the intestine morphometrics on the villi length in the initial phase, but the effect was not observed in other phases. The immunological parameters were not affected by metabolites of vitamin D.