999 resultados para nitrogen excretion
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Zootecnia - FCAV
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Pós-graduação em Zootecnia - FCAV
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Zootecnia - FMVZ
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The objectives of this study were to describe the potential for nitrogen retention by two techniques: comparative slaughter and nitrogen balance; compare the adjusted models for each technique and estimate the maintenance requirement for pullets. Assays were performed during 14 to 28, 56-70 and 98 to 112 days of age, using 168 pullets. The design was completely randomized with seven treatments and eight replications. Treatments consisted of protein levels ranging from 75 to 435gkg-1 of dry matter. The variables were collected by comparative slaughter and nitrogen ingested and deposited in nitrogen balance technique intake and nitrogen excretion. The intercept of the exponential relationship between ingested and excreted nitrogen was considered a requirement for maintenance. The adjusted models were compared by using the maximum likelihood ratio. The techniques described differently compared the requirement for maintenance of nitrogen. For comparative slaughter requiring maintenance was estimated at 342, 372 and 543mg/kgPC0,67 and for nitrogen balance was 342, 225 and 284mg/kgPC0,67 for the period of 14 to 28, 56-70 and 98 to 112 days of age, respectively.
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This study aimed at evaluating diets containing different fiber sources and two crude protein levels on the performance, egg quality, and nitrogen metabolism of commercial layers. In total, 392 48-wk-old Isa Brown layers were distributed according to a completely randomized experimental design in a 3x2+1 (control) factorial arrangement, resulting in seven treatments with seven replicates of eight birds each. Treatments consisted of three fiber feedstuffs (cottonseed hulls, soybean hulls, and rice hulls) and two dietary crude protein levels (12% and 16%). Cottonseed hulls associated with the high crude protein level (16%) resulted in the worst feed conversion ratio per dozen eggs. Diets with 16% crude protein resulted in the highest feed intake, egg production, egg weight, egg mass values, and improved feed conversion ratio (kg eggs/kg feed). The dietary inclusion of soybean hulls determined low yolk pigmentation, and of rice hulls, low egg specific gravity. The 16% crude protein diet with rice hulls promoted the best feed conversion ratio. Hens fed the reference diet presented higher egg mass and better feed conversion ratio per kg eggs and per dozen eggs. Hens fed the diets with low crude protein level (12%) had reduced nitrogen excretion, but presented worse egg production.
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Pós-graduação em Zootecnia - FCAV
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The objective was to evaluate levels of multiple supplements supplied to beef heifers in low supply of pasture on intake and nutrients digestibility, pH and concentration of ruminal ammonia nitrogen, nitrogen balance, synthesis and microbial efficiency. Five Nellore heifers with initial body weight of 344.00 +/- 21.10 kg and average initial age of 22 months were used. The following supplements were evaluated as fed to the animals: control (mineral supplement) and supplementation levels of 2, 4, 6 and 8 kg/animal/day, composing the following percentages of body weight (BW): 0.55, 1.11, 1.66 and 2.22%, respectively. The experimental design was a Latin square with five replications and five supplements. Intakes of total dry matter, crude protein (CP) and total digestible nutrients, and total apparent digestibility of dry matter, crude protein, total carbohydrates and no fiber carbohydrates increased linearly (P <0.0001) and dry matter intake of forage decreased (P <0.0001) with supplementation levels. Supplementation strategies promoted reduction on ruminal pH (P = 0.0343) and increased concentration of ruminal ammonia nitrogen (NH3-N) (P = 0.0004) before the supply of supplements, and after, this NH3-N presented quadratic behavior (P = 0.0023). Nitrogen intake, excretion of urea in urine and nitrogen excretion in feces increased linearly (P <0.0001) according to supplementation levels. The supply of high levels of multiple supplements reduces forage intake and presents itself as an alternative to cattle maintained in a systems with low supply of pasture in the dry season.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)