Uso racional de recursos naturais não-renováveis: aspectos biológicos, econômicos e ambientais

Lana, Rogério de Paula

doi:10.1590/s1516-35982009001300033

Cited by 16 publications

(15 citation statements)

References 20 publications

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“…As the nitrogen levels were increased, fertilization efficiency decreased, resulting in lower production at nitrogen levels greater than 240.72 kg ha -1 . This reduction might be related to the fact that fertilization efficiency is higher with the application of small doses of fertilizer (LANA, 2007). In addition, pastures subjected to long periods of deferment have lower potential of nitrogen utilization than that in pastures subjected to short deferment periods.…”

Section: Methodsmentioning

confidence: 99%

Agronomic and nutritional characteristics of Massai grass subjected to deferred grazing and nitrogen fertilization

Costa

Rodrigues

Araújo

et al. 2017

SCA

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This study aimed to evaluate the agronomic characteristics and nutritional value of Massai grass (Megathyrsus maximus 'Massai') pastures fertilized with different nitrogen levels and subjected to deferred grazing. A completely randomized experimental design (CRD) was adopted, with including five nitrogen levels (zero, 100, 200, 300, and 400 kg ha −1 ), and five replications (plots). The degradability trial used a CRD including a 6 × 5 factorial arrangement, consisting of six rumen-incubation times (6, 24, 48, 60, 84, and 96 h) and five levels of nitrogen in different plots. One fistulated sheep, with a live weight of 60 kg, was used in the experiment. Total herbage biomass, dead herbage biomass, and height showed a quadratic response to nitrogen fertilization levels of 100 to 200 kg ha -1 resulted in greater tillering. Protein and dry matter content increased linearly with nitrogen fertilization level, leading to increase in fibrous components. The increase in NDF and ADF contents might be a consequence of the reduction in NCE, and the high flowering rate of the grass, owing likely to the reduction in metabolism of the grass in an attempt to extend its lifetime. Nitrogen levels of 300 kg ha −1 or higher affected the productive characteristics positively, whereas the chemical characteristics were negatively affected. Key words: Deferred period. Degradability of dry matter. Megathyrsus. Nitrogen fertilization. ResumoObjetivou-se avaliar as características agronômicas e valor nutritivo do capim-Massai (Megathyrsus maximus 'Massai') submetido a diferimento e doses crescentes de nitrogênio. O delineamento experimental adotado foi o inteiramente casualizado (DIC) com cinco doses de nitrogênio (zero, 100; 200; 300 e 400 kg de N ha -1 ) com cinco repetições (parcelas). O ensaio de degradabilidade foi estruturado em DIC, com arranjo fatorial 6x5, seis tempos de incubação no rúmen (6, 24, 48, 60, 84 e 96 h) e cinco doses de N em parcelas diferidas. Utilizou-se um ovino fistulado com peso vivo de 60 kg. A biomassa de forragem total, morta e a altura respondeu à adubação nitrogenada de forma quadrática. A adubação nitrogenada nas doses 100 a 200 kg de N ha -1 proporcionou maior perfilhamento. A adubação nitrogenada proporcionou resposta linear sobre os teores de proteína e matéria seca em consequência também aumentou os constituintes fibrosos. O amento dos teores de FDN e FDA pode ser uma consequência da redução da ECN e da taxa de florescimento da gramínea, devido provavelmente à redução no metabolismo na tentativa de prolongar sua vida útil. A partir da dose de 300 kg de N ha -1 resultou em redução da degradação da matéria seca do capim-Massai. As doses de N influenciaram positivamente as características produtivas e negativamente as características químicas. Palavras-chave: Adubação nitrogenada. Degradabilidade da MS. Megathyrsus. Período de diferimento.

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Section: Methodsmentioning

confidence: 99%

Agronomic and nutritional characteristics of Massai grass subjected to deferred grazing and nitrogen fertilization

Costa

Rodrigues

Araújo

et al. 2017

SCA

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“…Observou-se que não houve efeito de nível de fubá de milho sobre o peso corporal nem na produção e composição do leite (Tabela 2), considerando que a resposta na produção de leite em virtude da suplementação concentrada, segue a saturação cinética típica de sistemas enzimáticos (Lana, 2009). Obtevese o seguinte modelo de dupla recíproca de Lineweaver-Burk (1934): 1/leite = 0,0384*(1/Mi) + 0,168, r² = 0,91, que permite obter as constantes cinéticas K max (produção máxima teórica de leite) e K s (quantidade de concentrado para causar metade de…”

Section: Resultsunclassified

“…Apesar da falta de significância estatística, a resposta marginal em produção de leite reduziu com o aumento da suplementação, estando de acordo com Lana (2009) .…”

Section: Resultsunclassified

“…No início do século passado, Mitscherlich (1909) propôs a teoria da resposta marginal (ou rendimentos) decrescente do fornecimento de nutrientes cujos princípios foram essenciais para definição do nível ótimo de suplementação concentrada utilizados na atualidade (Lana et al, 2005;Lana, 2009;Oliveira et al, 2010;Oliveira et al, 2012) mas, de acordo com o Biotechnology andBiological Sciences Research Council (1998), os sistemas alimentares em uso calculam os requerimentos dietéticos de energia e proteína que os animais requerem para satisfazer suas necessidades para manutenção visando a um dado nível de produção; todavia, na prática a situação é diferente, porque não existe qualquer necessidade do produtor satisfazer os requerimentos nutricionais das vacas se for contra os interesses econômicos. Evidencia-se, desta forma, a necessidade de estudos de resposta animal aos níveis crescentes de suplementos.…”

Section: Introductionunclassified

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Cinética da produção de leite em função da suplementação com concentrados energéticos e proteicos

Abreu¹,

Lana²,

Oliveira³

et al. 2013

Agraria

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RESUMOTrês experimentos foram conduzidos com o objetivo de avaliar os efeitos da suplementação energética e proteica sobre a produção e composição do leite de vacas mestiças. Doze vacas foram distribuídas em três experimentos, em quadrados latinos 4 x 4, em quatro períodos de quatorze dias. Os tratamentos consistiram de níveis crescentes de fubá de milho -M (0,0; 0,85; 1,70; e 3,40 kg vaca -1 dia -1 ), farelo de soja -FS (0,0; 0,65; 1,30; e 2,60 kg vaca -1 dia A produção máxima teórica de leite (1/a) foi de 5,9; 5,1 e 8,6 kg animal -1 dia -1 e a quantidade de concentrado para atingir a relação custo-benefício zero foi de 0,95; 0,60 e 0,90 kg para M, FS e GS. Os modelos de saturação cinética são apropriados para explicar esses efeitos e prescrever recomendação de nutrientes na alimentação animal.Palavras-chave: desempenho, gado de leite, Lineweaver-Burk, Michaelis-Menten, nutrição Kinetics of milk production as a function of energy and protein supplementation ABSTRACTThree studies were conducted to evaluate the effects of energy and protein supplementation on milk production by crossbred cows in pasture and feedlot. Twelve cows were allotted in three-4 x 4 Latin squares, in four periods of fourteen days. The treatments consisted of increased levels of corn meal-CM (0.0, 0.85, 1.7 and 3.4 kg.cow ), soybean meal-SM (0.0, 0.65, 1.3 and 2.6 kg) and grinded soybean grain-SG (0.32, 0.65, 1.3 and 2.6 kg). There were no treatment effects, although the mean data of milk production presented a curvilinear response to concentrate levels, following a Michaelis-Menten relationship, according to the next equations of Lineweaver-Burk: Exp. 1: 1/Milk = 0.0384*(1/CM) + 0.168 r 2 = 0.91; Exp. 2: 1/Milk = 0.0181*(1/SM) + 0.196 r 2 = 0.99; Exp. 3: 1/Milk = 0.0140*(1/SG) + 0.116 r 2 = 0.98. The theoretical maximum milk production (1/a) were 5.9, 5.1 and 8.6 kg.animal -1 .day -1 and the calculated amounts of supplements to reach marginal cost-benefit zero were 0.95, 0.6 and 0.9 kg for CM, SM and SG. The models of saturation kinetics are appropriate to explain these effects and to make nutrient recommendations.

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“…More recently, especially from the last decade of the 20th century onwards, concerns about the planet sustainability have generated a series of issues on agricultural production systems (MA, 2005;Lana, 2009;Place and Mitloehner, 2010;Groot et al, 2012;Dumont et al, 2013;Billen et al, 2014). Given the imminent depletion of certain natural resources, resource recycling has become a relevant strategy.…”

Section: Introductionmentioning

confidence: 99%

Linear Programming in the economic estimate of livestock-crop integration: application to a Brazilian dairy farm

2016

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-A linear programming mathematical model was applied to a representative dairy farm located in Brazil. The results showed that optimization models are relevant tools to assist in the planning and management of agricultural production, as well as to assist in estimating potential gains from the use of integrated systems. Diversification was a necessary condition for economic viability. A total cost reduction potential of about 30% was revealed when a scenario of lower levels of diversification was contrasted to one of higher levels. Technical complementarities proved to be important sources of economies. The possibility of reusing nitrogen, phosphorus, and potassium present in animal waste could be increased to 167%, while water reuse could be increased up to 150%. In addition to economic gains, integrated systems bring benefits to the environment, especially with reference to the reuse of resources. The cost dilution of fixed production factors can help economies of scope to be achieved. However, this does not seem to have been the main source of these benefits. Still, the percentage of land use could increase up to 30.7% when the lowest and the highest diversification scenarios were compared. The labor coefficient could have a 4.3 percent increase. Diversification also leads to drastic transaction cost reductions.

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Uso racional de recursos naturais não-renováveis: aspectos biológicos, econômicos e ambientais

Cited by 16 publications

References 20 publications

Agronomic and nutritional characteristics of Massai grass subjected to deferred grazing and nitrogen fertilization

Agronomic and nutritional characteristics of Massai grass subjected to deferred grazing and nitrogen fertilization

Cinética da produção de leite em função da suplementação com concentrados energéticos e proteicos

Linear Programming in the economic estimate of livestock-crop integration: application to a Brazilian dairy farm

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