59 research outputs found
Incorporating Environmentally Compliant Manure Nutrient Disposal Costs into Least-Cost Livestock Ration Formulation
Livestock rations are formulated to minimize feed cost subject to nutritional requirements for a target performance level, which ignores the potentially substantial cost of disposing of nutrients fed in excess of nutritional requirements. We incorporate nutrient disposal costs into a modified least-cost ration formulation model to arrive at a joint least-cost decision that minimizes the sum of feed and net nutrient disposal costs. The method is demonstrated with phosphorus disposal costs on a representative dairy farm. Herd size, land availability and proximity, crop rotation, and initial soil phosphorus content are shown to be important in determining phosphorus disposal costs.environmental compliance, linear programming, livestock rations, manure disposal, Agribusiness, Environmental Economics and Policy, Livestock Production/Industries, C61, Q12, Q52,
Valuing the absence of feral swine in the United States: A partial equilibrium approach
Feral swine (also called wild pigs; Sus scrofa Linnaeus) are known to cause damage to crops among other types of property damage. This research addresses the lack of economic welfare estimates of wild pig imposed crop damages in the literature by estimating the value of wild pig removal with respect to five crops in nine southern U.S. states. An equilibrium displacement model was used to assess the changes in price and quantity that would result from eliminating damage to corn, soybeans, wheat, rice, and peanuts in these nine states. Changes in price and quantity were used to calculate the changes in producer and consumer welfare in both the short- and longrun. The total producer and consumer surplus gains were found to be 89 million in the long-run
Valuing the absence of feral swine in the United States: A partial equilibrium approach
Feral swine (also called wild pigs; Sus scrofa Linnaeus) are known to cause damage to crops among other types of property damage. This research addresses the lack of economic welfare estimates of wild pig imposed crop damages in the literature by estimating the value of wild pig removal with respect to five crops in nine southern U.S. states. An equilibrium displacement model was used to assess the changes in price and quantity that would result from eliminating damage to corn, soybeans, wheat, rice, and peanuts in these nine states. Changes in price and quantity were used to calculate the changes in producer and consumer welfare in both the short- and longrun. The total producer and consumer surplus gains were found to be 89 million in the long-run
Drivers of low-input farmers’ perceptions of sustainable ruminant farming practices in the Eastern Cape Province, South Africa
A computational model of invasive aspergillosis in the lung and the role of iron
BACKGROUND: Invasive aspergillosis is a severe infection of immunocompromised hosts, caused by the inhalation of the spores of the ubiquitous environmental molds of the Aspergillus genus. The innate immune response in this infection entails a series of complex and inter-related interactions between multiple recruited and resident cell populations with each other and with the fungal cell; in particular, iron is critical for fungal growth. RESULTS: A computational model of invasive aspergillosis is presented here; the model can be used as a rational hypothesis-generating tool to investigate host responses to this infection. Using a combination of laboratory data and published literature, an in silico model of a section of lung tissue was generated that includes an alveolar duct, adjacent capillaries, and surrounding lung parenchyma. The three-dimensional agent-based model integrates temporal events in fungal cells, epithelial cells, monocytes, and neutrophils after inhalation of spores with cellular dynamics at the tissue level, comprising part of the innate immune response. Iron levels in the blood and tissue play a key role in the fungus’ ability to grow, and the model includes iron recruitment and consumption by the different types of cells included. Parameter sensitivity analysis suggests the model is robust with respect to unvalidated parameters, and thus is a viable tool for an in silico investigation of invasive aspergillosis. CONCLUSIONS: Using laboratory data from a mouse model of invasive aspergillosis in the context of transient neutropenia as validation, the model predicted qualitatively similar time course changes in fungal burden, monocyte and neutrophil populations, and tissue iron levels. This model lays the groundwork for a multi-scale dynamic mathematical model of the immune response to Aspergillus species. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12918-016-0275-2) contains supplementary material, which is available to authorized users
Valuing the absence of feral swine in the United States: A partial equilibrium approach
Feral swine (also called wild pigs; Sus scrofa Linnaeus) are known to cause damage to crops among other types of property damage. This research addresses the lack of economic welfare estimates of wild pig imposed crop damages in the literature by estimating the value of wild pig removal with respect to five crops in nine southern U.S. states. An equilibrium displacement model was used to assess the changes in price and quantity that would result from eliminating damage to corn, soybeans, wheat, rice, and peanuts in these nine states. Changes in price and quantity were used to calculate the changes in producer and consumer welfare in both the short- and longrun. The total producer and consumer surplus gains were found to be 89 million in the long-run
Incorporating Environmentally Compliant Manure Nutrient Disposal Costs into Least-Cost Livestock Ration Formulation
Livestock rations are formulated to minimize feed cost subject to nutritional requirements
for a target performance level, which ignores the potentially substantial cost of disposing of
nutrients fed in excess of nutritional requirements. We incorporate nutrient disposal costs
into a modified least-cost ration formulation model to arrive at a joint least-cost decision
that minimizes the sum of feed and net nutrient disposal costs. The method is demonstrated
with phosphorus disposal costs on a representative dairy farm. Herd size, land availability
and proximity, crop rotation, and initial soil phosphorus content are shown to be important
in determining phosphorus disposal costs
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