生猪养殖户兽药使用行为的主要影响因素研究——以阜宁县为案例

兽药在生猪养殖中具有不可替代的作用,但兽药的不当使用将导致生猪体内兽药残留,同时引起耐药细菌产生并在食物链体系中蔓延,对人体健康构成潜在危害。以江苏省阜宁县654个生猪养殖户为样本,基于收益预期的分析方法,运用MVP(Multivariate Probit)模型,分析生猪养殖户兽药使用行为及其主要影响因素。结果表明,养殖户在生猪养殖过程中超量使用兽药、不遵守休药期的行为较为普遍,其中不遵守休药期的养殖户约占样本比例的70%;养殖户的性别、年龄、家庭人数、养殖收入占家庭收入的比重、养殖规模、养殖年限,生猪销售对象、对兽药残留的认知与对政府违规处罚的了解程度等均不同程度地影响其兽药的使用行为,而政府监管仅对养殖户在生猪养殖过程中人药兽用的行为发生作用,对养殖户超量使用兽药与不遵守休药期的行为并无显著影响。     

Minimum viable population and conservation status of the Atlantic Forest spiny rat Trinomys eliasi

A population viability analysis (PVA) was conducted to assess the minimum viable population (MVP) of the Atlantic Forest spiny rat Trinomys eliasi, a species threatened by habitat loss and restricted geographical distribution. Objectives were to suggest quasi-extinction thresholds, estimate minimum areas of suitable habitat (MASH) and MVPs, and compare results with the species’ current status. The computer package VORTEX was used. The model predicted sizes of 200 animals to achieve demographic stability, but buffering declines in genetic variability required populations of 2000 animals. Estimated MASHs were approximately 250 and 2500 ha for demographic and genetic stability, respectively. Mortality rate and mean litter size were the most sensitive parameters to changes in model assumptions. The protection of known populations and the search for extant populations are the first steps in conservation. T. eliasi's issue could help protecting the coastal shrubland ecosystem of Rio de Janeiro state. Observing IUCN's criteria for listing threatened species, it is suggested that T. eliasi should be ranked as vulnerable in red lists.