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Phenotypic Characterization and Strategies for Genetic Improvement of WAD Goats under Backyard Systems
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作者 S. O. Oseni B. A. Ajayi 《Open Journal of Animal Sciences》 2014年第5期253-262,共10页
West African Dwarf (WAD) goats represent one of the predominant small ruminant breeds raised by resource-limited households in southern Nigeria as well as in the humid west and central Africa. This breed of goats is r... West African Dwarf (WAD) goats represent one of the predominant small ruminant breeds raised by resource-limited households in southern Nigeria as well as in the humid west and central Africa. This breed of goats is renowned for its adaptation to hot and humid environments, high fertility and prolificacy under backyard systems where they are raised almost with zero investment. On account of its contributions to household income and food security in southern Nigeria, there is the need for a detailed phenotypic and genetic characterization as well as the design of breeding strategies for its conservation through sustainable utilization. A critical challenge, however, is that there are no national breeding policies in most of the countries where WAD goats are raised. The objectives of this paper are: to review literature reports on trait-level information and estimates of genetic parameters for some economic characters of WAD goats;and to discuss a communal breeding scheme for its conservation through sustainable utilization. The presentation shows that WAD goats represent a highly diverse population, with particular reference to qualitative and performance-related traits, reflecting the role of traditional institutions in the maintenance of animal diversity in local populations. A genetic improvement programme involving dispersed open nucleus breeding scheme was discussed. The scheme involves backyard WAD goat units in villages as base population and dispersed communally managed schemes that maintain a population of bucks only, as nucleus units. Critical issues such as the definition of breeding goals by farmers, as well as communal project ownership, are emphasized. The ultimate goal of the breeding programme is to create opportunities for community-based management of WAD goat genetic resources for the benefit of backyard goat farmers in the region. 展开更多
关键词 WAD Goats Characterization trait-level information Genetic Improvement COMMUNAL Breeding Scheme BACKYARD SYSTEMS
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IRT中测验信息函数性质的解析及估值方法 被引量:1
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作者 田振清 《内蒙古师范大学学报(自然科学汉文版)》 CAS 2009年第6期671-673,共3页
介绍了项目反应理论(IRT)的三参数Logistic数学模型,给出测验信息函数和项目信息函数的数学表达式.通过分析项目信息函数的主要特性,设计了绘制被试的特质水平(θ)~测验信息函数(I(θ))曲线的算法,给出I(θ)值的估算方法.
关键词 项目反应理论 特质水平 测验信息函数 算法设计 数值估算
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