植物提取物饲料添加剂对仔猪生产性能的影响

本试验旨在研究植物提取物饲料添加剂免力特对仔猪生长性能的影响。试验选择来源相同、24日龄左右、健康状况良好的断奶仔猪198头，随机分为2个处理组，每组设5个重复，每个重复约20头。结果表明，抗生素组的腹泻率为6．2l％，而免力特组的腹泻率较抗生素组显著降低了37．19％（P〈0．05）；虽然免力特组的仔猪平均初始重为8．00kg，比抗生素组的低了140g／头，日采食量也略低于抗生素组（P〉0．05），但免力特组的日增重却比抗生素组提高了3g/头·天（P〉0．05），免力特组的料肉比为1．59，低于抗生素组。结论：饲料中添加500g／t免力特对减少仔猪腹泻效果较好，明显优于抗生素组，促生长效果与抗生素组相当，可完全或替代部分抗生素。

Attractive natural products with strained cyclopropane and/or cyclobutane ring systems

The strained cyclopropane and/or cyclobutane subunits occurred in many complex natural products including terpenoids, steroids and alkaloids. Natural products with cyclopropane and/or cyclobutane motifs not only furnished fascinating structures, but also exhibited versatile biological activities, such as cytotoxic, anti-HIM antimicrobial, antiviral, and immunosuppressive effects. This review covered a large array of structurally unique natural products with strained cyclopropane and/or cyclobutane motifs and summarized their structural features, distributions, biological activities, as well as biogenetic considerations.