Allen P C, Lydon J, Danforth H D
USDA-Agricultural Research Service, Beltsville, Maryland 20705, USA.
Poult Sci. 1997 Aug;76(8):1156-63. doi: 10.1093/ps/76.8.1156.
Four experiments were run to test the anticoccidial activity of dried Artemisia annua leaves and several of their chemical constituents for possible use as prophylactic feed additives. When fed over a period of 3 wk at a level of 5%, a dried leaf supplement of A. annua provided significant protection against lesions due to Eimeria tenella but not Eimeria acervulina or Eimeria maxima. When fed over a period of 5 wk at a level of 1% to chicks undergoing immunization with a live vaccine, it provided significant protection in partially immunized chicks against E. acervulina and E. tenella lesions from a dual species challenge infection. It also afforded lower mean lesion scores in challenged chicks immunized over a period of 5 wk. Artemisinin, an antimalarial component of A. annua, was present at a level of 0.034% in the dried leaf preparation. A 5% supplement thus afforded about 17 ppm artemisin. When the pure compound was fed at that level for a period of 3 wk, it protected weight gains and significantly reduced lesion scores attributable to E. tenella but not E. acervulina. Other components of A. annua, camphor and 1,8-cineole, at 119 ppm also protected weight gains, and reduced E. tenella lesion scores. Camphor reduced E. acervulina lesions. Artemisinin fed for 4 wk at levels of 2, 8.5, and 17 ppm significantly reduced oocyst output from separate E. acervulina and E. tenella infections and a dual species infection. Pure artemisinin thus appears to be effective against at least two coccidia species when used as a feed additive, and its activity may depend, in part, on the length of time it is administered before a challenge infection.
进行了四项实验，以测试黄花蒿干叶及其几种化学成分的抗球虫活性，看其是否有可能用作预防性饲料添加剂。当以5%的水平投喂3周时，黄花蒿干叶补充剂能显著预防柔嫩艾美耳球虫引起的病变，但对堆型艾美耳球虫或巨型艾美耳球虫无效。当以1%的水平投喂5周给正在用活疫苗进行免疫的雏鸡时，它能为部分免疫的雏鸡提供显著保护，使其免受双物种攻击感染引起的堆型艾美耳球虫和柔嫩艾美耳球虫病变。它还能使在5周内进行免疫的受攻击雏鸡的平均病变评分降低。黄花蒿的抗疟成分青蒿素在干叶制剂中的含量为0.034%。因此，5%的补充剂可提供约17 ppm的青蒿素。当以该水平投喂纯化合物3周时，它能保护体重增加，并显著降低由柔嫩艾美耳球虫而非堆型艾美耳球虫引起的病变评分。黄花蒿的其他成分樟脑和1,8-桉叶素，含量为119 ppm时也能保护体重增加，并降低柔嫩艾美耳球虫的病变评分。樟脑可减少堆型艾美耳球虫的病变。以2、8.5和17 ppm的水平投喂4周的青蒿素可显著减少单独的堆型艾美耳球虫感染、柔嫩艾美耳球虫感染以及双物种感染后的卵囊产量。因此，纯青蒿素用作饲料添加剂时似乎对至少两种球虫有效，其活性可能部分取决于在攻击感染前给药的时间长度。
