Brake J, Axtell R C, Campbell W R
Department of Poultry Science, North Carolina State University, Raleigh 27695.
Poult Sci. 1991 Sep;70(9):1873-5. doi: 10.3382/ps.0701873.
Single Comb White Leghorn pullets were fed cyromazine (Larvadex) continuously at levels of 0, 25, 250, and 1,000 mg/kg diet (ppm) from hatch to 20 wk of age. Fresh manure was bioassayed for toxicity to housefly, Musca domestica, larvae beginning at the 6th wk after removal of cyromazine from the feed, and at weekly intervals thereafter. At 6 wk after removal of the feed additive there was 51.6% fly mortality at 25 ppm, 75.7% at 250 ppm, and 86.5% at 1,000 ppm relative to the 0-ppm control. Fly mortality decreased to less than 10.7% mortality at 13 and 15 wk postremoval for hens grown on 25 ppm and 250 ppm cyromazine, respectively. Hens grown on 1,000 ppm cyromazine produced manure that was still exhibiting more than 50% fly mortality 20 wk after removal of the feed additive. These data demonstrate retention of cyromazine in laying hens for up to 20 wk after feeding the chemical to the birds at 5 to 200 times greater than the maximum recommended rate for the initial 20 wk of life.
单冠白来航小母鸡从孵化到20周龄期间，持续饲喂含量为0、25、250和1000毫克/千克日粮（ppm）的环丙氨嗪（Larvadex）。从饲料中去除环丙氨嗪后的第6周开始，每周对新鲜粪便进行家蝇幼虫毒性生物测定。去除饲料添加剂6周后，相对于0 ppm对照组，25 ppm时家蝇死亡率为51.6%，250 ppm时为75.7%，1000 ppm时为86.5%。分别在25 ppm和250 ppm环丙氨嗪饲养的母鸡去除添加剂后13周和15周时，家蝇死亡率降至10.7%以下。在1000 ppm环丙氨嗪饲养的母鸡所产粪便中，去除饲料添加剂20周后家蝇死亡率仍超过50%。这些数据表明，在最初20周的生命中，以比最大推荐剂量高5至200倍的剂量向母鸡投喂环丙氨嗪后，环丙氨嗪在蛋鸡体内可保留长达20周。
