皮蝇幼虫在牦牛体内移行动态与伊维菌素最佳驱除时间

2004年经剖检60头幼年牦牛,对牛皮蝇幼虫在牦牛体内移行动态进行了观察。8月份,第一期幼虫在牦牛体内出现,10月中旬牦牛体内第一期幼虫呈高峰。从11月中旬到第二年2月中旬第二期幼虫出现,元月中旬二期幼虫出现高峰,三期幼虫从元月中旬到6月初出现,3月中旬出现高峰。用伊维菌素给45头幼年牦牛投药:9月中旬,10月中旬和11月中旬各15头。9月中旬和11月中旬的投药群,在12月中旬均出现瘤疱,而10月中旬的投药群未发现瘤疱,表明10月中旬对第一期幼虫为最佳驱除时间。

Migration Dynamics of cattle Grub in Yak and Optimum Time of Ivermectin Treatment

The migration dgnamics of cattle grub in yak was abserved by autopsg of 60 young yaks in 2004.The first-instar grubs were detected in yak for the first time in August,The number of the first-instar grub peaked in the middle ten days of October.The second-instar grubs were detected in yak from the middle ten days of November to the middle ten days of February of next year.The number of the second-instar grub peaked in yak in the middle tea days of January.The third-instar warbles were detected in yak from the middle ten days of jammary to the first ten days of June.The number of the third-instar werble peaked in the middle ten days of March,45young yaks that were divided into three groups which were the treatment groups in the middle ten days of september,of October and of November were administered with ivermectin.The warbles were detected in the yaks of the trentment groups in the middle ten days of september and November,but no warbles were detected in the yaks of the treatment group in the middle ten days of October,These results suggested that the middle ten days of October was the optimum deworming time with ivermectin for the first-instar grub in yak.