用阿弗咪丁(Ivermectin)防止绵羊毛圆类线虫排卵春季高潮的研究

该试验的目的在于,研究和确定在生产条件下,早期驱虫对受阻幼虫的作用,以及4月中和5月初出牧时驱虫能否更好地消灭母羊在春季的虫卵排出。试验结果发现,不论在产羔时驱虫,还是在春季出牧时治疗都可防止春季和早夏对牧地的污染,并可推迟在同一牧地上放牧羔羊的感染期。

THE USE OF IVERMECTIN IN THE PREVENTION OF THE SPRINGRISE IN TRICHOSTRONGYLID EGG OUTPUT IN EWES

The present study was aimed to determine the effect of anthelmintictreatment in early spring on arrested larvae under field conditions and wea-ther treatment at the time of turnout either in mid-April or in May eliminatedfurther egg output of ewes during spring.The ewes,which lambed from February 13 to March 7,were divided into3 groups.Group Ⅰ was treated with ivermectin(200 micrograms/kg)during thelambing period,on February 27.Group 2 was treated at weaning on April 16and turned out on pasture.Group 3 was treated at weaning on May 1 andturned out on pasture.The weaned lambs were kept indoors until May 16 when they were allo-wed to graze on the pasture previously grazed by the ewes.It was found that the major helminth responsible for the increase was Hae-monc-hus which accounted for approximately 90% of the larvae observed.Othermajor helminth larvae noticed were Trichostrongyles,Cooperia and Oesopha-gostomum sp.The anthelmintic treatment of group 1 reduced the egg output to zero forthe next month,but a transient rise did occur during April.The anthelmintictreatment of the other two groups suppressed the egg output for at least twomonths.The lambs showed their first larvae at the end of June,and the outputincreased slowly in July but then rose to over 100 larvae per gram in August.The results of these trials were demonstrated that anthelmintic treatmenteither at lambing or at turn-out in spring can prevent pastgre contaminationin spring and early summer,and may delay the occurrence of infection inlambs grazing the same pasture.