Louw J P, Reinecke R K
Department of Parasitology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Republic of South Africa.
J S Afr Vet Assoc. 1990 Dec;61(4):163-7.
Suckling Merino lambs on lucerne pasture, demonstrated no appreciable mass gain when compared with untreated controls, despite regular treatment with anthelmintics. This was ascribed to severe parasitic challenge. After weaning and transfer to wheat stubble fields with no parasitic challenge, however, the live mass of the untreated lambs, still harbouring a residual burden of nematodes, was depressed. Control sheep produced 1.2 kg less wool than regularly-treated sheep, but produced finer wool which had a higher market value. Regularly-treated ewes (F1) produced 12.1% more lambs, but their mean live mass was 2.6 kg lower than that of ewes treated less frequently. The overall financial benefit was in favour of the group which received fewer anthelmintic treatments and was due mainly to the higher market value of the finer wool produced by these apparently stressed animals.
在苜蓿牧场上哺乳的美利奴羔羊，尽管定期使用驱虫药进行治疗，但与未治疗的对照组相比，体重没有明显增加。这归因于严重的寄生虫感染。然而，断奶后转移到没有寄生虫感染的小麦茬地时，仍携带残留线虫负担的未治疗羔羊的活体重下降。对照羊比定期治疗的羊少产1.2千克羊毛，但生产的羊毛更细，市场价值更高。定期治疗的母羊（F1）产羔数多12.1%，但其平均活体重比治疗频率较低的母羊低2.6千克。总体经济效益有利于接受较少驱虫治疗的组，这主要归因于这些明显受应激动物生产的更细羊毛的较高市场价值。
