Waller P J, Axelsen A, Donald A D, Morley F H, Dobson R J, Donnelly J R
Division of Animal Health, CSIRO McMaster Laboratory, Glebe, New South Wales.
Aust Vet J. 1987 Dec;64(12):357-62. doi: 10.1111/j.1751-0813.1987.tb09600.x.
Comparison was made of the performances of cross-bred ewes and their lambs on pastures of low helminth infectivity ("safe" pastures) or contaminated pastures and at high or low stocking rates. Ewes grazing the safe, but not the contaminated, pastures were given a single pre-lambing drench. The largest difference in parasite infection between treatments was the level of exposure of sheep to Trichostrongylus spp, which was negligible on the safe pastures. The effects of parasite control on lamb growth were significant only in twins during the last 2 months before weaning. However, 22% of lambs on contaminated plots became soiled in the breech area and 38% were flystruck, compared with 8% and 10% respectively for lambs on the safe pastures. Ewe bodyweight gains were greater at low than at high stocking rate and were not affected by the parasite control treatments; differences in breech soiling and fly strike were similar to those in the lambs. Most importantly the parasite treatment produced a highly significant effect on ewe fleece weight at weaning. Ewes drenched and lambing on the safe pastures produced an extra 0.43 kg of wool, calculated to represent an increase of at least 40% during this period at the low-level of parasitic infection.
比较了杂交母羊及其羔羊在低蠕虫感染性牧场（“安全”牧场）或受污染牧场以及高或低载畜率情况下的表现。在安全但未受污染的牧场上放牧的母羊在产前进行了一次驱虫。各处理之间寄生虫感染的最大差异在于绵羊感染毛圆线虫属的程度，在安全牧场上该感染程度可忽略不计。寄生虫控制对羔羊生长的影响仅在断奶前最后两个月的双胞胎羔羊中显著。然而，在受污染地块上，22%的羔羊臀部区域被弄脏，38%的羔羊遭蝇蛆侵袭，而在安全牧场上，羔羊的这两个比例分别为8%和10%。母羊在低载畜率时的体重增加大于高载畜率时，且不受寄生虫控制处理的影响；臀部弄脏和蝇蛆侵袭的差异与羔羊相似。最重要的是，寄生虫处理对断奶时母羊的羊毛产量产生了极显著影响。在安全牧场上接受驱虫并产羔的母羊多产出了0.43千克羊毛，据计算，在这种低水平寄生虫感染期间，这相当于至少增加了40%。
