Agyei A D, Sapong D, Probert A J
Animal Research Institute (CSIR), Achimota, Ghana.
Vet Parasitol. 1991 Jul;39(1-2):79-88. doi: 10.1016/0304-4017(91)90064-3.
The nematode egg output of two groups of ewes, a pregnant test group (2-3 years of age) mated between March and April and a non-pregnant control group (5-6 years of age) was followed. The worm burdens acquired by worm-free 'tracer' lambs were also followed on the same pasture from March 1988 to February 1989. There was a significant difference (P less than 0.05) in the magnitude of the egg output in the test group compared with the control group. In the test ewes, an initial rise in egg production occurred 2 weeks after lambing and was maintained for five consecutive months. Necropsy worm counts from the 'tracer' lambs revealed that pasture larval levels were directly related to the levels of rainfall. Adult nematodes (Trichostrongylus colubriformis, Trichostrongylus axei, Haemonchus contortus, Oesophagostomum venulosum and Trichuris ovis), and some Moniezia expansa were present in almost all the lambs throughout the year, with the exception of January and February 1989. The absence of immature larvae in these lambs indicates that arrested development is not a feature of the life cycle of these species in Southern Ghana. The occurrence of a periparturient rise of nematode eggs in West African Dwarf ewes, a year-round breeder, means that susceptible lambs could be open to infection throughout the year. Control should, therefore, be conducted by treating ewes after lambing and restricting the breeding season to particular periods of the year.
对两组母羊的线虫卵排出量进行了跟踪观察，一组是怀孕试验组（2 - 3岁），于3月至4月间交配；另一组是非怀孕对照组（5 - 6岁）。同时，从1988年3月至1989年2月，在同一牧场对无蠕虫的“追踪”羔羊所感染的蠕虫负荷量也进行了跟踪。试验组与对照组相比，卵排出量的大小存在显著差异（P小于0.05）。在试验母羊中，产羔后2周卵产量开始上升，并持续了连续五个月。对“追踪”羔羊的尸检蠕虫计数显示，牧场幼虫水平与降雨量直接相关。除1989年1月和2月外，几乎所有羔羊全年都存在成年线虫（蛇形毛圆线虫、斧形毛圆线虫、捻转血矛线虫、微小食道口线虫和绵羊鞭虫）以及一些扩展莫尼茨绦虫。这些羔羊中未出现未成熟幼虫，表明在加纳南部这些物种的生命周期中不存在发育停滞现象。西非矮种母羊是全年繁殖的品种，其线虫卵在围产期出现上升，这意味着易感羔羊全年都可能受到感染。因此，应在母羊产羔后进行治疗，并将繁殖季节限制在一年中的特定时期来进行控制。
