Smeal M G, Fraser G C, Robinson G G
Aust Vet J. 1980 Feb;56(2):80-6. doi: 10.1111/j.1751-0813.1980.tb05630.x.
Pasture plots in 3 climatic regions were contaminated with worm eggs of Ostertagia ostertagi, Trichostrongylus axei, Haemonchus spp and Cooperia spp in the autumn, winter and spring. Successive pairs of parasite-free calves were grazed on the plots for 7 to 10 days at 4-week intervals and then killed for worm counts 14 days after their removal from pasture. On the Northern Tablelands of New South Wales, irrespective of the season of pasture contamination, the degree of inhibition of O. ostertagi was low in winter and highest in spring. T. axei showed similar trends while Cooperia spp showed negligible inhibition. On the North Coast of New South Wales, inhibited larvae accounted for a very small proportion of the O. ostertagi burdens, while in comparison T. axei showed a much greater degree of inhibition. Larval inhibition of Haemonchus spp occurred in autumn and early winter after which it did not occur. There was negliglible inhibition in Cooperia spp. On the Central Coast of New South Wales, there was little inhibition of O. ostertagi and none in T. axei. For Haemonchus spp, inhibited larvae were found mainly in autumn and winter. The numbers of inhibited Cooperia larvae were also highest in autumn and winter and were associated with large worm burdens. The marked difference between the tablelands and coastal regions in the seasonal trends of inhibition of O. ostertagi was considered to be due to a difference in strains between the geographical regions. The possible effect of climatic factors on the inhibition-proneness of infective larvae on pasture is discussed for Ostertagia and other nematodes. The roles of host resistance and density-dependence are also discussed.
在秋季、冬季和春季，将3个气候区的牧场地块用奥氏奥斯特线虫、阿氏毛圆线虫、血矛线虫属和古柏线虫属的虫卵进行污染。连续成对的无寄生虫小牛每隔4周在这些地块上放牧7至10天，然后在从牧场移除14天后宰杀以进行蠕虫计数。在新南威尔士州的北部高原地区，无论牧场污染季节如何，奥氏奥斯特线虫的抑制程度在冬季较低，在春季最高。阿氏毛圆线虫呈现类似趋势，而古柏线虫属的抑制作用可忽略不计。在新南威尔士州的北海岸，受抑制的幼虫在奥氏奥斯特线虫虫负荷中占比非常小，而相比之下，阿氏毛圆线虫的抑制程度要高得多。血矛线虫属的幼虫抑制发生在秋季和初冬，之后不再发生。古柏线虫属几乎没有抑制作用。在新南威尔士州的中部海岸，奥氏奥斯特线虫几乎没有抑制作用，阿氏毛圆线虫则没有抑制作用。对于血矛线虫属，受抑制的幼虫主要在秋季和冬季被发现。受抑制的古柏线虫幼虫数量在秋季和冬季也最高，并且与大量的蠕虫负荷有关。奥氏奥斯特线虫抑制的季节性趋势在高原地区和沿海地区之间的显著差异被认为是由于地理区域之间菌株的差异。讨论了气候因素对牧场上感染性幼虫抑制倾向的可能影响，涉及奥氏奥斯特线虫和其他线虫。还讨论了宿主抗性和密度依赖性的作用。
