title: Forecasting the peak of gastrointestinal nematode infection in lambs.
abstract: The pattern of sheep nematode infective larvae on pasture shows a marked midsummer peak arising largely from the ewe peri-parturient egg output. Records of larval pattern over a nine-year period were examined in relation to meteorological data, and a correlation was demonstrated between the time of the summer peak and cumulative rainfall. A "wet score" was allocated to 12-hourly rainfall figures, and a "critical index" of 440 units of wetness was shown to be necessary before the larval peak was reached. A "warning index" of 350 to 380 wetness units is suggested which would allow a prediction to be made of the onset of major infection in lambs.
mesh_terms: D000818:Animals; D004739:England; D005260:Female; D009349:Nematode Infections / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D011247:Pregnancy; D011891:Rain; D012621:Seasons; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology* / Q000469:parasitology