Chiejina S N, Emehelu C O
Res Vet Sci. 1984 Sep;37(2):144-7.
The seasonal changes in the populations of trichostrongylid infective larvae (L3) on herbage and in soil samples collected from pastures grazed by beef cattle were studied at Nsukka, eastern Nigeria, from April 1980 to July 1981. Large numbers of L3 were recovered from all samples collected during the rainy season (April to October). The rainy season herbage infestation was characterised by three clearly defined peaks. The first, which followed an 'early rains' (April) rise, occurred in the second half of May while the larger second and third peaks occurred in late July and October respectively. It is suggested that each of these peaks represented a distinct wave of infestation by a separate generation consisting of the three trichostrongylids concerned, namely Cooperia, Haemonchus and Trichostrongylus species. Although there was a sharp fall in pasture infestation following the onset of the dry season, appreciable numbers of L3 were still present on herbage in early December. The implications of these findings have been discussed in relation to the choice of effective strategic anthelmintic programmes for the prophylaxis and control of bovine parasitic gastroenteritis in the Nsukka area.
1980年4月至1981年7月，在尼日利亚东部的恩苏卡，对从肉牛放牧的牧场采集的牧草和土壤样本中毛圆线虫感染性幼虫（L3）的种群季节性变化进行了研究。在雨季（4月至10月）采集的所有样本中都发现了大量的L3。雨季牧草感染的特点是有三个明确界定的高峰。第一个高峰在“早雨”（4月）上升之后出现，发生在5月下旬，而较大的第二个和第三个高峰分别出现在7月下旬和10月。有人认为，这些高峰中的每一个都代表了由相关的三种毛圆线虫（即古柏线虫、血矛线虫和毛圆线虫）组成的不同世代的独特感染波。尽管旱季开始后牧场感染率急剧下降，但12月初牧草上仍有相当数量的L3。已结合恩苏卡地区预防和控制牛寄生性胃肠炎的有效战略驱虫方案的选择，对这些发现的意义进行了讨论。
