Tawah C L
International Livestock Centre for Africa (ILCA), Addis Abeba, Ethiopie.
Rev Elev Med Vet Pays Trop. 1992;45(3-4):310-3.
The relative resistance to different cattle ticks of Gudali and Wakwa cattle with different levels of Brahman breeding, grazed on natural pastures in the subhumid tropics of Wakwa, Cameroon, was assessed using pasture tick infestations. The basic design consisted of 5 young bulls of each breed from different sire herds. Tick populations were observed in Gudali and Wakwa bulls over a period of four weeks when the climate was thought to be highly favourable for the free-living stages of ticks. Counting of adult, larval and nymphal ticks was carried out in the morning of each counting day on the body surface of cattle after restraining them. Ticks were identified by species and sex. Repeated measures analysis of variance technique was used to account for time trends and breed differences. Results showed that Wakwa cattle carried slightly more ticks than Gudali cattle. However, this difference was not statistically significant. Significant within breed differences in tick counts suggested that selection for resistance to ticks, particularly Amblyomma variegatum, can be effective within each breed. The tick species recorded by order of decreasing abundance were Amblyomma variegatum, Rhipicephalus lunulatus and Hyalomma spp. It was clear from this study that long-term investigations would be necessary to ascertain the extent of the differences in tick counts between these two breeds of cattle and to assess the biological mechanisms of resistance to Amblyomma variegatum as well as to estimate the heritability of tick resistance.
在喀麦隆瓦夸亚湿润热带地区的天然牧场上，对具有不同婆罗门牛血统水平的古达利牛和瓦夸牛对不同牛蜱的相对抗性进行了评估，评估方法是利用牧场上的蜱虫感染情况。基本设计是从不同种公牛群中选取每个品种的5头年轻公牛。在认为气候对蜱虫自由生活阶段极为有利的四周时间内，观察古达利牛和瓦夸牛身上的蜱虫数量。在每个计数日的早晨，在对牛进行约束后，对牛体表的成年蜱、幼虫和若虫进行计数。蜱虫按种类和性别进行鉴定。采用重复测量方差分析技术来分析时间趋势和品种差异。结果表明，瓦夸牛身上携带的蜱虫比古达利牛略多。然而，这种差异在统计学上并不显著。同一品种内蜱虫数量存在显著差异，这表明针对蜱虫抗性进行选择，特别是对变异革蜱的抗性选择，在每个品种内可能是有效的。按丰度递减顺序记录的蜱虫种类为变异革蜱、新月扇头蜱和璃眼蜱属。从这项研究可以清楚地看出，有必要进行长期调查，以确定这两个品种牛蜱虫数量差异的程度，评估对变异革蜱的抗性生物学机制，并估计蜱虫抗性的遗传力。
