Discipline of Animal and Poultry Science, University of KwaZulu-Natal, P. Bag X01, Scottsville 3209, Pietermaritzburg, South Africa.
Ticks Tick Borne Dis. 2011 Sep;2(3):172-7. doi: 10.1016/j.ttbdis.2011.07.001. Epub 2011 Aug 25.
Indigenous Nguni cattle are adapted to the semiarid rangeland and appear to be resistant to ticks; however, the mechanism for tick resistance is yet to be established. To understand tick resistance in cattle, relationships among skin thickness, hair length, coat score, and tick counts were estimated in Nguni (n=12) and Bonsmara (n=12) heifers on semiarid rangelands of South Africa. The tick species observed to infest the heifers were Rhipicephalus (Boophilus) decoloratus (frequency: 76%), Rhipicephalus (Boophilus) microplus (9%), Amblyomma hebraeum (5%), Rhipicephalus appendiculatus (5%), Rhipicephalus evertsi evertsi (3%), and Hyalomma marginatum (2%). Nguni heifers had lower (P<0.05) log(10) (x+1)-transformed coat scores (0.6±0.01), hair length (1.4±0.01), and tick counts (1.4±0.03) than Bonsmara heifers whose log(10) (x+1)-transformed coat score, hair length, and tick count values were 0.7±0.01, 1.5±0.01, and 1.8±0.02, respectively. The skin thickness between the two breeds were similar (P>0.05). There was a positive linear (P<0.05) relationship between log(10) (x+1) tick counts and log(10) (x+1) coat score in the Nguni (y=1.90x-0.40) and a quadratic relationship in the Bonsmara (y=-7.98x(2)+12.74x-3.12) breed. It was concluded that the smooth coats may be one of the important mechanisms of tick resistance in the indigenous Nguni breed. Determination of genetic resistance to ticks in the Nguni breed is recommended as this will give more specific indication to the mechanism of host resistance in this breed.
南非半干旱牧场的本土 Nguni 牛适应了这种环境，并且似乎对蜱虫具有抵抗力；然而，蜱虫抵抗力的机制尚未确定。为了了解牛对蜱虫的抵抗力，在南非半干旱牧场中，对 Nguni（n=12）和 Bonsmara（n=12）小母牛的皮肤厚度、毛长、被毛评分和蜱虫计数进行了估计。观察到寄生在小母牛身上的蜱虫有 Rhipicephalus（Boophilus）decoloratus（频率：76%）、Rhipicephalus（Boophilus）microplus（9%）、Amblyomma hebraeum（5%）、Rhipicephalus appendiculatus（5%）、Rhipicephalus evertsi evertsi（3%）和 Hyalomma marginatum（2%）。Nguni 小母牛的 log(10)（x+1）-转换后的被毛评分（0.6±0.01）、毛长（1.4±0.01）和蜱虫计数（1.4±0.03）均低于 Bonsmara 小母牛（log(10)（x+1）-转换后的被毛评分、毛长和蜱虫计数值分别为 0.7±0.01、1.5±0.01 和 1.8±0.02）。两种品种的皮肤厚度相似（P>0.05）。在 Nguni 中，log(10)（x+1）蜱虫计数与 log(10)（x+1）被毛评分之间存在正线性关系（P<0.05）（y=1.90x-0.40），而在 Bonsmara 中则存在二次关系（y=-7.98x(2)+12.74x-3.12）。结论认为，光滑的被毛可能是 Nguni 品种对蜱虫的重要抵抗力机制之一。建议确定 Nguni 品种对蜱虫的遗传抗性，这将更具体地指示该品种的宿主抗性机制。
