Murray M, Clifford D J, Gettinby G, Snow W F, McIntyre W I
Vet Rec. 1981 Dec 5;109(23):503-10.
The use of trypanotolerant livestock is considered to be an important strategy for the control of African animal trypanosomiasis. In order to define the extent of the differences in susceptibility and productivity, 10 Zebu cows (a breed considered trypanosusceptible) and 10 N'Dama cows (a breed recognised for trypanotolerance) were exposed to a natural field challenge from Glossina morsitans submorsitans Newstead. The animals were two-and-a-half to three years old and had not been previously exposed to trypanosomiasis. All Zebu died of trypanosomiasis within eight months of first exposure. In contrast, only three N'Dama died of trypanosomiasis; they had all been suckling calves before they succumbed 11 to 14 months after initial exposure. The prevalence, level and duration of parasitaemia were significantly less in the N'Dama, which, unlike the Zebu, did not become febrile during parasitaemia. The differences in parasitaemia were largely attributable to Trypanosoma vivax. The N'Dama also developed much less severe anaemia than the Zebu. The mean and standard deviation of the packed red cell volume of the N'Dama was not significantly different between eight months after exposure when all Zebu were dead, and 21 months when the experiment was terminated. The relative productivity of the N'Dama was impressive. In addition to reduced mortality, the N'Dama experienced no abortions and produced five calves, three of which were alive at the end of the experiment, at which time three of the surviving N'Dama were pregnant. In the Zebu, in marked contrast, abortions occurred both in early and late pregnancy and no live calves were produced. The study confirmed that N'Dama cattle are innately less susceptible to trypanosomiasis than Zebu cattle and can survive and be productive in endemic areas of trypanosomiasis where Zebu perish.
使用耐锥虫家畜被认为是控制非洲动物锥虫病的一项重要策略。为了确定易感性和生产力差异的程度，将10头瘤牛（一种被认为对锥虫敏感的品种）和10头恩达马牛（一种以耐锥虫著称的品种）暴露于莫氏舌蝇新亚种的自然野外感染环境中。这些动物年龄在两岁半到三岁之间，之前未曾接触过锥虫病。所有瘤牛在首次接触后的八个月内均死于锥虫病。相比之下，只有3头恩达马牛死于锥虫病；它们在初次接触后的11至14个月死亡，死亡前均处于哺乳期。恩达马牛的寄生虫血症患病率、水平和持续时间明显较低，与瘤牛不同的是，它们在寄生虫血症期间不会发热。寄生虫血症的差异主要归因于间日锥虫。恩达马牛的贫血程度也比瘤牛轻得多。当所有瘤牛都死亡的暴露后八个月，以及实验结束时的21个月，恩达马牛的红细胞压积均值和标准差并无显著差异。恩达马牛的相对生产力令人印象深刻。除了死亡率降低外，恩达马牛没有发生流产，还产下了5头小牛，其中3头在实验结束时存活，此时3头存活的恩达马牛中有1头怀孕。相比之下，瘤牛在妊娠早期和晚期均发生流产，没有产下活牛犊。该研究证实，恩达马牛天生比瘤牛对锥虫病的易感性更低，在瘤牛会死亡的锥虫病流行地区能够存活并保持生产力。
