Cattle tick breed susceptibility: Innate susceptibility of various cattle breeds to tick fever disease caused by Babesia bovis and Anaplasma marginale

Summary

In Australia, tick fever is a collective name for a disease of cattle caused by any one of three organisms (Babesia bovis, Anaplasma marginale and Babesia bigemina) carried and transmitted to cattle by the cattle tick. Previous trials have shown Bos indicus cattle to be naturally much more resistant to Babesia bovis, the most important cause of tick fever in Australia, than British/European Bos taurus breeds, which are quite susceptible. Bos indicus/Bos taurus crosses have levels of resistance somewhere in between. All breeds are susceptible to anaplasmosis. Since those trials, other exotic breeds have been introduced into northern Australia, however little information is available on the susceptibility of exotic breeds to tick fever.
This project compared Wagyu, Senepol and Tuli breeds to European Bos taurus and pure Bos indicus breed. In addition, the susceptibility of two crossbred (or composite) groups was assessed. The susceptibility was assessed by artificially inoculating naïve cattle with virulent tick fever organisms. Each animal was monitored after inoculation to assess the level of tick fever organisms in the blood, the development of anaemia and, in the case of B. bovis infection, also fever.
The results were consistent with those of the previous trials finding that pure Bos indicus cattle were quite resistant to Babesia bovis infection while pure Bos taurus breeds were more susceptible. The composite or crossbred groups had intermediate susceptibility to B. bovis infection, based on the criteria of parasite levels and the degrees of anaemia and fever that resulted.
This information can be used by producers who use or are considering these breeds to better evaluate their risk of tick fever disease and implement appropriate control measures as required.

Objectives

The objective of this study was to compare the relative susceptibilities to tick fever disease of some recently introduced exotic Bos taurus breeds of cattle.

Key findings

The results were consistent with those of the previous trials. Pure Bos indicus cattle were quite resistant to Babesia bovis infection while pure Bos taurus breeds were, as expected, quite susceptible. Interestingly, the Tulis, Senepols and Wagyus were as susceptible to B. bovis infection as the European cattle with development of marked anaemia and fever. Similar percentages in each of the breed groups required specific treatment. The composite or crossbred groups had intermediate susceptibility to B. bovis infection, based on the criteria of parasite levels and the degrees of anaemia and fever that resulted. All the breeds, even pure Bos indicus and crossbred groups, were quite susceptible to infection with Anaplasma marginale.

Whilst pure Bos indicus breeds are quite resistant to the effects of B. bovis infection, this effect declines quite quickly as the Bos taurus content increases. Consequently, as the Bos indicus content decreases, the tick fever risk will increase. All breeds of cattle, even pure Bos indicus, are very susceptible to anaplasmosis. Even exotic and tropically adapted Bos taurus breeds such as Tuli and Senepol are susceptible to all forms of tick fever.

Benefits to industry

This project will better inform producers about the risk of tick fever in exotic breeds, some of which have been promoted as being more suitable to harsher environments, however they are no more resistant to tick fever than other Bos taurus breeds. Producers utilising these breeds, either as purebreds or as part of a cross breeding program, will therefore need to consider other tick fever risk minimisation methods, such as vaccination, if using these breeds.