A Meat and Livestock Australia study has shown that tropically adapted Bos taurus breeds such as Senepol and Tuli are as susceptible to tick fever as British and European Bos taurus breeds.
The MLA-funded breed susceptibility study was conducted to help northern producers better evaluate the risk presented from tick fever when increasing the Bos taurus content of their herd at the expense of Bos indicus content.
Tick fever is caused by three organisms carried and transmitted to cattle by ticks. The disease is endemic in warm, humid areas of northern Australia. It costs the northern beef industry an estimated $27 million annually in lost production and control measures.
Brahman-type Bos indicus cattle are known to be naturally more resistant than British and European Bos taurus breeds to the most common disease organism, Babesia bovis.
The study confirmed this and showed that natural resistance declined rapidly as Bos taurus content increased in crossbreds or composites.
The report said no information had previously been documented to help assess the risk of tick fever in recently introduced “exotic” Bos taurus breeds of cattle. The study was the first detailed assessment of the innate resistance of Tuli, Senepol and Wagyu breeds to B. bovis and A. marginale.
The trial involved inoculating groups of Bos indicus, European Bos Taurus and composite cattle with virulent tick fever organisms. One composite group comprised 75pc Bos taurus genotypes, including 25pc Senepol; and the second comprised 50pc Bos taurus genotypes.
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 the results of previous trials. Pure Bos indicus cattle were quite resistant to Babesia bovis infection, while pure Bos taurus were quite susceptible.
A key finding was that Tulis, Senepols and Wagyu were as susceptible to B. bovis infection as the European cattle, with the development of marked anaemia and fever.
All breeds of cattle, including pure Bos indicus, were found to be very susceptible to the tick fever disease organism Anaplasma marginale— but this accounts for only about 13pc of tick fever cases.
The final report urged northern producers to take account of the increased risk of tick fever when looking to infuse a greater percentage of British, European or exotic Bos Taurus genetics into their herds.
“Crossbreeding programs aimed at utilising the hardiness of these breeds in order to reduce the Bos indicus content of the desired crossbred or composite may result in animals that are more susceptible to tick fever than crosses with higher proportions of Bos indicus,” the final report explained.
“Likewise, the Wagyu breed is also as susceptible to tick fever as the traditional Bos taurus breeds.
“It is therefore recommended that producers take this into consideration when introducing these breeds into their beef operation, evaluate the risk of tick fever disease and implement appropriate tick fever control strategies as required.”
Queensland Department of Employment, Economic Development and Innovation’s Phillip Carter led the research project.
He said knowing the susceptibility of newer breeds to tick fever was crucial so that northern producers could better evaluate the risk to their herds and implement appropriate control measures.
To view the final report, click here