Genetic susceptibility to Theileria orientalis (Ikeda) in Angus- and Hereford-sired yearling cattle born to dairy cattle on an endemically infected farm in New Zealand

Theileria orientalis (Ikeda) was first detected in New Zealand 2012, becoming endemic most of the North Island, and can cause incidences anaemia death. Research has been performed on incidence severity infection. Through this research anecdotal evidence found to suggest a potential genetic susceptibility component response host parasite. To investigate cattle T. (Ikeda), 99 calves born 2016 as part separate experiment grown six grazing herds, were examined for their In addition measuring live weight, two blood collections taken four months life which used measure packed cell volume by haematocrit qPCR assess parasite load. Heritability calculated low load, but result indicates that there is some increase resistance through selective breeding. The mechanisms differences load not elucidated research; however, significant variation among herds sires, indicating both selection environmental management could be utilised reduce growing calves.