PDS Bow Park, Investigation of effectiveness of practical vaccination protocols for reproductive wastage in north Australian breeder herds

Summary

A PDS established north of Julia Creek assessed the viability of vaccines to help reduce the effects of vibriosis, pestivirus and leptospirosis, each of which can reduce profitability. None of the three vaccines used affected either pregnancies or calf loss. However, the extended 2007-08 wet season experienced demonstrated the dramatic over-riding impact of Akabane disease and 3-day sickness, which appeared to be the primary reasons for low pregnancy rates per oestrus (30%) in the 495 maiden heifers. 
 These diseases are spread by biting insects during wet monsoonal conditions. Extreme weather conditions during late pregnancy and calving diluted any effects due to vaccines, and resulted in overall calf wastage of 24%, and a peak of almost 50% when calving during extreme wet conditions. The associated stress and loss in body condition resulted in only ~70% of dry cows and ~40% of wet cows cycling eight weeks into their second mating. As part of this project, recommendations were made for the cost-effective control, including vaccine use, in NW Queensland of vibriosis, pestivirus infection, leptospirosis and arboviral diseases. Recommendations were also made on correct use of vaccines in cattle, as well as how to minimise effects due to extreme weather conditions.