Prediction of mortality and conception rates of beef breeding cattle in northern Australia
D. G. Mayer A D , G. M. McKeon B and A. D. Moore C
+ Author Affiliations
- Author Affiliations
A Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, 41 Boggo Road, Dutton Park, Qld 4102, Australia.
B Office of Climate Change, Department of Environment and Resource Management, Ecosciences Precinct, 41 Boggo Road, Dutton Park, Qld 4102, Australia.
C CSIRO Sustainable Agriculture Flagship, GPO Box 1600, Canberra, ACT 2061, Australia.
D Corresponding author. Email: david.mayer@dpi.qld.gov.au
Animal Production Science 52(5) 329-337 https://doi.org/10.1071/AN11204
Submitted: 27 September 2011 Accepted: 27 January 2012 Published: 10 May 2012
Abstract
In current simulation packages for the management of extensive beef-cattle enterprises, the relationships for the key biological rates (namely conception and mortality) are quite rudimentary. To better estimate these relationships, cohort-level data covering 17 100 cow-years from six sites across northern Australia were collated and analysed. Further validation data, from 7200 cow-years, were then used to test these relationships. Analytical problems included incomplete and non-standardised data, considerable levels of correlation among the ‘independent’ variables, and the close similarity of alternate possible models. In addition to formal statistical analyses of these data, the theoretical equations for predicting mortality and conception rates in the current simulation models were reviewed, and then reparameterised and recalibrated where appropriate. The final models explained up to 80% of the variation in the data. These are now proposed as more accurate and useful models to be used in the prediction of biological rates in simulation studies for northern Australia.
Additional keywords: body condition ratio, body condition score, breed, lactation status, pregnancy.
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