North Australian beef fertility project: CashCow

McGowan, Michael, McCosker, Kieren D., Fordyce, Geoffry, Smith, Dave R., O'Rourke, Peter, Perkins, Nigel, Barnes, Tamsin, Marquart, Louise, Morton, John, Newsome, Tom, Menzies, Don, Burns, Brian and Jephcott, Sandi (2014) North Australian beef fertility project: CashCow. B.NBP.0382, School of Veterinary Science, The University of Queensland.

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Name Description MIMEType Size Downloads
Author McGowan, Michael
McCosker, Kieren D.
Fordyce, Geoffry
Smith, Dave R.
O'Rourke, Peter
Perkins, Nigel
Barnes, Tamsin
Marquart, Louise
Morton, John
Newsome, Tom
Menzies, Don
Burns, Brian
Jephcott, Sandi
Title North Australian beef fertility project: CashCow
School, Department or Centre School of Veterinary Science
Institution The University of Queensland
Report Number B.NBP.0382
Publication date 2014
Total pages 301
Publisher Meat & Livestock Australia
Language eng
Formatted Abstract/Summary
The causes of poor reproductive performance in northern Australian beef herds are multi-factorial and quantification of the impact of individual factors on performance of breeding mobs is lacking. The reproductive performance of ~78,000 cows managed in 142 breeding mobs located on 72 commercial beef cattle properties was measured over three to four consecutive years (2008-11) using a crush-side electronic data capture system. Percentage of lactating cows pregnant within four months of calving, annual pregnancy rate, percentage foetal/calf loss between pregnancy diagnosis and weaning, and annual percentage of pregnant cows missing (mortality) were used to define performance, with the commercially achievable level of performance proposed as the performance of the 75th percentile mob or cow for each measure. Also, methods of estimating liveweight production from breeding herds were developed, and an achievable level determined for each country type. The impacts of 83 property, environmental, nutritional, management, and infectious disease factors on performance were investigated. The major factors affecting performance included country type, time of previous calving, wet season phosphorous status, cow body condition, hip-height, cow age class, cow reproductive history, severity of environmental conditions, and occurrence of mustering events around the time of calving. Producer/manager opinion that wild dogs were a problem, evidence of recent pestivirus infection and vibriosis were factors that did not contribute to the final model, but did significantly affect animal performance when present. A framework was developed for conducting economic analyses to assess the impact of factors affecting performance.

Final report summary:
To date, there have been no population-based studies of the reproductive performance of commercial breeding herds in northern Australia, or of the major factors affecting performance in these herds. The former would provide producers with a commercial rather than biologically achievable level of performance, and the latter would enable producers to focus management changes and investment on those factors that have been shown to be contributing most to herd reproductive outcomes. Therefore, a four year prospective epidemiological study of region-, property-, mob-, and animal-level factors affecting the reproductive performance of commercial breeding mobs was developed. Approximately 78,000 cows managed in 142 breeding mobs located on 72 commercial beef cattle properties distributed across the major beef breeding regions of northern Australia were enrolled in the CashCow project and monitored for three or four consecutive years (2008-11) using a crush-side electronic data capture system. Co-operating properties were classed into four country types using broad vegetation criteria. Foetal ageing was used at the time of annual pregnancy diagnosis to enable the month of conception and calving to be estimated.

Workshops and training sessions were conducted at the commencement of the project and during the course of the project to ensure uniformity of data collection by all technical persons involved in the project. This enabled assessment of the impacts of environmental, nutritional, management, animal and infectious disease factors on:

1. how efficiently cows become pregnant,
2. the likelihood of pregnant heifers and cows rearing a calf, and
3. the likelihood of cows going missing (i.e., dead, lost ID tag, moved paddocks).

The measures used to define the performance of the CashCow mobs were percentage pregnant within four months of calving (P4M; percentage of cows likely to wean a calf in consecutive years), annual pregnancy rate, percentage foetal/calf loss, and annual percentage of pregnant cows missing (an estimate of mortality rate). For each measure of performance, the impact of approximately 83 selected management, environmental, nutritional, and infectious disease factors was assessed by univariable screening. Then, using the factors identified as having a significant impact on performance, candidate multivariable models were developed. These models enabled identification and quantification of the major factors affecting performance.

There was marked variation in the reproductive performance of enrolled breeding mobs both within and between country types. The median performance (50th percentile) and interquartile range (25th to 75th percentile) for cows by country type are presented in Table A. The mean annual incidence of pregnant cows missing, expressed as a percentage, for the Southern Forest, Central Forest, Northern Downs and Northern Forest was 10%, 9%, 8%, 17%, respectively.

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Created: Tue, 25 Mar 2014, 08:14:15 EST by Dr Geoffry Fordyce on behalf of Centre for Animal Science