Property Size and Rangeland Degradation in the Queensland Mulga Rangelands.

1992 ◽  
Vol 14 (1) ◽  
pp. 9 ◽  
Author(s):  
JGI Passmore ◽  
CG Brown

Small property size is often cited as one of the major causes of rangeland degradation in Australia. However, there is some conjecture as to the importance of this effect and the process by which small property sizes lead to rangeland degradation. Relatively little empirical analysis of these issues has been undertaken, especially in a dynamic context which is all important in the case of rangeland degradation. Regression and dynamic programming techniques are employed in this study to investigate and measure the impact of property sizes on the use and state of one of Australia's most important rangelands, the Queensland mulga rangeland. Regression analysis of cross sectional data reveals significant correlations between property size, stocking rate and degradation. These correlations are confirmed in a normative stochastic dynamic programming model which demonstrates that it is economically optimal for graziers managing smaller properties to adopt higher stocking rates. For these graziers, the longterm costs of land degradation are exceeded by short-term financial benefits of heavier stocking. Thus government policy aimed at arresting the serious degradation occurring in the mulga rangelands should focus on measures to facilitate property build-up..

2000 ◽  
Vol 67 (4) ◽  
pp. 515-528 ◽  
Author(s):  
CENGIZ YALCIN ◽  
ALISTAIR W. STOTT

An adaptive stochastic dynamic programming model was used to solve the optimum replacement decision problem for the dairy cow under a range of alternative mastitis control procedures. The model predicted that reducing milk yield losses and somatic cell count penalties by using milking machine test, post-milking teat disinfection and dry cow therapy added approximately £4, £10 and £13 respectively to an original annuity equivalent net present value for the replacement heifer of £286. Assuming that these procedures also reduced involuntary culling due to mastitis by 50% added £8·90 to the annuity. This latter figure indicated that an important part of the benefit of mastitis control procedures might come from a reduction in the culling risk of persistent clinical cases. We concluded that the strength of the dynamic programming model in this context was that it provided an integrated evaluation of the various impacts of each alternative mastitis procedure in the long term, which is essential for correct economic evaluation of mastitis.


1987 ◽  
Vol 35 (2) ◽  
pp. 195-197
Author(s):  
R.B.M. Huirne ◽  
A.A. Dijkhuizen ◽  
G.W.J. Giesen

A stochastic dynamic programming model was designed to determine the economically optimum replacement decisions for sows. Influences of changes in production and prices on the optimum policy were established. An economic index was calculated to be used as a culling guide for individual sows. (Abstract retrieved from CAB Abstracts by CABI’s permission)


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