Illius, A.W., Derry, J.F., and Gordon, I.J. (1999) A re-assessment of the value of strategies for tracking climatic variation in semi-arid grazing systems. In: People and Rangelands: building the future: proceedings from the 6th International Rangeland Congress (1) pp. 504-505. From: 6th International Rangeland Congress, 19-23 July 1999, Townsville, QLD, Australia.

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Abstract

This paper examines whether adaptive stocking and sales policies are successful in tracking environmental fluctuations and could be of value in limiting drought-induced mortality and maintaining animal production in pastoral systems. A simulation was conducted with 20 years of rainfall data from Bulawayo, Zimbabwe, to analyse the effects of rain and sales policies on livestock system performance. Rainfall sequence had a greater effect on system performance than any sales policy, causing a roughly 2-fold range in the 20-year mean of animal sales and mortality. Female sales policy also affected performance; unless adult females are sold to reduce stock numbers, the target stocking rate is exceeded, mortality is high and annual sales are reduced. Tracking policies in which the target stocking rate is adapted to current season rainfall produced no useful increase in mean annual sales compared with fixed stocking. It is suggested that without an ability to restock heavily after drought, the traditional policy among subsistence pastoralists of maintaining a high size of breeding herd or flock is correct, given that animal sales are not the only priority, and that high mortality is merely the cost of maintaining high animal numbers in an unpredictable environment.

Item ID:	42658
Item Type:	Conference Item (Research - E1)
ISBN:	978-0-9577394-2-0
Date Deposited:	10 Feb 2016 07:43
FoR Codes:	07 AGRICULTURAL AND VETERINARY SCIENCES > 0701 Agriculture, Land and Farm Management > 070102 Agricultural Land Planning @ 100%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 100%
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