Introduction of Dorper sheep into Australian rangelands: implications for production and natural resource management

Abstract

Abstract. The growing popularity of the Dorper breed of sheep potentially may have implications for the ecological sustainability of the semiarid and arid rangelands of southern Australia. The implications are heightened by forecasts of a warming and drying climate in these rangelands, which may in itself place native vegetation under increasing stress. While the Dorper breed of sheep offers important production advantages, little is known from research under Australian conditions about their grazing ecology and management requirements from a natural resource perspective. Key factors identified from this review of literature from other countries include a high fertility and fecundity, a generalist feeding strategy, a high growth rate and a capacity to survive and reproduce under low-rainfall conditions. The wider range of plant species selected by the Dorper compared with the traditional Merino breed of sheep potentially creates both opportunities and risks for rangeland condition. Less selective grazing may reduce pressure on some species but the capacity to harvest sufficient nutrients over a smaller area could concentrate grazing and promote resource degradation. High reproductive efficiency under a wide range of seasonal conditions may lead to more rapid onset of overgrazing and will require close attention to both natural resources and animal marketing if resource degradation is to be avoided.

Challenges, solutions and research priorities for sustainable rangelands

“…The challenges can be clustered in three main categories: degradation of natural capital, deterioration of water resources, and biodiversity loss. The introduction of European herbivores and overgrazing are recognised as the major drivers of degradation of natural capital in the Australian rangelands (Abel et al 2006;Alemseged and Hacker 2014). Overgrazing has led to the loss of perennial grasses, encroachment of woody weeds, and a subsequent cascade of losses in landscape function, including erosion and declines in soil structure, nutrient cycling and water infiltration (Ludwig et al 1997;Sparrow et al 2003;WLLS 2014).…”

Mixed farming diversification may be costly: southern Queensland case study

“…Feed availability can affect animal maintenance, liveweight gains and wool growth, as well as conception, lambing, weaning and lamb mortality rates (Pitta et al 2005). Compared with other sheep breeds, Dorpers are generalist feeders that can utilise low-quality diet plants species; this helps them to survive and reproduce under harsh conditions (Cloete et al 2000;Alemseged and Hacker 2014). Rangeland livestock systems in this case-study region are primarily supported by summer-active grasses and perennial shrubs (Bell et al 2008).…”

Evaluation of Rambouillet, Polypay, and Romanov–White Dorper × Rambouillet ewes mated to terminal sires in an extensive rangeland production system: Lamb production1,2

“…The Polypay has been productive and well adapted to both rangeland and intensive production systems but has not been compared with range breeds such as the Rambouillet in terminal-sire crossbreeding under rangeland conditions. In addition, evidence has accumulated that the Romanov is superior to the Finnsheep as a prolific breed (Thomas, 2010), and there is potential for hair sheep composite breeds such as the Katahdin and Dorper to increase ewe productivity, lamb survival, and other "easy-care" sheep characteristics (Notter, 1999;Alemseged and Hacker, 2014). This study therefore was designed to compare lamb performance and ewe productivity of Rambouillet, Polypay, and Romanov-White Dorper × Rambouillet (RW-RA) ewes mated to terminal sires under extensive rangeland conditions.…”