Simulation and economic modelling of sheep systems
Maternal efficiency in sheep production is a term used to describe the performance or productivity of a reproducing ewe. It is influenced by genetic selection and nutritional management, but these components are generally considered in isolation and the interaction with farm management is rarely investigated. The study investigates how changing components of maternal efficiency at an individual-animal level affects farm management at the whole-farm scale, including the impacts on profitability, labour use and groundcover.
The study showed that differences at an individual animal level has a large effect at the per hectare and whole-farm scale. To maximise profitability, the stocking and reproductive rate, and lamb slaughter weight were all varied to optimise feed use and input costs as animal traits were changed. Constraints on labour and groundcover further altered these relationships. Recommendations on genetic selection and farm management in the sheep industry should be from a whole-farm perspective and considered with other factors such as groundcover and labour.
The importance of maternal efficiency has escalated due to structural changes in the sheep industry in the last 25 years. Prior to this period Australia ‘rode on the sheep’s back’, a reference to the predominantly wool focussed production of the national sheep flock. With the collapse of the reserve price scheme and depression of the wool price, the national flock declined and now consists mainly of breeding ewes. At around the same time, the demand for lamb and sheep meat increased and a shift towards lamb production occurred across southern Australia.
This led to an expanded role for the ewe with greater emphasis on improving reproduction, lamb growth and carcass output, while maintaining wool production and resilience to disease and sub-optimal nutrition. Balancing the genetic improvement and applying the appropriate management in a whole-farm context is a major challenge for sheep producers. Understanding the impact of genetic selection on farm management, labour use and sustainability metrics is important for future growth of the sheep industry.