Effect of age, sex and fertility on the optimal structure of a static self-replacing ewe and wether flock

Abstract

This study investigated the optimal structure of a closed ewe and wether flock producing wool and meat. A range of price-weighted (net of a fixed set of costs) combinations of these products was considered, and optimal structures determined for each. The aim of the study was to throw some light on the effects of the main biological factors-age, sex and fertility-on flock structure (given that there is no nutritional stress). The general conclusions were that the optimal structure shifts from disposing of wethers as lambs and ewes as 5.5-year olds to disposing of wethers as 3.5-year olds and ewes as 4.5-year olds, as fertility declines or meat declines in value relative to wool. However, the former structure tends to dominate and is optimal over a wide range of conditions.