Effect of month of birth and first summer's nutrition on the productivity of Merino wethers

Abstract

Liveweight and greasy wool production of Merino wethers born in either mid-May, late June or early September in each of 2 years and subjected to three nutritional regimes (high, normal and low) over their first summer were studied over 4 years. Differences in liveweight of up to 9.0 kg between treatments due to month of birth persisted for 48 months while liveweight differences of as much as 15 3 kg due to nutritional treatment lasted only 24-30 months. Similarly, differences in greasy wool production of up to 0.8 kg between times of birth lasted for the duration of the study but differences between first summer nutritional treatment, although as much as 1.1 kg at the first adult shearing, persisted for only 2 years. The results strongly indicate that, in the high rainfall Mediterranean environment of southern Western Australia, sheep born late in the season will be of lower liveweight and will produce less wool than sheep born early in the season.