Performance of sheep systems grazing perennial pastures. 1. Pasture persistence and enterprise productivity

Abstract

Sheep production can be optimised by matching the pasture supply curve to feed demand. This study evaluated the production from four management systems with Merino ewes during 2006–2010 in southern New South Wales by using different combinations of lambing time (winter, split, spring), ram breed (Merino, terminal), and percentage of summer-active pasture species (40% or 20% lucerne, Medicago sativa). All systems were stocked at a similar midwinter rate (dry-sheep equivalents per hectare of 8, 10.2, 13, 11.2 and 11.2 in the successive seasons 2006–2010), and there were three replicates of each system. Groundcover and pasture persistence were not adversely impacted by sheep system because sheep were removed at predetermined biomass triggers. Wool production per hectare was up to 178% or 12 kg/ha higher (P < 0.001) in systems where a later month of lambing allowed an increase in number of ewes per hectare at the same midwinter stocking rate. The quantity of lamb sold was not consistently higher in any one system, or in systems producing both crossbred and Merino lambs vs only Merino lambs, owing to variation in the weight and age of lambs at sale, but was increased (P < 0.001) by 175 kg/ha with use of 40% compared with 20% lucerne in a high-rainfall year. The risk of requiring high levels of supplementary feeding was higher in systems with later lambing because of below-average rainfall between 2006 and 2009. Large increases in production can be achieved from the same pasture base through choice of management system with different lambing time, stocking rate or ram breed, but flexibility is needed to optimise production in varying seasonal conditions.