PGG Wrightson consultant Rob Phiskie said the Wilsons' Middlemarch farm usually had a reliable spring and autumn, but it burnt off during summer.
Supplying contracted prime lambs that matched the region's growing pattern was an option.
The Wilsons are the new Meat and Wool New Zealand Central Otago monitor farmers and last year provided a hint of how they could make money by buying store lambs in late summer to match their farm's grass growing pattern.
On April 1, they bought 1500 store lambs for $58 each landed, which were fed on short rotation pasture. These were sold from May on for $82.67 to give the Wilsons a net margin of $32,500, or $21.73 a head, on the deal.
Mr Phiskie said at those margins, returns from late season lamb finishing competed with dairy grazing.
A possible system for dryland farms was to contract a weaning draft of prime lambs, sell the rest as store but buy store lambs in autumn and finish them under contract.
Such a system gave flexibility, gave ewes more room and feed before tupping and took advantage of late autumn and winter prime lamb contracts.
Income from summer-supplied lamb was between 11c and 14c a kg of dry matter compared to 30c/kg DM from winter lambs.
The cost of lamb-finishing rape for both summer and winter was between 9c and 14c/kg DM.
Mr Wilson told about 40 people at the field day that for the past five years the autumns had not been kind, and he had struggled to get ewes up to target tupping weights, which was reflected in the lambing percentage.
This had been an issue especially for two-tooths which had lambed as hoggets.
Mr Phiskie said increasing performance per head was generally more economic than increasing numbers, and an option to get faster lamb growth rates was to use new pasture species.
Mr Wilson said he achieved a cut of baleage and a cut of hay off his lucerne paddocks as well as lamb finishing, with growth rates of over 200g a day.
Lambs did well and were clean, he said, but he had learnt that lambs could get red gut if they had too much. He tended to give them 10 days on lucerne, then two days on ryegrass.
Lucerne also tended to be more persistent in the Strath Taieri than some ryegrass pastures, which succumbed to grass grub.
Wrightson Seeds adviser Wayne Nichol said while lucerne was hardy and excellent stock feed, at some stage over summer and autumn it had to be spelled so it could flower and the roots forced to grow lower into the soil.
Whatever the pasture species or crop, Mr Phiskie said it had to be quality feed providing high amounts of metabolic energy to finish lambs quickly and economically.
The Wilsons were also growing sugar grass, which was hardy over summer, and Mr Wilson said farmers had told him stock did well and enjoyed eating it.
Mr Phiskie said seed made up 20% of a pasture renewal cost, so, having made that investment and spent the money, farmers should buy quality seed.
Summer brassicas such as forage rape were also a lamb-finishing option. The crop could provide growth rates of 150-200g a day.
He suggested paddocks be split in four and the lambs rotationally grazed so they ate the leaves and not the stalk. If lambs were forced to eat the stalk, growth rates would fall.
Mr Phiskie said stock had to be managed to avoid disorders such as nitrate poisoning.
A rape crop could be managed to provide winter feed, but frosts could affect stock health.
"Frost can soften the plant cells and, once it gets in the rumen, there can be a massive release of sugar."
As with all high quality winter feeds, Mr Phiskie said hay, silage or other roughage should be available or other steps taken to stop animals from gorging themselves.
Fescues were also an option for drylands but he said they need to be managed as stock did not like them when they went to seed.
Mr Phiskie said while sheep farming had been through difficult times, it was worth remembering that production paid the bills, not saving on costs.
Main points
• Callum and Kate Wilson
• Strathburn, Middlemarch
• Meat and Wool New Zealand Central Otago monitor farmers.
• 760ha, 120ha irrigated.
• 4500 Kelso ewes, 1300 hoggets.
• Rams put to ewes and hoggets.
• 113% lambing.