Smaller mob size benefits, especially in poor seasons

REDUCING the mob size of lambing ewes will have a significant impact on lamb survival, particularly during tough seasons, a study has shown.

REDUCING the mob size of lambing ewes will boost lamb survival, and the affect could be greater in tough seasons, a new study has shown.

The early findings were presented at the BestWool Best-Lamb conference in Bendigo last week.

“For every 100 less twin-bearing ewes in the mob, the survival of their lambs increases by 2 per cent, or you mark an extra four lambs,” said Murdoch University PhD student Amy Lockwood.

“If you have 400 ewes with lamb survival at 75 per cent, then a mob of 300 should have survival of at least 77 per cent.”

Those are the findings from a national project involving farm trials across the southern states over three years.

BestWool BestLamb chairman Jason Trompf said the research gave farmers the “next step” to boost the productivity of their sheep.

Dr Trompf said it encouraged them to give the best paddock allocation to twin-bearing ewes.

Twins now make up three-quarters of all lambs lost on Australian farms.

The study built on work done in the Lifetime Ewe Management and Lifetime Maternals projects.

Dr Trompf said farmers were now looking for the next obvious and practical approaches to keeping twin lambs alive.

Ms Lockwood said the research would also add to the limited information now available on density and stocking rates for lambing ewes, but was more specific to sheep farmers working with large-scale businesses.

The trials involved randomly allocating twin-bearing Merino and non-Merino ewes into one of four groups, with high or low mob sizes and stocking rates.

The lowest mob size averaged 95 ewes, with the highest 240 ewes.

Stocking rates ranged from a low of 4.7 ewes/ha to a high of 8.1 ewes/ha.

On the 60 research sites results showed it was mob size that had the most significant effect on lamb survival.

But the study found stocking rate had little to no impact.

The research was funded by Australian Wool Innovation and Meat and Livestock Australia, with collaboration from Agriculture Victoria, Murdoch University, Landmark, Elders, NSW Department of Primary Industries and the University of Adelaide.