TWO decisions a livestock manager makes routinely have a major impact on their enterprise.
They are how many stock do you put in a paddock and how long do you leave them there.
Lisa Warn, pasture agronomist with Melbourne University’s McKinnon project, has investigated the economics of set stocking versus rotational grazing.
The question of whether rotational grazing has any benefits to sheep and cattle producers compared to set stocking has been debated by livestock scientists and producers for decades.
Whether more than four paddocks in a rotation gives better results than a few paddocks has also been debated widely.
Based on the results of research conducted in Victoria in the 1990s and early 2000s, Lisa considers the answer to both questions is yes.
However, Lisa also acknowledged there were several practical reasons why set stocking may suit some producers, especially those running sheep breeding operations requiring multiple paddocks.
Set stocking also requires less labour and infrastructure and may be quite suitable in some landscapes and pasture systems.
Lisa found that a simple four-paddock rotation grazing system allowed up to a 10 per cent increase in stocking rate, while a system involving 20 paddocks allowed a 20 per cent increase in stocking rate.
Rotational grazing also changed pasture composition. Set stocked paddocks ended up with a higher clover and capeweed content, with small struggling phalaris plants, and were therefore bare in the autumn.
A four-paddock rotation resulted in larger phalaris plants, less capeweed and less obvious sheep camps.
The 20-paddock system had the largest phalaris plants, 95 per cent ground cover in the autumn, no capeweed and no obvious stock camps.
Of interest, Lisa determined the most intensive rotational grazing system required lower P maintenance levels per DSE (at 0.4 kg P/DSE) than the four-paddock system (at 0.5 kg P/DSE) and the set stocker system (at 0.6 kg P/DSE).
She considered this was because the more intensive system promoted deeper roots in the phalaris, higher pasture yields and a more even distribution of nutrients across the pasture.
Lisa concluded sheep producers were most likely to benefit from adopting rotational grazing if they wanted to increase autumn, winter pasture growth and build up feed in paddocks before a late winter early spring lambing.
Additionally, if producers have problems with perennial grass persistence, problems maintaining autumn ground cover and have large variable paddocks subject to preferential grazing, rotational grazing is most likely to be beneficial.
Conversely, if none of these are issues, then set stocking remains appropriate.
DO the results of this Victorian research apply to the central and southern tablelands?
We have invited Lisa Warn to speak to us at a seminar in Goulburn on October 25.
Dr Belinda Hackney, pasture research scientist with the DPI based at Bathurst (and an expert on appropriate grazing of different tablelands landscapes) and Philip Graham (DPI livestock officer based at Yass with wide experience in managing sheep and pastures on the southern tablelands) are key speakers.
We will set aside time for a panel discussion.
I will keep you posted.