THE SOUTH Australian Research & Development Institute is evaluating liveweight gain of bulls on both dryland and irrigated pastures using a new TechnoGrazing system established at Struan Research Centre, Naracoorte, in 2001.

The TechnoGrazing system is a complete cell grazing system involving the time-controlled grazing of livestock.

The basis of the system is that a farm is subdivided into a grid of grazing cells, less and 0.1 hectares using permanent and temporary electric fencing.

The system at Struan consists of 192ha of dryland and 58ha of irrigated pasture.

The 192ha consists of six systems of 32ha each, with eight lanes of 4ha, which are further subdivided into 60 cells of 0.067ha. The shifting of stock is carried out every two days.

The area given to each lane group varies, depending on pasture growth. Throughout the winter, intake it is restricted and post-grazing pasture residuals are very low, so rotation length is increased (about 50-60 days), and cell size is decreased to ensure pastures have time to recover.

As pasture growth increases towards and into the spring, the cell size for grazing is increased a shift and rotation length is decreased (about 20-30 days).

The area given to the animals governs the rotation length. The larger the area a shift, the shorter the rotation.

SARDI technical officer Ben Hebart said that in 2002 the system was stocked at three bulls a hectare, giving a total of 576 bulls.

"The season began very late and finished quite early, however, production reached a total of 600 kilograms of liveweight gain/ha," Mr Hebart said.

"During September and October, there was excess grass growth and so 25 lambs were introduced into each 4ha lane.

Over the month these lambs increased in liveweight by 300 grams a day."

This year the stocking rate was increased and differing stock classes were introduced into the system. There are now four 32ha systems stocked at four Friesian bulls a hectare, and one 32ha system of four crossbred steers a hectare. There is also a further 32ha system with 43 bulls stocked at three a hectare and two mobs of dry sheep at 24 and 36 DSE.

There are now 555 Friesian bulls, 128 crossbred steers and 480 sheep on 192ha in the system, and stock will be held from about May through to November.

"During this time we are collecting liveweight, pasture growth and botanical composition on a regular basis," Mr Hebart said.

The aim this year is to produce 1000 kilograms of liveweight gain a hectare from dryland pasture in 550 millimetre rainfall.

"We are on track to reach this aim, with bulls gaining 0.8-1.2kg over the past two months," Mr Hebart said.

"The average liveweight gain a hectare so far this year is 300kg, and animals are still on relatively long rotations (40 days) and restricted intakes (1.5-2 per cent of body weight)."

The TechnoGrazing concept was developed and commercialised by Harry Weir, Kiwitech International, in New Zealand.

* Details: Ben Hebart 08 8762 9153.