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We investigated the effect of an oral dose of 1, 2 or 4 soluble glass pellets containing cobalt, selenium and copper on the trace element and vitamin B12 status of sheep at pasture. Although the effective life of the pellet was intended to be 1 year, the retention of the pellet in the rumen was sometimes less than 6 months. Despite the apparently short retention period, an oral dose of 1 pellet was sufficient to provide physiologically significant quantities of copper, selenium and vitamin B12 to the animal for at least 45, 32 and 16 weeks respectively. The mean values for untreated sheep and sheep given 1 pellet were respectively 0.49 and 3.11 mmol copper/kg liver (dry matter) at week 45, 1.03 and 1.51 mol selenium/L blood at week 32, and 1.15 and 1.82 nmol vitamin B12/L plasma at week 16. Sheep of normal copper and selenium status may be at risk of copper toxicity if given an oral dose of 2 or more pellets and of selenium toxicity if given 4 or more pellets at the same time. In sheep dosed with 4 pellets, mean liver copper and selenium concentrations exceeded, for 16 and 8 weeks respectively, the concentrations acceptable for human consumption.

The rate of disappearance of the dry residues of nine pasture species was measured over a 139 day period during summer at Kybybolite in South Australia. Clovers and capeweed disappeared at about two to three times the rate of the perennial grasses. High rates of disappearance were associated with initially low fibre and high nitrogen, sulphur, calcium and sodium concentrations. Fibre, nitrogen and calcium concentrations tended to increase with time, potassium, sodium and chloride concentrations decreased and ash, sulphur, phosphorus and magnesium concentrations showed no consistent changes with time for all species. The rate of loss of dry matter and change in chemical composition of samples stored indoors was small and not significant.

Liveweight, seasonal wool growth rates, annual wool production, wool quality and hand feeding requirements were recorded for Merino wethers when autumn deferred or continuously grazed. The two management systems were compared at a series of eight stocking rates from 12.4 to 29.7 sheep per hectare for five years from 1967 to 1971 at the Kybybolite Research Centre, South Australia. Autumn deferment resulted in increased liveweight and wool growth rate during the months of June to September. However, liveweights and wool production under either management were similar for the remainder of the year. Because deferred grazing did not increase liveweights during the critical autumn period, and since hand feeding requirements were similar under either management system at the higher stocking rates, it is suggested that yearly stocking rates can not be increased by autumn deferment. Apart from the drought year of 1967, the continuously grazed sheep required little or no hand feeding up to 22.2 wethers per hectare. It is unlikely that the cost of hand feeding deferred sheep up to this stocking rate would be covered by the small increase in wool production. However, this would depend on the cost of conserved fodder and price received for the wool.

The effect of deferred autumn grazing and stocking rate on an annual pasture was monitored for five years at Kybybolite Research Centre in the south-east of South Australia. Pasture availability, yearly production and botanical composition were measured under a series of eight stocking rates from 12.4 to 29.7 Merino wethers per hectare. Autumn deferment resulted in extra available pasture during the winter months of June, July and August. However, the continously grazed pastures reached the same level of availability as the deferred pastures in spring. By the third year of the experiment yearly pasture production irrespective of grazing management was greatly reduced at the higher stocking rates. This reduction was associated with an invasion of Poa annua and Juncus bufonius. Autumn deferment tended to favour the growth of Wimmera ryegrass at the lower stocking rates whereas continuous grazing tended to favour clover growth at these stocking rates.