Seasonal Limitations to Nutrition of Sheep and Beef Cattle in High Rainfall Areas of South-eastern Australia

The cattle and sheep industries of Australia are almost entirely dependent on grazing animals. Weston and Hogan (1973) estimated that less than 5% of the feed consumed by domestic ruminants in this country is derived from sown grain crops, and only 5 or 6% from conserved forage. Consequently effective management and use of pastures are of prime importance for efficient animal production. Although the high rainfall zone of southern Australia is smaller than the wheat. sheep and pastoral zones, it carries a disproportionately high percentage of the sheep (about 33%) and cattle population. The ability of pasture in this zone to provide adequate nutrition for grazing animals varies during the year and has been the subject of research at various centres. In the following papers we have concentrated on our own work in the Western District of Victoria because the range of environments found within the high rainfall zone is extremely diverse , and cannot adequately be dealt with here. The initial paper gives a general overview of the pasture limitations to nutrition of grazing animals and the following one deals with seasonal variation in the most common pasture species of the area, and production from weaner sheep grazing a subclover pasture in the dry summerautumn period. The other contributions describe three managemental approaches which may reduce or eliminate the commonly experienced seasonal limitations to ruminant nutrition and consequent animal production. These are:the continued use of superphosphate to maintain wool growth in grazing sheep, particularly in autumn and winter; the potential of different pasture legumes to maintain a satisfactory voluntary intake of ruminants during summer-autumn dry periods and the scope for using grain or proteins to supplement the diet of grazing animals at times of pasture inadequacy.