Simulation of production variability from native pastures in south east Queensland.

Native pasture is the major feed source for beef cattle grazing in southeast Queensland (Scattini 1981a). The dominant grasses in these pastures are black spear-grass (Heteropogon contortus), forest blue grass (Bothriochloa bladhii) and Queensland blue grass (Dichanthium sericeum) (Scattini 1973). Rainfall has a 70% summer incidence with high variability and this is reflected in animal production. Animals gain weight when pastures grow in summer and lose weight in winter when pastures are almost dormant (Addison 1970). If summer rains fail, the resulting drought causes poor animal production and mortalities increase. However, the impact of variation in amount and distribution of rainfall on animal production varies with pasture management.