The climatic potential for beef cattle production in tropical Australia: Part IV— variation in seasonal and annual productivity

Abstract

In Part II liveweight loss in the dry season was found in most years to be closely related to cumulative ‘dry weeks’; extraordinary weight loss occurred in the dry season in years in which there were a low number of ‘growth weeks’ in the previous green season. Annual liveweight gain was related to the total number of ‘green weeks’. In this paper the geographic variation in these three agro-climatic parameters is described using a network of 77 stations across northern Australia, and the year-to-year variability is examined for eight representative stations. Variation in dry season severity was greater than variation in green season productivity (growth weeks). Median ‘dry weeks’ in the dry season varied from 29 to nil over the area. ‘Green weeks’ in the dry season as a result of winter rain is an important phenomenon in a relatively small part of the area, but in this area year-to-year variability is extremely high. It is concluded that the objectives of the study, to extend existing agro-climatic methodology to interface with cattle production and to use this in surveying the climatic potential for this form of land use over the entire tropical region of Australia, were achieved to the extent that the existing animal production data allow.