Capturing and understanding beef cattle production diversity in extensive environments to optimise productivity and welfare

Abstract

Beef production systems in Australia span diverse agro-climatic zones that are highly susceptible to climate variability. Extreme climate events, particularly heatwaves and rainfall variability, can adversely affect cattle production systems. Understanding how these events impact cattle productivity across landscapes is, therefore, critical to support farmer decision-making. This thesis advances understanding of the impacts of extreme climate events on cattle systems to help mitigate their effects and optimise productivity and welfare. Chapter 2 presents a literature review highlighting the impact of climatic extremes on cattle systems, advances in heat stress (HS) monitoring, feedbase dynamics, and resilience frameworks to enhance productivity. Developing such frameworks is essential to address the growing challenges posed by frequent and severe climate extremes. Chapter 3 validates the Optiweigh™ (OW) in-field weighing station for remotely monitoring liveweight (LW) in grazing conditions, providing a simple and accurate way to track LW changes through voluntary animal attendance. Chapter 4 evaluates the temporal effects of HS on cattle systems, defines thermal index thresholds, and explores adaptive strategies to sustain productivity under heat stress. Insights from relatively homogenous indoor-housed dairy systems may serve as useful benchmarks for managing HS in extensive beef systems. Chapter 5 assesses the impacts of seasonal rainfall across climatic zones, revealing interactions between climate and feedbases, contributing to improved management strategies. The delayed effects of HS and seasonal rainfall (Chapters 4 and 5) underscore the need for adaptive strategies to mitigate climatic pressures and sustain productivity and profitability. Overall, the findings demonstrate that quantifying the impacts of extreme climate events enables adaptive, data-driven strategies to enhance the productivity and welfare of extensive beef production systems.