Assessing extensive pasture-based beef production in South Africa under future climate change conditions

Abstract

CONTEXT : Assessing the impact of climate change on extensive pasture-based beef production across varied agro-ecological regions is crucial for designing customized adaptation measures. OBJECTIVE : This study assesses the effects of climate change on extensive pasture-based beef production systems in three South African agro-ecological regions (Bloemfontein, Phalaborwa and Buffalo Berlin) under two climate change scenarios, namely the representative concentration pathways (RCPs) 4.5 and 8.5. METHODS : The LiGAPS-Beef model, previously calibrated for the region, was used to evaluate the impact of climate change on beef cattle production under pasture-based extensive systems. Four breed types, namely Bos taurus, Composite, Zebu indicine and Sanga cattle were included in this study. Genetic parameters for each breed were obtained from SA Stud Book, Livestock Registering Federation (LRF) and literature. Measured historical weather data was obtained from the South African Weather Service for the three agro-ecological regions. An ensemble of eight regional climate model (RCA4) simulations from the CORDEX Africa initiative was used to generate future climate change projection data for the period 2036–2065 under RCP 4.5 and RCP 8.5 scenarios. The future nutritional composition data for forage was collected from studies that simulated and predicted future forage quality under climate change conditions. RESULTS AND CONCLUSION : The study found that the baseline average daily gain (ADG) was significantly higher (0.40 kg/head/day) than the simulated RCP 4.5 (0.21 kg/head/day, −48 %) and RCP 8.5 (0.20 kg/head/day, −51 %) ADGs regardless of breed type when both feed quality and feed quantity limited growth. Although the effect of the climate change scenarios on beef production was agro-ecological region dependent, the performance of Bos taurus declined more than other breeds under future climate scenarios while the Sanga and the Composite types were the most resilient, especially in hot climate areas. Model simulations predict that future climate change will have a greater negative impact on cattle in Buffalo Berlin and Phalaborwa, while those in Bloemfontein will be least affected. The study also highlights that under future climate change scenarios, pasture quality will be the key factor influencing cattle growth in Bloemfontein and Buffalo Berlin, while pasture quantity will be the dominant factor in Phalaborwa if stocking rates remain unchanged. The study highlights the need for nutritional and pasture management interventions for pasture-based extensive system (e.g., feed supplementation, adjusting the stocking rate to match pasture availability, identifying and integrating drought and/or heat tolerant ecotypes, fodder trees that provide shade for the animals) to mitigate the expected decline in beef cattle performance in South African agro-ecological regions. SIGNIFICANCE : Quantifying the impact of anticipated climate change on pasture-based extensive beef production and identifying specific factors that limit beef production per breed type in the different agro-ecological regions is crucial for assessing the potential ramifications on beef production. This information empowers farmers and policy makers to develop targeted mitigation and adaptation strategies that promote resilience of the beef production system in the respective regions.

HIGHLIGHTS • Quantifying climate change impact on beef production is vital for coping measures. • Beef cattle growth was simulated under RCP 4.5 and RCP 8.5 in South Africa. • 2050 simulated growth declined by 48 % in RCP 4.5 and 51 % in RCP 8.5 from baseline. • Growth of Bos taurus was most adversely affected, but Sanga was the most resilient. • Location-specific intervention is vital to sustain beef production in South Africa.