Intensifying Neotropical Beef Cattle Grazing Systems: Navigating Complexity Through Modelling

CONTEXT: Cow-calf and fattening grazing systems in the tropical, well-drained savanna ecosystem of the Eastern Plains in the Colombian Orinoco River Basin are being intensified to enhance technical efficiency. These systems, often starting from degraded pastures, present significant challenges for both researchers and producers in analyzing and predicting their transformation. OBJECTIVE: This study aimed to develop a model capable of simulating the multifaceted interaction between land use, beef herd management, animal productivity, enteric methane (CH4) emissions, and carbon footprint (CF) at the system level. The model should assist in making informed decisions towards sustainable beef farming systems that improve resource management. METHODS: The model compared three alternative regional scenarios (SCEs) using conceptual medium-sized 400ha farms. Scenario (SCE) 0 starts with degraded Urochloa humidicola pastures, followed by low-intensity rejuvenation to support a cow-calf system. SCE 1 follows a similar path but introduces, in later stages, 100 ha of moderately well-managed, better-quality U. brizantha pastures to further develop the cow-calf system. SCE 2 begins as SCE 1 but later transitions into a full-cycle beef production system. In all cases, the systems are conservatively managed to ensure sustainable production. RESULTS AND CONCLUSIONS: The outputs of the modelled SCEs reveal and quantify the complex interplay of numerous system feedbacks, determining system outputs and identifying quantitative variables that significantly influence system behaviors. Culling rates of cows and the fattening of feeder cattle are decisive events that modify the dynamics of the beef herds over time, impacting production and greenhouse gas emission outputs. Under conservative management, all three SCEs resulted in significant increases in production ha -1 and animal units -1 (AU; 450 kg), although the magnitude and temporal development of these increases varied among SCEs. These increases were accompanied by higher enteric CH4 emissions ha -1. However, emissions substantially decreased AU -1 and kg -1 liveweight sold, reducing CFs. This highlights the potential of well-managed Neotropical beef cattle grazing systems (NBCGS) to balance productive gains with environmental sustainability, offering actionable strategies to enhance NBCGS management. SIGNIFICANCE: This study underscores the importance of evaluating Neotropical beef cattle grazing systems (NBCGS) across various temporal and spatial dimensions and considering technical decisions. Simulation modelling constitutes a powerful tool for assessing system dynamics that are otherwise difficult to design and subject to long-term field research. This approach enables a deeper understanding of the trade-offs and interactions within NBCGS, facilitating more informed and sustainable decision-making.