In southern Brazil, beef cattle production systems generally rely on grazing on natural pastures. However, their forage production, and consequently metabolizable energy (ME) production, is seasonal and influenced by climatic events. Thus, there is a scientific and commercial interest in evaluating and understanding the biological impacts of intensification using pasture irrigation and the effects of El Niño-Southern Oscillation (ENSO) phenomena on the long term on the productivity of cow-calf systems. Therefore, our objective was to develop a simulation model to evaluate the effects of intensification levels, using cultivated pastures and irrigation, on the productivity and on the efficiency metabolizable energy utilization of beef cow-calf systems in a 10-year horizon. This period allows capturing the effects of several production cycles as influenced by ENSO events. The model includes three submodels: herd structure, herd ME requirements, and forage ME production. The results of the present study demonstrate that the proposed model is able to evaluate the influence of intensification of grazing systems on metabolizable energy production, carrying capacity, productivity and biological efficiency of beef cow-calf systems over a long-term horizon. Productivity was increased in 15.9% when 20% of the grazing area was intensified and irrigated compared with the modeled non-intensified system, independently of climatic events. The main productive response was the increase in the number of dams in the herd, especially as a result of the use of irrigation. This study proposes different alternatives for increasing the productivity of beef cow-calf systems in southern Brazil.

在巴西南部，肉牛生产系统通常依靠天然牧场放牧。但是，它们的草料产量以及因此产生的可代谢能量（ME）产量是季节性的，并受气候事件的影响。因此，评估和了解牧场灌溉集约化的生物影响以及长期以来对牛犊牛系统生产力的厄尔尼诺-南方涛动（ENSO）现象的影响具有科学和商业利益。因此，我们的目标是建立一个仿真模型，以评估集约化水平，使用耕种牧场和灌溉对牛肉和犊牛犊牛系统在10年内的生产率和可代谢能量利用效率的影响。这个时期可以捕获受ENSO事件影响的几个生产周期的影响。该模型包括三个子模型：畜群结构，畜群ME需求和饲料ME生产。本研究的结果表明，所提出的模型能够长期评估放牧系统集约化对肉牛犊牛系统可代谢能量产生，承载能力，生产力和生物效率的影响。与模拟的非集约型系统相比，与模拟的非集约型系统相比，加强和灌溉放牧面积的20％时，生产率提高了15.9％。主要的生产性响应是畜群中水坝数量的增加，特别是由于灌溉的结果。