Incorporating Multiple Feed Resources Reduces the Overestimation of Grassland Overstocking in China’s Major Pastoral Provinces

Accurately assessing grassland carrying status and its temporal dynamics is essential for implementing forage-based livestock management and advancing grassland ecological restoration. However, existing assessments often consider only natural grassland feed while overlooking other feed sources, which may lead to an underestimation of the total feed resources available for livestock production and introduce substantial uncertainty into assessments of forage–livestock balance. To address this limitation, we construct two accounting frameworks for assessing forage–livestock balance across eight provinces and autonomous regions encompassing China’s major pastoral and agro-pastoral areas. One framework considered natural-grassland forage alone, while the other also included cultivated-grassland forage and agricultural straw. Reasonable livestock carrying capacity and the carrying capacity index (CCI) were calculated under both frameworks and compared using temporal trend analysis, paired t-tests, and a ±10% parameter sensitivity analysis. Across the eight study regions, natural grassland forage accounted for an average of 86.53% of the estimated carrying capacity, while agricultural straw and cultivated-grassland forage contributed 11.25% and 2.22%, respectively. The combined contribution of these supplementary resources varied substantially among provinces, ranging from 1.08% in Qinghai and 1.30% in Xizang to 46.95% in Yunnan. Incorporating supplementary feed significantly increased estimated carrying capacity and reduced the CCI compared with the natural-grassland-only framework (both p < 0.001). The reduction was greatest in Yunnan, Ningxia, and Gansu. Nevertheless, the mean CCI remained above 1 throughout 2000–2020, and seven of the eight provinces remained overstocked under the comprehensive framework. The results were robust to the alternative parameter scenarios. These findings demonstrate that excluding cultivated forage and agricultural straw systematically overestimates regional overstocking, particularly in agro-pastoral regions, although incorporating these resources does not eliminate the underlying imbalance between feed supply and livestock demand.