ABSTRACT Reproductive efficiency is a core factor affecting the economic performance and sustainable development of dairy farms. The objective of this study was to systematically evaluate the current reproductive status of Chinese Holstein dairy cattle and to identify the key factors affecting their reproductive performance. This observational study utilized production data from 185 dairy farms nationwide collected between 2020 and 2024 to analyze the impact of region, season, farm size and 3 peripartum diseases on reproductive performance, with all analyses conducted at the farm level. Mixed linear models were employed to assess the correlation of these factors with conception rates. Our analysis indicates that from 2020 to 2024, all key reproductive indicators for both heifers and cows in Chinese Holstein cattle exhibited a consistent and significant improvement trend. Analysis of the 2024 data showed that the overall performance of cows in the NWID region was superior to that in other regions. In contrast, both heifers and cows in the Southern Subtropical Humid Climate Zone exhibited lower conception rates, while heifers in this zone also had a significantly higher proportion of non-pregnant heifers at 17 mo (14.66% ± 2.66%). Concurrently, seasonal factors demonstrated a significantly greater impact on reproductive efficiency in cows than heifers. Conception rates for cows across all regions reached their annual low in autumn, with the most pronounced decline observed in the Eastern Warm-Temperate Monsoon Climate Zone (25.54% ± 1.90%) and Southern Subtropical Humid Climate Zone (29.25% ± 2.00%). Analysis of data from dairy operations of different scales reveals that larger-scale farms exhibited superior reproductive performance in dairy cows and significantly mitigated the autumn reproductive trough in cows. Analysis of peripartum disease incidence revealed a significant decrease in the incidence of hypocalcemia with increasing herd size. The incidence of retained fetal membranes was negatively correlated with herd conception rate and was higher in summer (9.13% ± 0.46%). Conversely, metritis demonstrated no substantial variations across herd sizes or seasons and exhibited no statistical correlation with conception rates. In summary, this study emphasized the necessity of comprehending and integrating regional variations in environmental stressors, the buffering value of scaled professional management, and the differential impact patterns of key reproductive diseases when formulating comprehensive strategies to enhance reproductive efficiency in Chinese dairy herds. It provided critical evidence for implementing regionalized and group-specific precision management practices.
Chen et al. (Wed,) studied this question.