The status of timed artificial insemination technology in large-scale Chinese dairy farms

Here, we aim to review the evolution of timed artificial insemination (TAI) technology in large-scale dairy farms in China and provide experience and reference guidelines for the improvement of reproductive efficiency in such farms. We used data acquired from more than 1,000,000 dairy cows in more than 200 dairy farms that had been collected from 2019 to 2023. We systematically analyzed the current status and factors influencing the use of TAI technology from various perspectives, including regions, dairy farm scale, stage of parity, and the service. Our analysis revealed that from 2019 to 2023, the 21-d pregnancy rate of cows and heifers in China continued to rise, with the largest increase occurring in the northwest region. Compared with 2019, the proportion of dairy farms using TAI on cows in 2023 increased markedly (38.8% ± 3.45% vs. 76.1% ± 3.01%; ±SEM) and showed an increasing trend with the expansion of farming scale. Artificial insemination in heifers was predominantly based on natural estrus with TAI being primarily used to manage heifers that failed to become pregnant after several rounds of insemination; however, the cumulative number of TAI cycles has also followed an upward trend over recent years. In 2023, there was significant variation in the proportions of TAI cycles used on cows located in different regions of China; the highest usage was recorded in the northwest region (86.3% ± 4.05%) and the lowest usage was recorded in the southern region (57.9% ± 11.6%). In contrast to heifers, the proportion of TAI cycles used for cow breeding in large-scale dairy farms in China increased significantly from 2019 to 2023, irrespective of whether we considered first parity, second parity, or first and second service. With the widespread application of TAI, it is important to consider a range of critical factors, including region, farm scale, and herd characteristics. In conclusion, TAI technology has grown in popularity in large-scale dairy farms in China and has made valuable contributions to the reproductive efficiency of such farms. As the genetic improvement of dairy cows in China progresses and the milk production of dairy cows continues to increase, TAI technology is expected to be applied in a wider range of regions in the future.