Physiology and management: Reproductive Performance of Dairy Heifers after Estrus Synchronization and Fixed-Time Artificial Insemination

摘要

The reproductive performance of heifers after es- trus synchronization and fixed-time AI was compared with nonsynchronized heifers in 25 spring-calving herds. Within herds, heifers were divided into a syn- chronized (n = 1123) or a control (n = 1125) group. Heifers in the synchronized group were treated with a Combination of progesterone, estradiol benzoat4e, and PGF_2α and were inseminated between 50 and 54 h After progesterone treatment. Returns to first service Were resynchronized with progesterone treatment be- Tween 16 and 21 d after the fixed-time AI.