Progesterone-Based Estrus Synchronization Protocols in Cows: Mechanisms, Applications, and Economic Perspectives

Reproductive efficiency is a critical determinant of productivity and profitability in both dairy and beef cattle systems. Progesterone-based estrus synchronization protocols have emerged as essential tools to control the timing of ovulation, enhance artificial insemination efficiency, and optimize herd reproductive performance. These protocols exploit the physiological regulation of the hypothalamic–pituitary–ovarian axis, maintaining elevated progesterone levels to suppress ovulation and coordinating luteolysis and follicular wave emergence through prostaglandins, GnRH analogues, and, in some cases, equine chorionic gonadotropin. In beef cattle, progesterone supplementation facilitates fixed-time artificial insemination, shortens calving intervals, and improves calf crop uniformity, whereas in dairy cows it mitigates poor estrus detection, enhances service rates, and reduces days open. Fertility outcomes are influenced by cow physiological status, metabolic condition, and protocol adherence, with pregnancy per AI typically ranging from moderate to high in beef cattle and lower in lactating dairy cows. Economic evaluation indicates that these protocols are cost-effective in herds with moderate to large size, low estrus detection efficiency, and intensive management, although labor, drug costs, and handling requirements must be considered. Critical analysis suggests that synchronization cannot compensate for underlying nutritional, health, or metabolic deficiencies, and future research should focus on precision application, individualized protocols, and integration with automated reproductive monitoring to improve both biological and economic efficiency. This review summarizes physiological principles, protocol designs, practical applications, fertility outcomes, and economic considerations of progesterone-based estrus synchronization in cows, highlighting current challenges and perspectives for enhanced reproductive management.