Delayed ovulation in cattle: Physiological mechanisms, diagnostic approaches, and reproductive management strategies

Abstract

Abstract

Background and Aim: Delayed ovulation is an important but frequently underrecognized reproductive disorder in cattle that reduces fertility, prolongs calving intervals, and causes substantial economic losses in both dairy and beef production systems. Unlike anovulation or cystic ovarian disease, delayed ovulation is characterized by the late release of a mature oocyte despite normal follicular development, resulting in poor synchrony between ovulation and insemination. This review provides a comprehensive overview of the physiological mechanisms, etiological factors, diagnostic approaches, and management strategies associated with delayed ovulation in cattle. Current evidence published between 2000 and 2025 was critically evaluated to summarize the endocrine regulation of ovulation, emphasizing the coordinated roles of gonadotropin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone. The review highlights the multifactorial nature of delayed ovulation, demonstrating how nutritional deficiencies, negative energy balance, heat stress, postpartum physiological changes, endocrine and metabolic disorders, and reproductive tract inflammation interact to impair follicular maturation and ovulatory timing. Clinical manifestations, including follicular persistence, prolonged or silent estrus, repeat breeding, reduced conception rates, and extended calving intervals, are discussed together with their consequences for herd productivity. Available diagnostic methods, including transrectal ultrasonography, hormonal profiling, behavioral estrus monitoring, precision livestock technologies, and emerging molecular biomarkers, are compared with respect to their clinical applicability and limitations. Therapeutic and preventive strategies, including hormonal synchronization protocols, nutritional optimization, postpartum health management, environmental stress reduction, and assisted reproductive technologies, are reviewed as integrated approaches to restore normal ovarian function and improve reproductive efficiency. Emerging opportunities involving precision livestock farming, artificial intelligence, and biomarker-based prediction are also highlighted as promising tools for early detection and individualized reproductive management. Overall, this review synthesizes current knowledge on delayed ovulation as a distinct reproductive disorder and provides practical, evidence-based guidance for veterinarians, researchers, and livestock producers. Improved understanding, timely diagnosis, and targeted interventions will contribute to enhanced fertility, greater production efficiency, improved animal welfare, and more sustainable cattle production systems. Keywords: artificial insemination, cattle reproduction, delayed ovulation, fertility, follicular development, ovarian physiology, sustainable animal production, ultrasonography.