DIAGNOSTIC APPROACHES

Detecting and diagnosing delayed ovulation in cattle requires a comprehensive approach, as the condition is often subclinical and difficult to recognize through behavioral observations alone [120]. Various diagnostic methods are available, ranging from ultrasonography and hormone profiling to behavioral estrus detection technologies and molecular biomarkers [125]. It is important to differentiate between research-grade diagnostics, which provide detailed mechanistic insights but require laboratory infrastructure, and field-applicable tools that are feasible, rapid, and cost-effective for routine herd management. Table 2 presents a summary of diagnostic methods used to detect delayed ovulation in cattle.

Diagnostic method | Principle / Mechanism | Application / Notes | References
Ultrasonography | Non-invasive imaging to monitor ovarian and follicular dynamics | Serial scanning of dominant follicles (≥18–25 mm) to assess growth, persistence, regression, and ovulation; detection of delayed corpus hemorrhagicum or partial luteinization indicates delayed ovulation. Highly effective but requires skilled operator and equipment. | [126–131]
Hormonal profiling | Measurement of reproductive hormone levels (LH and progesterone) | LH surge detection indicates ovulation timing; progesterone measurement 5–7 days post-estrus confirms corpus luteum function. Provides mechanistic insight but requires laboratory infrastructure and frequent sampling; mainly used in research or advanced herd management. | [132–138]
Behavioral and estrus detection tools | Monitoring estrus-related behavior induced by estrogen | Field-applicable tools include activity sensors, pedometers, pressure mats, and visual observation (restlessness, vocalization, tail elevation, mucus discharge). Artificial insemination-based systems integrate activity, temperature, and historical cycle data to predict ovulation and flag cows at risk for delayed ovulation. | [139–145]
Molecular / Biomarker approaches | Analysis of inflammatory, metabolic, and follicular markers | IL-1β, IL-6, TNF-α reflect local/systemic inflammation; NEFA, BHB, glucose, and insulin indicate energy balance. Valuable for early detection and research; best used as complementary tools alongside ultrasonography and hormonal profiling. Not practical as standalone routine field diagnostics due to cost and infrastructure needs. | [146–156]