Inactive ovaries in high-yielding dairy cows before service: aetiology and effect on conception

Area of Science:

• Veterinary Medicine
• Reproductive Biology
• Animal Science

Background:

• Ovarian inactivity is a significant concern in dairy cattle reproduction.
• Understanding the factors influencing ovarian inactivity is crucial for improving herd fertility.
• Previous studies have explored various risk factors, but comprehensive analysis is needed.

Purpose of the Study:

• To determine the prevalence of inactive ovaries in lactating dairy cows.
• To identify associations between inactive ovaries and various reproductive and metabolic factors.
• To evaluate the impact of inactive ovaries on conception rates.

Main Methods:

• Retrospective analysis of 7751 lactations.
• Diagnosis of inactive ovaries via two consecutive rectal examinations.
• Statistical analysis to assess associations with parity, twinning, retained placenta, metritis, milk yield, and other factors.

Main Results:

• The overall rate of inactive ovaries was 8.5%.
• Inactive ovaries were associated with increased parity, twinning, retained placenta, primary metritis, and high milk yield in heifers.
• Inactive ovaries and metritis independently increased the risk of delayed conception, with a synergistic effect when both were present.

Conclusions:

• Uterine damage and postpartum energy deficits are key contributors to ovarian inactivity.
• Ovarian inactivity is not directly linked to fatty liver but may be indirectly related through postpartum uterine diseases.
• Managing uterine health and energy balance is critical for preventing ovarian inactivity and improving reproductive performance.