Environmental influences on the postpartum animal

Area of Science:

• Reproductive Physiology
• Environmental Science
• Animal Science

Background:

• Environmental factors significantly influence postpartum reproduction in ewes, cows, and sows.
• Photoperiod primarily regulates ewe reproductive cycles, with less impact during fall lambing.
• The effects of heat and humidity on breeding during anestrus or after estrous resumption require further investigation.

Purpose of the Study:

• To investigate the impact of hot ambient temperatures and high humidity on postpartum reproduction in ewes, cows, and sows.
• To explore the physiological mechanisms underlying impaired reproduction due to heat and humidity.
• To identify potential differences in impact across species and breeding seasons.

Main Methods:

• Observational studies analyzing reproductive performance in ewes, cows, and sows under varying environmental conditions (heat, humidity).
• Monitoring of rectal and uterine temperatures in heat-exposed animals.
• Assessment of hormonal levels and uterine blood flow in relation to environmental stressors.

Main Results:

• Hot ambient temperatures and high humidity severely impair postpartum reproduction in cattle of European breeding in southern US regions.
• Reduced reproductive efficiency is observed in postpartum sows during late summer and early fall in southern states.
• Elevated environmental, rectal, and uterine temperatures in ewes and cows are associated with reduced conception and pregnancy rates, potentially due to altered hormonal profiles and uterine blood flow.

Conclusions:

• Environmental heat and humidity are significant stressors negatively affecting postpartum reproduction in ewes, cows, and sows.
• The physiological mechanisms, including elevated body temperatures, hormonal changes, and reduced uterine blood flow, require further elucidation, especially in sows.
• Understanding these impacts is crucial for improving livestock reproductive management in warmer climates.