Effective heat detection and artificial insemination (AI) in pigs require precise timing and keen observation of estrus signs. Missing or misinterpreting these signs can lead to unsuccessful breeding, economic loss, and lower productivity. This article explores the critical aspects of estrus detection and AI timing to maximize conception rates.

 

Preliminary Signs of Estrus

The early indicators of estrus appear 24-48 hours before the standing heat period. Recognizing these signs allows farmers to prepare for timely insemination:

  • Vulva reddening – Increased blood flow makes the vulva appear more reddish.
  • Vulva swelling – A noticeable increase in size due to hormonal changes.
  • Mucus discharge – A clear or slightly cloudy mucus may be seen around the vulva.
  • Mounting behavior – The pig may attempt to mount pen mates but will not tolerate being mounted.
  • Increased vocalization – The sow or gilt becomes more vocal, calling for a boar.
  • Reduced appetite – Some pigs experience a temporary loss of interest in food.

⚠️ Important Note: Do not inseminate pigs during this phase. Many AI failures result from incorrect timing due to misreading these preliminary signs as standing heat. Instead, closely monitor behavior for further estrus development.

Standing Estrus Period (Optimal Breeding Time)

This phase lasts approximately 36-48 hours, during which ovulation occurs, making it the most critical time for successful AI. Key signs include:

  • Seeking the boar – The pig actively moves toward a heat-checking boar.
  • Standing reflex – The pig will stand still when pressure is applied to its back, whether from a boar, pen mate, or human.
  • Consistent behavior – Only pigs exhibiting a solid standing reflex should be inseminated.
  • Shorter estrus duration in gilts – Gilts typically display standing heat for 24-36 hours, while sows may show signs for 36-48 hours.

🐖 AI Timing and Ovulation:

  • Ovulation usually occurs 32-48 hours after the onset of standing heat.
  • Sperm requires 4-6 hours for capacitation before fertilizing the egg.
  • Eggs remain viable for 6-10 hours after ovulation.
  • Sperm is viable for 18-24 hours inside the reproductive tract.
  • Insemination too early or too late reduces conception rates. The ideal approach is to inseminate midway through standing estrus, with a second dose 12-24 hours later.

Signs of Estrus Ending

Estrus signs gradually decline, indicating that the optimal breeding window is closing:

  • Loss of standing reflex – The pig will no longer stand when pressure is applied to the back.
  • Mounting behavior returns – The pig may begin mounting others again.
  • Lower receptiveness to boars – The pig shows less interest in boar presence.

⚠️ Avoid Common Mistakes:

  • Skipping heat detection checks – Pigs should be checked for estrus at least twice daily.
  • Inseminating at the start or end of standing heat – Increases the risk of missed ovulation.
  • Wasting AI doses – Giving two doses in 4-8 hours is ineffective. A 12-24 hour interval between doses is optimal.

By following these heat detection and AI timing principles, farmers can significantly improve conception rates and overall herd productivity.

📞 Need expert AI support? Contact Vision Agribusiness Farm Ltd today!