Do your mated sows regularly return to estrus or are there other irregularities? Don Levis, University of Nebraska extension swine specialist, provides some reasons why bred sows recycle:

If your sows recycle in 18 to 24 days, possible reasons why include:


  • Eggs are not fertilized due to low quality sperm.
  • Failure of blastocysts to survive 10 days post mating:

      a. Problem with low quality semen.
      b. Eggs are fertilized too late after ovulation.



If your sows recycle in 25 to 35 days, possible reasons why include:


  • Failure of four piglets to implant.

      a. Stressful events during time of implantation.
      b. Low number of viable sperm cells.
      c. Late insemination.
      d. Inadequate time for uterine involution (weaning sow after less than 14 days in lactation).



If your sows recycle in 36 to 48 days, possible reasons why include:


  • Undetected estrus (18 to 27 days after mating).
  • Embryonic death.
  • Embryonic death plus undetectable estrus.



If your sows recycle in 49 or more days, possible reasons why include:


  • Pseudo-pregnancy.
  • Abortion.
  • Failure of implantation, plus failure to detect estrus.