Learning Reproduction in Farm Animals


Learning Objectives:

How was the Mechanism for Paturition Discovered?
  Hormonal Changes that Control Parturition:

Hormonal changes cause:

Significance of initial hormonal changes.

Events just Prior to Parturition:

  1. Pelvic ligaments soften - Tail head sinks due to ­ estrogens and relaxin.

  3. Cervix softens and begins secreting stringy mucus - ­ estrogens and relaxin.

  5. Swelling of vulva.



  7. Udder swells - fills with first milk and due to edema:

  9. Fetus moves into proper position - resting on thorax, front feet and head facing the cervix.



 Stages of Parturition:
  • Pressure of fetus in cervix stimulates oxytocin release and reflex contractions of abdominal muscles.
  • Sow Delivery of Piglets:
        Care of retained placentas:  Preventing retained placentas:  Uterine Involution: Artificial Induction of Parturition:

    Induction of Abortion in Feedlot Heifers

    1. Heifers that are less than 150 days into gestation can be aborted with a single intramuscular injection of 25 mg Lutalyse or 500 mg Estrumate. Efficiency of 90%.
    2. After 150 days of gestation, combination of 25 mg Dexamethazone and 500 mg Estrumate is needed to cause abortion. Efficiency of 95%.
    3. Abortion will occur over 2 to 10 days.
    4. All abortions should be recorded, and heifers which fail to abort re-examined.
    5. Failure to induce abortion is most likely caused by failure of luteolysis. Re-treatment will usually cause abortion.
    6. In the case of fetal mummification, Prostaglandin treatment will stimulate expulsion.
    7. Cows over 4 months pregnant will have a high percent of retained placenta (80%). Most cases will resolve themselves, but the producer needs to monitor health of females after abortion.

    Illustrated Notes

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