Fertility Problems Decision Tree

For class I had to summarize a paper by Dr. W.L Flowers titled “Trouble-shooting Fertility Problems”. From this summary I was to make a “Decision Tree” to help decide where Fertility Problems occur. I thought that it might be helpful to others. Please let me know if you would add anything to it, or even change it. I would love to hear from you as to its usefulness to you!

For clarity of definitions: A “Regular Return to Estrus” occurs no later than 28 days after breeding, and an “Irregular Return to Estrus” happens at 28 days after breeding, or later.

(#1) Farrowing Rate Bad; Number Born Alive Bad; Regular Return to Estrus: Causes:

(A) Poor Fertilization Rates: Sperm and/or Ova Check Boar Fertility!
(B) High Mortality of Embryos (day 1-12 after Breeding)
(C) Low Ovulation of Ova
(D) Inadequate Boar Exposure
(E) Poor Detection of Estrus
(F) Poor Insemination Techniques
(G) Too much Stress in the first two weeks after Breeding

(#2) Farrowing Rate Bad; Number Born Alive Bad; Irregular Return to Estrus (i.e. Greater than 28 days after Breeding) : Things that cause problems between day 12 of Pregnancy and day 28 are:

(A) Disease
(B) Mixing of Sows
(C) Heat Stress
(D) Mycotoxins
(E) Vacinations (? Controversial)

(#3) “Subset Problems” I + II + III

(I) Good Farrowing rate and Poor Number Born Alive: This is caused by High Fetal Death after 28 days Post-Breeding:
(i) Lots of Mummies: the Problem is after day 50 of Gestation.
(ii) Lots of Stillborn: The problem is most likely the last week of Gestation or during Farrowing. (iii) Lack of Mummies or Stillborn: The problem is most likely between days 28 and 50 of Gestation (i.e. Before the Calcification of Fetal Bones).
(iv) Low Ovulation Rate but sufficient to preserve Pregnancy.
(II) Subset II Poor Farrowing Rate; Good Number Born Alive; Regular Return to Estrus
(i) Problems during Breeding or
(ii) High Embryonic Mortality before day 12 of Pregnancy
(III) Subset III Poor Farrowing Rate; Good Number Born Alive; Irregular Returns to Estrus:
(i) High Embryonic Mortality after day 28 of Gestation
(ii) Diseases causing Abortions or Mummies
(iii) Mycotoxins causing Fetal Death

References:
(1) Flowers, Dr. W.L. “Trouble-shooting Fertility Problems” University of North Carolina State University Raleigh, N. C. , U.S.A. 27695-7621
(2) Flowers, Dr. W.L. Class notes “Lesson #10 Trouble Shooting Reproductive Problems”