Reproductive Medicine and Theriogenology Flashcards

Superovulation in cattle for embryo transfer is most commonly induced by:

Answer: Exogenous FSH or eCG administered during the mid-luteal phase to stimulate multiple follicle development

Multiple ovulations for embryo transfer are induced by exogenous FSH (given in decreasing doses over 4 days) or a single eCG injection during the mid-luteal phase, resulting in several transferable embryos.

In swine, maternal recognition of pregnancy requires a minimum number of viable embryos because:

Answer: Fewer than 4–5 embryos produce insufficient estrogen to rescue corpora lutea from prostaglandin-mediated regression

Porcine embryos must produce sufficient estrogen by days 11–12 to redirect uterine PGF2α secretion away from the vasculature, rescuing the CL; fewer than approximately 4–5 embryos fails to provide adequate signal.

Rectal palpation of pregnancy in mares typically becomes reliably diagnostic at approximately:

Answer: Day 25–30

Although ultrasound detects equine pregnancy from day 10–12, rectal palpation reliably identifies pregnancy at approximately day 25–30 when the uterine bulge and altered uterine tone are palpable.

Prolonged diestrus (persistent corpus luteum) in mares is characterized by:

Answer: Failure of the CL to regress beyond the normal luteal phase, with sustained progesterone suppressing estrus

Persistent CL in mares occurs when normal PGF2α-mediated luteolysis fails, often following early embryonic death, resulting in persistently elevated progesterone and behavioral anestrus.

The standard cryoprotectant used in equine semen cryopreservation is:

Answer: Glycerol

Glycerol (typically 2–5%) is the standard cryoprotectant for stallion semen freezing; it penetrates sperm membranes and protects against intracellular ice crystal formation during cryopreservation.

In dogs, which serum progesterone concentration most closely corresponds to the preovulatory LH surge?

Answer: 1–2 ng/mL (initial progesterone rise)

The canine LH surge coincides with a progesterone rise to approximately 1–2 ng/mL; ovulation follows ~48 hours later at ~5 ng/mL, and fertilizable oocytes are present when progesterone reaches 10–25 ng/mL.

The most common cause of early embryonic mortality in cattle is considered to be:

Answer: Failure of maternal recognition of pregnancy due to inadequate interferon-tau (IFN-τ) production

Failure of maternal recognition of pregnancy, caused by insufficient IFN-τ from the trophoblast to prevent endometrial PGF2α secretion, is the leading cause of early embryonic loss in cattle.