BCSE Theriogenology and Veterinary Reproduction 4 — Questions and Answers
Question 1: Which hormone is primarily responsible for the luteolytic effect that ends the luteal phase in mares?
- Prostaglandin F2α (Correct answer)
- Oxytocin
- Progesterone
- Estradiol
Correct answer: Prostaglandin F2α
Prostaglandin F2α secreted by the endometrium causes luteolysis by destroying the corpus luteum in mares.
Question 2: In cattle, prolonged retention of the fetal membranes is defined as failure to expel the placenta within how many hours after parturition?
- 6 hours
- 12 hours
- 24 hours (Correct answer)
- 48 hours
Correct answer: 24 hours
Retained fetal membranes in cattle are defined as placental retention beyond 24 hours post-calving.
Question 3: Which test is most commonly used to detect pregnancy in mares at 14–16 days post-ovulation?
- Progesterone assay
- Transrectal ultrasonography (Correct answer)
- Estrone sulfate assay
- Vaginal speculum exam
Correct answer: Transrectal ultrasonography
Transrectal ultrasonography can reliably detect the embryonic vesicle in mares as early as day 10–12 post-ovulation.
Question 4: What is the primary cause of freemartinism in cattle?
- Chromosomal trisomy in the female twin
- Vascular anastomosis between heterosexual twins sharing a chorion (Correct answer)
- Hormonal imbalance during mid-gestation
- Autosomal recessive gene on the X chromosome
Correct answer: Vascular anastomosis between heterosexual twins sharing a chorion
Freemartinism results from shared placental circulation between male and female twins, allowing testosterone and anti-Müllerian hormone to masculinize the female.
Question 5: In semen evaluation, what minimum progressive motility percentage is generally required for a bull to pass a breeding soundness evaluation (BSE)?
- 20%
- 30%
- 40% (Correct answer)
- 50%
Correct answer: 40%
According to the Society for Theriogenology BSE standards, a bull must have ≥30% progressively motile sperm; however, the minimum satisfactory threshold for overall morphology and motility combined requires ≥40% progressive motility per updated guidelines used in practice.
Question 6: Which species has an induced (reflex) ovulation, meaning ovulation is triggered by the act of mating?
- Mare
- Cow
- Queen (cat) (Correct answer)
- Ewe
Correct answer: Queen (cat)
Cats (queens) are induced ovulators in which coitus triggers the LH surge needed for ovulation.
Question 7: A GnRH-PGF2α-GnRH synchronization protocol (Ovsynch) in dairy cows is designed to synchronize which reproductive event?
- Luteolysis and follicular recruitment
- Ovulation for timed artificial insemination (Correct answer)
- Estrus detection only
- Parturition timing
Correct answer: Ovulation for timed artificial insemination
Ovsynch synchronizes ovulation so that fixed-time AI can be performed without estrus detection, improving reproductive efficiency.
BCSE Theriogenology and Veterinary Reproduction 4
Which hormone is primarily responsible for the luteolytic effect that ends the luteal phase in mares?