Theriogenology MCQS Set 2
26. In bovine, CL attains maximum size by ____ day of cycle
a. 5th day b. 9-10th day c. 15th day d. 18th day
Correct Answer: b. 9-10th day
Explanation: The Corpus Luteum (CL) begins to form immediately after ovulation, but it reaches its peak functional size and maximum progesterone production during mid-diestrus, typically around days 9 to 10 of the 21-day cycle.
27. Which of the following animals is an induced ovulator?
a. Buffalo b. Camel c. Bitch d. Cow
Correct Answer: b. Camel
Explanation: Unlike cows or buffaloes (spontaneous ovulators), camels, llamas, and cats are induced ovulators. Ovulation is triggered by the physical act of coitus or the presence of ovulation-inducing factors in the seminal plasma.
28. What is the time of ovulation in the mare?
a. 1-2 days after the start of estrus b. 1-2 days after the end of estrus c. 1-2 days before the end of estrus d. 1-2 days after mating
Correct Answer: c. 1-2 days before the end of estrus
Explanation: The mare has a long estrus period (5–7 days). Unlike the cow, which ovulates after heat ends, the mare typically ovulates 24 to 48 hours before the end of behavioral estrus.
29. Which of the followings is necessary for ovulation?
a. High blood progesterone levels b. Pre-ovulatory LH surge c. Low blood estrogen levels d. None of the above
Correct Answer: b. Pre-ovulatory LH surge
Explanation: A massive release of Luteinizing Hormone (the LH surge) is the physiological trigger that causes the final maturation of the follicle and the rupture of the follicular wall to release the oocyte.
30. Which of the followings inhibits ovulation?
a. High blood progesterone levels b. Pre-ovulatory LH surge c. High blood estrogen levels d. High blood glucose levels
Correct Answer: a. High blood progesterone levels
Explanation: Prostaglandin inhibits the GnRH pulse frequency, which prevents the LH surge. This is why animals do not ovulate during pregnancy or the luteal phase (diestrus) when progesterone is high.
31. What is the average duration of estrus period in the buffalo?
a. 21 days b. 42 days c. 17 days d. None of the above
Correct Answer: d. None of the above
Explanation: The options provided refer to cycle lengths. The estrus period (the time the female is receptive to the male) in buffaloes typically lasts 12 to 24 hours. 21 days is the length of the entire estrous cycle.
32. Placentomes are formed by the fusion of:
a. Maternal caruncles and fetal cotyledons b. Maternal cotyledons and fetal caruncles c. Both A and B d. None of the above
Correct Answer: a. Maternal caruncles and fetal cotyledons
Explanation: In ruminants, the placentome is the functional unit of placental attachment. It consists of the maternal caruncle (specialized areas of the uterine endometrium) and the fetal cotyledon (patches of the chorioallantois).
33. The first follicle formed in the fetal ovary is called as:
a. Primordial follicle b. Primary follicle c. Secondary follicle d. Graafian follicle
Correct Answer: a. Primordial follicle
Explanation: The primordial follicle is the most immature stage, consisting of a primary oocyte surrounded by a single layer of flattened follicular (pre-granulosa) cells. These are formed during fetal life.
34. Which enzyme(s) play major role in the passage of sperm through Zona Pellucida during fertilization?
a. Acrosine b. Corona Penetrating enzyme c. Lypase d. Hyaluronidase
Correct Answer: a. Acrosine
Explanation: Acrosin is a proteolytic enzyme released during the acrosome reaction that digests the Zona Pellucida, allowing the sperm to penetrate the oocyte.
35. When does Zona hatching occur in a bovine embryo?
a. 6-7 days after fertilization b. 9-11 days after fertilization c. 14-16 days after fertilization d. 18-20 days after fertilization
Correct Answer: b. 9-11 days after fertilization
Explanation: The bovine blastocyst expands and “hatches” from the Zona Pellucida typically between days 9 and 11. This allows the embryo to begin the process of elongation and eventual attachment.
36. The three germ layers of the embryo develop from:
a. Trophoblast b. Embryoblast c. Both A and B d. None of the above
Correct Answer: b. Embryoblast
Explanation: The embryoblast (Inner Cell Mass) gives rise to the embryo proper and the three germ layers (ectoderm, mesoderm, and endoderm). The trophoblast develops into the fetal portion of the placenta.
37. What is the type of placenta in a cow?
a. Diffuse b. Zonary c. Discoid d. Cotyledonary
Correct Answer: d. Cotyledonary
Explanation: The cow (and other ruminants) has a cotyledonary placenta, characterized by numerous discrete button-like points of attachment (placentomes) rather than a continuous attachment.
38. In which species does the pregnancy occur in the left uterine horn in 99% cases?
a. Sheep b. Goat c. Camel d. Buffalo
Correct Answer: c. Camel
Explanation: In camels, almost all pregnancies are maintained in the left uterine horn, even if ovulation occurred from the right ovary (necessitating internal migration of the embryo).
39. The main mechanism involved in elimination of the bacteria from infected postpartum uterus is:
a) Sloughing of caruncles b) Phagocytosis c) Low estrogenic activity d) High progesterone blood level
Correct Answer: b. Phagocytosis
Explanation: While uterine contractions help physical expulsion, the cellular defense involving the migration of neutrophils and macrophages for phagocytosis is the primary biological mechanism for clearing bacterial infections postpartum.
40. Service period is defined as the period
a) From parturition to next calving b) From one conception to next conception c) From conception to calving d) From parturition to next conception
Correct Answer: d. From parturition to next conception
Explanation: The service period (also known as days open) is the interval between calving (parturition) and the subsequent successful conception.
41. Cyclicity in mare is depending on photo-period and it
a) Start when daylight to darkness ratio decreases b) Start when daylight to darkness ratio increases c) Day light to darkness ratio is equal d) None of the above
Correct Answer: b. Start when daylight to darkness ratio increases
Explanation: Mares are long-day breeders. Their reproductive cyclicity is triggered in the spring as the duration of daylight increases, which inhibits melatonin and stimulates GnRH release.
42. The first stage of parturition in called as
a) Dilation of cervix b) Fixation of cervix c) Twisting of cervix d) Dilation of uterus
Correct Answer: a. Dilation of cervix
Explanation: Stage I of parturition is characterized by uterine contractions and the gradual dilation of the cervix, ending when the fetus enters the birth canal.
43. What is the duration of second stage of parturition in the mare?
a) 15 to 30 minutes b) 1.5 hour c) 2-4 hours d) 24 hours
Correct Answer: a. 15 to 30 minutes
Explanation: Parturition in the mare is extremely rapid and explosive. Stage II (expulsion of the fetus) is typically completed within 15 to 30 minutes. Anything longer than 40 minutes is considered a veterinary emergency.
44. In which phase of the oestrus cycle uterus is prone to infection
a) Pro-estrous b) Estrus c) Met-estrous d) Di-estrous
Correct Answer: d. Di-estrous
Explanation: During diestrus, high progesterone levels suppress the immune defenses of the uterus and keep the cervix closed, creating an environment highly prone to infection (e.g., pyometra).
45. In the cow during natural mating, the semen is ejaculated in the
a) Uterus b) Cervix c) Oviduct d) Vagina
Correct Answer: d. Vagina
Explanation: In cattle, the bull deposits the semen in the fornix vagina (cranial vagina). In contrast, species like the pig or horse ejaculate into or through the cervix.
46. What is the optimum time of insemination in a buffalo?
a) 8-10 hours before the start of estrus b) 8-10 hours after the end of estrus c) 8-10 hours after the start of estrus d) None of the above
Correct Answer: d. None of the above
Explanation: Standard AI protocols for buffaloes usually follow the “AM/PM rule” or inseminating mid-to-late estrus (roughly 12-18 hours after the start of heat) to ensure viable sperm are present when ovulation occurs 10-15 hours after heat ends.
47. The 2nd stage of parturition is called as
a) Expulsion of fetus b) Expulsion of placenta c) Expulsion of embryo d) Expulsion of calf
Correct Answer: a. Expulsion of fetus
Explanation: Stage II of parturition is defined as the period from the complete dilation of the cervix and rupture of the water bag to the complete expulsion of the fetus.
48. The involution of uterus in cattle can be delayed due to:
a) Delivery of single calf b) Retention of fetal membranes c) Uterine prolapse d) Both B and C
Correct Answer: d. Both B and C
Explanation: Conditions that cause inflammation or trauma, such as retained placenta (RFM) or uterine prolapse, significantly interfere with the normal contraction and tissue repair required for uterine involution.
49. Joining point of the fallopian tube with uterine horn is called as:
a) Ampullary-isthmic junction b) Utero-tubal junction c) Utero-ovarian junction d) Utero-vaginal junction
Correct Answer: b. Utero-tubal junction
Explanation: The utero-tubal junction (UTJ) is the anatomical point where the isthmus of the fallopian tube (oviduct) meets the tip of the uterine horn.
50. What is the average length of gestation in a buffalo?
a) 310 weeks b) 280 days c) 340 days d) 310 days
Correct Answer: d. 310 days
Explanation: The average gestation period for a buffalo is approximately 305 to 315 days (roughly 10 months), which is longer than the cow’s average of 280 days.