Theriogenology MCQS Set 6
126. The most important single technique devised for the rapid genetic improvement of animals is
a. Rectal palpation
b. Artificial insemination
c. Sperm sexing
d. In vitro maturation
Correct Answer: b. Artificial insemination
Explanation: While sperm sexing and IVM are advanced, Artificial Insemination (AI) remains the most impactful technique globally. It allows a single genetically superior sire to fertilize thousands of females, rapidly spreading desirable traits across a population.
127. The gametes are haploid cells containing
a. Either X or Y chromosome
b. XY chromosomes
c. XO chromosomes
d. YZ Chromosomes
Correct Answer: a. Either X or Y chromosome
Explanation: Gametes (sperm and oocytes) are formed via meiosis, reducing the chromosome number by half. A sperm cell will carry either an X or a Y chromosome, which determines the sex of the offspring upon fusion with the X-carrying oocyte.
128. Synchronization of estrus in a group of cattle can be achieved with prostaglandin F-2a if two injections are given
a. 5 days apart
b. 14 days apart
c. 11 days apart
d. 21 days apart
Correct Answer: c. 11 days apart
Explanation: In a random group of cycling cows, some will not have a responsive Corpus Luteum (CL) during the first injection. Giving a second injection 11 days later ensures that all cows have a mature, susceptible CL, resulting in synchronized heat.
129. The first birth of a cloned offspring took place in a
a. Sheep
b. Goat
c. Woman
d. Cattle
Correct Answer: a. Sheep
Explanation: The first mammal to be successfully cloned from an adult somatic cell was Dolly the sheep, born in 1996 in Scotland.
130. The current method of embryo transfer in buffalo is
a. Transcervical
b. Transabdominal
c. Through laparotomy
d. Through laparoscopy
Correct Answer: a. Transcervical
Explanation: Like cattle, the modern and most common method for embryo transfer in buffalo is transcervical. This non-surgical method involve passing a specialized catheter through the cervix to deposit the embryo into the uterine horn.
131. At 35 days of gestation in cattle, palpation of the following will confirm pregnancy
a. Asymmetry of uterine horns
b. Fluid fluctuation in the uterus
c CL on the ovary
d. Presence of amniotic vesicle
Correct Answer: d. Presence of amniotic vesicle
Explanation: At day 35, the amniotic vesicle is palpable as a small, turgid, slippery object (the size of a small bean). This is considered a “positive” or confirmatory sign of pregnancy, whereas horn asymmetry and fluid are only suggestive.
132. The chromosome number in the sperm of horse is
a 30
b 27
c 33
d 32
Correct Answer: d. 32
Explanation: The diploid number ($2N$) for a horse is 64. Since sperm are haploid ($N$), they contain exactly half that number, which is 32.
133. Standard practice to add antibiotics, penicillin and streptomycin in semen extender is at the rate
a Penicillin-1000 I.U and streptomycin-1 mg per ml of extender
b Penicillin 1500 I.U and streptomycin-2 mg per ml of extender
c Penicillin 1500 I.U and streptomycin- 1 mg per ml of extender
d Penicillin 2000 I.U and streptomycin-1 mg per ml of extender
Correct Answer: a. Penicillin-1000 I.U and streptomycin-1 mg per ml of extender
Explanation: This specific concentration is the classic standard for controlling bacterial growth in diluted semen without being toxic to the spermatozoa.
134. The temperature of liquid Nitrogen is
a -165c
b -180c
c -196c
d -79
Correct Answer: c. -196c
Explanation: Liquid nitrogen ($LN_2$), used for the long-term cryopreservation of semen and embryos, has a boiling point of -196°C.
135. The best temperature for thawing of semen is
a 4c for one minute
b 20c for five minutes
c 37c for one minute
d 70c for two minutes
Correct Answer: c. 37c for one minute
Explanation: For bovine semen frozen in 0.5 ml straws, the standard recommendation is thawing in a water bath at 37°C (body temperature) for approximately 30 to 60 seconds to ensure maximum survival and motility.
136. Teasing of bull before mounting results in
a) Increase sperm concentration
b) Decrease sperm concentration
c) Increase seminal fluid
d) Decrease prostate secretion
Correct Answer: a) Increase sperm concentration
Explanation: Teasing (false mounting and restraint) triggers the movement of sperm from the epididymal tail into the ductus deferens, significantly increasing the sperm concentration and total sperm count of the eventual ejaculate.
137. Best quality of bull semen may be collected by using
a) Artificial vagina
b) Electro-ejaculator
c) Seminal/Ampullary massage**
Correct Answer: a) Artificial vagina
Explanation: The Artificial Vagina (AV) provides the most physiological stimulus (temperature and pressure), resulting in a complete ejaculate with the highest sperm concentration and best motility compared to other methods.
138. Electro-ejaculation is a method of choice in
a) Young healthy bulls
b) Trainee bulls
c) Old or injured breeding bulls
d) None of the above
Correct Answer: c) Old or injured breeding bulls
Explanation: Electro-ejaculation does not require the bull to mount a teaser, making it the ideal method for injured, old, or arthritic bulls that are physically unable to perform natural service or use an AV.
139. At which developmental stage the bovine embryos are collected for transfer to recipient
a) Morula
b) Hatched blastocyst
c) Gastrula
d) Hatched embryo
Correct Answer: a) Morula
Explanation: Bovine embryos are typically recovered on Day 7 post-estrus, at which point they are usually at the compact morula or early blastocyst stage. They must be collected before they hatch from the Zona Pellucida.
140. Which is the most commonly used ultrasound display format in veterinary practice?
a) Motion mode
b) Amplitude mode
c) Brightness mode
d) None of the above
Correct Answer: c) Brightness mode
Explanation: Brightness mode (B-mode) is the standard 2D grayscale imaging used for most diagnostic procedures, including pregnancy diagnosis and organ evaluation. It represents the intensity of echoes as varying levels of brightness.
141. In B-mode ultrasound, the image of a Graafian follicle will be?
a) Bright
b) Black
c) Grey
d) None of the above
Correct Answer: b) Black
Explanation: Follicular fluid is anechoic (it does not reflect ultrasound waves). On a B-mode display, anechoic structures appear black.
142. Ultrasonically, bovine fetal sexing is done at:
a) 20-30 days of gestation
b) 30-40 days of gestation
c) 55-60 days of gestation
d) 90-100 days of gestation
Correct Answer: c) 55-60 days of gestation
Explanation: Fetal sexing is based on the location of the genital tubercle. The optimum window is between days 55 and 60, when the tubercle has migrated and is clearly visible, but the fetus is still small enough to be easily manipulated.
143. In a male fetus, the genital tubercles are located between:
a) Hind limbs and tail
b) Hind limbs and the umbilicus
c) Forelimbs and the umbilicus
d) Forelimbs and the head
Correct Answer: b) Hind limbs and the umbilicus
Explanation: In the male bovine fetus, the genital tubercle (the precursor to the penis) migrates toward the umbilicus. In the female, it migrates toward the tail (vulvar position).
144. In bovines, pregnancy can be detected ultrasonically as early as:
a) 12-15 days after fertilization
b) 20-25 days after fertilization
c) 30-35 days after fertilization
d) 50-60 days after fertilization
Correct Answer: b) 20-25 days after fertilization
Explanation: Experienced ultrasonographers can detect the embryonic vesicle as early as day 20 to 25. By day 25-28, the heartbeat of the embryo can usually be visualized.
145. Milk or (plasma) progesterone assay is a method of diagnosing pregnancy in cow after A.I/mating
a) At 9 days
b) 11 days
c) 24 days
d) 21 days (Note: Correcting option D)
Correct Answer: d) 21 days
Explanation: If a cow is pregnant, progesterone remains high. If she is not, it drops around day 21. Therefore, a high progesterone reading at day 21 to 24 post-mating is a strong indicator of pregnancy.
146. A teaser male is used for:
a) Estrus detection
b) Pregnancy testing
c) Natural mating
d) None of the above
Correct Answer: a) Estrus detection
Explanation: A teaser male (such as a vasectomized bull) is used to identify females in heat through behavioral interaction without the risk of an unplanned pregnancy.
147. Which of the following is the confirmatory sign of heat in a cow?
a) Urination
b) Bellowing
c) Stands to be mounted
d) Off feed
Correct Answer: c) Stands to be mounted
Explanation: While bellowing and restlessness are suggestive, standing to be mounted (standing heat) is the only confirmatory behavioral sign that the cow is in true estrus and ready for insemination.
148. Which is the main luteotropic hormone in mammals?
a) Prolactin
b) Follicle stimulating hormone
c) Luteinizing hormone
d) Gonadotropin releasing hormone
Correct Answer: c) Luteinizing hormone
Explanation: Luteinizing Hormone (LH) is the primary luteotropin; it is essential for the formation, maintenance, and progesterone secretion of the Corpus Luteum.
149. On a B-mode ultrasound, image of a bone will be_________.
a) Yellow
b) Bright
c) Blue
d) None of the above
Correct Answer: b) Bright
Explanation: Bone is hyperechoic because it reflects nearly all ultrasound waves. On the display, it appears very bright (white), often with a dark acoustic shadow behind it.
150. Which of the following is applied for recording of movements of a female in heat?
a) Urimeter
b) Pedometer
c) Pelvi-meter
d) Glucometer
Correct Answer: b. Pedometer
Explanation: Cows in heat significantly increase their physical activity and walking distance. Pedometers attached to the leg record this activity, providing an automated way to detect estrus in large dairy herds.