ALAT Breeding and Reproduction 5 — Questions and Answers
Question 1: Which condition describes a female mouse that shows signs of pregnancy (including a vaginal plug) but is not actually pregnant?
- Superfetation
- Pseudopregnancy (Correct answer)
- Anestrus
- Polyestrus
Correct answer: Pseudopregnancy
Pseudopregnancy occurs when ovulation happens without fertilization, causing hormonal changes that mimic pregnancy.
Question 2: What is the primary purpose of using a 'vasectomized male' in a rodent breeding program?
- To improve litter size
- To induce pseudopregnancy in females for embryo transfer (Correct answer)
- To select for dominant genetics
- To test female fertility
Correct answer: To induce pseudopregnancy in females for embryo transfer
Vasectomized males mate with females to induce pseudopregnancy, preparing the uterus for embryo transfer without producing offspring.
Question 3: At what age are female rats generally first bred in a laboratory setting?
- 4-6 weeks
- 8-10 weeks (Correct answer)
- 16-20 weeks
- 6 months
Correct answer: 8-10 weeks
Female rats are typically first bred at 8-10 weeks of age when they have reached sufficient body maturity.
Question 4: Which hormone surge triggers ovulation in cats, making them induced ovulators?
- Estrogen
- Luteinizing hormone (LH) (Correct answer)
- Follicle-stimulating hormone (FSH)
- Progesterone
Correct answer: Luteinizing hormone (LH)
In induced ovulators like cats, the mechanical stimulation of mating triggers an LH surge that causes ovulation.
Question 5: In laboratory animal breeding records, 'D.O.B.' refers to:
- Date of Breeding
- Date of Birth (Correct answer)
- Days of Gestation
- Designation of Breeder
Correct answer: Date of Birth
D.O.B. stands for Date of Birth and is a critical data point for tracking animal age, breeding eligibility, and study enrollment.
Question 6: What is 'cross-fostering' in laboratory animal breeding?
- Mating animals from two different genetic strains
- Transferring pups from one dam to another to equalize litter sizes or improve survival (Correct answer)
- Breeding animals across different facilities
- Using a surrogate male for mating
Correct answer: Transferring pups from one dam to another to equalize litter sizes or improve survival
Cross-fostering involves moving neonates from their biological dam to a surrogate dam to improve survival odds or balance litter sizes.
Question 7: Which of the following is a sign that a female hamster is in estrus and receptive to mating?
- Aggressive chasing of the male
- Lordosis posture (arched back, immobile stance) (Correct answer)
- Increased food consumption
- Nesting behavior without male presence
Correct answer: Lordosis posture (arched back, immobile stance)
Lordosis — a rigid, arched-back posture — is the characteristic receptivity signal in female hamsters during estrus.
ALAT Breeding and Reproduction 5
Which condition describes a female mouse that shows signs of pregnancy (including a vaginal plug) but is not actually pregnant?