Breeding and Reproduction Flashcards

What is the gestation period for laboratory rats?

Answer: 21-23 days

Rat gestation is approximately 21-23 days. Like mice, rats exhibit post-partum estrus and can become pregnant immediately after delivering.

What is the purpose of maintaining pedigree records in a breeding colony?

Answer: To track genetic lineage, prevent unintended inbreeding, and maintain strain integrity

Pedigree records enable colony managers to prevent inbreeding depression, maintain genetic consistency, and track genotypes in transgenic colonies.

What is the difference between inbred and outbred laboratory mouse strains?

Answer: Inbred strains are genetically nearly identical from 20+ generations of sibling mating; outbred stocks maintain genetic diversity

Inbred strains (C57BL/6, BALB/c) result from 20+ generations of brother-sister mating producing near-complete homozygosity. Outbred stocks (CD-1) maintain genetic heterogeneity.

What is timed mating and why is it used?

Answer: Pairing animals for a defined period to know exact gestational age for developmental studies

Timed mating involves introducing males and females at specific times and checking for mating evidence to establish a precise gestational timeline.

What special considerations apply to genetically modified mouse colony management?

Answer: Genotype tracking, appropriate mating schemes, surplus management, and phenotype monitoring for welfare

GM colonies require genotyping protocols, appropriate mating strategies, surplus animal management, and monitoring for unexpected phenotypes affecting welfare.

What is fostering in laboratory animal breeding?

Answer: Transferring pups from their biological dam to a lactating foster dam for nursing

Fostering places pups with a lactating foster dam when the biological mother cannot care for them due to death, illness, or poor maternal behavior.