Assistant Laboratory Animal Technician (ALAT) Practice Exam

Outbred stocks of mice are known to have what size of litters?

1. Smaller litters

2. Larger litters

3. Smaller and larger mixed

4. Consistent medium-sized litters

The correct answer is: Larger litters

Outbred stocks of mice are known to have larger litters compared to inbred strains. The reason for this is that outbred stocks maintain greater genetic diversity, which can lead to enhanced reproductive performance. In nature, genetic variability often contributes to more robust populations, allowing outbred mice to exhibit traits like increased fecundity, or reproductive capability. Larger litter sizes are beneficial for survival in the wild, as they ensure that some offspring can survive despite environmental pressures. This characteristic of larger litters in outbred stocks is particularly advantageous in laboratory settings where research relies on sufficient sample sizes and variability. The other options are less accurate in describing the litter size of outbred stocks. Inbred strains generally tend to have consistent but potentially smaller litter sizes due to their genetic uniformity and higher probability of genetic defects that can affect reproduction. Thus, the association of outbred mice with larger litters stands as the most accurate representation of their reproductive biology.