ALAT Animal Husbandry and Environment 2 — Questions and Answers
Question 1: What is the recommended temperature range for housing laboratory mice according to the Guide?
- 55-65 F (12.8-18.3 C)
- 64-79 F (17.8-26.1 C) (Correct answer)
- 80-90 F (26.7-32.2 C)
- 50-60 F (10.0-15.6 C)
Correct answer: 64-79 F (17.8-26.1 C)
The Guide recommends 64-79 F (17.8-26.1 C) for most common laboratory rodents. This range is a compromise between human comfort and animal thermoneutral zones.
The Guide recommends dry-bulb temperatures of 64-79 F for mice and rats. The thermoneutral zone for mice is actually 86-90 F, meaning mice at standard housing temperatures experience chronic mild cold stress. Facilities typically maintain 68-72 F as a practical compromise.
Question 2: How often should water bottles in rodent cages typically be changed?
- Daily
- At least twice per week (Correct answer)
- Once per month
- Only when empty
Correct answer: At least twice per week
Water bottles should be changed at least twice per week to prevent bacterial contamination and biofilm formation.
Biofilm and bacterial contamination (particularly Pseudomonas aeruginosa) can develop in water bottles and sipper tubes. When using bottles, technicians should also check that sipper tubes are functional during daily checks.
Question 3: What is the primary purpose of providing nesting material to laboratory mice?
- To increase cage cleaning frequency
- To allow thermoregulation and species-typical behavior (Correct answer)
- To reduce the need for food supplementation
- To prevent escape from the cage
Correct answer: To allow thermoregulation and species-typical behavior
Nesting material allows mice to build nests for thermoregulation and provides an outlet for species-typical nesting behavior.
Since standard housing temperatures are well below the mouse thermoneutral zone (86-90 F), nesting material allows mice to construct nests creating a warmer microenvironment. Nest building is also a highly motivated species-typical behavior that serves as a welfare indicator.
Question 4: What ventilation system provides HEPA-filtered air to individual cages and maintains cage-level containment?
- Static microisolator cages
- Individually ventilated caging (IVC) (Correct answer)
- Open-top shoebox cages
- Metabolic caging systems
Correct answer: Individually ventilated caging (IVC)
IVC systems supply HEPA-filtered air directly to each cage through a manifold and blower unit, maintaining cage-level environmental control.
IVC systems provide 60-80 air changes per hour of HEPA-filtered air to each cage. Benefits include reduced allergen exposure for staff, lower ammonia levels, reduced cage-to-cage pathogen transmission, and extended cage change intervals.
Question 5: What is the minimum recommended cage change frequency for rats housed on contact bedding?
- Daily
- At least once per week (Correct answer)
- Every two weeks
- Monthly
Correct answer: At least once per week
Rat cages with contact bedding should be changed at least once per week to maintain acceptable ammonia levels.
Cage change frequency must balance maintaining acceptable ammonia levels (below 25 ppm per the Guide) with minimizing disruption stress. For rats on contact bedding, weekly changes are the standard minimum.
Question 6: Why is it important to maintain a consistent 12:12 light-dark cycle in rodent housing rooms?
- It reduces electricity costs
- It synchronizes circadian rhythms critical for physiology and reproduction (Correct answer)
- It prevents coat color changes
- It eliminates the need for environmental enrichment
Correct answer: It synchronizes circadian rhythms critical for physiology and reproduction
A consistent photoperiod synchronizes circadian rhythms that regulate hormonal cycles, reproduction, activity patterns, and immune function.
Photoperiod is one of the most critical environmental variables. The 12:12 cycle entrains circadian rhythms controlling melatonin secretion, reproductive hormone cycling, corticosterone patterns, immune responses, and feeding behavior. Disruptions can cause altered drug metabolism and immune suppression.
ALAT Animal Husbandry and Environment 2
What is the recommended temperature range for housing laboratory mice according to the Guide?