Department of Education

Animal Ethics

Animal Ethics


Varietal range difference

Rat strains are almost entirely derived from the Norway rat. Mutations and hybridisations have led to rats with a variety of coat colours and patterns. Rat types can be broadly classified into two main groups: albino and hooded.

Physical characteristics

Size length from snout to base of tail: 17cm - 21cm; length of tail: 20cm - 23cm; overall length: 37cm - 44cm
Weight adult male: approximately 300g - 800g; adult female approximately 225g - 400g
Age at adult size 250-300 days
Average life span 2-4 years
Weight at birth 5g - 6g
Gestation period 21-22 days
Number of offspring 6-14 per litter
Weaning age approximately 3 weeks (30g - 55g)
Range of breeding ages can reach sexual maturity at 8 weeks; females should not be bred before 65 days; females are continuously polyoestrus (come into season regularly - every 4-5 days - throughout year unless bred); rats can come back into heat 48 hours after giving birth; recommended that rats are not bred after 15 months of age
Body temperature 38°C
Heart rate 320-480 beats/minute
Respiration rate 70-110 breaths/minute


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