Biological Data

Oestrus cycle4-5 days4-5 days
Gestation period19-21 days21-22 days
Litter Size6-106-14
Weaning Age18-21 days20-21 days
Birth Weight*1.5-2.0 g6-8 g
Weaning Weight*10-12 g40-60 g
Weight at Puberty*18-22 g150-200 g
Adult Weight*30-35 g350 g
Puberty42 days70-80 days
Diet-daily consumption5g15g
Water-daily consumption6ml35ml
This information has been obtained from standard textbooks and not from animals at the Animal Resources Centre. Weights (*) refer to outbred animals. Inbred animals generally have lower body weights than outbreds. Adult males may be considerably heavier than females.

Average organ weights of Wistar rats at 29 months

 MaleFemale%Bwt male%Bwt female
Whole Body (g)519341
Brain (g)2.0901.9700.40.4
Hypophysis (mg)19290.0040.009
Thyroid (mg)38270.0070.008
Thymus (g)0.1990.1410.1410.04
Heart (g)1.5631.1250.30.3
Liver (g)15.4959.9053.03.0
Spleen (g)1.6280.9070.30.3
Kidneys (g)4.4912.3370.70.7
Adrenals (mg)84800.020.02
Adrenals (g)3.6220.1270.70.04
Prostate (g)0.5570.1
Seminal Vesicles(g)1.3340.3
(Source: IFFA CREDO Laboratory Animals).