Rat Mouse — breeding (owner-practical care, Merck Veterinary Manual pet-owner)
Source: first-hand Merck Veterinary Manual pet-owner text, saved to source_file; every claim below is a C1 byte-substring of it.
Claims
Avoid allowing a buildup of ammonia (due to urine), which is produced when cage litter is not changed frequently enough.However, they are also very prolific breeders, so keeping only rats of the same sex in the same cage is recommended.Aggression is uncommon in domesticated rats that are raised together as littermates.Temperatures above 86°F (30°C) can cause heat exhaustion, especially if the cage is overcrowded.Boschert , DVM, DACLAM , Washington University Last updated: Sept 2024 v3230085 Male rats reach sexual maturity at about 6 to 10 weeks of age; females reach maturity at 8 to 12 weeks.The average gestation time is 21 to 23 days, and pregnancy is sometimes detectable at about 2 weeks by feeling the abdomen or noticing weight gain or mammary (breast) development.The cage should be kept in a quiet place and the litter should not be disturbed for at least 7 days after birth, especially if this is the female’s first litter.Female rats can quickly become pregnant again after giving birth; however, it is not healthy for a female rat to be both pregnant and nursing a litter.It is recommended that the female be given a rest period of at least 2 months between pregnancies and litter rearing to restore her body to full strength.In healthy rats, however, reproductive problems are uncommon.However, they are also very prolific breeders, so males and females should be kept in different cages.Aggression is uncommon in mice that were raised together as littermates.
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Source: pdf-raw/owner-care/merck_rat_mouse.txt · https://www.merckvetmanual.com/all-other-pets