How to obtain offspring from a rat? - briefly
Place a sexually mature female rat with a proven male in a clean cage equipped with nesting material and allow them to cohabit for several days; the female will typically become pregnant during this period. After a gestation of about 21 days, she will give birth to a litter of pups.
How to obtain offspring from a rat? - in detail
To produce a litter from a laboratory rat, follow a sequence that ensures reproductive success, healthy gestation, and viable newborns.
Select a breeding pair that meets health criteria: both animals must be free of infectious agents, display normal body condition, and possess no genetic defects. Ideal breeding age ranges from 8 to 12 weeks for females and 10 to 14 weeks for males; older or very young individuals exhibit reduced fertility.
Confirm the female’s estrous cycle. Rats cycle every 4–5 days; the proestrus and estrus phases are marked by a swollen vulva and increased receptivity. Introduce the male to the cage during these days, allowing a 24‑hour cohabitation period. Observe mating behavior; a copulatory plug or a brief “mount” indicates successful insemination.
After mating, remove the male to prevent aggression and stress. Monitor the female for signs of pregnancy: increased abdominal girth, nesting behavior, and weight gain of approximately 10 % by day 14. Gestation lasts 21–23 days; provide a nesting material (e.g., shredded paper) and maintain a stable environment with temperature around 22 °C, humidity 40‑60 %, and a 12‑hour light/dark cycle.
At parturition, ensure the dam has access to clean bedding and a protein‑rich diet (approximately 20 % protein). Newborns are altricial; they remain with the mother for 21 days, during which they nurse every 2–3 hours. Inspect the litter for uniform size and coloration; any pups that fail to thrive should be removed promptly to protect the remaining offspring.
Wean the pups at post‑natal day 21, separating males and females to avoid premature breeding. Record birth date, litter size, and any anomalies for future breeding decisions. Maintaining detailed records and adhering to the outlined protocol maximizes litter production and animal welfare.