How do rats reproduce? - briefly
Rats reproduce sexually, with females entering an estrous cycle roughly every four days, mating shortly after ovulation; gestation lasts about 21–23 days, after which the female gives birth to a litter of 5–12 pups.
How do rats reproduce? - in detail
Rats reach sexual maturity at 5–6 weeks for females and 6–8 weeks for males, depending on strain and environmental conditions. Female rats experience a 4‑day estrous cycle composed of proestrus, estrus, metestrus, and diestrus; ovulation occurs during estrus, triggered by the luteinizing hormone surge induced by copulatory stimuli.
Mating is initiated when a male detects pheromonal cues from a receptive female. Courtship involves sniffing, grooming, and mounting. Successful intromission lasts 15–30 seconds, after which a copulatory plug may form, preventing immediate re‑mating. Sperm transport to the oviducts is completed within minutes, and fertilization typically occurs in the ampulla.
Gestation lasts 21–23 days. During this period the embryo implants in the uterine wall, and placental development provides nutrients and gas exchange. Litter size averages 6–12 pups but can range from 2 to 20, influenced by the mother’s age, health, and nutrition. Birth is usually nocturnal; pups are born altricial, blind and hairless, weighing 1–2 g.
Post‑natal development proceeds rapidly:
- Day 0‑4: Pups remain clustered, dependent on maternal warmth and milk.
- Day 4‑7: Incisor eruption begins; ears open.
- Day 10‑14: Eyes open; locomotor activity increases.
- Day 21: Weaning; solid food introduced; females may enter estrus as early as 35 days.
Males reach full reproductive capacity around 8–10 weeks, producing viable sperm and exhibiting typical territorial and mounting behaviors. Adult rats can breed year‑round under laboratory conditions, with females capable of multiple litters per year due to the short gestation and rapid weaning cycle.