Rats are known for their fertility. Therefore, uncontrolled mating must be avoided at all costs.
Breeding pet rats is not recommended. Animal protection organizations are confronted with a flood of unwanted rats, for which it is difficult to find an animal-friendly home, simply through unplanned reproduction. Rats are extremely prolific. They become sexually mature at the age of 50 to 70 days and should therefore be separated according to gender from the fifth week.
About five to 20 young animals are born per litter, and the females can be successfully mated again immediately after birth. The gestation period is usually 20 to 23 days. During pregnancy, the rat females have an increased protein requirement, z. B. can be covered with mild cheese, natural yogurt, low-fat quark, and mealworms. In the whelping cage, the animals need a retreat and nesting material (e.g. pieces of soft toilet paper and kitchen paper).
Birth & rearing
Birth lasts from a few minutes to several hours. The number of offspring is usually six to twelve animals. After birth, the mother licks her young clean and nurses them. Rats are usually good and reliable mothers. However, as a result of social stress or disturbance, the female may kill her offspring. For this reason, it is important that the rats are left alone during pregnancy and rearing and can remain in their pack.
If all goes well, the mother carefully takes care of her young. She rarely leaves her nest and lies over her babies to keep her warm. The mother rat frequently cleans the young with her tongue (to encourage defecating and urinating) and also keeps the nest clean. Newborn rats are naked (with red-pink skin color) blind and weigh about 5 g. From the second day, the fur begins to grow. The ears open after three to four days and the eyes after 13 to 16 days.
Development of young animals
When the rats are about three weeks old, they are weaned from their mother. However, as early as the second week, the young animals can be offered solid food. Millet, grain feed, oat flakes, and fruit pulp are well suited. It makes sense to offer the mother and the young animals as many types of fruit and vegetables as possible so that the offspring get used to different types of food. Since young rats are very active and playful, they need a particularly large cage. While growing up, they already learn their distinctive social behavior.
When learning their natural social behavior, physical contact and playful arguments play an important role. It is important that the animals grow up in a harmonious social group and under housing conditions that are suitable for rats (e.g. a large enclosure with many opportunities to work and retreat). Negative experiences and stress can lead to behavioral disorders towards conspecifics and humans.