Breeding and Reproduction of Rabbits
Rabbit breeds of medium to large size are sexually mature at 4 to 4.5 months, giant breeds at 6 to 9 months, and small breeds (such as the Polish Dwarf and Dutch) at 3.5 to 4 months of age. The release of eggs in female rabbits is triggered by sexual intercourse, not by a cycle of hormones as in humans. Contrary to popular belief, the rabbit has a cycle of mating receptivity; rabbits are receptive to mating about 14 of every 16 days. A doe is most receptive when the vagina is red and moist. Does that are not receptive have a whitish pink vaginal color with little or no moisture. Feeling the doe’s abdomen for grape-sized embryos in the uterus is one technique for detecting pregnancy. The best time to do this is 12 days after breeding. False pregnancy, during which the rabbit shows signs of pregnancy but is not actually pregnant, is common in rabbits.
Pregnancy usually lasts about 31 to 33 days. Does with a small litter (usually 4 or less) seem to have longer pregnancies than those that produce larger litters. If a doe has not given birth by day 32 of her pregnancy, your veterinarian will likely induce labor; otherwise, a dead litter is almost always delivered sometime after day 34. Occasionally, pregnant does abort or resorb the fetuses due to nutritional deficiencies or disease.
Nest boxes should be added to the cage 28 to 29 days after breeding. If boxes are added too soon, they become fouled with urine and feces. A day or so before giving birth, the doe pulls fur from her body and builds a nest in the nest box.
Rabbit kits are born naked, blind, and deaf. They begin to show hair a few days after birth, and their eyes and ears are open by day 10. Newborn rabbits are unable to regulate their own body temperature until about day 7. Rebreeding can occur any time after giving birth. Most people raising rabbits for show or as pets rebreed 35 to 42 days after the birth of a litter.
Most medium- to large-sized female rabbits have 8 to 10 nipples, and many give birth to 12 or more young. If a doe is unable to nurse all the kits effectively, kits may be fostered by removing them from the nest box during the first 3 days and giving them to a doe of about the same age with a smaller litter. If the fostered kits are mixed with the doe’s own kits and covered with hair of the doe, they are generally accepted. Moving the larger kits to the new litter instead of the smaller kits increases the chance of success. Does nurse only 1 to 2 times daily, and kits nurse for less than 3 minutes at a time. Kits are weaned around 4 to 5 weeks of age.
Kits can be reared by hand, but the death rate is high. They should be kept warm, dry, and quiet. Kitten milk replacer or a formula of ½ cup evaporated milk, ½ cup water, 1 egg yolk, and 1 tablespoon corn syrup can be used. Feedings vary from ½ teaspoon to 2 tablespoons, depending on the age of the kits. Kits start eating greens around day 15 to 18.
Young does may kill and eat their young for a number of reasons, including nervousness, neglect (failure to nurse), and severe cold. Dogs or predators entering a rabbitry often cause nervous does to kill and eat the young. Cannibalism of the dead young occurs as a natural, nest-cleaning instinct. If all management practices are proper and the doe kills 2 litters in a row, she should not be used for breeding.