Rabbit Reproduction - Anatomy & Physiology

Male

• Male rabbit is known as the buck.

Penis

• Rounded penile sheath.
• Rounded penile urethra.
• Easily extruded in rabbits over 2 months of age.

Testes

• Two testes
• Descend at ~12 weeks of age
• Large with epididymal fat pads.
• In the adult male they lie in two almost hairless scrotal sacs.
• Scrotal sacs are cranial to the penis (In the majority of placental mammals they lie caudal to the penis).
• Inguinal canal remains open.

Accessory Sex Glands

Seminal vesicles

• Open into the prostatic section of the urethra.

Bulbourethral Glands

• Small and paired
• Form a bilobed swelling in the dorsal wall of the urethra, just behind the prostate.

Mammary Gland

• No nipples

Female

• Female rabbit is known as the Doe.

Reproductive Tract

Uterus

• Bicornuate duplex uterus.
  • Two seperate uterine horns.
  • No uterine body
  • Each horn has its own cervix.
  • Two cervices open into a single vagina.

Attachments and Blood Supply

• Mesometrium is a major fat storage organ.
• Only minor anastomoses exist between the uterine and ovarian vasculature.

Puberty and Sexual Maturity

• Age of sexual maturity varies with breed.
  • Small breeds mature at ~5 months
  • Larger breeds mature as late at as 8 months.

Breeding Characteristics

• Induced ovulator with no well-defined oestrous cycle.
• Periods of sexual receptivity every 4-6 days.
• Oestrus period lasts ~14 days.
• Ovulation occurs within 10 hours of coitus.
• Breeding season January-October in the UK.

Gestation and Offspring

Gestation

• Gestation period is 28-32 days.
• Pseudopregnancy may occur.
  • Lasts 18 days.
  • May be due to infertile mating, or the presence of a male nearby.
  • Dam is unable to conceive during this time.
  • Corpus Luteum secretes progesterone, which causes the uterus and mammary glands to grow.

Litter

• Litter size 4-12.
• Young are altricial
  • Born hairless, deaf and blind.
  • Totally dependent on their mother for the first few weeks of life.
  • Protected from the environment and predators by the nest which is made by the Doe using hair from the dewlap.
  • If the nest is disturbed, the Doe may cannibalise the offspring.

Mammary Gland and Lactation

• Doe has 4/5 pairs of nipples.
• Mammary gland develops in the last week of pregnancy.
• Suckling is stimulated by a pheromone produced by a gland near the nipple.
• Consumption of water and caecotrophs increases 10-fold during lactation.
• Rabbit milk is richer than cow's milk:
  • Unusually low lactose content
  • Very high protein and fat content
  • Composition: 13% Protein, 9% Fat, 1% Lactose, 2.3% minerals