the stomach; the bacteria within continue to digest the plant carbohydrates. This double-digestion process enables rabbits to use nutrients that they may have missed during the first passage through the gut, as well as the nutrients formed by the microbial activity and thus ensures that maximum nutrition is derived from the food they eat. This process serves the same purpose in the rabbit as rumination does in cattle and sheep. Because rabbits cannot vomit, if buildup occurs within the intestines (due often to a diet with insufficient fibre), intestinal blockage can occur. Reproduction The adult male reproductive system forms the same as most mammals with the seminiferous tubular compartment containing the Sertoli cells and an adluminal compartment that contains the Leydig cells. The Leydig cells produce testosterone, which maintains libido and creates secondary sex characteristics such as the genital tubercle and penis. The Sertoli cells triggers the production of Anti-Müllerian duct hormone, which absorbs the Müllerian duct. In an adult male rabbit, the sheath of the penis is cylinder-like and can be extruded as early as two months of age. The scrotal sacs lay lateral to the penis and contain epididymal fat pads which protect the testes. Between 10 and 14 weeks, the testes descend and are able to retract into the pelvic cavity in order to thermoregulate. Furthermore, the secondary sex characteristics, such as the testes, are complex and secrete many compounds. These compounds include fructose, citric acid, minerals, and a uniquely high amount of catalase. The adult female reproductive tract is bipartite, which prevents an embryo from translocating between uteri. The two uterine horns communicate to two cervixes and forms one vaginal canal. Along with being bipartite, the female rabbit does not go through an estrus cycle, which causes mating induced ovulation. The average female rabbit becomes sexually mature at three to eight months of age and can conceive at any time of the year for the duration of her life. Egg and sperm production can begin to decline after three years. During mating, the male rabbit will mount the female rabbit from behind and insert his penis into the female and make rapid pelvic hip thrusts. The encounter lasts only 20–40 seconds and after, the male will throw himself backwards off the female. The rabbit gestation period is short and ranges from 28 to 36 days with an average period of 31 days. A longer gestation period