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I NTRODU CTION The domestic rabbit (Oryctolagus cuniculus) descended from the European wild rabbit originating in countries around the Mediterranean Sea and was introduced into England in the late eleventh or early twelfth century. The various breeds of modern domestic rabbits have been developed since the eighteenth century. There are now several hundred varieties throughout the world, varying in size, color, type of hair coat, and other characteristics. Thirty-eight breeds representing a wide range in size and other characteristics are now recognized by the American Rabbit Breeders Association. Rabbits are produced for meat, research, and wool and as pets or for a hobby. Meat production is the most important commercial aspect and will be emphasized in this report. The New Zealand White and Californian breeds are marketed most extensively for meat. These are medium weight breeds (3.6-5.4 kg), providing a size of carcass to which the retail purchaser has become accustomed. Skins or pelts find some use in industry. Blood and other organs and tissues used as specimens for biological and medical research are also important by-products from the large slaughtering units. Some slaughterhouse by-products may be used in pet foods. Production of woo} from Angora breeds was popular at one time, but presently there is little commercial production of angora wool. Official statistics are not available on the numbers of rabbits produced annually in the United States. It has been estimated that 4.5 to 5.4 million kg of rabbit meat is consumed annually, some of which is imported. Approx- imately 6 to 8 million rabbits are produced annually for all purposes. Peak production was reached in 1944, when it was estimated that about 24 million rabbits were pro- duced. In times of national emergency, such as occurred during both world wars and in other times of food short- age, production of rabbits has traditionally increased. A growing phase of the rabbit industry is that of supplying animals for laboratory or research use. Current usage for this purpose is about 600 thousand annually. The domestic rabbit is primarily herbivorous and will consume most types of grains, greens, and hay. Diets provided, whether home grown or commercially pre- pared, consist almost entirely of ingredients from plant sources. Although a few producers may still rely on homegrown feeds, a major portion of the rabbit feed presently used is commercial, pelleted feed. Since Me rabbit can utilize a certain amount of forage, it has a place in food production by making use of some non-competi- tive feeds. Rabbits habitually practice coprophagy, sometimes re- ferred to as pseudorumination. This refers to the produc- tion of two kinds of fecal matter, one hard and one soft, the latter being consumed directly from the anus as it is excreted. This practice begins In rabbits shortly after they begin eating solid feed at about 3 to 4 weeks of age but is not practiced by germ-free rabbits. Fe~entation in the large intestine and the practice of coprophagy probably provide the necessary amounts of most B vitamins, pros vice some bacterially synthesized protein, and may per- mit further digestion of some nutrients by multiple pas- sage through the digestive tract. The high digestibility of forage protein in rabbits may be due partially to co- prophagy. The subcommittee considered the inclusion of Stan- dard Reference Diets but found insufficient information on such diets that had been adequately tested in feeding trials. Specific requirements for many of Me nutrients assumed to be needed by rabbits have not been estab- lished. The literature contains some information, and a number of significant reports have been published since the previous revision of this publication. The require- ments summarized and presented in Table 1 reflect published data on intake levels reported to insure normal health and performance. A safety factor has not been added, and increased intakes may need to be considered under conditions of stress, variability in content, and availability of nutrients in the feed. Possible additional requirements under such conditions have not been eval- uated, and no separate recommendations are made. Ma- ture rabbits vary in size from 1 to 6 kg, so it is not possible to state requirements on a daily basis. 1