Biology of the Rabbit
by François LEBAS
 Directeur de Recherches honoraire de l'INRA
English revised version of "Biologie du lapin" , translated from French by Cathy R. Martin and Joan M. Rosell
Edition 2020
                                                                                                                                  Les dernières modifications

1- Taxonomy and Origin of the Rabbit

      Taxonomic position
     

The origin and domestication of Oryctolagus cuniculus

      The development of modern breeds.
      The use of local populations, breeds and strains

 

  Taxonomic position
   

The European rabbit (Oryctolagus cuniculus) belongs to the Lagomorph order. It has 2 x 22 = 44 chromosomes. The Lagomorphs (literally: those that look like a hare) differ from the Rodents in that they have a second pair of incisors in the upper maxilla. In addition while male rodents have a penil bone in their penis, this type of bone is absent in all lagomorphs. . Table 1 contains a simplified classification of Lagomorphs and some photos. With regard to the taxonomic position of the rabbit, it should be remembered that it is the only species of its genus and therefore cannot be crossed with other lagomorphs. There is no possibility of hybridation between this species and any other lagomorph, type hare or sylvilagus etc

Table 1 : Simplified classification of the lagomorphs , with some illutrations
(click on the image to open the table)
  The origin and domestication of Oryctolagus cuniculus
    Oryctolagus cuniculus is the only domesticated mammal whose paleontological origin is Western Europe. The oldest fossils of this genus are about 6 million years old and were found in Andalusia (Spain). From the upper Pleistocene (- 100,000 years) to the Neolithic (-2,500 years), the species was distributed in the Iberian peninsula, southern France and apparently, at the end of this period, North West Africa. Rabbit meat was an essential part of the diet of the inhabitants of Provence coast 7,000-8,000 years B.C. From the Bronze Age (~ 2.000 years B.C.) to the V century A.D., the distribution of Oryctolagus cuniculus changed very little. However, at some stage during this period it was taken to certain islands in the western Mediterranean (Balearic Islands, and Zembra island north of Tunisia, amongst others).
         A little bit of history and the origin of the name

Rock Hyras
   From the historical perspective, the rabbit was "discovered" in Spain by the Phoenicians about 1.000 years B.C. When these great navigators from the eastern Mediterranean reached the coasts of the Iberian peninsula, they were taken aback by the very great number of these small, burrowing animals, nowadays called rabbits. As they were similar to their own hyraxes, not a lagomorph nor a rodent, but which live in colonies and make burrows, the Phoenicians named the region "land of the hyraxes ", "I-Saphan-Im". Saphan (or sephan) actually means hyraxes in Phoenician (in ancent Hebrew too) and this latinized denomination later became Hispania (Rougeot, 1981). So, the name Spain it-self is linked to the historical presence of rabbits in its territory. The roman poet Catullus (87 B.C. - 54 A.D.) described Spain as "cuniculosa".
      The etymology of the genus "Oryctolagus" Lilljeborg 1874 is derived from the Greek oruktês = excavator and lagôs = hare. The name of the species cuniculus is Latin for rabbit, directly derived from Iberian and initially transcribed as/in "ko (n) niklos" by the Greco-Roman historian Polybius, in about 150 B.C.
         In search of traces of the first rabbits
 


Rabbit in a Roman mosaic

   Studies carried out on the mitochondrial ADN of rabbit bones found in archaeological excavations and tissues taken from rabbits today have enabled us to determine that two maternal lines of the species were separated 2 million years ago. Line A still exists today, but only in south west Spain and southern Portugal. All other wild or domestic rabbits belong to line B. The geographical distribution of this line B was also limited to eastern Spain and southern France exclusively, until the Roman Age (Monnerot et al., 1996). Different studies carried out on the genetic polymorphism of various enzymes, mitochondrial ADN, or microsatellites, all show that wild and domesticated rabbits belong to one group only, with possible differences in variants but no significant ones between domestic and wild rabbits (Zaragoza et al., 1987; Vachot, 1996). In other words, domestic rabbits are descendants of wild rabbits, even if for centuries, humans have more or less directly povoked a return of domestic rabbits back to nature.
         Switching from wild animals raised in enclosures to domestic rabbits
    The first records of rabbit-breeding were by Varro (116-27 B.C.), who recommended keeping rabbits in leporaria, walled enclosures where hares, rabbits and other species were kept, to make hunting easier. This form of raising wild animals was the origin of similar enclosures used in the Middle Ages until the end of the XVIIIth century, but the animals were still not domesticated. During this period, Romans adopted the same habit as the Iberians of eating "laurices", that is newborn kits (or foetuses). With rabbit does inside of an enclosure it was easy to obtain these delicacies.
          Gourmet monks
    At the end of the VIth century A.D., Gregoire de Tours (a French bishop, 538-594) mentioned rabbits in his history of the Franks. At this occason he reproached monks for consuming fetus and newborn kits during Lent, monks arguing as these dishes were of "aquatic origin" like fishes normally authorised during Lent (sic!). The position of the monks would also be based on an authorization given by Pope Gregory I (540-604).. It may be thinked like Zeuner (1963) that monks tried keeping breeding females rabbits in strict confinement (very small pens inside of a building) to have easy access to the laurices without slaughtering the mothers. Actually, at that time breeding of rabbits become a speciality of convents. Written proof has been found that convents used to exchange pairs of rabbits during the mid XIIth century.
         The very first development of the domestic rabbit in the Renaissance as a "curiosity".
      Outside the monasteries, thanks to the initiative of the nobility in possession of hunting rights, rabbits were kept in warrens ( garennes in French), closed or open areas derived of the Roman leporarias, but with only rabbits. These warrens created some disturbances for the neighborhood, thus several ordinances of the kings of France must regulate the development of warrens in the 14th and 15th century, because of the damage caused by rabbits escaping from these warrens. In the middle through the XVth century, rabbits were definitively domesticated . In the XVIth century Agricola mentions the existence of black, white, ash grey and piebald (large spots of black and white) rabbits. Aldrovandi marvelled at finding in Verona (Italy) domesticated rabbits four times the size of wild ones.
          A real production farm described by Olivier des Serres (France) at the beginning of the XVIIth century
    In his reference work on agricultural techniques, Olivier de Serres (1605) differentiates between three types of rabbit: wild (the most delicious-tasting), garenne (pleasant to the palate) and clapier rabbits (more insipid). However, it should be pointed out that the author linked the characteristics of these three types of rabbits to food and exercise rather than genetics. He devotes at least 13 pages to the construction and maintenance of warrens and clapiers (hutches). He advises that no more than one male per 20 or 30 females should be kept in the enclosure and young males should be castrated to improve the quality of their meat. For controlled breeding (highly encouraged), rabbits were housed in individual hutches. The female was brought to the male’s hutch for mating, immediately after kindling. Mating was supervised and the female was taken back to her litter straight away. In other words, postpartum mating had already been recommended by Olivier de Serres 400 years ago.
  The development of modern breeds
      A breed inside of a species is generally considered to be a group of specimens with certain morphological and physiological characteristics in common. These characteristics are perpetuated when the animals breed amongst each other.
      Generally different types of breeds are condidered
      a/ Primitives or primary or geographycal breeds : groups from which all others breeds have differentiated. They are direct descendants of wild rabbits.
      b/ Breeds obtained by artificial selection from the previously-mentioned ones. It is generally the work of few breeders. Some examples: Fauve de Bourgogne, New Zealand White, Champagne d'Argent, amongst others.
      c/ Synthetic breeds obtained by the organized crossing of different breeds. It is most generally the result of the work of one breeder or of one coordinated small group of breeders. Some examples, Bouscat White Giant or Californian.
      d/ Mendelian breeds obtained by fixing a newly discovered characteristic, with simple genetic determination, and appearing by mutations, for example, Castorrex, Satin, Harlequin, Angora, etc
     
      It is convenient to group the breeds according to their adult size. In addition, this is often related to production characteristics: precocity, prolificacy, speed of weight growth, speed of reaching maturity
          Heavy breeds
     

The adult weight is over 5 kg. Fertility is generally moderate to low. The high growth potential of heavy breeds is presently used for terminal crossings They include French Lop, Bouscat White Giant, Chekered Giant, Great Chinchilla, Spanish Giant and the largest of all, Flemish Giant, weighing 7-8 kg . The French Lop, 5.5 kg or more, was during the first part of the XIXth century, the reference rabbit breed for meat production. However, as an adaptation to the local conditions , the weight of an originally heavy breed can be reduced as it was observed for the Bouscat (Boscat) raised in Egypt with about 3 kg adult weight instead 5-6 kg for this original French breed at it's first presentation in 1924
        Medium breeds
      The adult weight of medium breeds varies between 3.5 and 4.5 kg. They are the basis of populations, lines or breeds used for intensive meat production under western European conditions and are the most numerous. Some examples are given below :
     


The Champagne d'Argent is an example, like the Fauve de Bourgogne, of a breed selected since a very long time from a regional population (the Champagne area). This rabbit is known, in addition to the characteristics of its once appreciated argent-grey fur, for its production abilities : high prolificacy, strong growth, good muscle development, and appreciated meat quality. It is raised in France on small farms, quite exclusively on straw bedding because of it sensibility to pododermatis (sore hocks).

The Fauve de Bourgogne is also a French breed of regional origin (Burgundy), which has spread widely in France and other European countries (Italy, Belgium, Switzerland).

The Californian is a synthetic American breed and was first introduced in California in 1928. The aim of its creator was to obtain a rabbit for meat production with good quality/strong fur. The adult weight is 3.6-4 kg.

The New Zealand White is a breed native to the United States. He is descended from colorful rabbits of which he is the albino. It was selected from the start, in large meat-producing farms in California on zootechnical qualities: prolificity, maternal abilities of females, speed of growth and precocity of body development for slaughter at the age of 56 days (1.8 kg), aiming to produce a young lightweight carcass. The adult weight is around 4 kg, a little higher than that of the Californian. This breed has spread widely in Western Europe and around the world since 1960 with the adoption of wire mesh breeding.

The Chinchilla, a true rabbit unrelated with the rodent named chinchilla, was selected in Gremany for meat and/or fur production. It's adult weight is generally 4.5 kg.
          Light breeds
      The adult weight of light breeds is usually between 2.5 and 3 kg. The Russian, Little Chinchilla, Dutch or Habana, amongst others, are examples. . The Russian rabbit is also called the "Himalayan". It has a coat similar to that of the Californian. This white rabbit with black extremities and red eyes carries the himalaya gene "ch" in dupicate. Gene "ch" is one of the alleles of the "C" locus (coloured) for which one of the other allele "c" produces the true albinism (cc rabbits, like NZW). In general, light breeds have early body development and may have an excellent mothering abilities.
          Small or dwarf breeds.
     

These breeds have an adult weight of the order of 1 kilogram. They are represented mainly by the Polish rabbit, and the many colored dwarf rabbits. Selection for the smallnest weight has led in these breeds to a very low prolificacy and frequently to dental problems resulting from shortening of the face. They are mainly raised as pets.
  The use of local populations, breeds and strains
     

Rabbits used in different countries for commercial meat production sometimes belong to one breed but more often to populations of animals that may resemble a particular breed (but only resemble, without reaching the criteria of origin and standards of race), or not resemble any breed. These rabbits are "common" rabbits, gray, spotted or white, issued from various unplanned crosses (farm breeding), or belonging to local populations. Developing countries may have local populations, for example the Baladi rabbit from Sudan or Egypt (in Arabic, Baladi means indigenous or local), the Maltese from Tunisia, the Creole rabbit from French West Indies. The most widely used breed is undoubtedly the New Zealand White , or at least populations of albino rabbits strongly related to this breed.

There are also strains of rabbits. A strain is a genetically closed herd, of limited numbers, raised without introduction from the outside for several generations. A strain may or may not be selected. These strains can be found in research laboratories which maintain them to study their biological and zootechnical characteristics with a view to obtaining their best use in selection. Different public or private breeders also select strains of rabbits, following the example of what has been done in poultry breeding since 1930. The strains are often genetically more homogeneous than the breeds.

In Western Europe most commercially active breeders use controlled crossing among specialized and complementary strains. A large part of the work of rabbit breeding firms consists in choosing the selection criteria for their different strains so that their complementarity makes it possible to increase the technical and economic performance of rabbits exploited in crossbreeding. These rabbits are the commercial "hybrids" already mentioned at the beginning of this chapter.
     

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