Rabbit Growth of Fur

The normal fur of the rabbit consists of two types of hair, theundercoat which is soft and varies in different breeds, betweenabout I and ri inches, and the guard hairs which are strongerand longer. The diameter of the undercoat hairs variesbetween four and eight thousandths of an inch, whilst the guard hairs may be as much as sixteen thousandths of an inch indiameter or even more. These typical hairs have beenmodified in different breeds. For example in the Rex, theguard hairs have been shortened until they are about the samelength or slightly less than the undercoat hairs, whilst in theAngora both types of hairs are much increased in lengths.All hairs consist of a medulla, a series of cells in the centre ofthe hair, a cortex, which surrounds the medulla, and the cuticleor scales, which overlap each other. In the undercoat hairs thescales cover the entire hair, but they are not present on the tipsof the guard hairs which are swollen slightly to form a bulb.The normal undercoat hairs of the rabbit are slightly waved,but in the Angora, the wool fibres forming the undercoat arecrimped. In all cases the undercoat hairs are approximatelyuniform in diameter throughout their lengths, but guard hairs Each hair grows from a deep pit in the skin, known as ahair follicle, and growth from each hair follicle is more or lesscontinuous. The first hairs to grow on the newborn rabbitare the guard hairs, but growth of the undercoat quicklyfollows and hair is well developed after a few days. Thisfirst baby coat persists for between four and six weeks, and ismuch softer than the later coats of the same rabbit. Theintermediate coat starts to replace the baby coat at five or sixweeks of age, and is completed usually between 41-51 months.On the completion of the growth of the intermediate coat,the pelt may be free of both loose hairs and new growth, thatis to say that it is in tight ' coat and free from moult. Thisoccurs in the Chinchilla when the intermediate pelt may betaken for fur work.
After completion of the intermediate coat, the growth of theadult coat begins. There are marry factors which affect thegrowth and moulting of the hair, and depending on these,the adult coat may be completed at between six and eightmonths of age or even later. From this period onwards therabbit will usually have one main moult a year, althoughthis is very variable and there are many exceptions.

Moult normally starts on the head and proceeds backwardsand downwards. The areas of the flanks (in the region of thetail) and belly are thus the last places to be cleared of moult,and it is here that signs of moulting should be sought when theanimal is being examined to determine whether it is in tightcoat and therefore suitable for pelting. The annual moult ofthe adult animal is really a continuous process, althoughthe severity of loss of hair and growth of nest hair variesconsiderably. The loss of some hairs may be started in earlyspring, but it may not be until the autumn that the animalsheds an appreciable number of hairs and the moult is apparent.In some cases a very severe loss of hair and rapid growth of newhair may occur, when the appreciable moult period may bevery short. In other cases the moulting period may be verylong.

Apart from what may be termed the normal moult, severalother types of moult may occur. In the pregnant doc there isa loosening of the hair on the belly and chest, and she is thus able to pluck out fur easily to line her nest. The sameloosening, which is due to the effects of hormones producedduring pregnancy, occurs when the doc is pseudo-pregnant.There may be a double moult : that is to say the rabbit maystart and complete a moult immediately after a first moulting.This process may be further extended until the rabbit moultsagain immediately following the growth of new hair, andindeed several such moults may occur during the year.Although the fineness of the hairs, the rapidity of its growth,and the length of moult period are determined basically by theinheritance of the rabbit (and this inheritance is by no meansof a simple nature), these characteristics are much affectedby environment, of which feeding and temperature are thetwo most important. A high level of nutrition will tend toproduce a thicker fibre, but the increased density of the pelt(which is slightly increased by the thicker fibre) will not be soapparent as the animal will be rather larger, and the actualdensity of the hairs thus slightly reduced. 'There is somerelationship between size of animal and weight of hair grown,although this is not strictly correlated. Thus in the Angora,selection should be based on a weight of wool weight of animalbasis rather than on the basis of wool yield only.

The growth of an entire coat will impose some additionalstrain on the rabbit, and to assist it to overcome this strain,its nutrition should be good. The hair itself is composed verylargely of protein, and rations designed to help in this wayshould therefore be adequately balanced.

There are several abnormalities in growth and moult. Inthe Angora areas of retarded wool growth may occur. Theseare usually small, the wool on the area remaining short. Incertain cases of skin troubles irregular falling away of the hairmay also be caused.