The selection of animals for breeding, ignoring their inherited characteristics for the moment, depends on health, condition and age. No matter how good an animal may be because of its ability to transmit a good inheritance to its progeny, unless it has good health, and is in the right condition, it is not suitable for breeding. A sick doe cannot possibly be a good mother, and may quite easily infect all her offspring. Condition suitable for breeding is rather more difficult to define. The doe should not be fat, but should be well fleshed, and most important, site should be in improving condition. The correct age for first breeding is important. It is often wise to breed slightly before the age of sexual maturity, and in this the breeder should be guided by the bodily development of the animal rather than by a question of months. Too early an age is not desirable, but neither should an animal be left too long, except for some special reason such as showing, before it is mated. Does will continue to breed in some cases for a number of years, but in general a three year old doe will often be discarded unless she is above average quality. In the case of the smaller breeds, five months at the earliest, and usually six months, is the age at which breeding should start. For the largest breeds, it is not usual to commence before eight or nine months.
The number of litters which a doe should be allowed to have during the year is often the subject of argument. In general the fancier will usually breed the doe twice and occasionally a third time. The aim of the commercial breeder should be to take four litters a year. There is little harm likely to result from frequent breeding. Indeed the reverse is true. If feeding and management are satisfactory, then frequent breeding is desirable.
A method sometimes adopted to obtain as many off spring as possible from a particular pair of animals is the repeated mating of the doe and the fostering of the young on to foster does. In this way as many as eleven litters can be taken in the year, the doe being remated immediately after kindling. Contrary to general belief such a system imposes less strain on the doe than does intermittent pregnancies and suckling. A similar system is sometimes used to increase average litter size and fertility. In some of the smaller breeds, the Netherland Dwarf in particular, difficulty may be experienced with breeding. Thus several does are mated at the same time, and average litters of five or six fostered on to some does, whilst the others are rebred. This assists in getting fertile mattings, and also assists in keeping youngsters small, a desirable characteristic in these breeds.
The doe should never be mated in her own hutch for this may lead to her resenting the intrusion of the buck and consequent fighting. She should always be placed in the buck's hutch, or in a special service hutch. It is of advantage to allow a buck at least his first services in his usual surroundings. Some bucks may refuse or be sin,' to serve in strange conditions.
The doe should not be left with the buck for any considerable period, and the mating, which should normally be accomplished in a very short time, should always be observed. If no mating takes place within a few minutes then the doe should be removed and retried later. By placing his hand infront of the doe, a breeder may often make her stand to the buck instead of running from him.
As soon as the mating is completed, the buck falls back-wards, or in the case of a less vigorous buck scrambles from the doe. The falling of the buck is due to his becoming unbalanced. Usually when mating is accomplished a scream will be heard. This is usually uttered by the buck, although it may occasionally be made by the doe. It is the result of some pain and is perfectly normal.
A method of assisted mattings has been developed for use with reluctant does, and also in cases of shy bucks. The doe is grasped by the loose skin on the shoulders whilst with the other hand the hind-quarters are slightly raised, the vulva being pressed backwards and upwards with the finger and thumb. The doe thus adopts the normal mating posture and is available for the buck. This system does not, contrary to some belief; affect the number of infertile mattings, but is of assistance in procuring more mattings than would otherwise be the case.
The stud buck is a most important animal in a rabbitry, and should be used carefully. There is little doubt that young bucks are easily spoilt by overuse, but on the other hand it is equally true that fully mature bucks are not often given sufficient work.
The first few services of a young buck should be well spaced; that is one or at most two a week. When the buck is fully mature, and well managed and fed, he can accomplish atleast six mattings a week with ease. The first services of a buck which has been rested for a long period may be infertile and in these cases a double mating should be made.
Some authorities advocate regular double mattings. This method is to mate a doe and then an hour or two later to mate her to a second buck. The system has little to recommend it for a vigorous buck will accomplish all that is desired, and when two bucks are used the parentage is not known, a serious disadvantage for future selection.
A buck should not be put to service immediately after feeding, for mating at such times imposes an unnecessary strain upon hint. Similarly it is better to space mattings on the same day as much as possible. It must always be remembered that a stud buck used reasonably frequently is being hard worked, and should be fed well and looked after. It is frequently said that the quality of the young is affected by the age of the buck. There is no truth whatsoever in this statement. Many breeders will discard a buck simply on the grounds of age. Such a practice should be strongly condemned. The older a buck gets, provided he still remains capable of service, the more valuable he may become, for the breeder will have a greater knowledge of his capabilities as a stock getter. This argument also points that of the early use of a buck. The snore young a buck begets, the more able is a breeder to assess his qualities, for the value of a stud buck lies entirely in his ability to transmit good characteristics to his progeny.
Fostering is the art of transferring offspring from one doe to another. There are advantages in using this art, but in some cases there may also be disadvantages. One dis-advantage is that unless the new born animals are well marked their true identity may be completely lost unless whole litters are transferred and the young of the foster doe destroyed. Secondly the true value of the mother cannot be assessed unless she is left with a full sized litter. Fostering enables a breeder to obtain young from a doe with particular characteristics, but very often her quality as a milk producer and rearer of young are ignored. Its general this is not very satisfactory.
On the other hand fostering would enable a breeder to produce a large number of young from a particular mating, and it also enables litter size to be averaged out, thus getting the best results. Sometimes when it is only desired to rear a particular type of animal, as for example reasonably well marked patterned animals, fostering would assist in that all the does can be mated, the desired youngsters selected from all those produced, and then fostered on to one or two does, the remainder being again mated. This same procedure may be adopted when animals of a particular sex are required, for example for laboratory use. When a doe dies, or produces her first litter, fostering may be of use. Thus the decision to foster must depend upon the particular requirement of the individual breeder, and provided the objections are considered and overcome then fostering can be extremely useful. Young rabbits up to the age of three weeks may be fostered, although at this late age it will not always be successful. When it is proposed to reduce a litter it is best to reduce it only after a few days. This is because suckling will stimulate the milk secretion, and consequently by fostering only after a week the maximum activity of the mammary glands will have been achieved. As far as possible however, fostering should be carried out within at most ten days of birth.
Litters as much apart as three days can be successfully amalgamated, although usually it is preferable that the litters should be as close in age as possible. When differently aged litters are being amalgamated it is of advantage to foster the younger animals and not the older.
Fostering is accomplished by transferring the young into the nest of the foster doe. It is advisable to remove the doe for a short period and then give her some tit-bit when she is returned to her hutch. Care should also be taken to observe that she takes to the youngsters and does not attack them. When a doe is being used as a foster for the first time, or when her mothering qualities are rather uncertain, then it may be advisable to affect her sense of smell for a short period. This may be accomplished by rubbing a very little " Vick "ointment or paraffin on to her nostrils and fore legs. It is desirable for the breeder to be able to tell as soon as possible after a mating whether that mating has been successful. If the doe is not in kindle she can be remated, or a watch kept for signs of her being pseudo-pregnant. If the doe proves to be in kindle then she can be managed and fed accordingly.
The most reliable method, and that giving the earliest confirmation of pregnancy is palpation of the abdomen. The method consists of feeling the abdomen to decide whether developing embryos are present in the uterus. The tips of the fingers should gently press the abdomen just in front of the pelvis, when, if the doe is pregnant the embryos can be felt. These are about the size of marbles (between the 12th and14th day), but care should be taken to make sure that the faecal pellets are not mistaken for the embryos. If a pregnant doe of about 12 days duration is sacrificed and opened, then the relative position and size of the organs can be determined easily. It is important when palpating the abdomen that the doe should be relaxed, for tightened abdominal muscles make the task more difficult. Does cannot be palpated easily before about the twelfth day of pregnancy.
A method 'which, although it has been used very widely, is not very reliable, is that of test mating. The doe is returned to the buck some days after mating and it is assumed that if she accepts the buck then she was not pregnant, whereas if she refuses the buck it is assumed that she seas. A pregnant doe will however often accept the buck during pregnancy, and a doe not in kindle may sometimes refuse him.
The third method which may be employed on about the 24thday of pregnancy is quite reliable and consists in noting the increase in thickness of the mammary glands. The mammary glands start to increase in thickness about the middle of pregnancy, and by the 24th day are sufficiently different from mammary glands in non-pregnant does to decide easily. It is of advantage to feel the thickness of the glands in a known non-pregnant doe at the same time as testing the supposed pregnant doe.
The domestic rabbit has been widely used to develop artificial insemination, and thus the correct techniques are known and available. It is doubtful however whether they will be much employed by the rabbit breeder, except possibly for special purposes, such as the mating of animals very different in size.
Briefly the technique consists of the collection of sperm from the buck in an artificial vagina, consisting of a glass tube about inches in diameter into which is fitted a rubber sleeve. This sleeve terminates in a small tube. Warm water is introduced into the large tube and thus warms the rubber sleeve. The artificial vagina is held between the legs of the doe or in an artificial muff, and the buck induced to serve into it. The semen is collected in the small tube and diluted with a solution of up to 15 times its original volume. The doe is then ovulated, either by injection of appropriate hormones, or by mating with a buck which has been made sterile by surgical operation. The semen is then introduced into the vagina with the aid of a glass syringe.