The design of rabbit housing is governed by the behavioral characteristics of the animals and their reactions to environmental temperature and humidity.
Some kinds of behavior have already been analyzed in this book and others have been mentioned briefly. They all have an influence on rabbit housing so they will be summarized at this point. Since the domestication of the rabbit is recent in terms of species evolution (200 to 300 generations at most) the behavior of the domestic rabbit is still much like that of the wild rabbit. The reactions of wild rabbits will often provide explanations for the problems of housing domestic rabbits and suggest ways of solving them.
Territorial behavior. Wild rabbits live in sedentary fashion in a territory the size of which depends on the conditions of food supply. They mark their territory, their fellows and their offspring with the aid of a gland found in hair follicles under the chin. The bucks also mark off their territory with their urine. The rabbits dig burrows in which they take shelter at the slightest sign of warning. There they live in a "society". Before parturition, however, the doe digs a special burrow where her young are born and where she returns once a day to nurse them.
This is why domestic rabbits should have durable living quarters, providing either a refuge from disturbances or a peaceful environment that makes a refuge unnecessary. Any new and sudden change (noise, presence, smell) will make the first rabbit in the group to notice the disquieting novelty thump his hind foot to warn his fellows of danger. To prevent panic in the rabbitry the breeder should take care that changes that might upset the animals are avoided.
When a rabbit is put in a new cage he will explore it and then mark it with his smell. The more strange odors there are in the cage the longer this task will take.
The burrow is not only a refuge in case of alert, it is also a rest area during the day, as rabbits are mostly nocturnal. Temperature and humidity are far more constant in the burrow than outside.
Social behavior. Wild rabbits live in colonies in which females outnumber males. Each female, with or without offspring, attacks the young of other does. Bucks act as moderators at this stage. When the young males reach puberty, however, the adult males try to eliminate them as rivals by castrating them.
The method used in rational European rabbit production to prevent such conflicts is to isolate each adult rabbit in an individual cage. Before puberty, young rabbits can be reared in groups. Attempts to rear breeding animals in groups are bound to fail because the does are so aggressive towards the young, especially when the animals' living space is cramped. Females without young can be reared in groups provided each female has at least half a square meter of space for herself.
Sexual behavior. Ovulation in the does is brought on by mating (see Chapter 3, Reproduction), so one might expect mating to be possible on a quasi-permanent basis. In fact, does do have a behavioral cycle of acceptance of the male but unfortunately this varies greatly from one doe to the next. Attempts at servicing often have to be repeated, which means the animals must be moved about a great deal.
The buck is so very territorial that when he is put in a female's cage his first act is to mark this new territory with his smell, while the doe tries to eliminate the intruder. But if a doe is put in a buck's cage the immediate reaction of both animals is sexual. For a receptive doe preparation for mating takes 20 to 120 seconds, and the act itself less than a second. For servicing, therefore, it is the doe that should be moved. This is relatively easy because does are calmer and weigh less than bucks (3 to 6 kg). For mating to be supervised, the animals need to be visible in all parts of the cage. Access to the buck's cage should be simple so that the does can be easily introduced and removed.
With this kind of mating, people have to move the animals physically within the rabbitry and this will influence the planning of the general layout of the unit to limit the distances to be covered. The rather unsatisfactory results obtained with special cages reserved for mating should be mentioned. Many males waste a lot of time marking a mating cage that is impregnated with the smell of their predecessor, and the cage is also a possible site for the spread of diseases.
Maternal behavior. Before kindling, the doe makes a nest with various materials plus fur that she pulls from her abdomen. The wild doe's nest is made at the end of the private burrow she digs for kindling. The domestic rabbit does not usually have the opportunity to do this, so a private area should be set apart for her. In farm rabbitries using straw litter the doe might be satisfied to dig into the straw to make a nest. But producers have noticed that it is preferable to provide her with a nest box that approximates the natural burrow.
A box like this is useful in a farm rabbitry and essential in wire cage production. After the young are born (six to 12 per litter), the doe nurses them once every 24 hours for about a month. To allow the motor coordination and heat-regulation capacity of the baby rabbits to develop, the nesting box should be maintained for at least two weeks. It should be big enough to accommodate the doe and her litter during nursing.
Feeding behavior. Laboratory research has shown that rabbits will drink and eat at any time in the 24 hours, although they tend to feed nocturnally. Intake is rather slow, even if the animals' feed is rationed. Feed and water should therefore be available over periods of several hours, whether feed is rationed or ad lib. The feed must not be allowed to get dirty, which is inevitable if it is strewn on the ground (see Chapter 5, Pathology).
From the age of three weeks young rabbits begin to eat the same feed as the doe. Their small size allows them to slip easily into forage racks or dry feed hoppers, so this equipment must be designed to keep them out.
Practically speaking, these features mean that the breeder must provide a drinker and feeding rack for each cage, and perhaps a fodder rack. The animal must be able to reach the feeders and fodder racks, as must the caretaker to top them up frequently. An automatic or semi-automatic drinker is easy to make, however. These constraints mean that solid feed distributors are almost always placed in front of the cages, which can easily hinder visibility and accessibility.
Hygiene, habitat and breeds
There would be no point in reiterating here all the rules of hygiene dealt with in other chapters, particularly preventive hygiene. However, the design of the rabbitry will be heavily influenced by some of these rules.
One of the major rabbit diseases in traditional small-scale production using straw litter is coccidiosis. Contamination is via oocysts eliminated with the faeces. Breeders have cut the incidence of this disease by using wire-mesh floors through which the excrement drops.
The wire-mesh flooring system, combined more recently with single, portable, interchangeable cages, has led to considerable progress in disinfecting equipment. Some diseases have been cut down or even wholly eliminated. But not all rabbit breeds can adapt to this type of flooring. Heavy or nervous breeds, in particular, are subject to sore hocks, a bacterial infection developing on the foot pads and irritated by the wire mesh (too much weight per cm2). The risk is greater when the animals are raised in environments with high temperatures (31° to 32°C), or very high humidity (constant relative humidity above 85 percent), or when the rabbits are frequently under stress and thus thump their hind feet on the ground to warn the other rabbits of impending danger. A mesh floor also cannot be insulated, and rabbits are more liable to respiratory ailments if air flow is not controlled.
Breeders therefore have to make a decision: either they rear New Zealand White or Californian breeds, which have been adapted to mesh flooring, and thus meet modern hygiene standards, or else they rear heavier or more excitable breeds - but then how do they control coccidiosis and other diseases?
As well as these hygiene-linked problems there are other advantages and disadvantages with both mesh floors and traditional straw litter. With a mesh floor, through which droppings can fall, automated or very infrequent cleaning is possible because droppings accumulate under the cage). But it also makes the rabbits very dependent on the microclimate or ventilation in the rabbitry. Straw litter, on the other hand, has to be cleaned often (at least once a week) so the producer has to have the material on hand (straw, wood shavings, etc.). An advantage is that a cage with a straw litter floor can be put almost anywhere, as the cage itself partly insulates the animals from variations in the external climate.
In Europe today most new production units use solely wire-mesh cages and New Zealand White or Californian rabbits. But this implies doing without the genetic pool of other breeds. Would it not be possible to design other types of flooring, recognizing that slatted floors have never been very satisfactory? Whatever the answer, for many developing countries the wire-mesh cage will probably remain a theoretical solution for many years to come, until the special mesh necessary is made available to producers at reasonable prices.
Temperature. Temperature is the most important factor as it directly affects a number of elements. Rabbits have a constant internal (rectal) temperature so heat production and losses must vary to maintain body temperature (Table 49). They do this by modifying their feed intake level (regulating production), as described in the chapter on nutrition. They use three devices to modify heat loss: general body position, breathing rate and peripheral temperature, especially ear temperature (Table 49).
If the ambient temperature is low (below 10°C) the animals curl up to minimize the total area losing heat and lower their ear temperature. If the temperature is high (above 25° to 30°C), the animals stretch out so they can lose as much heat as possible by radiation and convection, and step up their ear temperature. The ears function like a car radiator. The efficiency of the cooling system depends on the air speed around the animal. At the same time the animal pants to increase heat loss through evaporation of water (latent heat). The sweat glands are not functional in rabbits and the only controlled means of latent heat evacuation is by altering the breathing rate. Perspiration (the evacuation of water through skin) is never great because of the fur.
TABLE 49 Exportation of heat, rectal temperature and ear temperature in adult New Zealand White rabbits, according to ambient temperature
These systems work between 0° and 30°C but when ambient temperatures reach (and mainly when they exceed) 35°C rabbits can no longer regulate their internal temperature and hyperthermia sets in.
The regulation methods described above, based on observations of adult animals, are applicable to young rabbits from the age of about one month, when they can move about and feed themselves and the juvenile coat has grown. Heat regulation of newborn rabbits is somewhat different: they have no fur and cannot correctly adjust their food intake as the doe's milk output is the result of an involuntary reaction. At birth they have rather good fat reserves which help them maintain body temperature if two conditions are met. The surrounding temperature must be at least 28°C (30° to 32°C if possible), and they must have other young to huddle against to reduce heat loss.
At birth, young rabbits cannot modify their body shape by curling up. The only way they can limit heat loss through convection and radiation is to huddle together with the other young in the litter. In fact, if ambient temperature varies during the day the young rabbits will move apart when the temperature is high and huddle back together when it goes down. But a sudden temperature drop may well exhaust their thermoregulation potential before they can get back in the huddle and they can die of cold 10 cm away from the group. The new-born rabbit is blind and the incomplete myelinization of the nervous system that governs motor control hampers coordinated movement. The producer must make sure the temperature in the nest remains constant to prevent this sort of accident.
Humidity. Rabbits are sensitive to very low humidity (below 55 percent) but not to very high humidity. This may be explained by the fact that wild rabbits spend much of their lives in underground burrows with a humidity level near saturation point (100 percent).
The rabbit has more to fear from abrupt changes in humidity. Constant humidity is therefore the best solution, and this will depend on the housing design. French breeders find 60 to 65 percent humidity levels successful, using only auxiliary heating in winter.
While the humidity level does not seem to trouble the rabbit in moderate temperatures, this is not so with temperature extremes.
When the temperature is too high (close to the rabbit's body temperature) and humidity is also high, not much latent heat can be exported as water vapor through evaporation. The result is discomfort which can be followed by prostration. Very hot spells with near 100 percent humidity can cause serious problems. Unfortunately this is common in tropical climates during the rainy season.
When the temperature is too low and humidity close to saturation point, water condenses on poorly insulated walls, especially at so-called "heat bridges". Water is a good heat conductor and so the cold becomes more penetrating, causing heat loss in the animals through convection and conduction. Digestive and respiratory disorders often follow. When the surrounding air is cold, excess humidity modifies the secretion and viscosity of the mucus protecting the upper respiratory apparatus.
Air which is too dry (below 60 percent relative humidity) and too hot is even more dangerous. Not only does it upset the secretion of mucus but the ensuing evaporation shrinks the size of the droplets carrying infection agents, enabling them to penetrate more easily the respiratory apparatus.
Ventilation. The rabbitry must have a certain minimum of ventilation to evacuate the harmful gases given off by the rabbits (CO2), to renew the oxygen and get rid of excess humidity (evaporation, exhalation) and excess heat given off by the rabbits.
Ventilation needs can vary enormously, depending especially on climate, cage type and population density. Ventilation standards for temperate climates based on several French studies are given in Table 50. This table combines the various parameters (temperature, air flow, humidity) to determine optimum air flow per kg of rabbit live weight. If there is an imbalance, especially between air flow and temperature, accidents like those illustrated in Figure 24 occur.
It is relatively easy and cheap to measure temperature and humidity, but exact air flow measurement requires sophisticated, expensive, hard-to-get equipment such as a hot-wire anemometer (a revolving-cup anemometer is not sensitive enough). However, the producer can estimate the rate of air flow near rabbits by using a candle flame, as shown in Figure 25.
High ammonia air levels, 20 to 30 parts per million (ppm), greatly weaken the rabbits' upper respiratory tract and open the door to bacteria such as pasteurella and bordetella. To keep NH3 levels down, ventilation can be increased. The risk is then over ventilation, with all the negative consequences illustrated in Figure 24. A more effective solution is to limit NH3 production from fermenting floor litter (droppings and urine) by removing the litter quickly or keeping it dry. The maximum permissible NH3 content in the air rabbits breathe is 5 ppm.
Few studies have been made on the influence of light on rabbits, and these are almost exclusively concerned with the duration of lighting and seldom with light intensity. Furthermore, practical recommendations on lighting are based more on observations in rabbitries than on experimental findings.
Exposure to light for eight out of 24 hours favors spermatogenesis and sexual activity in bucks. Conversely, exposure for 14 to 16 hours a day favors female sexual activity and fertilization. In rational European production all breeding animals of both sexes get 16 hours of light. The slight drop in male sexual activity is amply compensated by good female reproduction rates (acceptance of the male and fertilization).
TABLE 50 Ventilation standards in France for enclosed rabbitries
Performance is more constant in windowless rabbitries with artificial lighting than in rabbitries which supplement sunlight by artificial lighting. Twenty-four-hour light trials caused reproduction disturbances in rabbits. It therefore seems best to limit the duration to 16 hours.
Observations from different rabbitries indicate that breeding does need considerable luminosity, at least 30 to 40 lux. In fact, many breeders who light their premises for 16 hours a day but not uniformly find that the does receiving the least light have the worst reproduction performance. When light distribution is made uniform, reproduction performance picks up.
In European rabbitries lighting is provided by incandescent lamps or fluorescent tubes (neon daylight type). The latter provide the necessary lux at a lower energy cost than incandescent lamps, but their installation cost is much higher. For flat-deck units the power consumption is 3 to 5 watts per square meter with light sources located no more than three meters from the animals.
Very young rabbits do not really need light, but 15 to 16 hours per day do no harm. Twenty-four-hour lighting, however, can cause disturbances which are hard to explain, such as diarrhoea unrelated to changes in the rate of caecotrophy. So breeders use either sunlight (in rabbitries with windows) or artificial lighting for one or two hours a day to satisfy the young rabbits' needs, at a set time so as not to disturb caecotrophic behavior. A much weaker light (5 to 10 lux) can be used for young rabbits.
Equipment in direct contact with the rabbits or their excrement becomes contaminated by the bacteria, viruses and fungi that accompany the animals. Cages, fittings and building walls must be designed so they can be easily cleaned, disinfected or replaced and not in turn become sources of contamination.
Portable components which can be cleaned outside the rabbitry building are especially recommended. Away from the rabbits stronger cleaning agents and more effective methods can be used - powerful disinfectants, lengthy soaking, prolonged exposure to the sun's rays.
Some materials are easier to disinfect than others. Wood is very hard to clean, but it can be periodically replaced in countries where it is plentiful. Plywood can be disinfected by steeping it in disinfectant solutions. Galvanized iron is easy to clean and disinfect but, unlike wood, is a poor insulator. Concrete, provided it is smooth, can be cleaned and disinfected, but portable concrete installations are virtually ruled out by their weight. Glazed earthenware can be used for some accessories (troughs, or even nest boxes).
FIGURE 24 Effect of air speed (V) and temperature (T°) on health of rabbits
FIGURE 25 Estimating air flow with a candle flame
TABLE 51 Brightness of various types of lighting
Cages (hutches) with straw litter. Traditional European rabbitries use straw litter. This material can be replaced by any other dry fibrous product which is not rough to the touch (soft shavings, hay, industrial cotton waste and so on). The cages are either of concrete (lasting 15 to 30 years) or wood (lasting not more than two years). Cages for breeding animals usually have at least a 60 to 70 cm × 80 to 100 cm floor space and are 50 to 60 cm high. Identical cages are often used for fattening five or six young rabbits (to 2.5 to 2.8 kg). The litter should be replaced weekly to control parasitism.
A variation called "deep litter" is used in slightly taller cages. The floor is covered with a bed (minimum thickness 15 to 20 cm) of absorbent material (turf, wood shavings) evenly covered with straw. Every six or seven weeks the whole lot, absorbing layer plus accumulated straw, has to be replaced. This system saves labor in cleaning and has the advantage of the comfort provided by the straw, but it does use a great deal of absorbent material so it is only applicable where this material is both readily available and cheap.
Cages without litter. In some regions rabbits are raised on litter less floors (hard earth or wooden planking). The hygienic conditions are nearly always deplorable (uncontrolled local humidity favoring parasitism), despite daily cleaning. This system is not recommended because of the health risks involved. The only exception is desert or sub desert regions, such as southern Tunisia, where humidity is not a problem.
The solution to the problem of changing litter has been to separate the animal from its excrement as soon as this is dropped. The rabbits are raised above the ground on a wire-mesh or slatted floor. Wire-mesh floors should be thick enough not to injure the pads of the rabbits' feet (diameter 2.4 mm, minimum 2 mm); the mesh should be wide enough to let the droppings fall through (diameter 1 to 1.3 cm, according to feed) but narrow enough to prevent the feet getting caught in the mesh.
There are good commercial meshes available in Europe. These measure, for example, 25 × 13 mm, 76 × 13 mm or 19 × 19 mm. To avoid injury to the rabbits' feet the wire is welded and then galvanized. Plastic mesh is impractical because no plastic material can withstand the animals' gnawing.
Various kinds of slats have been tried: wood, bamboo, plastic and metal, but the individual slats of the structure have to be spaced about 1.3 to 1.5 cm apart so droppings can fall through. Problems of comfort (slippery slats) and hygiene (materials which cannot be disinfected) are unfortunately very common. Wherever possible, wire mesh is preferable to slats. If slats are used instead of mesh, bamboo should be preferred to wood if possible. For heavy breeding animals, metal or inflexible plastic slats have been developed by French rabbit equipment manufacturers. While the results are satisfactory, the cost is unhappily much higher than that of wire mesh.
Only lightweight, calm animals or specially selected breeds (New Zealand White, Califorian) can be raised entirely on wire-mesh floors. Producers often compromise by raising the male and female breeding animals on litter and the fattening stock on mesh floors. The breeding animals of heavy breeds can be reared on slatted floors and the young on wire mesh; but slatted floors must be cleaned more frequently.
The dimensions of breeding cages without litter used in France are shown in Table 52 (floor generally of wire mesh but sometimes of metal or plastic slats). As may be seen by comparing these figures with the dimensions given earlier for cages using litter, the mesh floor makes it possible to reduce the area of the breeding cages. At the same time the animal density per square meter (fattening animals) can be increased to 16 to 18 on a mesh floor compared with ten on litter. This is because excrement is immediately eliminated, cutting the risk of parasite contamination. Densities exceeding 16 rabbits per square meter can reduce growth in 2.3 to 2.4 kg fattening rabbits (Table 53).
Cage systems. Cage systems vary in accessibility, supervision and comfort for the animals, as well as in convenience of waste removal. Straw-litter cages will be examined first. These are either single level (cages with wooden or plywood framework) or built on several levels (concrete cages, with watertight floor beneath straw litter). The principle is generally the same. Access is by a door in the front of the cage, usually made of mesh, or hardwood latticework that must be replaced fairly often. The other walls have no openings. They must be built in such a way that the rabbits cannot gnaw them. A rabbit cannot chew on a flat wall but will slowly but surely gnaw away any protruding part of the cage. Some examples of proper wood construction are given in Figure 26. Obviously, softwoods can be gnawed more easily than hardwoods.
Litter removal can be made more efficient if the rear walls of the cages are designed to swing out, as shown in Figure 27. The cages in the illustrations were built for a colony of French Angora rabbits (which have to be reared on litter), but can be used by any rabbitry using litter, whether the cages are of concrete, as in Figure 27, or wood.
For cages without litter, mainly cages with wire-mesh floors, the structure is usually in metal or wood (the latter out of reach of the rabbits' teeth). Walls are usually entirely in wire mesh, but this is not obligatory. There are four main systems: flat-deck, Californian, inclined-slope battery and compact battery. Figure 28 illustrates the four systems. All have been used in European rational production, which means that none is perfect. However, producers prefer the flat-deck system because it has the lowest rabbit density, thus alleviating the problems which arise when many animals are reared in the same building. The main characteristics of each system are described below.
Flat-deck. In this system the cages are all on one level. They usually open at the top. They can be suspended by chains or set on feet or low walls. Floor litter drops into pits (ranging in depth from 20 cm to 1.5 m). Shallow pits are cleared daily or every two or three days and deep pits every one to three years. The advantages of the flat-deck system are:
TABLE 52 Cage sizes for breeding animals in France (in centimeters)
TABLE 53 Influence of animal density on fattening rabbits
The main drawback is the low animal concentration per square metre of building, which increases the investment per animal housed despite the low-cost cages. However, flat-decks are recommended for nurseries. They could also be used for fattening, but at a higher investment cost per cage. This is usually the only type of housing in European production units now being established or enlarged.
California cage. In this system the cages are staggered, one deck higher than the other but not above it. The cages on the lower level open at the top and those on the upper level at the front (poorer access). Floor litter drops beneath the cages and is collected as in the flat-deck system. Advantages of the California system are:
Inclined-slope battery. The cages are placed one above the other. Waste slides down ferrocement or metal panels into troughs from which it is removed manually with scrapers or with running water. Cages obviously open at the front. Advantages of the inclined slope are:
Compact batteries. Waste can be removed by conveyor belt or vats can be installed beneath the cages and emptied by cable-operated scrapers (manual or electric).
FIGURE 26 Examples of correct and incorrect cage assembly, fostering good hygiene and resistance (a)
FIGURE 26 Examples of correct and incorrect cage assembly, fostering good hygiene and resistance (b)
FIGURE 26 Examples of correct and incorrect cage assembly, fostering good hygiene and resistance (c)
As with the inclined-slope battery, the cages must open from the front. The advantage of this system is that the maximum density of animals reduces costs per animal housed.
Compact batteries have virtually been abandoned for nurseries in rational European rabbitries.
A permanent dispenser of clean water is an essential item in each cage, wherever rabbits are not fed green forage alone. Using old cans or glass or earthenware pots as drinkers can create a hygiene problem. Rabbits tend to soil their water, especially if they are reared on straw litter. The drinkers should be fastened so that the rabbits cannot overturn them and so that the breeder can easily clean and refill them once or twice a day.
FIGURE 27 Swinging rear wall in concrete hutch for waste removal (a)
FIGURE 27 Swinging rear wall in concrete hutch for waste removal (b)
FIGURE 28 Four systems for using wire cages (a)
FIGURE 28 Four systems for using wire cages (b)
FIGURE 28 Four systems for using wire cages (c)
FIGURE 28 Four systems for using wire cages (d)
One possible improvement is an inverted water-bottle drinker. A bottle is inverted over a small trough (Figure 29), which is small enough to restrict pollution. The bottle is big so that it needs to be refilled less often and the breeder can see at a glance whether the animals' water intake is normal.
The best solution is an automatic drinker in every cage (Figure 30). The open drinker guarantees that the rabbits will be watered but it is expensive and there is a high risk of water pollution. A nipple drinker requires some learning on the part of the rabbits and wastes water. Even if there is no leak, the rabbits do not drink all the water that drips out. This can then wet litter or waste. The cost, however, is usually half that of an automatic open drinker. Above all, it ensures that the rabbits will always have clean water. A nipple drinker is the only kind that can be used if the rabbits are fed meal.
FIGURE 29 Inverted water-bottle drinker
Automatic drinkers are fed by water from a low-pressure tank 50 to 150 cm above cage level. This tank can be used to administer medicine with the water. It is usually filled either by water under pressure (automatic watering) or manually (semi-automatic watering). The tank must be in the shade so that the water will not heat, which would be bad for the rabbits. Further solutions are seen in Figure 31.
Feed troughs and racks
Cages should be fitted with troughs (feed hoppers for grain or pellets, small troughs for feed mashes) or forage racks, or both, depending on how the rabbits are to be fed. Troughs must be easy to clean and disinfect, so they should be detachable.
Figure 32 shows a hopper for grain or pellet feed. Troughs and racks should be easy to fill from outside the cage without having to open the access door, but the feed must be protected from bad weather and predators. The racks should hold at least one day's ration, the hoppers enough for two or three days, and the mash troughs a single ration.
The bars of the rack should be strong enough to withstand the rabbits' teeth and keep out the young rabbits, who like to lie on the forage but soil it. The feed hopper should also have a trap to keep the young out. The width between partitions in the feed box should be about 7 to 8 cm for medium breeds. The bars of the racks can be more closely spaced (1 to 2 cm) to prevent waste.
The nest box
The nest box should be considered one of the most important items of equipment in rabbit production. It directly affects the viability of the young in the preweaning stage, which is the high-risk mortality period (15 to 40 percent of live born rabbits). The job of the nest box is to reproduce conditions in the burrow of a wild doe and protect the young against attacks from the outside environment so that they can get through the first few difficult days of life in optimal comfort. To do this the nest box must:
FIGURE 30 Automatic drinkers (Open drinker)
FIGURE 30 Automatic drinkers (Nipple drinker)
FIGURE 31 Drinker made from a nipple in plastic bottle (a)
FIGURE 31 Clay drinker used as inverted water bottle (b)
FIGURE 32 Feed hopper (a)
FIGURE 32 Feed hopper (b)
The nest box is strongly advised for rabbitries using straw litter; it is essential in modern production. The box most recommended to meet these requirements, especially the doe's comfort when kindling and nursing, is a rectangular paralleled pipe at least 50 × 25 × 25 cm. If there is a dividing panel to keep the young together, at least 30 × 30 cm must be left on that side so that the mother can nurse them in comfort (Figure 33).
The nest box should be made from materials that are impossible to gnaw, easy to disinfect, insulating and resistant to moisture. In a well-heated rabbitry or a warm climate, galvanized iron can be used if some other material such as plywood, wood or plastic is used for the bottom. Untreated wood, fibreboard, plywood or plastic are frequently used in Europe. They insulate better than metals, but except for plastic are not always easy to disinfect.
To comply with the habits of the doe and her young, and to make the breeder's work easier, the box should have the following features:
FIGURE 33 Design for a nest box
The doe needs materials in addition to her own fur to make a good nest. Clean straw or soft, untreated wood chips are suitable and dried grasses can be used. Cellulose cottonwood must never be used.
The nest box can be placed inside or outside the cage. If it is outside it can be fastened to the side of the cage or preferably to the front, to make inspection easier.
In temperate climates
In countries with temperate or cool climates, rabbits are reared in buildings that are more or less closed in order to ensure year-round production. Traditional rabbit production in Europe and North America used to be outdoors in hutches and the animals stopped breeding from the end of summer until early spring. More regular or even nonstop production has been made possible by putting the cages indoors.
Temperature and lighting can be controlled to suit the animals. Now the use of wire-mesh cages makes the rabbits more susceptible to the temperature and air flow in their environment and these cannot be controlled fully except inside a building. Even so, if the rabbits are reared in semi-open, fairly unprotected environments, as is increasingly the case for fattening rabbits in Europe, the temperature and ventilation standards in Table 50 are no longer applicable. Animals raised outside are more tolerant of weather variations than indoor rabbits.
In Europe, breeding rabbits are usually reared in floor-level wire-mesh cages, and European rabbits are thus increasingly reared inside closed buildings, with controlled ventilation, artificial lighting, winter heating and possibly summer cooling. Such solutions are costly and the producer needs substantial initial capital to house all his or her animals.
In France, for example, the total outlay (building, caging, other equipment) is figured in terms of the "mother-cage". This reference unit corresponds to the total investment necessary for housing does, bucks, fattening young and future breeders, divided by the number of does. In France the outlay per mother-cage corresponds to the value of the young rabbits produced by the mother-cage in about 12 to 18 months.
Technically speaking, the buildings are like those used for battery chickens, with similar insulation, heating, ventilation and lighting. The standards for rabbit production, described at the beginning of this chapter, are, of course, different, but for the rest the rabbit breeder can make convenient use of descriptions of buildings designed for chickens. The many instances of old stables, barns and similar buildings being converted for rabbitries is worth mentioning. Some work is usually needed: sometimes insulation, nearly always ventilation, even for flat-deck systems. Unlike compact batteries, the flat-deck system does not need a very long building, and can therefore usually be installed in any existing construction.
In constant hot climates
In countries where the climate is hot but fairly constant (mean minima and maxima between 20° and 30°C) closed buildings are not really necessary. All that is needed is to protect the rabbits against the weather. If the cages are of wood or concrete (solid walls) it may be enough to roof each hutch, as shown in Figure 34. A roof should keep off rain and also heat from direct sunlight. The hutches can also be placed under trees big enough to shade them all day long. A roof should overhang enough to keep water out on rainy, windy days. The hutches should face away from the prevailing winds.
Wire-mesh cages can be grouped under a common insulating roof. This system, illustrated in Figure 35, was first tried in California. It is satisfactory provided the roofs overhang far enough at the sides to protect the animals properly. A hedge or fence around the roof structure is useful in protecting the rabbits from strong winds, and from predators.
In variable hot climates
In such climates the rabbits must be reared either on litter in hutches out in the open, or in cages placed inside a building which will serve as a buffer against the heat. Very satisfactory results have been obtained in Burkina Faso with buildings constructed with local palmyra (Borassus aethiopium), and a straw roof. The temperature in a building like this is more constant than in a more costly one made with concrete perpend.
At the Irapuato National Rabbit Centre in Mexico, solid buildings are generally left open in the front during the day and at night the shutters are closed to offset the drop in outside temperature. A daily temperature range of 20°C is common in the region. These shutters also make it possible to ventilate the interior during the daytime; they can be opened to suit the wind direction and regulated to respect the air-flow standards mentioned at the start of this chapter.
In some dry tropical regions of Africa where wood is scarce, producers have made satisfactory housing by building small round huts of unbaked earth bricks covered with straw, used for both cage and housing. Litter changing is often quite a problem with this sort of construction, however. The floor should slope slightly and be off the ground. Parasitism can be partially controlled by demolishing the hut every year and rebuilding it a few metres away. Such housing is thus only suitable for backyard rabbitries in which labor is not a problem.
FIGURE 34 Outdoor wooden cage
FIGURE 35 Wire-mesh cages under a common roof
The problem of predators differs greatly from region to region. The first step is to build cages sturdy enough to withstand the rabbits themselves and the numerous dogs and cats found in many villages. The rabbitry should be fenced to keep out children and large predators such as dogs. This also helps provide the quiet surroundings that rabbits require. According to needs, the building or complex of cages making up the rabbitry should be fenced with wire netting, a living thorn hedge or sturdy pickets.
Rats, mice and other rodents are also dangerous predators as they attack the young and carry diseases. Any rats in the rabbitry should first be exterminated, then the legs of the cages and the poles holding up the roof can be fitted with tin plates or cones at a height that will prevent rats from climbing them. Wire-mesh or concrete cages are more effective in keeping out rats than are wooden ones.
These pests can sometimes get into the feed racks or hoppers. Where such a risk exists the openings of these accessories have to be protected too, because a mother rabbit does not usually guard her young as a dog or even a mother rat would do. Snake control, in countries where this is a problem, is a far more difficult matter. Breeders get used to paying a certain toll to snakes. Fortunately, this is a small percentage of the rabbits.
Apart from the danger of predators, the risk of escape must also be considered. If the cages and buildings are not properly closed the rabbits can get out: either during handling operations or if the rabbitry is attacked by dogs or other large animals. A well-made outer fence usually ensures that the escaped rabbits can be recaptured quickly. If they do get away, they may well be irremediably lost.
There is no risk that escaped domestic rabbits will adapt to living wild and multiply, as they did in Australia and New Zealand. In almost every other country, escaped domestic rabbits have been unable to adapt to the wild. There are numerous predators of animals the size of rabbits (dog and cat families, birds of prey), which soon destroy them. The only risk is on certain islands where potential predators do not already exist, as was the case in Australia in the last century.
The usual techniques for cages and buildings known to give reliable results in all climates have been described so far. This does not rule out other practical solutions, some examples of which are given below.
In the southern parts of Tunisia and Algeria, breeders traditionally rear rabbits in a dry "well" 1.5 to 2 m deep (Finzi, Tani and Scappini, 1988). Breeders first dig the well and then lower the rabbits who will breed a colony, building burrows at the bottom of the well. These are used by does as nests, reflecting wild rabbit burrows. The breeder simply throws down fodder, which can occasion significant waste. In more elaborate rabbitries, the breeder digs a sloping tunnel from the bottom up to ground level where it emerges into a small pen. The feed is set in the pen and the rabbits come for it at will (usually at night). A trapdoor in a corner of the pen allows the rabbits to be caught. Of course this system can only work in countries where it hardly ever rains and the ground remains dry down to 1.5 to 2 m. Another drawback is uncontrolled breeding and the breeder may easily maintain totally unproductive rabbits for long periods. Predator control is virtually impossible as well, particularly for rats.
Finzi (1992) describes another underground pen for group rearing, the result of field observations and experiments, shown in Figure 36. Note the simple predator control and rabbit shelter concepts.
A system of cages using broad cement channels (0.8 to 1 m wide) laid horizontally has been described in Spain by Contera (1991). The rabbits live on a wire-mesh floor slightly narrower than the channels, and the droppings fall into the channel. The cage/shelters are conventionally equipped. In the hottest hours of summer, systematically sprinkling the outer walls of the channels cools the temperature compared with the outside, the water evaporating through the fairly porous cement of the channels.
Another heatproof device was described by De Lazzer and Finzi (1992): a system of dual-zone cages. Outside is the conventional wire-mesh cage with the feed racks and inside an "area" of equal volume buried beneath a layer of thick earth but accessible to the breeder through a trap, with the two connected by a 20 cm fibrocement tube (Figure 37). These authors have reconstituted a living area for the fattening or nursery rabbit(s) in the cage that resembles the living space of wild rabbits. During the hot hours of the day, or when there is a disturbance (or to kindle), the rabbits stay underground. When hungry or thirsty, they move into the wire-mesh cage. Experience has shown that the animals always use the outside as a latrine area. The technical results obtained by these authors in one year indicate a productivity wholly comparable with conventional closed rearing in cages, but at lower cost. No information is available on the labor required to build the system.
FIGURE 36 Rational enclosure for rabbitries
In every type of rabbit production unit the producer has to remove the excrement and waste from the rabbitry (straw litter and droppings which pile up under cages). These can be put to good use on the farm. The amounts and composition of waste vary according to housing and feeding conditions.
Rabbits eating balanced concentrate feeds and raised on mesh floors produce about 25 to 400 g of faeces and 0.5 to 0.8 liter of urine per mother-cage a day, depending on production intensively. This waste is much richer in nutrients than ordinary farm manure (Table 54). In fact, farm manure contains only 0.4 to 0.6 percent of each of the main fertilizer components: N, P2O5 and K2O.
The composition of the waste varies with the type of rabbit (Table 55). A comparison of the figures in Tables 54 and 55 shows a greater risk for nitrogen and phosphorus losses during storage than for other elements.
The average composition of the manure of rabbits reared on litter depends partly on the kind of feed but mostly on the kind and amount of litter used. If well preserved, the waste collected weekly will contain the nutrients in the faeces, part of those in the urine and those in the litter. Fertilizer "production" is therefore at least equal to that in a rabbitry not using litter.
FIGURE 37 Two-zone cage: wire-mesh (at left) and underground (at right). The breeder has access through the corrugated top laid over the underground area
TABLE 54 Average composition of excrement collected under wire-mesh cages of rabbits receiving balanced concentrates (percentage)
TABLE 55 Quantities and composition of excrement produced by different categories of rabbit
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