Other Causes of Hair Loss
Hair loss only on the face may be caused by improperly cut wire for feeder installation or rough places on the feeder itself. Such rough spots scratch the rabbit’s face, and a bacterial infection (usually Staphylococcus) sets in, causing hair loss on the face. Changing the feeder or smoothing the rough spots with emery cloth will alleviate the problem.
Sanitation
Sanitation is very important in controlling disease. Ideally, cages should be cleaned daily. Any manure hanging on the bottoms of cages should be removed with a wire brush. This helps control enteritis and hepatic coccidiosis. A wire brush mounted on a long handle is a handy tool. A battery-driven electric drill with a wire brush head can be mounted on a handle and used for cleaning the bottoms of cages. A plastic toilet-bowl brush will be less damaging to the galvanizing on the wire but will need more frequent replacement. Cages may be brushed or sprayed with a bleach solution (30 ml of bleach per liter of water). Disinfectants are effective only on the surface, so cages must be thoroughly cleaned to remove attached dirt prior to disinfecting. Rabbits excrete large amounts of calcium carbonate in their urine; calcium deposits may build up (Fig. 5.18). Calcium carbonate is soluble in acid, so a mildly acidic solution (e.g., vinegar) will aid in removing these deposits.
Fig. 5.18. An example of a deposit of calcium carbonate in a rabbit cage. Rabbits excrete large amounts of calcium in their urine. (Courtesy of OSU Rabbit Research Center)
Hair should not be allowed to build up on cages and elsewhere in the rabbitry (Fig. 5.19). Hair can be removed from cages by burning with a propane torch. Be careful with a torch, as it can be a fire hazard. Do not use a torch to burn hair or cobwebs off the ceiling or walls. A vacuum cleaner may also be used for removing hair.
Fig. 5.19. Accumulation of hair on cage bottoms. (Courtesy of D.J. Harris)
Flies in the rabbitry are a nuisance. It is conceivable that they could be vectors in the spread of diseases such as pasteurellosis, but this hasn’t been proven. In an urban or suburban area, the rabbit raiser can be the target of legal action if the rabbitry is the neighborhood source of flies. Flies can be controlled by the use of screens to keep them out of the rabbitry and by the use of baits and spraying programs to eliminate them if they do gain entrance. Such management procedures as repair of leaky water valves are important to keep the manure habitat as dry as possible. (This also helps minimize ammonia production.) Insecticides can be of the organophosphate type, such as malathion, or of the natural type, such as pyrethrum products (obtained from the pyrethrum flower). Spray contact with the rabbits should be mini-mized-especially with organophosphates. A good rule of thumb is to use only spray products that are safe for use around lactating dairy cattle. Another method of fly control is the use of natural fly predators, such as beetles and wasps, that can be purchased from commercial sources. The naturally occurring black soldier fly, Hermetia illucens, is also beneficial for fly control in the rabbitry. The females, about the size of wasps, live on nectar from flowers and only enter the rabbitry to lay eggs. They fly close to the ground, lay their eggs in the manure pack, and leave. The larvae are about 2 cm long and are a dirty gray color. They out-compete the filth fly larvae (primarily houseflies and stable flies) for food and will reduce the numbers that hatch. They also will reduce the volume and water content of the manure pack. They are very active and will result in the manure pack moving into the aisles each night. Shoveling the material back under the cages each day is a small price to pay for good fly control.
Growing earthworms in the manure pack will also help keep filth fly populations under control by stirring and drying the manure. However, moisture requirements for worms are much higher than are generally advisable for rabbits, so growing worms under the rabbits may result in increased incidence of pas-teurellosis and other respiratory diseases.
A white fungus is often observed on the manure beneath the cages (Fig. 5.20). It is probably harmless, although it is possible that spores released by mature fungi could contribute to respiratory disease of the rabbits. It can be controlled if desired by application of a fungicide to the manure.
Fig. 5.20. A white fungus is often observed growing on rabbit manure beneath the cages. (Courtesy of P.R. Cheeke)
Shedding or Molting
The rabbit’s coat is prime when the hairs have a good sheen, are tight, and have attained their maximum length. The skin is white and the hair flows back into place evenly when the coat is rubbed from the rump to the shoulders.
Unprimeness is indicated by a dull, uneven coat and loose hair. The hair does not flow back evenly when the coat is rubbed from the rump to the shoulders. Patches of new fibers can be seen, and these new fibers will appear in a growth pattern that varies from animal to animal. The skin of these new hair growth areas is dark and easily detected on rabbits with colored coats.
The pattern of shedding in rabbits has not been definitely established. There is a juvenile molt that begins when a rabbit is about two months old and lasts until it is four to six months of age. Heavy feeding of the young tends to cause the molt at an earlier age. In addition, there is the annual molt with mature rabbits. This molt varies in time of appearance in different geographical areas. Rabbits may be thrown into molt by disease, going “off feed,” the sudden occurrence of unseasonably high temperatures, or other stresses. Evidence of molting in the herd is the accumulation of loose hair on the wire sides and in the corners of the cages and the droppings being bound together by embedded fibers.
Shedding first occurs on the sides of the rump and the thighs, followed by the back, then increasingly in areas down over the sides. There is a pronounced degree of similarity in the size and location of the ingrowing new coat areas on both the right and left sides of the rabbit.
A high quality diet and high feed intake promote molting. The growth rate of hair is more rapid with a high nutrient intake, so the rate of turnover of hair is greater. Restricted feeding of adult show animals reduces the amount of hair shedding and keeps the fur in prime condition for a longer period. Some rabbit raisers claim that molting adversely affects reproductive performance, but this belief is not well substantiated. In fact, little attention is paid to molting in commercial meat rabbit operations.
Environmental Effects on Rabbit Performance
Temperature
Rabbits are very susceptible to heat stress because they have few functional sweat glands and have difficulty in eliminating body heat when the environmental temperature is high. Heat stressed animals stretch out to maximize body surface area for heat elimination. Animals respond differently to a sudden acute exposure to high temperature than to chronic exposure when reared under high environmental temperatures. In the tropics, rabbits can be successfully raised under
