2023
RABBIT NUTRITION
MASTER DEGREE - CLASS 2023
DR/ YOUSRIA AHMED OSMAN
NUTRITION AND CLINICAL NUTRITION DEPARTMENT
Faculty of Veterinary Medicine, Benha University
Nutrition of Rabbits
Index
• Nutrient Requirements
• Water Requirements
• Calculation of Calorie Intake
• Carbohydrates
• Pelleted Diets
• Recommended Fiber Levels
Rabbits are small herbivores with specialized feeding needs and
digestive systems. They are selective eaters and choose nutrient-rich
leaves and new plant shoots over mature plant material that is higher
in fiber. Rabbits are therefore considered concentrate selectors,
because they naturally pick and choose foods higher in energy density,
which predisposes them to obesity in captivity.
Anatomically, rabbits are nonruminant herbivores with an enlarged
hindgut (hindgut fermenters). The large cecum supports a population
of microorganisms that uses nutrients not digested in the small
intestine.
Most of the bacterial population in the cecum is made up of the gram-
positive Bacteroides sp. This makes the rabbit very sensitive to oral
antibiotics; administration of oral antibiotics can disturb
the Bacteroides population and lead to fatal GI upsets. Separation of
digesta on the basis of particle size occurs in the hindgut. Peristaltic
action rapidly moves large particles (>0.5 mm), primarily lignocellulose,
through the colon and excretes them as hard fecal pellets. This is the
"indigestible fiber" component of the diet.
The clinical importance of a diet high in long particle length is to
maintain the motility of the cecum and colon. This is why these fibers
are sometimes referred to as "scratch factor," because they
mechanically stimulate GI motility.
Anti-peristaltic action moves smaller particles (<0.3 mm) and soluble
material into the cecum, where they undergo fermentation. This
component of the diet is known as "digestible" or "fermentable" fiber.
At intervals, the cecal contents are expelled as “soft feces” or
cecotrophs and consumed by the rabbit directly from the anus.
Cecotrophs ingestion is highest when rabbits are fed a diet high in non-
digestible fiber.
This reingested material provides microbial protein, vitamins (including
all the B vitamins needed), and small quantities of volatile fatty acids,
which are essential in rabbit nutrition. However, because amino acids
obtained in this manner make only a minor contribution to the rabbits’
protein needs (particularly young, growing rabbits), the diet must
supply the additional amino acids, although the requirements for
essential amino acids in rabbits have not yet been defined.
Rabbit with hay
Rabbits digest fiber poorly because
of the selective separation and rapid
excretion of large particles in the
hindgut. A generous amount of
dietary fiber (~15% crude fiber) is
needed to promote intestinal motility
and minimize intestinal disease.
High-fiber intake can be provided by
Use of ad lib timothy hay (~30%–
35% fiber).
Fiber may also absorb bacterial
toxins and eliminate them via the
hard feces. Diets low in fiber promote
an increased incidence of intestinal
problems, eg, enterotoxemia.
Carbohydrates will actually inhibit motilin release. Motilin is a
polypeptide hormone secreted by cells of the duodenum and jejunum,
which stimulates the GI smooth muscle. Excess starch can also be
substrate for the proliferation of pathogenic bacteria such
as Clostridium spiroforme, which produce a potent toxin.
Cecum fermentation produces volatile fatty acids, which are
responsible for 40% of the rabbits' calorie requirement. Volatile fatty
acids also aid in the control of pathogenic organisms by helping to
maintain the normal pH (6–7) in the cecum.
A dietary supply of vitamins A, D, and E is necessary. Bacteria in the
gut synthesize B vitamins and vitamin K in adequate quantities; thus,
dietary supplements are unnecessary.
Disease and stress may increase the daily vitamin requirements.
Feed preparation and storage must be done in a manner that will
reduce losses from oxidation, which destroys vitamins A and E more
readily than other vitamins.
Diets containing ≥30% of alfalfa meal generally provide sufficient
vitamin A. Levels of vitamin A in the diet must be >5,000 IU/kg
and <75,000 IU/kg. Levels out of this range may cause abortion,
resorbed litters, and fetal hydrocephalus.
Vitamin E deficiency has been associated with infertility, muscular
dystrophy, and fetal and neonatal death.
Pet rabbit diets sold in pet stores or even in bulk at feed stores may
not have adequate turnover, which may result in nutritional deficiency.
All the components of the basic diet (ie, protein, fiber, fat, and energy)
should be managed in consideration of the life stage (growth,
gestation, lactation, and maintenance), breed, condition, and lifestyle
of the rabbit. Ratios should meet the nutrient requirements of the
National Research Council
(Table 1: Nutrient Requirements of Rabbits).
Total (and Digestible) Fat % Fiber % Digestible Total Digestible
Protein % Carbohydrate % Nutrient %
(NFEa)
Maintenance 12 (9) 1.5–2 14–20 40–45 50–60
Growth and 16 (12) 2–4 14–16 45–50 60–70
finishing
Gestation 15 (11) 2–3 14–16 45–50 55–65
Lactation (with 17 (13) 2.5–3.5 12–14 45–50 65–75
litter of 7–8)
a
NFE = nitrogen-free extract
Pelleted rabbit feeds provide good nutrition at reasonable cost. Fresh,
clean water should always be available. Prolonged intake of typical
commercial diets containing alfalfa meal by laboratory or pet rabbits
kept for extended periods under maintenance conditions may lead to
kidney damage and calcium carbonate deposits in the urinary tract.
Ad lib timothy hay is usually recommended for the maintenance diet of
adult rabbits. Reducing the calcium level to 0.4%–0.5% of the diet for
non-lactating rabbits helps reduce these problems.
This can be accomplished by feeding pelleted diets with a timothy hay
base.
Adult pet rabbits not intended for breeding should be fed a high-fiber
pelleted diet, restricted to ¼ cup/5 lb body wt/day to prevent obesity
and maintain GI health.
Water Requirements for Rabbits
It has been shown in metabolic
studies that a rabbit will
consume water at a rate of
approximately 120 mL/kg/day.
This is about twice the amount
usually calculated for an equally
sized dog or cat. The higher
water consumption makes
sense when considering the
physiology of the GI tract and
metabolic scaling. Dehydrated
rabbits should receive twice the
maintenance fluids (240
mL/kg/day, or 10 mL/kg/hr) for
at least 24 hours of
hospitalization. If a rabbit is
presented for anorexia, it is most often also dehydrated. It has also
been shown that a rabbit will drink significantly more water from an
open bowl than a sipper bottle.
Calculation of Calorie Intake for Rabbits
To establish the daily maintenance calorie requirement for a rabbit,
the animal’s basal metabolic rate (BMR) should first be calculated as
follows:
• BMR = kW to the power of 0.75 (BMR= kcal/kg/day; k =
kcal/kg constant; W = weight in kg; for placental mammals, the
k constant is 70).
• The BMR is the amount of calories necessary only to maintain
the rabbit, not taking into consideration the clinical
presentation.
• The BMR is multiplied by an illness factor of 1.2–2.0 to
account for metabolic needs greater than maintenance.
Growth also increases the metabolic rate (illness factor of 1.5–3.0).
However, starvation and emaciation decrease the metabolic rate,
lowering the caloric requirement (illness factor of 0.5–0.9).
Carbohydrates for Rabbits
The role of carbohydrates in rabbit diets is often oversimplified, and
generalized statements such as "carbohydrates are bad for rabbits"
do not paint an adequate picture.
The sensitivity to high-starch diets is controversial in adult rabbits,
and the role of starch as a predisposing factor for dysbiosis remains
unclear. However, it has been shown that adult rabbits seem to
digest starch more efficiently than young ones.
Polysaccharides, such as gluco-oligosaccharides (starches that
release glucose after hydrolysis), have been shown to cause
diarrhea in young rabbits. Other starches, such as fructo-
oligosaccharides (composed of short chains of fructose, found in
many fruits and vegetables, such as onion, chicory, garlic,
asparagus, banana, artichoke, and many others) or galacto-
oligosaccharides (short chains of galactose, found in the group of
prebiotics) do not have the same effect.
Diet supplemented with fructo-oligosaccharides was shown to
decrease morbidity in rabbits after the introduction of
pathogenic Escherichia coli. Thus, fructo-oligosaccharides are now
included in many rabbit foods. In addition, it has been shown that
15% of molasses in the food is well tolerated by growing rabbits.
Molasses is also rich in calcium, iron, and magnesium.
Pelleted Diets for Rabbits
When pellets are made, the ingredients need to be ground and
pressed together to form a cylinder. Extruded or expanded diets are
coarse ground, maintaining intact longer fibers, then cooked to form
a paste, which is forced into a shaped pellet. The process of
extruding food results in a lightweight biscuit. The advantage is that
long-fiber particles can be incorporated without the pellets becoming
friable and disintegrating.
The heat treatment applied while cooking the raw ingredients
increases starch digestibility. In addition, extruded diets are more
palatable and digestible than pelleted rations.
Pelleted diets should be fed according to the manufacturer's
recommendations, because an overconsumption of pellets can
cause obesity or hypercalciuria.
Recommended Fiber Levels for Rabbits
Indigestible fiber is important for stimulating GI motility, preventing
behavioral problems (ex, fur chewing), providing dental wearing, and
stimulating appetite and ingestion of cecotrophs. Up to 20% of crude
fiber, with 12.5% of indigestible fiber, is generally recommended for
pet rabbits. Because crude fiber is mainly a measurement of the
lignin and cellulose component of the diet (indigestible fiber), it is not
helpful for determining the fermentable or digestible fiber.
