Camel Physiology

Camels are a member of the suborder Tylopoda, which is located between the suborders Suina (including pigs) and Ruminantia (including cattle).  Camels have adapted to the harsh arid environments inhabit allowing them to maximise the digestion of low quality feeds to a greater extent than ruminants. Through browsing, camels are able to select a high quality diet. There is a lack of research into camel nutrition and data is often extrapolated from ruminants.

With racing camels, the aim is to feed a pseudo-ruminant to perform like a horse.  That is, to provide digestible energy (DE) to supplement the energy from roughage to meet the energy demands for high intensity exercise. In horses, the additional DE is traditionally provided by feeding grains together with digestible fiber. It is now known that feeding high levels of starch to both ruminants and horses is the main cause of temperament changes (fizzy or hot behavior), and metabolic disorders including colic, laminitis and tying up. The effects of starch have been alleviated in most cases by replacement of dietary starch with digestible fiber and non starch, energy feeds such as oil. Anecdotal evidence suggests that camels also suffer from temperament changes and metabolic disorders on high grain diets.


The mucosal membrane of the “rumen” in camels is smooth, which is different to all other ruminants. The rumen sacculations contain accessory salivary glands which aid in recycling to the rumen during periods of water deprivation.  Like ruminants, the camel “rumen” contains bacteria and protozoa.

The recycled saliva is very alkaline, and subsequently the pH of the rumen is normally pH 7.5. In the wild, the camels can browse most types of vegetation, and the rumen can operate as an efficient organ. With hand feeding grains and short chopped roughages however, the incidence of rumen dysfunction is greater.

The omasum in camels is also very different to that in cattle. The mucous membrane is glandular, and is not packed in leaves as seen in cattle. It is joined directly to the abomasum, and the contents are moist. This contributes to the higher efficiency of digestion in camels.

Physiology of Exercise

The energy cost of locomotion in camels is considerably lower than horses at moderate to high speeds. At 15km per hour, the horse requires 25% higher energy, and at 30km/hour, the horse requires 50% more energy than camels.  The energy cost of locomotion (ml O2/kg at 22 km/hour) was 85 in camels compared with 160 in horses.

The lower energy cost for locomotion in camels relates to the combined effects of

  • Musculoskeletal function. Unlike cattle, camels have less fusion in the bones of the lower leg which allows them to move faster and more efficiently (Ferguson 1997)
  • camels pace rather than gallop,
  • Low oxygen requirement. The maximal capacity of an animal to exercise aerobically is determined by oxygen consumption. VO2max is a measure of aerobic capacity, and is the volume of oxygen consumed during a minute of exercise. The aerobic capacity of camels (VO2max) was 53ml/kg/min at 30km/hour, which is significantly lower than that in thoroughbreds (100-160 ml/kg/min). The VO2max in cattle was 55-60 ml/kg/min. This reflects the very low oxygen requirement of camels for rest and exercise in comparison with horses
  • Higher lactate threshold. Camels can perform at high levels of intensity before lactate accumulates in the blood. It is considered that 4mM/L of serum lactate represents the anaerobic threshold in many species, i.e. the level of exercise above which aerobic exercise is supplemented by anaerobic exercise. The Lactate Threshold is the level of exercise beyond which the rate of lactate production from pyruvate exceeds the rate that pyruvate is used in aerobic energy metabolism in the mitochondria. The accumulation of lactate causes a block to energy production, and rapid muscle fatigue.

Camels will perform at up to 95% of VO2max before plasma lactate levels reach 4 mM/L, whereas this occurs in other species at 50-60% VO2max.  Elite horses have lactate thresholds at or above 80% of VO2max. Camels can achieve this normally.

  • At rest, the racing camel depends on lipid combustion to provide energy substrates. At low, sub maximal speeds, carbohydrates are the dominant fuels, and there is a good balance between lactate metabolism and accumulation, because lactate does not accumulate until close to VO2max. Camel has extraordinarily high Krebbs cycle activity.

Muscle Fibers

There is a large variation between muscle types, and between camels in the proportion of Type I and Type II muscle fibers. Camels predominantly have slow twitch, slow contracting fibers (Type I) suitable for endurance exercise. Type II, fast acting fibers (for explosive exercise) is not common. Camel muscles have very high levels of oxidative enzymes compared to horses. Camels can utilize various types of energy substrate for ATP production for muscular activity, i.e. glycogen, oil, glucose, lactate, and amino acids.


During endurance exercise (20km/hour for 90 minutes), camels preferentially use slow twitch muscles (Type I), which use aerobic metabolic pathways to supply ATP from glycogen and fat.

High Intensity Exercise

High intensity exercise in camels is in an 8 km race where speeds exceed 33 km/hour. During high intensity exercise, camels use fast twitch (Type II) fibers, and rely on anaerobic metabolism of glucose to produce ATP.  Once anaerobic metabolism is activated, metabolic acidosis due to lactate accumulation quickly occurs. Camels take longer than horses to clear lactate; however they can quickly restore muscle glycogen.

In horses sprinting over short distance races, the aerobic energy system still provides up to 70% of the total energy. This emphasizes the importance of the type of energy substrates supplied to support the aerobic energy system and anaerobic energy systems.