Feed Intake and Digestibility
Camels have a lower dry matter intake than cattle or horses. Camels typically consume only 1.7% of bodyweight as dry matter, compared with 3-4% bodyweight for horses and cattle. Camels require 70% of dry matter intake as roughage. Camels typically have higher digestibility coefficients compared with ruminants.
Camels can efficiently digest low quality roughage’s because of the wide range of ruminal micro flora which can adapt to a range of forages, active rumination, and high levels of urea recycling.
Fermentation
Camels produce the volatile fatty acids acetate, propionate and butyrate from fermentation in their fore stomach, in similar molar proportions to ruminants given roughage based diets. Compared with ruminants, camels can extract more energy from the food they consume. This has been attributed to their specialized metabolism of glucose and urea recycling.
Energy
The ME requirement for maintenance in camels is lower than for cattle. A 450kg camel requires only 37 MJ ME for maintenance compared with 52 MJ ME for cattle. The DE requirement for a 450kg horse is 48 MJ DE/day, which approximates 40 MJ ME/day. Camels therefore have an energy requirement similar to horses for maintenance.
Racing camels have an energy requirement of 2 MJ ME/ km travelled, i.e. an additional 20 MJ ME for an average 10km race. For feeds with an energy density of less than 10, this represents an additional feed intake of over 2 kg/day, which is a 25% increase in feed intake. The challenge therefore is to increase energy intake without increasing the amount of bulky feed, and without causing rumen dysfunction by feeding excess grain.
Camels, like horses have an increased energy demand for muscular function for racing, which requires supplementation of the basal diet with an additional energy source from hay or grain.
Glucose metabolism
The blood glucose concentrations (130 mg/100ml) in camels are much higher than in ruminants (63 mg/100ml) and horses (90 mg/100ml) (Table 1), despite having a ruminant pattern of digestion which does not yield glucose for absorption.
Although the glucose turnover rate is similar between camels and sheep (1.7 mg/min/kg bodyweight), when corrected for metabolic body size, camels have a glucose entry rate at least 60% greater than in sheep (4.3 and 2.6 mg/min/kg Bwt 0.75).
Camels have higher concentrations of the hormone glucagon compared with other mammals. The role of glucagon is to increase glucose output from the liver by increasing glycogenolysis (glucose from glycogen) and gluconeogenesis (glucose from amino acids).
Camels therefore produce greater quantities of glucose compared with true ruminants, presumably as a survival mechanism. This also allows camels to produce higher levels of ATP from glucose for muscular function, and highlights the importance of feeds that can provide glucose or glucose forming substrates (gluconeogenic amino acids).
Oil
Camels can store fat efficiently in their hump, and in the adequately fed camel, the hump can represent 20% of the camel’s total body weight. The oxidation of fat in adipose tissue yields more energy (1g fat=9.3 kcal) than the oxidation of carbohydrates (1g=4.2 kcal).
Racing camels require an additional 2.0 MJ ME /km travelled, and therefore require an additional energy dense feed in addition to roughage. It has been suggested that inclusion of energy dense oils in racing camel diets may be beneficial. Up to 200g/day of protected fat has been fed without causing metabolic and nutritional disorders. Little research has been conducted however into the type and nature of dietary oil.
Oils are useful feed supplements to provide slow release energy for endurance exercise, or long distance races. It is believed that camels don’t begin to metabolize fat stores until after a period of 1.5 hrs of sub maximal exercise (20km) suggesting that energy provided by fats is only of importance for endurance races. It is further suggested that oils are of no value for short races (8-10km) because of the slow metabolism of oils.
Research suggests that the maximum oil inclusion in camel diets is 3%, because of the effects of oil on reducing fermentation. There is no information available on feeding different types of oils to camels.
In cattle, it is the free fatty acid concentrations that impact on rumen fermentation, and not the total fat concentration. In ruminants, rumen function is impaired at free fatty acids (FFA) at levels greater than 3-4% in the diet. For example, polyunsaturated oils such as canola and soybean contain approximately 80% FFA, and so can only be fed at 3-4% of the diet. By comparison, saturated oils such as coconut oil contain only 30- 35% FFA, and so can be fed up to 9-10% of the diet.
In horses, polyunsaturated oils which are long chain (C18) are slowly absorbed into the lymphatics and then slowly metabolized in the liver. By comparison, medium chain fatty acids (C12-C14) such as in coconut oil are readily absorbed into the portal blood and metabolized in the liver.
Saturated oils such as coconut oils have been shown to be beneficial energy sources to both cattle and horses, and may well be beneficial to racing camels as an energy substrate. Coconut oils can be fed at higher levels, and are more readily digested and absorbed compared to polyunsaturated oils.
Protein
Basal protein requirements in camels (450 kg bodyweight) have been estimated at 300g DCP / day for adult working and racing camels.
Nitrogen retention in camels is greater than sheep given a diet of 4% crude protein. During a state of dehydration the camel’s nitrogen retention is increased by 150%, whereas in sheep it is only increased by an increment of 34%. Supplementation of urea has found to have a variable effect on the VFA producing microbes in the camel.
Camels recycle greater quantities of urea to the rumen, which in turn would support higher levels of digestion. It is reported that young camels given low protein diets respond well to supplements of bypass protein, as shown with weaned sheep and cattle. Proteins with a high biological value give the best results.
Grain feeding
The main source of roughage for the racing camel is fresh cut alfalfa. Typically, much of the camel’s energy is derived from barley. A normal diet for the racing camel consists of “10kg of alfalfa tops, 3-4kg of soaked whole barley, 1kg dates, 2L of fresh milk, occasional hay, and some electrolyte, vitamin and mineral supplements”.
Although camels perform well on these diets, they often suffer digestive upsets including colic and rumen dysfunction, similar to grain poisoning in cattle.