I. INTRODUCTION

Camel milk: What possible importance can camel milk have in the year 1981 in a world beset with a multitude of problems? The answer to this is clear when we consider that one of the biggest problems confronting mankind today is malnourishment. Camel milk can certainly play a far more important role in the prevention of malnutrition than it does today. Growing and raising foodstuffs for the rapidly increasing human population is especially precarious in the hot and arid zones of the world - the very areas where the camel is one of the few animals not only to survive, but also to benefit man.

Before presenting data on milk production, both quantity and quality, one must consider in detail all the relevant information about the camel in order to ascertain the full value that this animal can play in human nutrition.

Camels, or the family of camels, the Camelidae, are found throughout the world and all camels will be mentioned when possible; however, this report deals mainly with the one-humped dromedary, which is found in the desert and semi-desert areas.

Milk is the main food obtained from a herd of camels, (Dahl, 1979). The one-humped camel was domesticated about 3000 B.C.E. in southern Arabia (Bullet, 1975), mainly for its meat and milk (Epstein, 1971). The camels were, and still are, valued as riding, baggade and work animals, as well as providers of hair and hides. In arid zones the camel is a better provider of food than the cow, which is severely affected by the heat, scarcity of water and feed (Sweet, 1965).

Camels originated in North America when the land masses were still joined (Leuner, 1963). These animals were no larger than hares. Here they remained from the upper Eocene throughout the Tertiary period, into the Pleistocene epoch, a period of 40 million years. Continued evolution produced the very large American camels. From North America, meanwhile, the animals migrated to other parts of the world, finally disappearing from their original area. The various types and breeds in the camel family are probably a result of evolutionary adaptation to the various environments to which the animals were exposed.

Some of the camels migrated to the deserts and semi-deserts of northern Africa and the Middle East. Remains of camels have been found in old Palestine, dating to 1800 B.C.E. Field (1979) considered that further migration of camels in Africa was prevented by their susceptibility to tsetseborne trypanosomiasis. However, the camel has been incriminated as the probable host which became infected with Trypanosoma brucei in the northern tsetse areas and spread the infection which evolved to mechanically-transmitted T. evansi, throughout northern Africa into Asia. These camels have one-hump and long spindly legs.

The two-humped camel, the Bactrian, was domesticated on the border of Iran and Turkmenistan and spread to an area bordered by the Crimea, southern Siberia, Mongolia and China. These animals are stockier than the dromedary and covered by a thicker wool.

The new-world Camelidae are smaller versions of the camels and live in the heights of the mountains in South America.

All the members of the camel family are found in the order of the Artiodactyla (even-toed ungulates); suborder: Tylopoda (pad-footed); family: Camelidae. The old-world genus is the Camelus, having the two species of the Bactrianus (two-humped) and Dromedarius (one-humped). The new-world genus of the Lama has three species, while the genus of Vicugna has only one species.

Although they chew cud, camels differ from true ruminants in a few anatomical features (Cloudley-Thompson, 1969). Adult camels have two incisor teeth in their upper jaws; they lack an omasum, the third stomach division of the ruminants, which is considered the water reabsorbing portion of the stomach; they have no gallbladder; and the hooves have been reduced to claw-like toes, projecting beyond the pads. In India, camel meat is not eaten by the Hindus (Simoons, 1961), nor by the Christian Copts of Egypt, Zoroastrians of Iran, Mandaeans of Iraq and Iran, Nosaioris of Syria, Ethiopians of Christian Faith nor in Israel the camel is considered as being unsuitable as a source of meat.

Within the arid regions the camel-breeding tribes have maintained a dominant position over other societies by virtue of their ability to exploit the often poor grazing ranges (Sweet, 1965). Camel-owning tribes are continually on the move, looking for grazing and water for their animals (Elamin, 1979). They can wander over 1 000 km in a season. The distance covered depends on the availability of water and feed. With rapidly expanding urbanization, these wanderings are causing clashes between cultures and destroying the grazing areas of the camels.

Because of its importance as a means of survival for the desert dwellers, the camel often plays an important role in the social and cultural heritage of the tribes. For instance, in various cultures (Hartley, 1979) ownership of a camel begins when a male child is born. He is presented with a femalecalf. The child's umbilical cord is placed in a sac and tied around the neck of the camel. In other societies the camel is used for attracting wives or paying off “criminal” offences (Dickson, 1951).

Camels have been introduced by man into various parts of the world, mainly as baggage animals for the arid zones of the country. This happened in Australia, where the camels escaped into the wild and are now considered vermin (McKnight, 1969). In Italy, Spain, South Africa and Texas in the USA camels were also introduced as pack animals, but they soon disappeared. Camels were introduced into the Canary Islands from Morocco in 1402 (Buillet, 1975), where they are still in use in agriculture and as beasts of burden.

In Sudan (El-Amin, 1979) there is at present one of the largest populations of one-humped camels in the world. They are found mainly in the arid and semi-arid areas of the country, where the average rainfall is less than 350 mm per year.

In the Horn of Africa (Hartley, 1979) the camel is found in the arid and semi-arid rangelands in Ethiopia, Djibuti, Somalia and Kenya. In these areas water supplies range from abundant in the riverine areas, to extreme aridity. In these areas the inhabitants are mainly pastoral and the camels roam according to the range conditions. In the dry season the camels are watered once every 10–20 days, compared with every 3–8 days for sheep and goats and every 2–3 days for cattle. The movement of the camels away from the living centres is divided primarily into far-moving dry herds and the closer-by milch animals.

Baggage camel
Photo 1

Ploughing with aid of the camel
Photo 2

The Boran of Ethiopia and Somalia rank their animals as follows: lactating caws, dry cows, lactating camels, dry camels, sheep and goats (Lewis, 1974). The pastoral Somali nomads have only two types of herding units. The first consists of the camels herded by the young unmarried men, which sometimes graze hundreds of kilometers from wells. The second group of milch animals are herded by the family unit of husband, wife, unmarried daughters and young sons. During the rainy season, when feed is freely available, the two herding units meet, and with both milk and meat in abundance, collective rituals and feasts take place.

For the Gabbra and Rendille tribes of northern Kenya, the camel is still the most important livestock (Sato, 1976; Torry, 1973). Much of their culture revolves around the camel owing to the animal's ability to survive the extreme aridity and to supply milk, which is the staple diet of these tribes.

In Pakistan, as well, there are areas with extremely arid pastures in which the only livestock that can produce milk, meat, wool and skins is the camel (Knoess, 1979). The camels are also valued as pack animals, carrying up to 600 kg on their backs and are also used for pulling carts.

In China, Mongolia and Russia the two-humped Bactrian camel thrives. (Dong Wei, 1979). They are mainly used as pack, riding and draught animals. The wool is of some importance, reaching 1 500 tons per year. Meat and milk are of lesser importance (Dong Wei, 1981).

In South America the guanaco and vicugna are the wild forms of the camel family (Bustinza Choque, 1979). The llama and alpaca have been domesticated. These Camelidae are utilized mainly as pack animals, but also supply meat, skin and fur. The South American cameloids live in a semidesert habitat that ranges from sea level to the Andean high country, at elevations of 5 000 m or more.

The questions that must be answered are:

1. What makes the camel, particularly the one-humped Arabian camel, so special? Or how is this animal able to adapt so perfectly to his environment?

2. Can the natural traits of the animal be improved upon for man's use?

3. If this animal can be of such benefit to man, why hasn't it been more widely used up to now?

4. What is the composition of camel milk? How much milk can it give? What is its fertility capability?

5. What does the camel eat?

The reason why the camel has not been more widely used is given in the opening remarks of the International Symposium on camels in Sudan, organized by the International Foundation for Science (El-Karouti, 1970). It was stated that “the prejudice against the camel stems from a misconception that it is of low economic value and is synonymous to under-development”. It is universally accepted that milk and meat for human consumption in established communities are supplied mainly by cattle, sheep and goats. This applies even to arid zones, although it is actually the dromedary which can survive and let alone producing milk and meat for humans in these areas, while other animals have difficulty in staying alive.

Thus, almost no research as to the capacity of the camel to produce milk and meat under drought conditions, in areas, or under conditions where human nutrition is so precarious, has been done. As former camel owners become sedentary, the camel disappears. No thought is given to the ability of this animal to produce food in severe drought periods. In many places of the world the development of infrastructure, especially roads, has caused the camel to lose its value as a riding animal or beast of burden. Motor transport can now reach most outlying areas. However, in countries such as Afghanistan, Pakistan and India, motor transport is still extremely expensive and in those areas, which are undeveloped and not suited for motor vehicles, the camel is still a prized animal. The trends in camel holding ca be seen in Table 1. Thus it can be seen that in most countries the camel population is declining. The present-day distribution of camels shows that the limit of camel breeding does not pass the 50 cm rain area (Mason, 1979). The Bactrian camel is not found in temperatures over 21°C.

Research in physiology, endocrinology, husbandry, various diseases and their control are among the basic requirements from which further development and reorientation of the camel industry can start. While many aspects of camel anatomy, physiology and diseases are well documented, knowledge of husbandry is lagging far behind. Improved methods of breeding and intensive husbandry have not been systematically examined. The introduction of hardy plants into arid areas for camel fodder is only in its embryo state.

The changes in shape and size of camels from their original small size (Zeuner, 1963) were obviously caused by interractions with their environments. This is also true for the wide changes that have been described for the various physiological mechanism. The changes in normal physiological responses to the environment not only allow the animal to survive, but explain the ability of this animal to supply nutrition for their young. This supply cound be used for man, who is attempting to live in these areas. Furthermore, basic knowledge of breeding and lactation is a primary requirement for planning improved husbandry and farming with these animals.

The physiological mechanisms, which allow the camel to survive periods of over two weeks without drinking water and to eat the most unpalatable plants, all have to do with the conservation of water. The appropriate physiological mechanisms will be discussed further. What is of interest now is that severe desiccation is tolerated. Up to 30 percent of its body weight can be lost by loss of water - amounts that would be fatal in the case of other farm animals or even man (Schmidt-Nielsen, 1964). Moreover, this loss can be replenished in a matter of minutes (Yagil et al., 1974). The camel has the lowest water-turnover of all animals (Macfarlane, 1977) and is able to regulate water and salt uptake from the colon and their excretion from the kidneys (Yagil and Etzion, 1979). Camels do not need to sweat to lower body temperature, thus conserving water (Schmidt-Nielsen, 1964). The camel increases its body temperature from 34°C in the early morning to over 41°C in the late afternoon, at which time the environment cools greatly. Thus the camel stores its heat during the day and cools off by conduction and convection in the evening. The water-deprived camel reduces its metabolism (Schmidt-Nielsen et al., 1967; Yagil et al., 1975) which also conserves water.

Together with the examples of physiological adaptation mentioned above, there are also behavioral adaptations. These consist mainly of presenting the smallest possible surface area to the rays of the sun (Ingram and Mount, 1975) and by being less active in the heat of the day. Even the covering of the camel changes from a wool in the winter to a sleek shiny reflecting hair in the summer. Equatorial camels do not shed their hair, but maintain a smooth reflecting coat throughout the year. The hump does not serve as a water reservoir, nor solely as an energy reserve, but its greatest use is that being a concentration of body fat it leaves the subcutaneous tissues virtually fat-free, thus allowing for an efficient cooling to a relatively cooler environment (Cloudley-Thompson, 1969).

The future of the camel lies in the exploitation of the milk and meat producing capabilities in areas where perennial drought conditions cause many human deaths each summer. In addition, the interaction between livestock and vegetation will decide the degree of continued desert encroachment or rehabilitation.

* FAO Production Yearbook (No. 16 (1962) and No. 32 (1978)