BIOLOGICAL FEATURES OF CAMELS

No species of farm animals combines so successfully the features of high milk production ability, working capacity, meat yield, fleece yield and adaptation to desert conditions, as the camel. It is explained by certain biological features of the camel body.

Unlike other animals, camels have incisers on their upper jaw, their mucous mouth membrane is covered with cornified papillars, their lips, especially the upper one, are forked and very agile. Their wrinkled nose membrane can retain a considerable portion of moisture from the air breathed out and absorb the moisture from air during breathing. The stomach consists of three sections: the belly, the reticulum and the abomasum, and it is of considerable capacity (250 l). The stomach membrane is well-adapted to accumulation of water and food juice. Unlike cattle or sheep, camels have no foliole, but the belly in two folia, where it is protruded, has cellular formations, enabling to preserve moisture reserves (other animals have no protruding like that). In the belly these formations are defined more clearly, than in the reticulum.

The camel body is deep and comparatively short, the extremities, especially the hind ones, are long. Due to such body composition, the animals have sweep pace and are well-adapted to transportation of packs. The extremities end in not hoofs but twin-fingered paws with little hoofs in the form of nails. When stepping on the ground, these paws widen. Such constitution of  legs enables the animals to move on friable sand and crumbly snow, but makes it difficult for them to move on muddy and slippery roads. Unlike the hoofed animals, camels almost don’t trample the pasture grass, which affects the productivity of pasture lands in a positive way.

Camels can quickly increase their weight and accumulate a large amount of fat (100-150 kg) in their humps, which gives them much more power per unit of live weight than food. Fat reserves in their humps form an original insurance fund of power and force for them, which is used during the season of food and water shortage. When 1 gram of this hump fat is oxidized, 1,07 grams of water are formed by lung evaporation. At the same time the hump fat is consumed very quickly, and, to compensate it under pasture conditions, about 3-4 months are required. Only well-fattened camels with humps full of fat are of full physiological power and are resistant towards the impact of environment and infectious diseases. Keeping camels all the year round in good fattening status is the main condition for successful camel breeding.

By winter camels become overgrown with dense fleece, preventing them from cold. In spring it comes out and for summer the animals have no dense fleece. Camel fleece is of great adaptive importance: it protects them from overheating, reduces evaporation and retains moisture. Sheared camels lose much more water by the surface of their skin, than those not sheared.

Camels survive when their liquid loss is equal to one fourth of their live weight (human beings die when theirs  is twice less than that one).

All this shows high adaptive capacity of camels under desert conditions.

Camels have a unique for warm-blooded animals capacity to change their body temperature in a wide range: from 34⁰C at night to 42⁰C at midday. Such body temperature fluctuations enable camels to reduce substantially the escape of moisture from their body: the lower is the temperature, the less moisture is lost. Camels are characterised by extremely slowed down breath. They make only 8-10 inhales and exhales per minute, while the cattle makes those up to 25. This difference is very important, because with each exhale a drop of water is lost as vapour. Camels keep their mouth constantly close, preventing the evaporation of moisture.

The lactation period of  female camels is 18 months, so the yield of young camels per 100 females and the farm’s work for head reproduction are evaluated for two adjacent years.

The camel skin is twice thicker than that of the cattle. The thickest part covers the hump, then – the buttocks and then – certain parts of the chest. The hump skin is elastic, capable to stretch much, when the humps are filled, and to reduce without wrinkles, when they are getting empty. In general, the skin fits close to the camel body without any wrinkles even on the knees.

The epidermis of camels is also almost twice thicker than that of the cattle, being in the range of 40-100 mcm. Hair follicles are positioned in groups, sebaceous glands consist of 2-3 lobules and are placed especially deep in the humps. There are few sweat glands, and most of them are in the groin.

Behind the occipital crest in the skin of dromedaries there are clustery  poll glands, secreting the dark-brown material with a pungent odour, the quantity of which increases during the mating period.

On the skin of camels there are seven fleece-free paddy formations. Dromedaries have thicker pads, with their breast pad of up to 2cm thickness. These pads enable the animals to lie on the ground of up to 70⁰C.

Sexual dimorphism. The sexual dimorphism of camels is quite well-defined. The males are characterised by high muscularity, breast depth, good development of mane, beard, culottes and epaulets. The body type of castrates changes not much, they are characterised by just a bit higher legs, since after castration the tubular bones continue to grow.

The ovaries in female camels are not large, of a hazel-nut size, tuberous. The oviducts are long, thin and firm. The uterus is two-horned, of a smaller size than that of a mare or a cow.

The physiological sexual maturity occurs in dromedaries at the age of 12-15 months, but the farm maturity – not earlier than at the age of two years. Bactrians become sexually mature at the age of 15-18 months, being passed to mating at the age of three years only. Since the sexual instinct shows itself by the age of two years, beginning from this age the males are separated from females. The males are used as tupping animals not earlier than since the age of 4 years.

Figure 1 - The scrotum lies much deeper in the male camel between its thighs, than in the ox. The testicles are not large, but, in comparison with other animals, they are turned over along their whole length. Their penis is in the bursa, where in front of testicles there is an S-shaped bend. The free penis part is turned back and, separating under the belly as a papillar, can change its position due to special muscles on the abdominal fascia.

The breeding use of males is restricted by the age of 20 years, since already since the age of 16-17 years their sexual activity drops. Females are usually used till the age  of 25 years , after which they are rejected.

Embryogenesis. Embryogenesis or embryonal development is the central problem of modern camel biology. The embryonal development is carried out under the control of genetic information, received by the embryo from the moment of ovicell insemination. But the use of this information depends on the genotype and environmental conditions’ interaction and is carried out by a complicated system in the genotype of the ovicell inseminated. Various environmental conditions can change the activity of genes within certain limits, which determines the phenotypic variety of embryos.

The prenatal development of camels can be divided into four periods. The first, ovicell or preimplantation period begins from the ovicell’s insemination by the spermatozoid and ends in its implantation. In female camels this period is 20-25 days. During this time the  inseminated ovicell goes through the number of splittings, and at the stage of blastocyst it is implanted in the left horn of the uterus.

The second period is blastogenic. The placenta is formed and the organs and tissues begin to be formed. The nutrients come to the embryo mainly from the mother’s blood. The length of that blastogenic period in dromedaries is 40 days, Bactrian’s – 50 days and interspecific hybrids – from 45 to 50 days.

The third period is prefetus. In dromedaries it is 40 days,  Bactrians – 45 days and interspecific hybrids – from 40 to 46 days.

The fourth, fetus period ends with foaling of female camels. During the last period the elements of organs and tissues are differentiated, and they begin to function. The embryo is growing and developing rapidly. The length of that fetus period in Bactrians is 315 days, dromedaries – 305 days and interspecific hybrids – from 300 to 312 days.

Table 1 shows the gestation length and standard deviations in female camels.

The above data show that the gestation length in female camels is characterized by interspecific and interbreed distinctions.

The gestation length in pure-bred female camels is characterized by high inheritance rate. The similar phenomenon can be seen in variation parameters - the standard deviation and the variation coefficient. Hence, one can speak of high hereditary stabilization of that trait.

Table 1 – Gestation length in female camels, days

Densed mating and foaling of female camels. The main reserve for further increase in the total number of camels is to carry out the densed mating and foaling of female camels to receive 2 little camels per three years. Carrying out of this important measure is connected with certain difficulties. These difficulties are as follows. The matter is that, unlike other species, camels have a restricted mating period and a long gestation period. Besides, the long lactation period prevents, in a certain way, the next gestation in the female camel. Meanwhile, there are some cases, when female camels become pregnant during the year of foaling and foal twice per three years.

I.I.Lakoza [1], who performed the research on the Chimkent experimental station in 1932, noted that 11 of 12 females had rutted after foaling. Only one female with a placenta delay hadn’t rutted. At the same time on the Shaulder camel breeding farm 69 camel females were mated, having given birth to little camels in the same years, with dromedaries having a higher percent of insemination, than Bactrians and hybrids.

Making experiments on the Urda camel breeding farm in 1938, Yu. Barmintsev reached insemination in 67% dromedaries during the years of foaling.

K.B.Saparov [2],  making experiments in 1982 to study the insemination of female camels during the foaling year, received the following data: during natural mating 12 female camels or 6,3% of 198 female camels became rutted and pregnant. In the course of three years of observations in 1982-1984, 17 heads or 5,98% of 284 female camels became pregnant. These data show the conservativeness of camels’ reproducing capacity. But, when using the active stimulating preparations, we can reach sufficiently high percent of female camels’ insemination.

According to K.B.Saparov [2], when using the megestrene acetate preparation together with the SZhK preparation, the females’ insemination of up to 60,0% can be obtained. The highest percent of females rutting was in the group, where estrophan was used. In the said group the females’ insemination and foaling reached 92,0%.

Good results were received in using the vitamin-hormone method of stimulation in the foaled females on the state farm named after Amangeldy in the Atyrau region. The females chosen within the age of 7-15 years of 500-700 kg live weight were injected vitamins A, E, D in physiological doses on the 10^th, 15^th and 20^th days after foalbirth. Then, during 6 days, they had every day intramuscular injections of 6-7 ml 1% oil solution of progesterone, and on the 7^th day – the SZhK preparation, depending on the live weight: the female camels of 500-600 kg weight – 5000 MU, those of 600-700 kg weight – 7000 MU. In the result of this all of them became rutted in 3-5 days and were mated. The insemination reached above 50%. The estimates show that for the age period of 7-15 years old it is possible to carry out 2-3 densed foalings, without any damage to the seasonal character of reproduction in these animals.

References

1. Lakoza, I.I. Camel Breeding.- Moscow, 1953. –312p.

2. Saparov, K.B. Development and meat qualities of young offsprings in milky female camels, Arvana breed: Autoref. diss…Cand. s.-kh.nauk. TSKHI. Ashkhabad. –1994. –21 p.

Источник для подробного ознакомления:

1. Baimukanov D.A., Baimukanov A.B. Evolution and genetics of Camels.  –Almaty, 2014. -55 p., tabl.19, fig.22 (in English).

2. Баймуканов А., Баймуканов Д.А., Амерханов Х.А., Юлдашбаев Ю.А., Гаряев Е.Б., Гаряева Х.Б. Селекция верблюдов: теория и практика // Монография (ISBN 978-5-9675-1836-2). – Москва: РГАУ-МСХА имени К.А. Тимирязева.2021. -333 с. https://www.elibrary.ru/item.asp?id=46806628

3. Баймуканов Д.А., Юлдашбаев Ю.А., Баймуканов А., Монгуш С.Д. Продуктивное и племенное верблюдоводство / Учебник. Кызыл, 2020. 220 с. https://elibrary.ru/item.asp?id=48225900

4. Продуктивное и племенное верблюдоводство: учебник для вузов (ISBN 978-5-507-46122-6) / А. Баймуканов, В. И. Трухачев, Д. А. Баймуканов, Ю.А. Юлдашбаев, Х. Б. Гаряева. — Санкт-Петербург: Лань, 2023. — 308 c.: вклейка (16 с.). — Текст: непосредственный. https://www.elibrary.ru/item.asp?id=46806628   https://www.labirint.ru/books/960308/