Although this report will not deal in depth with camel fertility, the reproductive characteristics of both male and female camels must be examined before the importance of camel milk for human nutrition in drought areas can fully be assessed. It is often stated that the most negative argument against camel breeding is their slow and uncertain reproductive rate (Novoa, 1970). In some areas camel breeding is even considered to be too hazardous to be undertaken systematically (Gast et al., 1969).
The camels are sexually mature at 4 to 5 years of age (Evans and Powys, 1979; Mares, 1954; Yasin and Wahid, 1957), although a 3-year old camel can be used for reproduction (Leonard, 1894; Novoa, 1970; Williamson and Payne, 1959). In the male, full reproductive prowess is not developed until six years (Novoa, 1970) or even seven years (Hartley, 1979) of age. Domesticated vicugnas could reproduce at one year of age (Romero, 1927), but the fertility of both males and females at this age was low (Koford, 1957). Alpacas and vicugnas are not normally bred until they are at least two years old (Novoa, 1970).
Aristotle reported that breeding time of camels is in November and December (Leonard, 1894). However, camels, both male and female, are seasonal breeders (Yasin and Wahid, 1957), mating during the rainy, or cold season (Yagil and Etzion, 1980). Longer hours of daylight initiate the breeding season (Chen and Yuang, 1979). Must (1969) described an all-year-round oestrus in the female camel, but this was not found in any other publication.
The pattern of the reproductive cycle appears to relate to the harsh environment in which the camels live (Novoa, 1970). The calves are born in the months most suitable to quarantee their survival. The breeding season differs in various countries. In the region of Pakistan (Yasin and Wahid, 1957), China (Chen and Yuan, 1979), Egypt (Shalash, 1965) and Israel (Yagil and Etzion, 1980), the breeding season is from December to April. This is the period in which both males and females are fertile. In Somalia the male camel ruts in the spring from April to May, (Mares, 1954). In India the breeding period is from November to February (Singh and Prakash, 1964). In Morocco the rutting season occurs in winter and spring. Both rutting season and consequent births coincide with adequate water and feed supplies. In Russia the domesticated Bactrian was found to be polyoestrus, having oestrus cycles all the year round (Bosaev, 1938). The wild camel in the Gobi desert, however was a seasonal breeder (Bannikov, 1945). The rut occurring between January and February. In the Sudan, Musa and Abusinea (1978) report the season as being from March to August.
Oestrus cycle and ovulation
As previously mentioned, the female camel is a seasonal polyoestrus animal. The period of oestrus is easily recongnizable by the animal's general restlessness, often aggresiveness in manner, and by swelling and discharge from the vulva (Yasin and Wahid, 1957; Yagil and Etzion, 1980). The length of the oestrus cycle is normally 2–3 weeks (Bodenheimer, 1954; Leonard, 1894), although in the Bactrian camel the period can extend to 30–40 days (Bosaev, 1938). The actual heat lasts for 3–4 days (Bodenheimer, 1954; Leonard, 1894), although 21 days was considered by Yasin and Wahid (1957) as being the period of heat.
Ovarian cycle activity was fully described by Musa (1979). He reports a 28-day cycles in which pollicles mature in 6 days maintaining their size for 13 days, then regress in 8 days. There is no spontaneous ovulation in the camel (Chen and Yuan, 1979; Musa, 1979; Shalash, 1965), so that without mating there is no luteal phase. Manual stimulation of the cervix for 15 minutes did not induce ovulation, although luteinization of the mature Graafian follicle occurred (Musa and Abusina, 1978). Ovulation occurs 30–48 hours following copulation (Chen and Yuan, 1979). Shalash (1965) stated that without pregnancy there is no formation of a corpus luteum. The size of the corpus luteum depends on the ovarian activity (Musa and Abusinea, 1978). The corpus luteum was larger and lasted longer when mating occurred at the time of maximum follicular development. When mating took place later, the corpus luteum was smaller and disappeared in a short period of time. In Beersheva (Israel) research was carried out using radio-immuno assay of sexual hormones in the blood of the female. There was an increase in oestradiol activity from the beginning of December which ended toward the beginning of April. Surprisingly enough, there were also peaks of progesterone activity, although no male was present. The peaks in hormone activity were 23 days apart. From the middle of January there were peaks of oestradiol accompanied by peaks of progesterone 2 days later, every 7 days. Twenty-four to 48 hours following mating, the luteinizing hormone (LH) appeared. The LH then declined steadily for 6 days and a second period peak even greater than the first, was found almost two weeks later. At that time, the progesterone levels were extremely high. The oestrogen levels were low, but both hormones showed peaks in activity every 4 days. LH activity was non-existent. These 4-day fluctuations continued almost right through the pregnancy. While undertaking physiological research on body fluids and renal function, two camels aborted. In these camels the hormone activity declined to base-line levels.
Oestrus has been known to re-occur a day after calving (Barmicev, 1939). If the camel is well fed, oestrus can occur within one month post partum (Mares, 1954; Yasin and Wahid, 1957). If the camel has no milk, then oestrus occurs within 28 days (Evans and Powys, 1979). This means that with good feeding conditions camels can be mated as soon as the young calves start grazing.
The Lama pacos have prolonged periods of oestrus interrupted by short periods of an oestrus (San Martin, 1961). Ovulation occurs 26 hours after copulation. Injections of HCG lead to ovulation 24 hours later.
Sexual cycle of the male camel
The male camel is a seasonal breeder, the season corresponding with that of the female (El Amin, 1979; Yagil and Etzion, 1980). The male undergoes behavioral and hormonal changes during the rutting season (Chen and Yung, 1979; Yagil and Etzion, 1980).
The male is normally docile and easily controlled, however, in the rutting season he can become so aggressive that he is dangerous and cannot be handled. He is extremely restless. He blows a balloon-like flap out of the side of his mouth which is called a palatal flap (Charnot, 1963; Yagil and Etzion, 1981) (Photo 5). Its appearance is accompanied by a roaring-gurgling sound. The lips are often covered with saliva. The glands between the ears secrete a dark, bad-smelling, watery secretion. This area is constatly rubbed against all objects in the surroundings, including grass mounds. The back legs are spread, and the tail is then beaten against the penis. Drops of urine are deposited on the tail and spread over the back. Eventually, the hindquarters have a strong urine odor.
The rutting males readily attack each other and timid males soon learn to keep away from the territory staked out by more aggressive males.
In the rutting periods there was increased secretion of androgens. The increase in hormone secretion was found in the blood (Yagil and Etzion, 1980) and urine (Charnot, 1958). Adenohypophysis (increased neurosecretory activity) also occurred (Charnot and Racadot, 1963; Santini, 1964). Secretions from the neck, poll and glands were also found to contain large amounts of androgens (Yagil and Etzion, 1980).
There were no changes in behaviour when the blood and neck gland hormone levels were low. The female camel also has a palatal flap and neck glands (Leese, 1927), but these are dormant. This suggests the dependency of secondary sex characteristics on the angrogens.
Male alpacas have no changes in appearance or behaviour in the breeding season (Novoa, 1970). This is surprising as there is a strong similarity between the behaviour and external appearances of the rutting camel and the in-musth Asiatic elephant (Jairudeen, et al., 1972). The latter also becomes extremely aggressive, secretes from the head glands, plays with his penis and urinates onto the ground.
The male camel can mate at 3 years of age, but the optimal age to begin is between 4–5 years (Hartley, 1979; Mares, 1954; Yasin and Wahid, 1957). At 6 years of age they are in full reproductive vigour. The best males are selected for breeding: the rest are castrated or used as baggage camels (Mares, 1954). The male can breed for 7 years (Hartley, 1979). The male dromedary can mate with 50 to 80 females a season, when he is in good condition (Leese, 1927; Yasin and Wahid, 1957). The Bactrian male mates with 10 females per season (Terentjev, 1951).
Male camel in rut - palatal flap
In Somalia the calving interval is 24 months. As a female can live up to 30 years, she can produce about 8 calves in a life-time (Yasin and Wahid, 1957). With good feed and management the inter-calving time can be reduced to one every two years (Evans and Powys, 1979). This would mean two calves every 4 years and a total of 13 calves in a lifetime. Even two calves in 2 ½ years can be attained and this would greatly improve the fertility of these animals.
At 4 or 4 ½ years of age the animals are first used for breeding (Hartley, 1979). The best male is chosen on the basis of his vigour and judged by the performance of his parents. The females should also be culled for defects, such as slow breeding, poor milk yield, bad mothering and weak offspring (Hartley, 1979). Herds are normally too few in number, for culling to be undertaken and all females are mated.
There are many reports concerning the copulation of camels. These vary from being rarely observed (Mares, 1954) to the act being screened from humans by other members of the herd (Yasin and Wahid, 1957). The author has not only watched a male serving various females in a herd, but has assisted him in the act. If not aided, courting and mating can be very violent. If the male selects a female and she is not willing to go down quietly when he approaches her, he will bite at her neck and eventually roughly force her to the ground. There the female utters her guttural protest, while the male first straddles her and then gently slides down until he is squatting on his back legs (Photo 6). Copulation lasts for about 15 minutes. This is accompanied by much gurgling and grunting. The male pushes forward continuously with many pelvic thrusts. The male gives about 7 ml of semen with an average of 615 million sperm per mm (Chen and Yuang, 1979).
In order to improve the efficiency and increase the economical viability of camel breeding, it is important to know if and when the females are pregnant. This can be done by rectal palpation (Chen and Yuang, 1979; Musa, 1979) and by biological assay using infantile mice (Musa, 1979). The latter method is only feasible at certain stages of pregnancy. The surest method is by radio-immuno assay. Pregnancy determination is important in the care of the females, the selection of males and in long-term planning.
Yasin and Wahid, (1957) report a gestation of 365 to 395 days whereas Evans and Powys (1979) record a gestation period of 373 to 393 days. The gestation period of the Bactrian camel is 402 days (Chen and Yuang, 1979).
Signs of approaching parturition are restlessness and leaving the herd (Chen and Yuang, 1979), if in a paddock, the pregnant camel pushes against the railings and gazes off into the distance. In the first stage of parturition the cervix gradually relaxes, the forefeet of the calf, with the amnion, are forced into the vagina. In the second stage the animal increases straining. The feet become visible, still enclosed in the amnion. The head then appears and the rest of the body quickly follows. The first two stages average 27–30 minutes. In the third stage the placenta is expelled. This
Copulation of camels
takes about 50 minutes, but can take much longer. The calves stand within 20 minutes of birth and in a short while start suckling.
Fertilization rate and infertility
The fertilization rate of camels is considered very low (Novoa, 1970). Fifty percent fertility, or even less, has been recorded (Keikin, 1976; Yuzlikaev and Akhmedier, 1965). Repeated matings were often due to improper development of follicles (Barmintsev, 1951). Injections of Pregnant Mare Serum Gonadotropin (PMSG) with an interval of 48–72 hours led to 100 percent calving rate (Yuzlikaev and Akhmediev, 1965). Anatomical abnormalities of the females are the main causes of infertility (Shalash and Nawito, 1963). Another cause of infertility is foetal death (Shalash, 1965; Tayeb, 1953). This was suspected when a single foetus was born, but more than one corpus luteum was found.
Infertility and slow breeding habits of the camel can be associated with poor feeding and management. Better selection, disease control, and improved husbandry could not only improve the standard of milk production, but could shorten the time for first calving, intercalving intervals and quality of the herds in general.