Postpartum

Genital tract involution

Involution of the vulva

Softening of the vulva is usually observed a few days before parturition but maximum dilation occurs during birth. At the end of parturition, the vulva is very edematous and remains that way for about 2 to 3 weeks. In the dromedary, the size of the vulva returns to prepartum size 16 to 42 days after parturition (mean 31.7 ± 2.5 days).⁽²¹⁸⁾ Involution of the vulva is faster in primiparous than pluriparous animals.⁽²¹⁸⁾

Postpartum vaginal discharge (lochia) is minimal in the camelidae and only a small amount of reddish fluid is noticed during the first few days after parturition. In normal cases, this discharge becomes thicker and very infrequent within one or two weeks.^{(77, 183, 218)}

Involution of the uterus

Uterine involution is rapid in the female camelidae due to the microcotyledonary and diffuse nature of the placentation in these species which does not cause a great loss of uterine tissue. In the dromedary, the involution of the uterus is completed as early as 20 days.^{(77, 183)} The major decrease in size is observed during the first 10 to 15 days postpartum. Some authors have reported, however, that size of the uterus does not return to normal until 31 to 54 days postpartum (40 ± 2.1 days).⁽²¹⁸⁾ This process is completed in 94% of the cases between 30-50 days and in 6.7% per cent after 50 days of parturition. Primiparous females have a significantly more rapid involution than pluriparous animals.⁽²¹⁸⁾ The cervix remains open during the first 20 days of the postpartum period.⁽¹⁸³⁾ Even after complete involution, the left uterine horn tends to increase in size with each new pregnancy. It measures 80-105 mm, 100 -115 mm, and 110-140 mm in females with 2, 4, and 6-7 pregnancies respectively.⁽²⁷⁷⁾ Involution of the uterus seems to be faster in the Bactrian camel where the uterus is completely involuted and readily palpated by 15 days postpartum.^{(69, 70)}

In the alpaca, a rapid change in the weight of the uterus is observed during the first 10 days postpartum.^{(121, 232, 248)} Uterine weight decreases from its original 883 g at 24 hours to one third of that at 5 days and one fifth at 10 days postpartum.⁽²⁴⁸⁾ The diameter of the left horn decreases from 15 cm at delivery to 3.5 and 3 cm at 10 and 20 days postpartum, respectively.⁽²⁴⁸⁾

Postpartum ovarian activity

Corpus luteum regression

The corpus luteum of pregnancy regresses rapidly during the first week postpartum and then slowly after that to form a corpus albicans. Many of the corpora albicantia can be observed on the surface of the ovary of old pluriparous females as well-circumscribed, spherical, white, hard structures protruding from the ovary and giving it its characteristic multilobulated. irregular appearance (cf. Anatomy of the ovaries). Their diameter varies between 15 and 18 mm early after calving and then decreases to 4-8 mm later.^{(98, 100, 249)} The consistency of corpora albicantia is hard and fibrous. Their color is gray-white but sometimes yellowish-white. In cross section, a thick, grayish-white, tough, fibrous capsule of 2-3 mm is seen surrounding a central zone of light-to dark-brown tissue. Regression of the corpus luteum probably starts just before parturition under the effect of massive secretion of PGF2α which causes luteolysis and degeneration of the luteal tissue.⁽¹⁰³⁾ Greatly-thickened, fibrous capsule and trabeculae together with excessive fibrosis of the tortuous arterioles, indicates advanced regression.

In the alpaca, corpus luteum size decreases rapidly during the first 10 days postpartum and then slowly between 10 and 20 days postpartum.⁽²⁴⁸⁾

Follicular activity

The time of resumption of ovarian function and follicular activity following parturition in camelidae is highly variable and depends on the species and rearing conditions. In the dromedary, postpartum anestrus was reported to last anywhere from 15 days to one year (Table 15).^{(95, 135, 158, 168, 211, 260, 264, 274)}
 

P.O. = Personal observation
 

Discrepancy in duration of postpartum anestrus is probably due to several factors including lactation, sucking, nutritional status, and method of evaluation. According to some authors, estrus detection is not a reliable method for evaluation of postpartum activity because the first estrus is usually "silent".^{(92 262)} Also, it appears that the timing of postpartum estrus and its intensity depend on the time of year.^{(92 262)} Early and late in the breeding season, intensity of estrus is lower, and it lasts longer, than in the middle.^{(94, 95)} According to our observations, the major factors affecting length of postpartum anestrus in the dromedary are nutritional status and suckling. In well-fed females, ovarian activity as assessed by ultrasonography is evident in 70 to 80% of the females by 30 days postpartum and conception rate is normal at 45 days. Also, all females that lose their offspring or are weaned show a mature follicle within 10 to 12 days. Similar observations were reported in the Bactrian camel with ovarian activity resuming only 3 to 12 days after weaning or losing the newborn⁽⁶⁹⁾ while ovarian activity in suckling females (follicles of 10 to 14 mm or high estrogen) is observed 35 to 60 days after parturition.^{(35, 69)}

In the llama and alpaca, ovarian activity resumes within the first week after parturition.^{(11, 52, 55, 56, 138, 232, 236, 248)} In llamas the interval from parturition to resumption of ovarian follicular activity is about 5 days and follicles can be ready to ovulate by 10 days after parturition. Successful breeding of animals can occur as early as Day 15 postpartum. In alpacas, ovarian follicles are less than 3 mm in diameter 24 hours after parturition and increase steadily during the next 10 days.

The interval from mating to ovulation (2.0 ± 0.1 days) and growth rate of the preovulatory follicle (0.8 ± 0.2 mm/day) are not affected by lactation status in the llama.⁽¹¹⁾ However, the interval between two follicular waves is shorter by 2.5 ± 0.05 days in lactating compared to non-lactating females. In addition, the size of the dominant follicle is smaller in lactating that in non-lactating females (10.4 ± 0.2 vs. 11.7 ± 0.3 mm).⁽¹¹⁾ This shows that although no lactational anestrus is observed in this species, there is a definite effect on the ovarian function that could be exacerbated it nutritional requirements are not met.

Interval from parturition to conception

Interval from parturition to first acceptance of the male is variable in the dromedary and should not be used as a criteria to evaluate ovarian activity and postpartum fertility. We have observed accidental mating as early as 2 days after parturition. Normal conception cannot be expected until the uterus is completely involuted and ovarian function is restored. The time from parturition to the establishment of these conditions is not known with precision. However, we have obtained pregnancies in several females as early as 45 days postpartum. Others have reported no conception in females mated 12 and 40 days after parturition and suggest that low conception rate is to be expected if breeding occurs before 50 days postpartum because uterine mucosa has not yet returned to its normal status before this stage.^{(92, 98)} Our preliminary studies on the histology of the uterus in the postpartum period show that uterine conditions are compatible with embryo survival and pregnancy as early as 26 days postpartum. Also, we have been able to obtain normal fertilization rates and collection of viable embryos in females bred 3 weeks after induction of abortion at 3 to 10 months of pregnancy. In the Bactrian camel, conception was obtained as early as 10 days postpartum but follicular development was induced by eCG (PMSG) treatment.^{(89, 275, 276)}

In alpacas and llamas, females can accept males as early as 24 hours after parturition^{(206, 248)} but normal conception rates are not achieved until 10 to 15 days after parturition.^{(52, 55, 248)} The breeding observed at 24 hours after parturition is only behavioral and is never associated with an ovulation. The first postpartum ovulation is at 5 days with a pregnancy rate of 30%.^{(55, 248)} In one study, all females were bred and ovulated by Day 17 or 18 postpartum in conjunction with a second ovarian follicular waved.^{(55, 56)} The interval from parturition to breeding also has a significant effect on the incidence of ovulation and on embryo survival beyond day 40. The proportion of alpaca females ovulating at 10, 20 and 30 days postpartum was respectively 64.5%, 76.9%, and 83.9% with conception rates of 62.5%, 87.5%, and 90.4% respectively. However, the proportion of females that experienced pregnancy loss by day 40 was 24%, 11.4%, and 6.4% for breeding at 10. 20, and 30 days postpartum.⁽⁵⁵⁾

Endocrinology of the postpartum

The endocrinology of the immediate postpartum period is characterized by a fall of progesterone due to regression of the corpus luteum of pregnancy. Some authors have reported a gradual fall during the first week postpartum⁽²⁰⁾ whereas others found that progesterone levels were negligible as early as 24 hours after parturition.^{(120, 149)} Progesterone levels in the blood or urinary pregnanediol glucoronide remain low with a short intermittent increase until the females are bred. In this case, an increase is observed 3 to 4 days following breeding showing ovulation and formation of normal coipus luteum.^{(53, 56, 149)}

Plasma estradiol and urinary estrone sulfate concentrations closely follow follicular activity in the postpartum period. In the llama, significant estrone sulfate levels compatible with the presence of a normal follicular wave with a dominant follicle were observed between 5 and 10 days postpartum.^(56,149)

No studies are available on the profile of pituitary hormones during the postpartum period in camelidae. However, from the observations on ovarian function and steroid hormone profiles, one can assume that pituitary activity (FSH and LH secretion) are re-established very early during the postpartum period. Low LH surge following breeding in the first 10 days postpartum has been observed in the llama and alpaca. This could be due to low response of the pituitary gland to copulation and may be the cause of increased ovulation failure at this stage. Suckling does not seem to have a great impact on pituitary and ovarian function in the New World camelidae, but it does seem to be an important factor in the delay of resumption of activity in the dromedary. More detailed endocrinological studies on the effect of lactation and suckling on ovarian function are needed.

References

1.    Abdel-Rahim. S. E.. K. Abdel-Rahman, and A. E. El-Nazier. 1994. Production and reproduction of one-humped camels in the Al-Qasim region, Saudi Arabia. Journal of Arid Environments. 26:53-59.
2.    Abdel-Rahim. S. E. A., and A. E. El-Nazier. 1990. Factors affecting camel reproductive performance in the tropics. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 131-147.
3.    Abdo, M. S„ A. S. Al-Janabi, and A. A. Al-Kafawi. 1969. Studies on the Ovaries of the Female Camel During the Reproductive Cycle and in Conditions Affected with Cysts. Cornell Vet. 59:418-425.
4.    Abdou. M. S. S., A. B. Elwishy. M. S. Abdo. and S. A. Elsawaf. 1971. Hormonal Activities of the Placenta of the one Humped Camel, Camelus dromedarius Part I - Gonadotrophic, adreonocorticotrophic and thyrotrophic hormones. J. Anim. Morphol. Physiol. 18:11-16.
5.    Abdunazarov, N. H. 1970. Biological characteristics of reproduction in the one humped camel. Trudy Turkman-selkhas Inst. (Anim. Breed. Abstr., 39: 767. 1971). 15:134-141.
6.    Abou-Ela, M. B. 1994. Reproductive performance of the one-humped camel under traditional management in the United Arab Emirates. Journal of Arid Environments. 26:47-51.
7.    Adam. C. L., D. Bourke, A., C. E. Kyle, P. Young, and M. T. G. 1992. Ovulation and embryo recovery in the llama. Proc. 1^st int. Camel Conf., Dubai. UAE: 125-127.
8.    Adam. C. L„ C. E. Moir, and P. Shiach. 1989. Plasma progesterone concentrations in pregnant and non-pregnant llamas (Lama glama). Veterinary Record. 125:618-620.
9.    Adams, G. P.. P. G. Griffin, and O. J. Ginther. 1989. In Situ Morphologic Dynamics of Ovaries, Uterus, and Cervix in Llamas. Biology of Reproduction. 41:551-558.
10.    Adams, G. P.. E. D. Plotka, C. S. Asa, and O. J. Ginther. 1991. Feasiblity of Characterizing Reproductive Events in Large Nondomestic Species by Transrectal Ultrasonic Imaging. Zoo Biology. 10:247-259.
11.    Adams, G. P., J. Sumar, and O. J. Ginther. 1990. Effects of lacational and reproductive status on ovarian follicular waves in llamas (Lama glama). J. Reprod. Fert. 90:535-545.
12.    Adams, G. P.. J. Sumar, and O. J. Ginther. 1991. Form and function of the corpus luteum in llamas. Animal Reproduction Science. 24:127-138.
13.    Adams, G. P.. J. Sumar. and O. J. Ginther. 1991. Hemorrhagic Ovarian Follicles in Llamas. Theriogenology. 35:557-568.
14.    Agarwal, S. P., V. K. Agarwal, N. D. Khanna, and P. K. Dwaraknath. 1989. Serum estrogen and progesterone levels in camel (Camelus dromedarius) during estrus cycle. Indian Vet. J. 66:605-608.
15.    Agarwal, S. P.. and N. D. Khanna. 1990. Endocrine Profiles of the Indian Camel under Different Phases of Reproduction. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' -Paris: 77-104.
16.    Agarwal, S. P., N. D. Khanna, V. K. Agarwal, and P. K. Dwaraknath. 1986. Thyroidal status of male camel during breeding and non-breeding seasons. Indian Journal of Animal Sciences. 56:1036-1038.
17.    Agarwal, S. P., N. D. Khanna, V. K. Agarwal, and P. K. Dwaraknath. 1987. Circulating Levels of Estrogen and Progesterone in Female Camel (Camelus dromedarius) During Pregnancy. Theriogenology. 28:849-859.
18.    Agarwal, S. P„ N. D. Khanna, V. K. Agarwal, and P. K. Dwaraknath. 1989. Circulating Concentrations of Thyroid Hormones in Pregnant Camels (Camelus dromedarius). Theriogenology. 31:1239-1247.
19.    Agarwal, S. P., A. K. Rai. and N. D. Khanna. 1991. Serum progesterone levels in female camels during oestrous cycle. Indian Journal of Animal Sciences. 61:37-39.
20.    Agarwal. S. P.. A. K. Rai, and N. D. Khanna. 1992. Hormonal studies in postpartum female camels and their neonates. Proc. First International Camel Conference. Dubai. UAE. 143-148.
21.    Al-Eknah. M. M., E. A. Dafalla, A. M. Homeida, A. K.    A. Galil, and A. Y. Al-Taher. 1993. Spontaneous uterine activity during the oestrous cycle of the camel (Camelus dromedarius). Animal Reproduction Science. 32:91-97.
22.    Alfuraiji, M. M., and I. A. Moussa. 1995. Gonadropin-Releasing Hormone-like factors in the seminal plasma of the dromedary camel (Camelus dromedarius). Theriogenology. 43:154.
23.    Anouassi, A. 1984. Activite luteale chez la chamelle non gestante (Camelus dromedarius). These de Doctorat Veterinaire, Institut Agronomique et Veterinaire Hassan II, Rabat, Maroc.
24.    Anouassi, A., M. Adnani, and E. Raed. 1992. Artificial insemination in the camel requires induction of ovulation to achieve pregnancy. Proc. 1^st Int. Camel Conf., Dubai, UAE: 175-177.
25.    Anouassi, A., and A. Ali. 1990. Embryo Transfer in Camel (Camelus dromedarius). Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 327-332.
26.    Anouassi, A., Y. Combarnous, F. LeCompte, C. Cahoreau, and F. Guillou. 1987. Purification and characterization of luteinizing hormone from the dromedary (Camelus dromedarius). Biochimie. 69:647-654.
27.    Anouassi, A., A. Lahlou-Kassi, Y. Combarnous, A. Sghiri, and N. Martinat. 1988. Performance and Endocrine Approach for Reproductive Management in the Camel (Camelus dromedarius). Workshop Fis/Sida, Addis-Ababa, Ethiopia.
28.    Anouassi, A., N. Martinat, and Y. Combarnous. 1991. Purification, Characterization and Setting up of Immunoassays of Camel Pituitary Hormones. Isotope and Related Techniques in Animal Production and Health - Proceedings of an international symposium on nuclear and related techniques in animal production and health, jointly organized by the International Atomic Energy Agency and the Food and Agricultural Organization of the United Nations, Vienna. 318:371-377.
29.    Anouassi, A., A. Tibary, M. Adnani, and A. Sghiri. 1994. Preovulatory phase characterization in Camelus dromedarius and induction of ovulation. Proceedings of conference organized by FIS in Niamy, Niger.
30.    Arthur, G. H. 1992. An overview of reproduction in the camelids. Proc. 1st Int. Camel Conf., Dubai, UAE: 109-113.
31.    Arthur, G. H., and A. T. Al-Rahim. 1982. Aspects of Reproduction in the Female Camel (Camelus dromedarius) in Saudi Arabia. Vet. Med. Rev. 1:83-88.
32.    Arthur, H. G., A. T. Rahim, and A. Hindi. 1985. Reproduction and genital diseases of the camel. Br. Vet. J. 141:650-659.
33.    Asdel, S. A. 1946. Patterns of mammalian reproduction. Ithaca, New York; Comstock.
34.    Barhat, N. K.. M. S. Chowdhary, and A. K. Gupta. 1979. Note on Relationship Among Gestation Fength, Birth Weight, Placental Weight and Intra-Uterine Development Index in Bikaneri Camel. Indian J. Anim. Res. 13:115-117.
35.    Barmintsev, Y. N. 1951. Rectal examination of the reproductive organs of the camel. Konevodstvo (Vet. Bull., 22: 725, 1952). 21:38-42.
36.    Beniwal, B. K., and A. F. Chaudhry. 1984. Age at first calving in Bikaneri camel. Indian J. Anim. Sci. 54:598-599.
37.    Berg, R., S. Taher, and M. S. Moustafa. 1968. Comparison of prenatal growth of some organs in the camel (Camelus dromearius) and the Egyptian water buffalo (Bos bubalus bubalis L.). Zentralbl. Veterinaermed., Reihe A 15:438-447.
38.    Bodenheimer, F. S. 1954. Problems of the physiology and ecology of desert animals. In: Cloudsley-Thompson, J.F. Biology of deserts., Fondon, Institute of Biology.
39.    Bono, G. 1986. Fa reproduccion el los Camellos del Viejo Mundo: el dromedario (Camelus dromedarius). Revista de Camelidos Sudamericanos. 3:9-16.
40.    Bono, G., A. M. Dahir, and J. M. Ahmed. 1985. Variazioni stagionali de l'FH ematico nel dromedario (Camelus dromedarius). Atti Soc. Ital. Sci. Vet. 39:101-103.
41.    Bono, G., A. M. Dahir, A. Comin, and M. A. Jumale. 1985. Seasonal variations of FH response to GnRH treatment in camels (Camelus dromedarius). J. Reprod. Fertil. 73:335-339.
42.    Bono, G., A. M. Dahir, A. Comin, and M. A. Jumale. 1989. Plasma FH. Corticoid and Sex Steroid Variations in Camels (Camelus dromedarius) in Relation to Seasonal Climatic Changes. Animal Reproduction Science. 21:101-113.
43.    Bono, G., A. M. Dahir. and M. A. Jumale. 1985. Determinazione delle concentrazioni ematiche de l'LH nel dromedario (Camelus dromedarius) mediante RIA. Bolettino scientifico Facolta di Zootecnia e Veterinaria, UNS, Pacini Ed., VF41-48.
44.    Bono, G., D. A. Moallim. A. Comin. and J. M. Ahmed. 1990. Seasonal Effects on the Endocrine Reproductive Activity of the Dromedary Camels. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?1 - Paris: 107-115.
45.    Bosaev, J. 1983. Sexual activity of camels and organization of service. Konevodsevo. 26:8-9.
46.    Bourke, D. A., C. L. Adam, and C. E. Kyle. 1992. Ultrasonography as an aid to controlled breeding in the Flama (Lama glama). Veterinary Record. 130:424-428.
47.    Bourke, D. A., C. F. Adam, C. E. Kyle, P. Young, and T. G. McEvoy. 1992. Superovulation and embryo transfer in the llama. Proc. 1^st int. Camel Conf.. Dubai, UAE: 183-185.
48.    Bravo, P.. G. Stabenfeldt, M. Fowler, and B. Easley. 1996. Pituitary response to repeated copulation and/or gonadotropin-releasing hormone administration in llamas and alpacas. Biol Reprod. 47:884-888.
49.    Bravo, P., D. Stewart, B. Lasley, and M. Fowler. 1996. Hormonal indicators of pregnancy in llamas and alpacas. J. Am. Vet. Med. Assoc. 208:2027-30.
50.    Bravo, P. W. 1992. la fase follicular de circlo ovarico y la respuesta de la glandula pituitaria a la copula repetida en la alpaca. Allpak'a. 2.
51.    Bravo, P. W. 1993. Basic reproductive physiology in female South American Camelids. In: Fowler, M.E. (ed) Zoo and Wild Animal Medicine. WB Saunders Co, Philadelphia, 1993, 532-536.
52.    Bravo, P. W. 1994. Reproductive Endocrinology of Llamas and Alpacas. Veterinary Clinics of North America: Food Animal Practice. 10:265-279.
53.    Bravo, P. W.. M. E. Fowler, G. H. Stabenfeldt. and B. Lasley. 1990. Endocrine Responses in the Llama to Copulation. Theriogenology. 33:891-899.
54.    Bravo, P. W.. M. E. Fowler, G. H. Stabenfeldt, and B. L. Lasley. 1990. Ovarian Follicular Dynamics in the Llama. Biology of Reproduction. 43:579-585.
55.    Bravo, P. W., D. Pezo, and V. Alarcon. 1995. Evaluation of early reproductive performance in the postpartum alpaca by progesterone concentrations. Animal Reproduction Science. 39:71-77.
56.    Bravo, P. W., G. H. Stabenfeldt, M. E. Fowler, and B. L. Lasley. 1991. Urinary Steroids in the Periparturient and Postpartum Periods Through Early Pregnancy in Llamas. Theriogenology. 36:267-278.
57.    Bravo. P. W., G. H. Stabenfeldt, M. E. Fowler, and B. L. Lasley. 1993. Ovarian and endocrine patterns associated with reproductive abnormalities in llamas and alpacas. JAVMA. 202:268-272.
58.    Bravo, P. W., G. H. Stabenfeldt, B. L. Lasley, and M. E. Fowler. 1991. The Effect of Ovarian Follicle Size on Pituitary and Ovarian Responses to Copulation in Domesticated South American Camelids. Biology of Reproduction. 45:553-559.
59.    Bravo, P. W„ and J. Sumar. 1989. Laparascopic Examination of the Ovarian Activity in Alpacas. Animal Reproduction Science. 21:271-281.
60.    Bravo, P. W.. and M. H. Varela. 1993. Prenatal development of the alpaca (Lama pacos). Animal Reproduction Science. 32:245-252.
61.    Bravo, W. 1988. Breeding practices in South America. Llama Life. 7:16-17.
62.    Bravo, W., and J. Sumar. 1985. Follicular activity of the ovary in alpacas. In: Proceedings of the
International Convention on South American Camelids: 7.
63.    Bravo, W. M., and J. K. Sumar. 1981. Desarrolo fetal de la alpaca. Proc. 4^th Conv. Int. Camelidos Sudani., Punte Arenas, Chile: 14-15.
64.    Bucher, F. 1968. Haltung und Zucht von Vikunjas (Vicugna vicugna) im Ziircher Zoo. Der Zoologische Garten (NF). 36:153-159.
65. Burgemeister, R. 1974. Probleme der Dromedarhaltung und Zucht in Siidtunisien. Institute fur Technische Zusammenarbeit. Giessen: 99 pp.
66.    Burgemeister, R. 1975. Elevage de chameaux en Afrique du Nord. Deutsche Gesellschaft fur Zusammenarbeit GmbH, Eschborn: 86 p.
67.    Bustinza, J., A. Matusita, and M. Gallegos. 1970. Contribucion al patron embriologico de la alpaca. Anales Ira. Convencion sobre Camelidos Sudamericanos (Auquenidos): 148-149.
68.    Bustinza, J. A. 1961. Estudio macro y microscopio de la placentacion en Lama pacos (Alpaca). B. S. Thesis, San Marcos University, Lima Peru.
69.    Chen. B. X., and Z. X. Yuan. 1979. Reproductive pattern of the Bactrian camel. Workshop on Camels, IFS Symposium. Khartoum. 6:251-270.
70.    Chen, B. X., and Z. X. Yuen. 1979. Pregnancy diagnosis by rectal examination. Paper presented at Workshop on Camels, Khartoum. International Foundation for Science, Stockholm: 271-278.
71.    Chen. B. X., and Z. X. Yuen. 1984. Pregnancy Diagnosis by Rectal Examination in the Bactrian Camel. In: Cockrill, W.R. (ed.): The Camelid. An all-purpose animal. Scand. Inst. Afric. Studies, Uppsala Sweden: 399-406.
72.    Chen. B. X.. and Z. X. Yuen. 1984. Reproductive Pattern of the Bactrian Camel. In: Cockrill. W.R. (ed.) The Camelid, an all-purpose animal, Scand. Inst. Afric. Studies, Uppsala Sweden: 364-386.
73.    Chen. B. X., Z. X. Yuen, C. I. Kang, and G. Y. G. 1980. Reproductive pattern of the Bactrian camel. II. The sexual activities of the camel. Acta Vet. Zootech. Sin. 11:65-76.
74.    Chen, B. X., Z. X. Yuen, and C. W. Pan. 1984. Factors Inducing Ovulation in the Bactrian Camel. In: W.R. Cockrill (Ed.): The Camelid. An all-purpose animal. Scand. Inst. Afric. Studies, Uppsala, Sweden: 387-398.
75.    Chen, B. X., Z. X. Yuen, and G. W. Pan. 1985. Semen-induced ovulation in the Bactrian camel (Camelus bactrianus). J. Reprod. Fert. 73:335-339.
76.    Chen. B. X.. Z. X. Yuen, G. W. Pan. Y. M. Huang, and Y. H. Gao. 1983. Studies on the ovulation mechanism in the Bactrian camel. II. The role of semen in induction of ovulation. Acta vet. Zoo-Tech. Sin. (In Chinese). 14:161-166.
77.    Chriqui, A. 1988. Conduite de Felevage du dromadaire dans le Sud Marocain. These de Doctorat Veterinaire, Institut Agronomique et Veterinaire Hassan II. Rabat, Maroc.
78.    Combamous, Y., J. C. Huet, N. Martinat, M. Mansion, A. Anouassi, and J. C. Pernollet. 1989. N-Terminal Amino-Sequencing of Camel (Camelus dromedarius) Luteinizing-Hormone CX and p Subunits. Pathologie Biologie. 37:814-818.
79.    Combamous, Y., N. Martinat, and A. Anouassi. 1990. Molecular Endocrinology of Reproduction in the Dromedary. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 51-64.
80.    Condorena, N., J. Sumar, E. Franco, and V. Alarcon. 1988. Largo de gestacion en llamas. Anales del XI Congreso Panamericano de Ciencias Veterinarias (Lima): 62.
81.    Cooper. M. J., J. Skidmore, M. Ali, T. Billah. S. Wensvoort. and A. A. Billah. W. R. 1990. An attempt to induce and synchronise ovulation and superovulation in dromedary camels for embryo transfer. Proceeding from the workshop Is is Possible to Improve the Reproductive Performance of the Camel?' - Paris: 313-326.
82.    Cooper, M. J., J. A. Skidmore. W. R. Allen. S. Wensvoort, M. Billah, M. A. Chaudhry, and A. M. Billah. 1992. Attempts to stimulate and synchronise ovulation and superovulation in dromedary camels for embryo transfer. Proc. 1^st Int. Camel Conf., Dubai. UAE: 187-191.
83.    Cristofori, F., G. Aria. L. Vincenti, S. Callegari, A. S. Aaden. and A. M. Gheddi. 1989. Short Communication:    Mating-Dependent Endocrinological Variations in Female Camelus dromedarius. Animal Reproduction Science. 21: 73-77
84.    Cristofori. F., and G. Quaranta. 1990. Steroids Serum Levels During Sexual Cycle and Pregnancy in the Female One-Humped Camel. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 65-75.
85.    Cristofori. P., G. Aria. E. Seren. G. Bono. S. Ahmed, and H. M. Nur. 1986. Endocronological aspects of reproduction in the female camel. Rev. Mond. Zootech. 57:22-25.
86.    Dafalla, E. A.. B. E. Musa. A. M. Homeida. D. Rath, and H. Merkt. 1987. Induction of Oestrus in a Camel (Camelus dromedarius) Using PMSG and Diagnosis of the Ovarian Activity. Zuchthyg. 22:229-231.
87.    Dahir. M. A., A. M. Jumale, M. I. Halane, and A. Prandi. 1990. Effects of Progestagen - PMSG Treatment on Oestrous Activity and Fertility of She-Camel Dromedaries at the End of the Dry Season. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 189-195.
88.    Dzitumaenk, I. K. 1977. Sroki plodonosheniya verblyudits. Pregnancy duration in camels. Konevodstvo Konnyi Sport. 10:29.
89.    Dzumagulov, I. K. 1969. The use of PMSG in camel breeding. Konevod. Konnyi Sport(Anim. Breed. Abstr., 37: 680, 1969). 39:32.
90.    El-Azab, E. A., and B. Musa. 1976. Early Detection of Pregnancy in the Camel by using biological methods (Brief communication). Zuchthyg. 11:166-168.
91.    El-Belely, M. S. 1994. Endocrine changes, with emphasis on 13, 14-dihydro-15-keto -prostaglandin F2CX and corticosteroids, before and during parturition in dromedary camels (Camelus dromedarius). Journal of Agricultural Science, Cambridge. 122:315-323.
92.    Elias, E. 1990. Early Weaning and Postpartum Conception in the One-Humped Camel (Camelus dromedarius) - Review. Proceeding of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' -Paris: 239-255.
93.    Elias, E., E. Bedrak, and D. Cohen. 1985. Induction of oestrus in the camel (Camelus dromedarius) during seasonal anoestrus. J. Reprod. Fert. 74:519-525.
94.    Elias, E., E. Bedrak, and R. Yagil. 1984. Estradiol Concentration in the Serum of the One-Humped Camel (Camelus dromedarius) during the Various Reproductive Stages. General and Comparative Endocrinology. 56:258-264.
95.    Elias, E., E. Bedrak, and R. Yagil. 1984. Peripheral Blood Levels of Progesterone in Female Camels during Various Reproductive Stages. General and Comparative Endocrinology. 53:235-240.
96.    Elias, E., and D. Cohen. 1986. Parturition in the camel (Camelus dromedarius) and some behavioral aspects of their newborn. Comp. Biochem. Physiol. 84A:413-419.
97.    Elmi, A. A. 1989. Camel Husbandry and Management by CEEL-DHEER pastoralists in Central Somalia. London, Pastoral Network Development Paper 27d.
98.    El-Wishy, A. B. 1987. Reproduction in the Female Dromedary (Camelus dromedarius): a Review. Animal Reproduction Science. 15:273-297.
99.    El-Wishy, A. B. 1990. Genital Abnormalities in Camels (Camelus dromedarius). Proceedings of the workshop 'Is it possible to Improve the Reproductive Performance of the Camel?' -Paris: 163-174.
100.    El-Wishy, A. B. 1992. Functional morphology of the ovaries of the dromedary camel. Proc. 1st int. Camel Conf., Dubai. UAE: 149-154.
101.    El-Wishy, A. B., and S. A. El Sawaf. 1971. Functional activity of the ovaries and uterine horns in fat-tailed sheep and camels (Camelus dromedarius). Fortpflanz. Haustier. 7:181-187.
102.    El-Wishy, A. B.. and I. M. Ghoneim. 1986. Breeding Activity of the Camel (Camelus dromedarius). Animal Reproduction Science. 11:75-77.
103.    El-Wishy. A. B., N. A. Homeida, M. A. I. El Sayed, A. A. Seida, A. M. Ghallab, and T. Reimers. 1984. Estrogen and progesterone levels in the blood of pregnant and non-pregnant camels (Camelus dromedarius). J. Med. Res. Inst. Alex. 5:39-49.
104.    El-Wishy, A. B., N. A. Homeida, M. A. Omar, A. M. Mobarak, and M. A. I. El-Sayed. 1981. Functional Changes in the Pregnant Camel with Special Reference to Foetal Growth. Br. Vet. J. 137:527-537.
105.    England. B. G„ A. G. Cardozo, and W. C. Foote. 1969. A review of the physiology of reproduction in the New World Camelidae. Intern. Zoo Yearbook. 9:104-109.
106.    England, B. G., W. C. Foote, A. G. Cardozo, D. H. Matthews, and S. Riera. 1971. Oestrous and mating behaviour in the llama (Lama glama). Anim. Behav. 19:722-726.
107.    England. B. G.. W. C. Foote, D. H. Matthews, A. G. Cardozo, and S. Riera. 1969. Ovulation and Corpus Luteum Function in the Llama (Lama Glama). J. Endocr. 45:505-513.
108.    Ennassiri, A. 1985. Activite folliculaire chez la chamelle (Camelus dromedarius). These de Doctorat Veterinaire, Insititut Agronomique et Veterinaire Hassan II, Rabat, Maroc.
109.    Escobar, R. C. 1984. Animal Breeding and Production of American camelids. Lima, Peru: Talleres Graficos de ABRIL.
110.    Evans, J. O., and J. G. Powys. 1979. Camel husbandry to increase the productivity of ranchland. Camels IFS symposium, Khartoum (Sudan): 241-250.
111.    Femandez-Baca, S. 1970. Luteal Function and the Nature of Reproductive Failures in the Alpaca. Ph.D Thesis, Cornell University, Ithaca, N. Y.
112.    Femandez-Baca, S., W. Hansel, and C. Novoa. 1970. Corpus Luteum Function in the Alpaca. Biology of Reproduction. 3:252-261.
113.    Femandez-Baca, S., W. Hansel, and C. Novoa. 1970. Embryonic mortality in the alpaca. Biol. Reprod. 3:252-261.
114.    Femandez-Baca, S., W. Hansel, R. Saatman, J. Sumar, and C. Novoa. 1979. Differential Luteolytic Effects of Right and Left Uterine Homs in the Alpaca. Biology of Reproduction. 20:586-595.
115.    Femandez-Baca, S., D. H. L. Madden, and C. Novoa. 1970. Effect of Different Mating Stimuli on Induction of Ovulation in the Alpaca. J. Reprod. Fert. 22:261-267.
116.    Femandez-Baca. S., C. Novoa, and J. Sumar. 1972. Actividad reproductiva en la alpaca mantenida en
separacion del macho (Alpaca reproductive activity maintained separate from the male). Assoc. Latinoamericana de Produccion Animal. Memorias. 7:7-18.
117.    Fernandez-Baca, S., C. Novoa, and J. Sumar. 1972. Seasonal variations in the reproduction of the alpaca. Anim. Breed. Abstr. 40:336.
118.    Fernandez-Baca, S., J. Sumar, C. Novoa, and V. Lejva. 1973. Relacion entre la ubacacion del cuerpo luteo y la localizacion del embrion en la alpaca. Rev. Inv. Pec. (IV1TA) Univ. Nac. S. Marcos. 2:131-135.
119.    Fernandez-Baca, S., J. Sumar, C. Novoa, and V. Leyva. 1974. Localizacion del cuerpo luteo y la ubicacion del embrion en la alpaca. Mem. ALPA, Guadalajara. Mexico. 9:87-88.
120.    Foote, W. C. 1982. Determination of pregnancy in the llama by progesterone analysis. Llama World. 1:18.
121.    Fowler, M. E. 1989. Medicine and Surgery of South American Camelids. Ames, Iowa, Iowa State University Press.
122.    Fowler, M. E., and H. J. Olander. 1990. Fetal membranes and ancillary structures of llamas (Lama glama). Am. J. Vet Res. 51:1495-1500.
123.    Gauthier-Pilters, H., and A. I. Dagg. 1981. The Camel: its Evolution, Ecology, Behaviour and Relationship to Man. University of Chicago Press, Chicago 11: 90-100.
124.    Ghazi, S. R., A. Oryan, and H. Pourmirzaei. 1994. Some Aspects of Macroscopic Studies of the Placentation in the Camel (Camelus dromedarius). Anat. Histol. Embryol. 23:337-342.
125.    Ghoneim, I. M. 1985. The ovary of the pregnant camel with special reference to the corpus luteum. M. V. Sc. Cairo University: 68 pp.
126.    Gimbo, A., and A. Zanghi. 1979. L'atresia follicolare nella femmina di Camelus dromedarius. Osservazioni istogenetiche e considerazioni funzionali sul corp luteo atretico. Clin. Vet. 102:200-225.
127.    Gupta, A. K.. M. S. Chowdhary, and N. K. Barhat. 1978. A note on optimum time for service in camel (Camelus dromedarius). Indian J. Anim. Sci. 48:324-325.
128.    Hafez, E. S. E. 1955. Foetal-Maternal Attachments in Buffalo and Camel. Indian J. Vet. Sci.
25:109-115.
129.    Herre, W. 1963. Einiges vom Vicuna, dem zierlichen Bergkamel. Freunde des Kolner Zoo. 6:23-26.
130.    Heshmat, H. A., A. Taha, A. A. Ismail, and M. B. A. Sami. 1984. Levels of thyroid hormones in the plasma of pregnant camels (Camelus dromedarius). Indian J. Anim Sci. 54:663-665.
131.    Hira, I. M. 1947. Camel breeding in India. Indian Farming. 8:504.
132.    Homeida, A. M. 1990. A gonadotrophin-like bioactivity of the serum of pregnant camel (Camelus dromedarius). Animal Reproduction Science. 23:327-333.
133.    Homeida, A. M„ M. G. R. Khalil, and A. A. M. Taha. 1988. Plasma concentrations of progesterone, oestrogens, testosterone and LH-like activity during the oestrus cycle of the camel (Camelus dromedarius). J. Reprod. Fert. 83:593-598.
134.    Hussein. F. M., M. B. Noseir, I. E. El-Bawab, and D. L. Paccamonti. 1991. Prenatal assessment of weight and dimensions of the camel conceptus (Camelus dromedarius). Animal Reproduction Science. 26:129-136.
135.    Islamy, A. 1950. Riding camel around Khas and Iranshahr. Thesis Abst. from Rev. Fac. Med. Vet. Teheran. 12:87.
136.    Ismail, S. T. 1987. A Review of Reproduction in the Female Camel (Camelus dromedarius). Theriogenology. 28:363-371.
137.    Jessup, D. A., and W. R. Lance. 1982. What Veterinarians Should Know About South American Camelids. California Veterinarian. 11:12-18.
138.    Johnson, L. W. 1989. Llama Reproduction. Veterinary Clinics of North America: Food Animal Practice. 5:159-182.
139.    Joshi, C. K. 1972. Studies on certain aspects of reproduction in she-camel. M.V.Sc. Thesis, University of Udaipur, Udaipur.
140.    Joshi, C. K.. K. K. Vyas, and P. K. Pareek. 1978. Studies on oestrus cycle in Bikaneri she-camel (Camelus dromedarius). Indian J. Anim. Sci. 48:141-145.
141.    Kamoun, M„ and R. T. Wilson. 1994. Improving early reproductive characteristics of Tunisian camels by nutritional and management interventions. Journal of Arid Environments: 89-94.
142.    Khaldoun, M. 1990. Reproductive potentialities of one-humped she-camel. Adaptation to environment. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 37-50.
143.    Khanna, N. D.. A. K. Rai, S. N. Tandon. and H. K. Jindal. 1987. Camel reproduction: A review. Annals Arid Zone. 26:143-155.
144.    Khanna, N. D„ S. N. Tandon, and A. K. Rai. 1990. Breeding parameters of Indian camels. Indian Journal of Animal Science. 60:1347-1354.
145.    Khanna, N. D„ S. N. Tandon, and A. K. Rai. 1990. Reproductive Status of Bikaneri Camels Managed Under Farm Conditions. Proceeding of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' -Paris: 337-352.
146.    Koford. C. B. 1957. The vicuna and the puna. Ecol. Monogr. 27:153-219.
147.    Lahlou-Kassi, A.. A. Sghiri, and A. Chriqi. 1990. Reproductive performance of a herd of camels in the region of Laayoune and Guelmim. Proceedings of the workshop 'Is it possible to improve the reproductive performance in the camel?' - Paris. Abstract presentation
148.    Leese, A. S. 1927. A Treatise on the One-humped Camel in health and disease. Hayres & Son Maiden Lane, Stamford, Lincoln Shire.
149.    Leon. J. B., B. B. Smith, K. I. Timm, and G. LeCren. 1990. Endocrine changes during pregnancy, parturition and the early post-partum period in the llama (Lama glama). J. Reprod. Fert. 88:503-51 1.
150.    Leonard, A. G. 1894. The Camel. Its Uses and Management. Longman, London: 335pp.
151.    Leyva V., and Sumar J. 1981. Evaluacion del peso corporal al empadre sobre la capacidad reproductiva de hembras alpacas de un ano de edad. Proc. 4^th Conv. Int. Camelidos SudAm., Punta Arenas, Chile.
152.    Leyva, V., and J. Sumar. 1981. Determinacion del patron anual de presentacion de celo y ovulacion expontanea en alpacas. Investigaciones en Camelidos Sudamericanos y ovinos. Programa Colaborativo de Investigacion en Rumiantes Menores. Titulo XII-AID. IVITA-Universidad Nacional Mayor de San Marcos.
153.    Mares, R. G. 1954. Animal husbandry, animal industry and animal disease in the Somaliland protectorate. Br. Vet. J. I 10:411-423.
154.    Marichatou, H. 1989. Contribution a la mise en place du dosage immunoenzymatique de la LH cameline. These de doctorat veterinaire, IAV Hassan II, Rabat, Morocco.
155.    Marie, M., and A. Anouassi. 1986. Mating-Induced Luteinizing Hormone Surge and Ovulation in the female camel (Camelus dromedarius) Biology of Reproduction. 35:792-798.
156.    Marie, M. and Anouassi A., 1987. Induction of luteal activity and progesterone secretion in the nonpregnant one-humped camel (Camelus dromedarius). J. Reprod. Fert. 80:183-192.
157.    Marie, M. E. 1987. Bases endocriniennes de la fonction sexuelle chez le dromadaire (Camelus dromedarius). These de doctorat de L'Universite. Paris 6.
158.    Matharu B.S. 1966. Camel care. Indian Farming. 16:19-22.
159.    McKinnon. A. O., and A. H. Tinson. 1992. Embryo transfer in dromedary camels. Proc. 1^st int. Camel Conf., Dubai, UAE: 203-208.
160.    Mehta, V. S„ A. H. A. Prakash, and M. Singh. 1962. Gestation Period in Camels. Indian Vet. J. 39:387-389.
161.    Merkt. H„ M. Boer, D. Rath, and H. A. Schoon. 1988. The presence of an additional fetal membrane and its function in the newborn guanaco (Lama guanicoe). Theriogenology. 30:437-439.
162.    Meschia, G., H. Prystowsky, A. Hellegers, W. Huckabee, J. Metcalfe, and D. Barron. 1960. Observations on the oxygen supply to the fetal llama. Am. J. Physio 49: 284-291.
163.    Meuli, L.. N. Erb. R. Schaffer, and R. Thau. 1982. Estrogen and progesterone levels in the female camel. J. Steroid Biochem. 17 (abstract 28-298A).
164.    Moallin. A. S. M„ and H. M. Mohamed. 1990. Observations on Reproductive Performance of the Dromedary in Central Somalia. Proceeding of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 367-377.
165.    Moldagaliev, T. M. 1975. The effect of fetal size and pelvic measurements on parturition in different species of camels. Temat. Sb. Nauch. Tr. Alma-Atinsk. Semipalatinsk. Zoovet. Inst. (Anim. Breed. Abstr., 44: 653, 1976). 36:81-83.
166.    Moniem, K. A. 1968. Some histological and histochemical studies on the placenta of the camel (Camelus dromedarius). Master Thesis, University of Khartoum.
167.    Morton, W. R. M. 1961. Observations on the full-term foetal membranes of three members of the camelidae (Camelus dromedarius, Camelus hactrianus and Lama Glama). J. Anatomy. 25:200-209.
168.    Moslah, M. 1990. Early separation and artificial suckling of the new-born to improve the breeding performance of the dromedaries in Tunisia. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 225-238.
169.    Moslah, M. 1990. L'amelioration de la productivite du dromedaire en Tunisie. Proc. UCDEC Workshop, 'Is it possible to improve the reproductive performance in the camel?' Paris.
170.    Mukasa-Mugerwa, E. 1981. Reproductive performance. In the Camel (Camelus dromedarius). A bibiliographical Review. ILCA Monograph. Int. Livestock Centre for Africa: 11-32.
171.    Musa, B.. and M. E. A. Abusineina. 1976. Pregnancy diagnosis in the camel. Acta. Vet. Beograd. 26:107.
172.    Musa, B., H. Merkt. B. Hago, H.-A. Hoppen. and H. Siente. 1990. The Female Camel (Camelus dromedarius) and the Artificial Insemination. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 257-262.
173.    Musa, B. E. 1969. Some Aspects of Reproduction in the Female Camel. M. V. Sc. Thesis, University of Khartoum.
174.    Musa, B. E. 1977. A New Epidermal Membrane Associated with the Foetus of the Camel (Camelus dromedarius). Zbl. Vet. Med. C. Anat. Histol. Embryol. 6:355-358.
175.    Musa, B. E. 1979. The Development, Presentation. Position and Posture of the Foetus in Camel (Camelus dromedarius). Sudan J. Vet. Sci. & Anim. Husb. 20:37-42.
176.    Musa, B. E. 1979. Reproductive patterns in the female camel (Camelus dromedarius). In: Workshop in Camels, Karthoum, Sudan. Inti. Fnd. For Sci.: 279-284.
177.    Musa, B. E. 1979. Studies on the Ovary of the Camel (Camelus dromedarius). Sudan J. Vet. Sci. & Anim. Husb. 20:51-56.
178.    Musa, B. E. 1983. Normal Parturition in the Camel (Camelus dromedarius). Vlaams Diergeneeskundig Tijdschrift. 52:255-268.
179.    Musa, B. E„ and M. E. Abusineina 1978. Development of the Conceptus in the Camel (Camelus dromedarius). Acta Veterinaria (Beograd). 26:17-24.
180.    Musa, B. E., and M. E. Abusineina. 1976. Some Observations on Reproduction in the Female Camel (Camelus dromedarius). Acta Veterinaria (Beograd). 26:63-69.
181.    Musa, B. E., and M. E. Abusineina. 1976. Studies on the allantoic and amniotic fluids of the camel (Camelus dromedarius). Acta Vet. (Beograd). 26:107-114.
182.    Musa. B. E.. and M. E. Abusineina. 1978. The oestrus cycle of the camel (Camelus dromedarius). Veterinary Record. 103:556-557.
183.    Musa, B. E.. and S. A. Makawi. 1985. Involution of the uterus and the first postpartum heat in the camel (Camelus dromedarius). Conference on Animal Production in Arid Zones, Damascus, Syria, 1985.
184.    Nawito, M.. M. R. Shalash. R. Hoppe, and A. M. Rekha. 1967. Reproduction in female camel. Bulletin No. 2, National Research Centre, Cairo.
185.    Nawito, M. F. 1967. Some reproductive aspects in the female camel. D. V. M. Thesis Warsaw Agric Univ. Poland: 109 pp.
186.    Novoa, C. 1970. Review: Reproduction in the Camelidae. J. Reprod. Fert. 22:3-20.
187.    Novoa, C., S. Fernandez-Baca, J. Sumar, and V. Levya. 1972. Pubertad en la alpaca. Rev. Inv. Pec (IV1TA), Univ. Nac. San Marcos. 1:29-35.
188. Novoa. C., J. Sumar. and E. Franco. 1970. Empadre complementario de alpacas hembras vacias. In: Anales de la I Convencion Intemacional sobre Camelidos Sudamericanos. Organizado por la Universidad Tecnica del Altiplano (Puno. Peru): 144-147.
189.    Nur, H. M. 1984. Some Reproductive Aspects and Breeding Patterns of the Somali Camel (Camelus dromedarius). in: Camel Pastoralism in Somalia. Hussein, M. A. (ed). Proceedings from Workshop in Baydhabo, Mogadishu, Somali Academy of Science and Arts, (Camel forum Working paper, #7): 91-110.
190.    Ordonez, T. H. 1994. Llamas, llama production and llama nutrition in the Ecuador highlands. Journal of Arid Environments. 26:67-71.
191.    Osman. A. 1968. Anatomical Study of the Female Genital System of the One-Humped Camel (Camelus dromedarius) - III - The Uterus and Placenta. Sudan J. Vet. Sci. Anim. Husb. 9:477-500.
192.    Pan, G. W„ X. X. Zhao, B. H. Chen, S. Jiang, Y. M. Huang, Y. S. Zu, and H. Y. Wang. 1992. The ovulation-inducing effect of seminal plasma in the Bactrian camel. Proc. 1st Int. Camel Conf., Dubai. UAE: 159-161.
193.    Paul-Murphy, J. 1989. Obstetrics, Neonatal Care, and Congenital Conditions. Veterinary Clinics of North America: Food Animal Practice. 5:183-202.
194.    Paul-Murphy, J., L. A. Tell. W. Bravo. M. E. Fowler, and B. L. Lasley. 1991. Urinary Steroid Evaluations to Monitor Ovarian Function in Exotic Ungulates: VII. Correspondence of Urinary Plasma Steroids in the Llama (Lama glama) During Nonconceptive and Conceptive Cycles. Zoo Biology. 10:225-236.
195.    Podberezki, J. 1951. Improved camel breeding. Konevodstvo. 10:41 -43. 196. Pollard. J. C.. R. P. Littlejohn, and G. H. Moore. 1995. Seasonal and other factors affecting the sexual behaviour of alpacas. Animal Reproduction Science. 37:349-356.
197.    Pollard. J. C„ R. P. Littlejohn, and I. C. Scott. 1994. The effects of mating on the sexual receptivity of female    alpacas. Animal Reproduction Science. 34:289-297.
198.    Prakash, A., and V. Singh. Normal Parturition in Camels. Indian Veterinary Journal: 551-553.
199.    Prescott. J. 1981. Suckling Behavior of llama (Lama glama) and Chapman's zebra (Equus burchelli antiquorum) in captivity. Appl Anim. Ethol. 7:1977.
200.    Qureshi, M. H. 1986. The camel. Paper presented at MINEADEP Seminar on Camel Production and Health, Kuwait.
201.    Rai, A. K.. S. P. Agarwal, V. K. Agarwal, and N. D. Khanna. 1990. Induction of Early Puberty in Female Camels. Proceedings of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 211-224.
202.    Rai, A. K., S. P. Agarwal. V. K. Agarwal, and N. D. Khanna. 1991. Induction of early puberty in female camels. Indian Journal of Animal Sciences. 61:1265-1268.
203.    Ram, S., and B. D. Singh, O. P. 1977. A Note on Genetic Studies on Gestation Length, Birth Weight and Intra-Uterine Development Index in Indian Camel {Camelus dromedarius) and Factors Affecting Them. Indian Vet. J. 54:953-955.
204.    Rodriguez, A. R. P. 1959. Ovulacion en Las Alpacas. B. S. Thesis, San Marcos University, Lima, Peru.
205.    San Martin, M. 1961. Fisiologia de la reproduccion de las alpacas. Symposium Sobre problemas ganaderos, Lima, Peru.
206.    San-Martin, M., M. Copaira, J. Zuniga, R. Rodreguez, G. Bustinza, and L. Acosta. 1968. Aspects of Reproduction in the Alpaca. J. Reprod. Fert. 16:395-399.
207.    Schmidt, C. R. 1970. Breeding seasons and notes on some other aspects of reproduction in captive camelids. International Zoo Yearbook: 387-390.
208.    Schmidt. C. R. 1975. Captive Breeding of the Vicuna: Breeding Endangered Species in Captivity. Academic Press, London: 271-283.
209.    Schmidt, P., and L. Baptidanova. 1966. peculiarities of embryonic and gestation periods during the prenatal development of the two-humped camel. Reports of the Academy of Science of the U.S.S.R. 169.
210.    Schwarzenbeger, F., G. Speckbacher, and E. Banberg. 1995. Plasma and fecal progestagen evaluations during and after the breeding season of the female vicuna {Vicuna vicuna). Theriogenology. 43:625-634.
211.    Sghiri, A. 1988. Evaluation des performances de reproduction d'un troupeau camelin a Laayoune (Camelus dromedarius). These de Doctorat Veterinaire, Institut Agronomique et Veterinaire Hassan II, Rabat, Maroc.
212.    Shalash, M. R. 1965. Some reproductive aspects in the female camel. World Rev. Anim. Prod. 4:103-108.
213.    Shalash, M. R. 1980. Reproduction in camel. Proc. 9th Int. Cong. Anim. Prod, and A. I. (Madrid). 2:559-567.
214.    Shalash, M. R. 1987. Review Article: Reproduction in Camels. Egypt J. Vet. Sci. 24:1-25.
215.    Shalash. M. R., and M. Nawito. 1964. Some Reproductive Aspects in the Female Camel. 5^th ICAR: 263-273.
216.    Sharma, S. S., and K. K. Vyas. 1970. Parturition in the Camel (Camelus dromedarius). Ceylon Vet. J. 18:7-9.
217.    Sharma, S. S.. and K. K. Vyas. 1971. Factors Affecting Gestation Length in the Bikaneri Camel (Camelus dromedarius). Ceylon Vet. J. 19:67-68.
218.    Sharma, S. S., and K. K. Vyas. 1972. Involution of Uterus and Vulva in Camels. Ceylon Vet. J. 20:9-10.
219.    Sharma, S. S., and K. K. Vyas. 1981. Studies on Sexual Physiology of Stud Camel. Indian Vet. J. 58:743-744.
220.    Shawki. H., S. K. Verma, and R. K. Chandolia. 1992. Studies on Corpus Luteum of Pregnancy in She-Camel (Camelus dromedarius) Throughout the Year. IJAR. 13:80-82.
221.    Shmidt, G. A., and V. E. Bondarenko. 1971. Blastocysts of Bactrian Camel (Camelus Bactrianus). Translated from Doklady Akademii NaukSSSR. 196:482-485.
222.    Shmidt, G. A., Y. A. Plyasov, and Y. P. Baptidanova. 1966. Special Features of the Embryonic and Prefetal Periods of Intrauterine Development of the Two-Humped Camel. Translated from Doklady Akademii Nauk SSSR. 169:245-248.
223.    Skidmore, J., W. R. Allen, M. J. Cooper, M. A. Chaudhry, M. Billah. and A. M. Billah. 1992. The recovery and transfer of embryos in the dromedary camel: results of preliminary experiments. Proc. 1st Int. Camel Conf, Dubai, UAE: 137-142.
224.    Skidmore, J.. F. Wooding, and W. Allen. 1996. Implantation and early placentation in the one-humped camel (Camelus dromedarius). Placenta. 17:253-62.
225.    Skidmore, J. A., W. R. Allen, and R. B. Heap. 1994. Oestrogen synthesis by the peri-implantation conceptus of the one- humped camel (Camelus dromedarius). Journal of Reproduction and Fertility. 101:363-367.
226.    Skidmore, J. A.. M. Billah, and W. R. Allen. 1992. Ultrasonographic and videoendoscopic monitoring of early foetal developmet in the dromedary camel. Proc. 1st Int. Camel Conf., Dubai. UAE: 193-201.
227.    Skidmore, J. A., M. Billah, and W. R. Allen. 1995. The ovarian follicular wave pattern in the mated and non-mated dromedary camel (Camelus dromedarius). Journal of Reproduction and Fertility Supplement. 49:545-548.
228.    Skidmore. J. A., M. Billah, and W. R. Allen. 1996. The ovarian follicular wave pattern and induction of ovulation in the mated and non mated one humped camel. Journal of Reproduction and Fertility. 106:185-192.
229.    Skidmore, J. A.. M. Billah, and W. R. Allen. 1996. Patterns of hormone secretion throughout pregnancy in the one-humped camel (Camelus dromedarius). Reproduction Fertility and Development. 8:863-869.
230.    Smith. B. B., E. G. Pearson, and J. Leon. 1989. Evaluation of normal triiodothyronine and tetraiodothyronine concentrations in llamas (Lama glama). Am J. Vet. Res. 50:1215-1219.
231.    Smith, B. B„ K. I. Timm, and P. J. Reed. 1992. Morphometric evaluation of growth in llamas (lama glama) from birth to maturity. JAVMA. 200:1095-1100.
232.    Smith, C. L„ A. T. Peter, and D. G. Pugh. 1994. Reproduction in Llamas and Alpacas: A Review. Theriogenology. 41:573-592.
233.    Steel, J. H. 1890. A Manual of Diseases of Camel and his management and uses., Ist ed. Lawrence Asylum Press, Madras.
234.    Stekleniov, E. P. 1968. Des particularites anatomo-morphologiques de la structure et des fonctions physiologiques des trompes de Fallope chez les camelides (genres Lama et Camelus). 6th ICAR. 1:74.
235.    Sumar, J. 1983. Studies on Reproductive Pathology in Alpacas. MS Thesis, Dept Obstet and Gynaec., College of Vet Med, Swedish Univ of Agric Sci,. Upsala.
236.    Sumar, J. 1985. Reproductive Physiology in South American Camelids. in: Land, R.B., Robinson D.W. (eds), Genetics of Reproduction in Sheep, Butterworths, London: Chapt. 9, 81-95.
237.    Sumar, J. 1985. (Some Aspects of Obstetrics of the Alpaca) Algunos Aspectos Obstetrics de la alpaca. Boletim Tecnico 2.
238. Sumar, J. 1988. Removal of the Ovaries or Ablation of the Corpus Luteum and its Effect on the Maintenance of Gestation in the Alpaca and Llama. ACTA Vet. Scand. 83 (Suppl): 133-141.
239.    Sumar, J. 1988. South American camelid raising and reproduction in the high Andes. In: Hjort al Omas (ed), Camels in development: Sustainable Production in the African Drylands. Uppsala: Scandinavian Institute of African Studies, 1988, pp: 81-95.
240. Sumar, J. 1996. Reproduction in llamas and alpacas. Animal Reproduction Science. 42: 405-415.
241.    Sumar, J. 1994. Effects of various ovulation induction stimuli in alpacas and llamas. Journal of Arid Environments. 26:39-45.
242.    Sumar, J„ P. W. Bravo, and W. C. Foote. 1993. Sexual receptivity and time of ovulation in alpacas. Small Ruminant Research. 11:143-150.
243.    Sumar, J., W. Bravo, E. Franco et al. 1985. Laparoscopy in alpacas, llamas and vicunas. In: Proceedings of the International Convention on South American Camelids: 11.
244.    Sumar, J., G. Fredriksson, V. Alarcon, and FI. Kindahl. Edqvist, Lars-Eric. 1988. Levels of 15-keto-13, 14-dihydro-PFG2a , Progesterone and Oestradiol-17p after Induced Ovulations in Llamas and Alpacas. Acta vet. scand. 29:339-346.
245.    Sumar, J., and M. Garcia. 1984. Fisiologia Reproductiva en Los Camelidos Sudamericanos: Alpaca Y Llama. IAEA-SM-292/16:26-27.
246.    Sumar, J., and M. Garcia. 1986. Fisiologia de la reproduccion de la alpaca. In: Nuclear and Related Techniques in Animal Production and Health. IAEA. Vienna: 149-177.
247.    Sumar, J., and V. Leyva. 1972. Relacion entre la ubicacion del cuerpo luteo y la localizacion del embrion en la en la llama (Lama glama). Res. Proyectos Investigacion. Univ. Nacional Mayor de San Marcos, Periodo 1975-1979. 1:21-27.
248.    Sumar, J., C. Novoa, and S. Femandez-Baca. 1972. Fisiologia Reproductiva Post-Partum en la Alpaca. Rev. Inv. Pec. (IVITA). 1:21-27.
249.    Tayeb. M. A. F. 1948. Studies on the Anatomy of the Ovary and Corpus Luteum of the Camel. Brit. Vet. J. 104:179-190.
250.    Tayeb. M. F. 1946. The anatomy of the genital organs of the camels, male and female. M. V. Sc. Thesis, Fouad 1st Univ., Cairo, Egypt.
251.    Terentjev, S. M. 1951. Experience in stud work on a camel breeding farm. Konevodstvo (Anim. Breed. Abstr., 20: 171. 1952). 11:20-23.
252.    Thibault, C. 1973. Sperm Transport and Storage in Vertebrates. J. Reprod. Fert.. Suppl. 18:39-53.
253.    Tibary. A.. and A. Anouassi. 1996. Ultrasonographic changes of the reproductive tract in the female camel (Camelus dromedarius) during the follicular cycle and pregnancy. Journal of Camel Practice and Research. 3:71-90.
254.    Tibary, A., and M. Bakkoury. 1994. Reproduction Equine: La Jument. Actes Edition, Institut Agronomique et Veterinaire Hassan II, Morocco.
255.    Urquieta, B., R. Cepeda, J. E. Caceres, L. A. Raggi, and J. R. Rojas. 1994. Seasonal variation in some reproductive parameters of male vicuna in the High Andes of northern Chile. Journal of Arid Environments. 26:79-87.
256.    Urquieta, B., and J. R. Rojas. 1990. An introduction to South American camelids. In: Livestock Reproduction in Latin America. FAO/IAEA, Vienna, Austria, 389-406.
257.    Urquieta. B., and J. R. Rojas. 1990. Studies on the reproductive physiology of the vicuna (Vicugna vicugna). In: Livestock Reproduction in Latin America, Proc. of the Final Research Coordination Meeting of the FAO/IAEA/ARCAL. Vienna. 1990: 407-428.
258.    Van Leenep. E. W. 1964. The placenta of the one humped camel (Camelus dromedarius) during the second half of gestation. Acta Morph. Neesl. Scand. 5:373-379.
259.    Vasil'eva. L. P., A. F. Shapilov, and K. Baimukhambetov. 1984. Fetal membranes of the camel. Dokl. Vses. Akad. Skh. Nauk (Vet. Bull., 54: 797. 1984). 5:31-32.
260.    Williamson. G. and Payne. W.J.A.. 1978. An introduction to animal husbandry in the tropics. Tropical series in Agriculture, London, Great Britain, Longman, 744 pages.
261.    Wilson, R. T. 1984. The Camel. Longmans, London.
262.    Wilson. R. T. 1984. Quelques parametres de la reproduction chez la chamelle de l'Air (Republique du Niger). Reproduction des ruminants en zone tropicale, Colloque INRA No 20. 20:147-155.
263.    Wilson, R. T. 1986. Reproductive Performance and Survival of Young One-Humped Camels on Kenya Commercial Ranches. Anim. Prod. 42:375-380.
264.    Wilson, R. T. 1989. Reproductive performance of the one-humped camel. The empirical base. Revue Elev. Med. Vet. Pays Trop. 42:117-125.
265.    Wilson Wiepz, D., and R. J. Chapman. 1985. Non-Surgical Embryo Transfer and Live Birth in a Llama. Theriogenology. 24:251 -257.
266.    Xu, Y. S„ Y. H. Gao, and G. Q. Zeng. 1990. Studies on the Mechanism of Ovulation in Bactrian Camel - Hormonal profile in semen with special emphasis on their relation to ovulation. Proceedings of the workshop 'Is it Possible to Improve the Performance of the Camel?' - Paris: 17-24.
267.    Xu. Y. S„ H. Y. Wang. G. Q. Zeng, G. T. Jiang, and Y. H. Gao. 1985. Hormone concentrations before and after semen-induced ovulation in the Bactrian camel (Camelus bactrianus). J. Reprod. Fert. 74:341-346.
268.    Xu. Z. Y„ D. C. Wang, X. S. Su, and C. Sun. 1987. Studies on semen freezing techniques and insemination    in the Bactrian camel. Experimental    organization Ningxia Hue Nationality and Inner Mongolia Autonomous Regions, (in Chinese).
269.    Yagil. R. 1982. Camel and Camel Milk. FAO Animal production and health paper.
270.    Yagil. R. 1986. The camel: Self-sufficiency in animal protein in drought-stricken areas. World Animal Review (FAO). 57:2-10.
271.    Yagil, R., and Z. Etzion. 1980. The effect of drought conditions on the quality of camel's milk. J. Dairy Res. 47:159-166.
272.    Yagil, R., and Z. Etzion. 1984. Enhanced Reproduction in Camels (Camelus dromedarius). Comp. Biochem. Physiol. 79A:201-204.
273.    Yagil. R., Z. Etzion, and J. Ganani. 1978. Camel thyroid metabolism: effect of season and dehydration. J. Appl. Physiol. 45:540-544.
274.    Yasin, S. A., and A. Wahid. 1957. Pakistan camels - a preliminary survey. Agric. Pakistan. 8:289-297.
275.    Yuzliakaev. R. D., and A. Akhmediev. 1965. Rapid reproduction in camel. Zhivotnovodstvo Mosk. 27:61-66.
276.    Yuzlikaev, R. D. A., A. 1965. A method of accelerating reproduction in the camel. Zhivotnovodstvo (Moscow) (Anim. Breed. Abstr.,34: 260, 1966). 27:61-63.
277.    Zaganelli, M., and B. C. 1975. Variazioni Metriche Dell'Utero Di Camelus dromedarius. Atti della Societe Italiana Scien Vet. 29:238-240.
278.    Zaghloul, A. H., and S. H. Shehata. 1991. Oestradiol and progesterone levels in the serum of she-camel as related to different ovarian structures. Assiut Veterinary Medical Journal. 25:217-223.
279.    Zhao, X. X. 1985. Reproductive hormone profiles before and after ovulation induced by intramuscular injetion of seminal plasma in the Bactrian camel (Camelus dromedarius) (IN CHINESE). M.S. thesis. Gansu Agricultural University, Gansu, China.
280.    Zhao, X. X., Y. M. Huang, and B. X. Chen. 1992. Biological activity of Gonadotrophin-releasing Hormone-like factors in the seminal plasma of the Bactrian camel. Proc. 1st Int. Camel Conf., Dubai, UAE: 163-168.
281.    Zhao, X. X., G. W. Pan, Y. M. Huang. Y. H. Gao, and B. X. Chen. 1990. Studies on the ovulation-inducing factor in the seminal plasma of Bactrian camel. Proceeding of the workshop 'Is it Possible to Improve the Reproductive Performance of the Camel?' - Paris: 197-210.
282.    Zhao. X.-X., Y.-M. Huang, and B.-X. Chen. 1994. Artificial insemination and pregnancy diagnosis in the Bactrian camel (Camelus bactrianus). Journal of Arid Environments. 26:61-65.
283.    Zhao.X.X.. Huang, Y.M. , Nie, Q.C.. Zhang. Y..R., Chen B.X. 1996. Effect of different extenders on motility, survival and acrosomal integrity of camel spermatozoa frozen in ampouls. J.Camel Pract. Res. 3: 23-25.