Incidence of spontaneous ovulation and development of the corpus luteum in non-mated dromedary camels (Camelus dromedarius)

The occurrence of spontaneous ovulation in dromedaries was examined in two separate studies including 20 non-lactating, barren and 12 lactating dromedaries, respectively. Lactating camels were milked twice a day with an automatic bucket milking machine. Ovarian activity was monitored by repeated ultrasonography. Blood samples for progesterone were collected daily or two to three times a week. To compare CL development after spontaneous and induced ovulations, ovulation was induced by a GnRH analogue in eight lactating dromedaries. Spontaneous ovulation was observed in one non-lactating camel (1 of 20 camels, 5%; 1 of 70 follicular waves, 1.4%), whereas, spontaneous ovulation was detected more frequently in lactating dromedaries (5 of 12 camels, 41.7%; 13 of 91 follicular waves, 14.3%). In one lactating camel, spontaneous ovulation occurred repeatedly for nine times. There was a significant effect of type of ovulation (spontaneous versus induced, P < 0.05) and day (P < 0.001) on serum progesterone concentration. Mean serum progesterone levels and total progesterone production (AUC) were higher after induced ovulation. Luteal diameter and serum progesterone concentration were positively correlated (r = 0.71, P < 0.001), but there was a significant difference between morphological and functional development of the CL. In dromedaries, morphological development starts earlier, morphological regression starts later and last longer than functional development and regression of the CL. Compared to induced ovulation, functional development of the CL after spontaneous ovulation might be altered but the morphological development is not affected.