Fertility after ovarian follicular wave synchronization and fixed-time natural mating compared to random natural mating in dromedary camels (Camelus dromedarius)

Abstract

The objective of the study was to compare the efficiency of two ovarian follicular wave synchronization protocols coupled with fixed-time natural mating with that of random mating in dromedary camels. Dromedaries were assigned randomly to one of the three treatment groups. Group 1 animals (RM; n = 46) were mated randomly. Group 2 camels (1×GnRH-FTM; n = 46) were given a GnRH analog (Buserelin, 20 μg/animal, i.v.; Receptal, Intervet, Holland) at random, then were mated 14 days later. In Group 3 animals (2×GnRH-FTM; n = 41), random GnRH analog was followed by repeated GnRH injection 14 days later and fixed-time natural mating on Day 28. Transrectal examination and ultrasonography were performed at weekly intervals to evaluate ovarian follicular status, diagnose ovulation and pregnancy. Blood samples were collected for progesterone determination by ELISA to confirm ovulation and pregnancy. All female dromedaries were assigned randomly to one of thirteen fertile bulls and were bred once on Days 1, 14 and 28 in Groups 1-3, respectively. Ovarian follicular status and ovulation rate was similar among groups at the start of the study. Seventy-five of the 133 dromedaries (56.4%) ovulated after random natural mating or random GnRH treatment. Mean length of mating was 386 ± 17.8 (±SEM) seconds. There was no significant difference in mating time among groups and in pregnancy rate among dromedary bulls. In Group 3 (2×GnRH-FTM), ovarian follicular status before mating (P < 0.05), ovulation rate (n = 37, 90.2%, P < 0.001) and pregnancy rate at 21 and 60 days (PR 21 days n = 22, 53.7% and PR 60 days n = 19, 46.3%, P < 0.05) were greater compared to random natural mating (Group 1: OR n = 25, 54.3%, PR 21 days n = 13, 28.3% and PR 60 days n = 12, 26.1%). In Group 2 dromedaries (1×GnRH-FTM), treatment tended to improve follicular status before mating, ovulation rate (n = 34, 73.9%) and pregnancy rate at 21 and 60 days (PR 21 days n = 21, 45.7% and PR 60 days n = 16, 34.8%), but the effect was not significant compared to random natural mating. In conclusion, this is the first study demonstrating that favorable pregnancy rate can be achieved following ovarian follicular wave synchronization with repeated GnRH analog and fixed-time natural mating at 14 days intervals in dromedary camels.