The influence of active immunization against inhibin on dromedary camel ovarian and hormonal dynamics

•Inhibin immuneneutralization was used to promote ovarian activity in camels.•Inhibin vaccination generated ovarian hyperstimulation compared to camels with normal ovarian cycle (control).•This technique significantly reduced the anestrus phase of the transition period in camels.

The efficiency of neutralizing endogenous inhibin on promoting camel ovarian dynamics during the transition period in Egypt (mid-August-mid-December) was investigated. Ten pluriparous dromedary camels, Camelus dromedarius, were divided into 2 groups of five animals each. Animals of the first group were actively immunized against recombinant bovine inhibin-A, whereas animals of the second group served as control. Ovarian follicular activity was monitored by transrectal ultrasonography throughout the entire experimental period. Changes in hormonal profiles of estradiol 17-β (E2), follicle stimulating hormone (FSH) and circulating inhibin-A (INH-A) were also determined. The results showed that on day 28 following initial immunization (mid-September), mean values of total no. of follicles, FSH and E2 concentrations in the immunized camels were 3.5, 3.3 and 2.6 times higher than those of control, respectively. Furthermore, the immunized group exhibited improvement in ovarian follicular activity throughout the transition period, whereas ovarian dynamics in the control group remained limited until the onset of the breeding season (mid-December). Additionally, the immunized camels recorded a positive correlation (P < 0.05) between serum E2 concentrations and each of FSH (r = 0.77), circulating inhibin-A (r = 0.56), total no. of follicles (r = 0.75) and diameter of dominant follicles (r = 0.69). These results elucidate that active immunization against inhibin may provide a sufficient method to enhance ovarian activity and can override seasonal anestrus in dromedary camels prior to the onset of the breeding season.