Induction of ovulation with buserelin in jennies: In search of the minimum effective dose

•We treated estrus jennies with progressively lower doses of GnRH agonist buserelin.•The minimum dose of buserelin effective to induce ovulation was 0.04mg.•Positive response to treatment was different between jennies.•Repeated treatments with buserelin in the same jennies had similar effect. The aim of this study was to evaluate the minimum dose of buserelin acetate (buserelin) able to induce ovulation between 24 and 48h from treatment (positive response) in estrous jennies. Jennies were studied during a total of 172 estrous cycles: ovarian activity was routinely monitored by ultrasound; when the dominant follicle reached a diameter of 33±1mm, estrous jennies were treated by subcutaneous administration of different doses of buserelin, 3.3mg (N=11), 1.5mg (N=21), 0.8mg (N=12), 0.4mg (N=16), 0.2mg (N=13), 0.1mg (N=16), 0.04mg (N=14), 0.02mg (N=16), or employed as controls (N=53). Single jennies (P=0.0001) and GnRH dose (P=0.003) significantly affected ovulation rates. Ovulation rates between 24 and 48h of each treated group, except for the 0.02mg group, was higher than in the control group (P