Sperm parameters following hormonal induction of spermiation in an endangered frog [the alpine tree frog] (

Abstract

Context With global amphibian biodiversity rapidly declining, improving reproductive technology outcomes has become essential. Captive breeding programs have struggled because amphibian breeding physiology often requires specific environmental cues that reproductive technologies can circumvent. Aims This study tests the efficiency of hormonal induction by evaluating sperm quality in the endangered Litoria verreauxii alpina. Methods We assessed the effects of exogenous hormones – gonadotrophin-releasing hormone agonist (GnRH-a, Lucrin), and human chorionic gonadotrophin (hCG, Chorulon) – on sperm quality. Key results Hormone induction with hCG showed high efficacy while GnRH-a yielded a low response in producing sperm. Sperm quantity was affected by time post injection, with the greatest quantity at 1 h post injection. Sperm quality was also affected by time, where the sperm head size decreased by 11% at 7 h post injection. Conclusions Based on the results from this study, we recommend that that sperm be collected soon after induction, and not more than 4 h post induction in L. v. alpina. More work needs to be completed before recommending an optimal hormone induction method and dose, but 120 IU of hCG per male was successful for inducing spermiation. Implications This study represents a useful starting point for developing assisted reproductive techniques for non-model organisms.