Abstract

Effects of gonadotropin releasing hormone (GnRH) superagonist implants, deslorelin (Suprelorin®), on circulating luteinizing hormone (LH) concentrations and semen quality were examined in variable flying foxes (Pteropus hypomelanus). Plasma was collected from treated (n=3 male; n=5 female) and untreated (n=3 male; n=8 female) bats. Semen was collected from all males and a bachelor group (n=7) before and after treatment. Treated males were housed with untreated females and untreated males were housed with treated females. A GnRH challenge revealed serum LH concentrations increased in control, untreated bats (n=2 female; n=2 male) but not in deslorelin-treated bats (n=2 male; n=2 female). Mean serum LH concentrations did not significantly decrease (p>0.05) after deslorelin treatment in males (pre = 1.4±0.9 ng/ml, post = 1.2±0.7 ng/ml) or females (pre = 2.1±1.1 ng/ml, post = 1.6±0.8 ng/ml) and were comparable with untreated males (pre = 1.2±1.1 ng/ml, post = 1.7±0.9 ng/ml) and females (pre = 1.4±0.5 ng/ml, post = 1.3±0.5 ng/ml) during the same time period. Variability in ejaculate quality was observed in treated, untreated, and bachelor males. It appears that deslorelin implants are ineffective for male P. hypomelanus contraception as spermic ejaculates, sustained by tonic LH secretion, were obtained. However, results of the GnRH challenge suggested pulsatile LH was eliminated, so deslorelin should be a useful contraceptive in females by preventing the preovulatory LH surge. Results of offspring production later this year will provide further practical results.