Abstract:
This study investigated the effect of superovulation with exogenous porcineFSH/LH on the normal hormonal milieu of the tammar wallaby(Macropus eugenii). During seasonal and lactationalquiescence, groups of 6 females were treated with either multiple doses ofporcine follicle-stimulating hormone (FSH) (8 6 mg i.m., 12 h apart) followedby a single subcutaneous injection of 4 mg porcine luteinizing hormone (LH) onDay 5 or saline. Blood samples were collected throughout each 10-dayexperimental period and each female was examined twice daily for signs of arecent copulation. On Day 9, females were killed and their reproductive tractsremoved for examination and flushed for eggs. During both seasonal andlactational quiescence, treatment with porcine FSH/LH induced circulatingconcentrations of progesterone, porcine FSH and porcine LH that were withinthe normal range of the natural tammar oestrous cycle. However, higher plasmaoestradiol concentrations (30-50 g mL<emph type="7">-1)than would be expected in a natural tammar preovulatory rise and the presenceof ‘highly stimulated’ ovaries in several of the treated animalssuggests that some degree of over-stimulation was occurring. During bothseasonal sampling periods, behavioural oestrus was detected in treated tammarsin the absence of a withdrawal of progesterone. This data suggests that plasmaprogesterone is not the critical factor inducing behavioural oestrus.