Hormonal profiles in the tammar wallaby, Macropus eugenii following FSH/LHsuperovulation

This study investigated the effect of superovulation with exogenous porcine FSH/LH on the normal hormonal milieu of the tammar wallaby (Macropus eugen ii). During seasonal and lactational quiescence, groups of 6 females were t reated with either multiple doses of porcine follicle-stimulating hormone ( FSH) (8 x 6 mg i.m., 12 h apart) followed by a single subcutaneous injectio n of 4 mg porcine luteinizing hormone (LH) on Day 5 or saline. Blood sample s were collected throughout each 10-day experimental period and each female was examined twice daily for signs of a recent copulation. On Day 9, femal es were killed and their reproductive tracts removed for examination and fl ushed for eggs. During both seasonal and lactational quiescence, treatment with porcine FSH/LH induced circulating concentrations of progesterone, por cine FSH and porcine LH that were within the normal range of the natural ta mmar oestrous cycle. However, higher plasma oestradiol concentrations (30-5 0 mug mL(-1)) than would be expected in a natural tammar preovulatory rise and the presence of 'highly stimulated' ovaries in several of the treated a nimals suggests that some degree of over-stimulation was occurring. During both seasonal sampling periods, behavioural oestrus was detected in treated tammars in the absence of a withdrawal of progesterone. This data suggests that plasma progesterone is not the critical factor inducing behavioural o estrus.