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

This study investigated the effect of superovulation with exogenous porcine FSH/LH on the normal hormonal milieu of the tammar wallaby (Macropus eugenii). During seasonal and lactational quiescence, groups of 6 females were treated with either multiple doses of porcine follicle-stimulating hormone (FSH) (8 x 6 mg i.m., 12 h apart) followed by a single subcutaneous injection of 4 mg porcine luteinizing hormone (LH) on Day 5 or saline. Blood samples were collected throughout each 10-day experimental period and each female was examined twice daily for signs of a recent copulation. On Day 9, females were killed and their reproductive tracts removed for examination and flushed for eggs. During both seasonal and lactational quiescence, treatment with porcine FSH/LH induced circulating concentrations of progesterone, porcine FSH and porcine LH that were within the normal range of the natural tammar oestrous cycle. However, higher plasma oestradiol concentrations (30-50 microg mL(-1)) than would be expected in a natural tammar preovulatory rise and the presence of 'highly stimulated' ovaries in several of the treated animals 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 oestrus.