Monitoring ovarian cycle and pregnancy in the giant anteater (Myrmecophaga tridactyla) by faecal progestagen and oestrogen analysis

Oestrogen and progestagen metabolites were measured in the faeces of five female giant anteaters (Myrmecophaga tridactyla), to characterise the oestrous cycle and pregnancy. Faecal samples were collected twice weekly for a minimum of 6 months, and immunoreactive progestagens and oestrogens were analysed using enzyme immunoassays (EIA). For progestagens, two antibodies that cross-reacted with 20 alpha-hydroxy- or 20-oxo-progestagens were used, Both assays effectively monitored ovarian cyclicity; however, the concentrations obtained using the antibody for 20 alpha-hydroxy-progestagens were higher, and the hormonal changes were more pronounced. Regular ovarian cycles were identified in three of the five females. Average (+/-SEM) length of the oestrous cycle (n = 10) was 51.4 +/- 5.6 days. Peak concentrations of 20 alpha-hydroxy-progestagens ranged from 80-660 ng/g of faeces and those of oestrogens from 20-100 ng/g. Hormone concentrations were measured during parts of two pregnancies and during four post-partum periods. The length of one gestation (from oestrous oestrogen peak until parturition) was 184 days. In the second half of gestation, progestagen concentration started to increase above luteal phase values; in the week before parturition it was similar to 20 times higher than those during the luteal phase. Concentrations of excreted oestrogens began to increase after two thirds of gestation and exceeded that of the follicular phase by similar to 2.5-fold in the week before parturition. Onset of ovarian cyclicity after parturition varied from 4-11 weeks. In conclusion, the measurement of faecal immunoreactive progestagens and oestrogens in the giant anteater indicated an ovarian cycle of similar to 7 weeks in length and provided potentially useful data for successful breeding management. (C) 1998 Elsevier Science B.V. All rights reserved.