Circadian rhythm of salivary cortisol secretion in female zoo-kept African elephants (Loxodonta africana).

Salivary samples were collected over a 24-hr period from one group of six juvenile (7-12 years) and one group of three adult (24-25 years) African elephant females, Loxodonta africana, and the cortisol concentration was measured in unextracted samples by EIA. Samples were collected during May, June, and November 2012 (n = 147) using cotton swabs at 4-hr intervals from 20:00 to 20:00 of the next day (seven samples per animal in each trial). The animals are kept under standard zoo management: the herd is maintained in their indoor enclosures until 10:00 and then released into the outdoor enclosures until 21:00-21:30 (May/June) and 18:30-19:00 (November). No adult elephant bull was present at the zoo during this time. The results demonstrate a clear diurnal pattern of cortisol secretion with the lowest concentration observed at 20:00 (2.03 ± 0.08 ng/ml saliva) and the peak concentrations at 08:00 (5.26 ± 0.35 ng/ml saliva). Although the cortisol values were higher in the adult cows compared to the juvenile cows in the May-June period, the differences were not significant. However, the values obtained in November from the juvenile group were significantly higher (P < 0.05) than the concentrations measured in this group in June. In conclusion, salivary cortisol in zoo elephants follows a circadian rhythm (sleep-wake cycle) adapted to daily zoo husbandry routines.

Assessment of ovarian cycles in the African elephant (Loxodonta africana) by measurement of salivary progesterone metabolites.

Monitoring ovarian cycles through hormonal analysis is important in order to improve breeding management of captive elephants, and non-invasive collection techniques are particularly interesting for this purpose. However, there are some practical difficulties in collecting proper samples, and easier and more practical methods may be an advantage for some institutions and/or some animals. This study describes the development and validation of an enzymeimmunoassay (EIA) for progestins in salivary samples of African elephants, Loxodonta africana. Weekly urinary and salivary samples from five non-pregnant elephant cows aged 7-12 years were obtained for 28 weeks and analyzed using EIA. Both techniques correlated positively (r = 0.799; P < 0.001), and the cycle characteristics obtained were identical. The results clearly show that ovarian cycles can be monitored by measuring progestins from salivary samples in the African elephant. This is a simple and non-invasive method that may be a practical alternative to other sampling methods used in the species.