Assessment of Pregnancy Status of Asian Elephants <i>(Elephas maximus)</i> by Measurement of Progestagen and Glucocorticoid and Their Metabolite Concentrations in Serum and Feces, Using Enzyme Immunoassay (EIA)

Abstract

The study was to find patterns of progestagen (progesterone and its metabolite) and glucocorticoid and their metabolite concentrations in serum and feces of pregnant Asian elephants (Elephas maximus). The 5 female Asian domestic elephants were naturally mated until pregnancy. After that, blood and feces samples were collected monthly during pregnancy for progestagen, glucocorticoid and their metabolites analysis by enzyme immunoassay (EIA). The results showed the serum progestagen concentration during gestation was 2.11 ± 0.60 to 18.44 ± 2.28 ng/ml. Overall, serum progestagen concentration rose from the 1st month to reach peak in the 11th month, after which it declined to its lowest level in the 22nd month of pregnancy. Fecal progestagen concentration varied from 1.18 ± 0.54 to 3.35 ± 0.45 µg/g during pregnancy. In general, fecal progestagen concentration increased from the 1st month to its highest level in the 12th month. After this, it declined reaching its lowest point in the 22nd month of pregnancy. Glucocorticoid hormones and their metabolite concentrations both in serum and feces fluctuated from low to medium throughout almost the entire pregnancy period and then rapidly increased around the last week before calving. Our study suggests that this profile of progestagen and glucocorticoid hormones and their metabolite concentration levels in serum and feces can be used to assess the pregnancy status of Asian elephants. If serum and fecal progestagen concentrations were found in very low levels and glucocorticoid and their metabolite concentrations were found in very high levels, it was indicated that the cow elephant would calve within 7 days.

Effects of physiological changes and social life events on adrenal glucocorticoid activity in female zoo-housed Asian elephants (Elephas maximus)

“…This study confirmed the presence of intrinsic cortisol patterns associated with reproductive state, ovarian cycle phase, and age in female Asian elephants, similar to that shown in other species and in previous studies of elephants [ 17 , 37 , 40 , 41 , 72 – 77 ]. Results further highlight the importance of accounting for these patterns when evaluating the impact of environmental factors on adrenal GC activity.…”

“…Gobush et al . [ 25 ] found that fecal GC metabolites (fGCMs) increased with stage of gestation in free-ranging African elephants, while in Asian elephants, overall cortisol concentrations did not appear to be significantly altered during gestation, but increased sharply peripartum [ 40 , 41 , 83 ]. In examination of daily serum samples at the end of gestation, Meyer et al .…”

“…Similar gestational increases in cortisol have been found in elephants, but not consistently, whereas increases around parturition have been widely reported. Gobush et al [25] found that fecal GC metabolites (fGCMs) increased with stage of gestation in free-ranging African elephants, while in Asian elephants, overall cortisol concentrations did not appear to be significantly altered during gestation, but increased sharply peripartum [40,41,83]. In examination of daily serum samples at the end of gestation, Meyer et al [83] observed additional surges in cortisol between 8 and 11 days prior to parturition, which was supported by Kaewmanee et al [84] who reported cortisol increases before parturition, 5-10 days in African elephants and 30-40 days in Asian elephants.…”

“…For example, captive female elephants exhibited increased GCs and behavioral changes during the process of social introduction [ 30 , 31 ]. However, it is important to note that increases in GCs in elephants occur under normal physiological conditions; e.g., diurnally in a circadian rhythm (24 hour sleep-wake cycle) with higher concentrations in the morning [ 32 – 35 ], seasonally, albeit not consistently in temperature-controlled captive environments [ 32 , 36 ], across the estrous cycle in females [ 37 ] and during musth in males [ 38 , 39 ], and in association with stage of gestation and parturition [ 17 , 40 , 41 ]. Increases in GCs can also indicate arousal [ 5 ].…”

Stress and body condition are associated with climate and demography in Asian elephants

“…This ensures that the seasonal patterns captured reflect changes in the environment, rather than effects of growth or pregnancy; elephants in the young age category were still growing rapidly, and weight gain in pregnant females may be because of pregnancy rather than changes in condition. Pregnant females may also exhibit patterns of stress hormone changes associated with pregnancy ( Kajaysri and Nokkaew, 2014 ) rather than the seasonal variation in the environment we aim to study. Our aim is to focus on variation in markers of body condition and stress, rather than already pregnant ones.…”