Fecal Testosterone Concentrations Research Articles

Annual Changes in Testicular Size and Serum and Fecal Testosterone Concentrations in Male Bharals, Pseudois nayaur

The serum and fecal testosterone (T) concentrations and testicular sizes of two male bharals (Pseudois nayaur) were determined for approximately one year. The profiles of the fecal T concentrations showed a similar tendency as the profiles of serum T concentrations, and there was a significant correlation between serum and fecal T concentrations (r=0.72). T concentrations rose drastically in October and decreased gradually until January. The maximum testicular size was observed between November and January. Semen collected between December and January was excellent in quality and comparable to domestic sheep and goats. The active periods of the testes were synchronized with the early breeding season of females.

Seasonal changes in fecal testosterone concentrations and their relationship to the reproductive behavior, antler cycle and grouping patterns in free-ranging male Pampas deer ( Ozotoceros bezoarticus bezoarticus)

The purpose of this study was to validate noninvasive endocrine monitoring techniques for Pampas deer and to evaluate seasonal changes in testicular steroidogenic activity and their correlation to reproductive behavior, antler cycle and group size. Thus, fecal samples, behavioral data and observations of antler status were collected at monthly intervals during 1 year from free-ranging Pampas deer stags (three radio-collared individuals and 15 random individuals) living in Emas National Park, Brazil (18°S latitude). Fecal steroids were extracted using 80% methanol and steroid concentrations were quantified by a commercial enzyme immunoassay (EIA). Fecal testosterone concentrations peaked in December–January (summer), March (early autumn) and in August–September (winter–spring), with minimal values from April–July. Reproductive behavior had two peaks, the first in December–January, characterized by predominately anogenital sniffing, flehmen, urine sniffing, chasing and mounting behavior, and the second peak in July–September (behavior primarily related to gland marking). There were significant correlations between fecal testosterone and reproductive behavior ( r = 0.490), and between fecal testosterone and antler phases ( r = 0.239). Antler casting and regrowth occurred under low testosterone concentrations, whereas velvet shedding was associated with high concentrations of testosterone. We inferred that Pampas deer stags exhibited a seasonal cycle that modulated sexual behavior and the antler cycle, and we concluded that fecal steroid analysis was a practical and reliable non-invasive method for the evaluation of the endocrine status of free-ranging Pampas deer.

Concentrations of four fecal steroids in wild baboons: short-term storage conditions and consequences for data interpretation

One source of both bias and “noise” in fecal steroid analysis is temporal change in steroid concentrations resulting from duration or conditions of fecal sample storage. However, no consensus currently exists regarding correct procedures or precautions necessary for fecal sample storage, and conditions vary widely within field endocrinology literature. This study considered the effects of short-term, weeks-long, storage conditions on quantifiable fecal testosterone (fT), glucocorticoids (fGC), estrogens (fE), and progestagen (fP) metabolite concentrations in wild baboons ( Papio cynocephalus). Quadruplicate subsamples of fecal samples ( n=29) collected at Amboseli National Park and its environs were subjected to four different storage conditions prior to lyophilization, in order to determine the effects of storage on subsequent steroid concentrations, as assessed by 125 I radioimmunoassays. As expected, the best alternative to the “initial condition” of lyophilization at three days after collection was to freeze fecal samples at −20 °C for two weeks prior to lyophilization. This storage method resulted in no significant change from initial steroid concentrations for fE, fT, or fP, although fGC showed a slight but significant decline. Storage for two weeks in a charcoal refrigerator caused a mean increase in all four steroid concentrations. However, the results from this storage condition were robust in terms of practical questions asked of the data: fE and fP values still reflected pregnant versus non-pregnant states in baboon females; a fGC profile constructed by age class resembled that created from the samples from the initial condition, although slightly inflated across age classes; and there were only moderate changes in relative fT concentrations across adult males. Knowledge of the effects of storage upon each steroid analyzed within one’s study is a necessary component in determining the optimal compromise for storage protocol in a particular research project.

Fecal Testosterone Concentrations May Not Be Useful for Monitoring Reproductive Status in Male Blue-Tongued Lizards (Tiliqua nigrolutea: Scincidae)

Assessment of reproductive status in animals generally depends on monitoring hormone concentrations in plasma, but blood sampling often involves significant stress to the subject. Monitoring steroid profiles by assaying excreted steroids in urine and/or fecal samples is non-invasive, but does pose some problems.There are, however, only two published reports of the application of fecal steroid monitoring to reptiles. We compare the profile of fecal T with that for plasma T through the reproductive cycle of blotched blue-tongued lizards, and also examine the relative proportions of conjugated and free T in feces. Testosterone was detected in all samples assayed, and fecal T concentrations ranged from ~ 500 ng g-1 to ~1500 ng g-1 dry feces. Plasma hormone cycles were not reported, but the patterns of variation in fecal T concentrations appeared to show some correlation with reproductive activity. In contrast, our results suggest that there is an inverse relationship between concentrations of T in feces and in plasma of male blue-tongued skinks, with fecal T concentrations being highest during the non-breeding season, when plasma T levels are low. Our results suggest, therefore, that assay of fecal T concentrations may not be useful for assessing reproductive status in blue-tongued lizards because of the lack of correlation between T concentrations in feces and plasma.

Fecal Testosterone Concentrations May Not Be Useful for Monitoring Reproductive Status in Male Blue-Tongued Lizards (Tiliqua nigrolutea: Scincidae)

Fecal Testosterone Concentrations May Not Be Useful for Monitoring Reproductive Status in Male Blue-Tongued Lizards (Tiliqua nigrolutea: Scincidae)

Seasonal Changes of Reproductive Behavior and Fecal Steroid Concentrations in Père David's Deer

From July 1997 to September 1997 and from March 1998 to July 1998, we studied reproductive behaviors of Père David's deer in Dafeng, China. During the field behavioral observations, we collected fresh voided fecal samples from the Père David's stags and hinds periodically and kept those samples under −20°C until laboratory analysis. We analyzed the fecal testosterone, estradiol, and progesterone concentrations in those samples using radioimmunoassay. During this study, we also recorded 17 types of male reproductive behaviors and nine types of female reproductive behaviors. Reproductive behaviors and the fecal steroid concentrations showed overt seasonal fluctuations. There were statistically significant correlations between some male reproductive behaviors, such as anogenital sniffing, urine sniffing, urine spraying, wallowing, bellowing, antler adorning, Antler swags mud, chasing, herding hinds, chin resting, mounting and copulating, with the fecal testosterone concentrations. These results suggested that seasonal reproductive behaviors in stags are strongly associated with circulating testosterone. We also found that some female reproductive behaviors fluctuate corresponding with changes in fecal estrogen concentrations. Although there was no direct evidence to confirm the correlations between female reproductive behaviors and fecal estrogen in our experiment, we could not rule out that reproductive activities of hinds were largely related to ovarian estrogen secretion, and estrogen is necessary for inducing female reproductive behaviors.