Faecal steroid analysis in two captive female cheetahs

Introduction and aim. Cheetahs (Acinonyx jubatus), as most wild felid species, is an induced ovulator and reproduces poorly in captivity, a problem attributed to inappropriate husbandry (1). Monitoring endocrine activity is essential for assessing the reproductive potential, but hormonal determination trough blood serum sampling is an unpractical procedure in these species, as it requires anaesthesia and restraint. It has been demonstrated in the domestic cat that estrogens and progesterone are secreted into faeces (1,2) and some Authors already applied this method to other wild felids (1,3,4), as well as to cheetahs (5,6). However, cheetah management, i.e. social groups and caging situations, was not standardized throughout the period of the study or a low number of samples were collected during short time periods. The aim of the present work was to evaluate the dynamic of faecal estrogens and progesterone throughout an entire year in two cheetahs constantly housed with conspecific males in the Northern of Italy. Materials and methods. Two female cheetahs (Geijsha and Duchessa, 2 years of age) maintained at Le Cornelle Animal Park (Valbrembo, BG, Italy) and housed with 3 conspecific males were included in this study. Faecal samples were collected daily for one year (from August 2007 to July 2008) and immediately frozen and stored at -20°C. Faecal oestradiol (E2) and progesterone (P4) metabolites were extracted from fresh samples as previously described in dry samples (1). The metabolites were quantified using radioimmunoassay. Basal E2 and P4 values and the duration of the estrous cycle on the whole sampling period were calculated according to the method proposed by Brown et al., 1996 (6). Data are resumed as mean ±SD. Results. Faecal E2 basal values were 21.6+5.8 ng/g and 19.3+5.1 ng/g with peak concentrations ranging from 30.6 to 73.8 ng/g and from 29.6 to 164.8 in Geijsha and Duchessa, respectively. Estrous cycle duration was 10.4±3 (n=13, range, 6-15 days) and 11.3 ± 6.9 days (n=10, range, 5-23 days) in the two females. The males did not show any interest in the females which did not display evident behavioural signs of estrus throughout the year. Faecal P4 basal values of 112.6+41.5 ng/g and 100.6+23.4 ng/g remained at baseline values all year. In addition, none of the female were continuously cyclic: follicular activity was interrupted by anestrous periods of 1 to 4 months in duration and not associated with season. Conclusions. These data suggest that captive cheethas show a discontinuos ovarian ciclicity which duration and anestrus periods are similar to those described in the literature (6) in which estrous cycle duration from 10.4±1 to 19±2.2 days and anestrous periods of 2 to 5 months are reported. In the present study extraction of steroid metabolites was performed from fresh faecal sample, thus a comparison with hormonal concentrations in dry samples reported by other authors is not possible. It is generally accepted that behavioural signs of estrous are difficult to interpret in cheetahs, however lack of mating and of subsequent luteal phase were likely due to the continous presence of males which sexual interest was inhibited. Thus, adequacy of husbandry conditions is necessary and enforced social living should be avoided in order to increase reproductive activity of captive cheethas. Aknowledgements. We thank E. Benedetti, N. Benedetti and Dr. R. Schneider of Le Cornelle Animal Park for logistical support and sample collection. This study was supported by PUR 2008. References. 1) Brown et al., Biol Reprod 1994;51:776-86; 2) Shille et al., Zoo Biol 1984;3:201-09; 3) Brown et al., J Reprod Fertil 2001;Suppl 57:71-82; 4) Graham et al., Zoo Biol 1995;14:233-37; 5) Czekala et al., Zoo Biol 1994;13: 119-28; 6) Brown et al., J Reprod Fertil 1996;106:337-46