Abstract
The royal python (Python regius) is commonly bred in captivity. To have a successful breeding season, accurate monitoring of the reproductive activity is necessary. The use of non-invasive monitoring methods in exotics is important in order to minimize stress. For this purpose ultrasound has been anecdotally used to monitor royal python reproductive activity. However, there is limited information regarding the reproductive cycle of this species. The aim of the present study is to monitor the female reproductive cycle of the royal python using ultrasonography and gonadal steroid metabolite measurements in the faeces. The reproductive activity of one hundred twenty-nine adult female P. regius was examined during two consecutive years. We performed brief scans on non-anaesthetized snakes using a portable ultrasound system and a 10–12 MHz linear array transducer (MyLab™ 30 Gold, Esaote). Ultrasound features, dimension and echogenicity of the reproductive structures were determined. During the second reproductive cycle, the hormonal profiles of 30 animals were also evaluated, with a monthly collection of faecal samples. These samples were classified according to reproductive stage, as identified by ultrasonographic examination, and the mean faecal progesterone and 17β-estradiol levels were calculated using the results from an enzyme-linked immunosorbent assay (ELISA). Progesterone levels increased during the reproductive cycle. Estradiol levels showed greater variability, although they appeared to increase before coupling when compared to the levels between coupling and egg laying. The present study suggests that it is possible to identify different phases in the female royal python reproductive cycle: anovulatory phase, transition, folliculogenesis and embryogenesis. Ultrasound is also useful for identifying follicular regression or slugs. Gonadal steroid metabolite measurements from the faeces could help integrate reproductive information. The use of ultrasonography in addition to the steroid metabolite measurement in the faeces gives an accurate picture of ovarian activity in captive adult female royal pythons.
Highlights
Reptiles have become increasingly popular pets in recent years, which has led to an increase in captive bred reptiles [1]
The enclosures are conditioned by gradually lowering the highest temperature to 25 ̊C (1 ̊C per day) and so maintained for three months (October, November and December), which is identified as the cooling period (CP)
intraobserver variability (IAOV) resulted similar (P>0.05) to IEOVin the first reproductive phase (1.61 vs 1.88%), in the second (0.89 vs 0.85%) and in the third one (11.05 vs 17.32%). Both variabilities were low in CP end–coupling and coupling-deposition (IAOV: 1.29 and 0.89%; interobserver variability (IEOV): 1.89 and 0.85%, respectively) and high in deposition-CP end (IAOV: 11.05%; IEOV: 17.32%)
Summary
Reptiles have become increasingly popular pets in recent years, which has led to an increase in captive bred reptiles [1]. Ultrasound appearance of reproductive organs in reticulated pythons (Python reticulatus) allowed recognition follicles in various stages of development, as well as calcified eggs [44] In this species, ultrasound is a potential diagnostic method for highlighting pathological conditions and monitoring healthy animals to identify the optimum time for mating [44]. Detecting concentrations of sex steroids in the serum is the most direct method of assessing hormone levels, obtaining blood samples could be difficult due to the technical complexity of the sampling It is stressful for the animal, in exotic and wild species. The aim of this study is to monitor the reproductive cycle of captive female royal pythons using ultrasonography and gonadal steroid faecal metabolite analysis
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