Dear MARMAM Readers, My co-authors and I are happy to share our recent publication: "Characterizing estrus by trans-abdominal ultrasounds, fecal estrone-3-glucuronide, and vaginal cytology in the Steller sea lion (Eumetopias jubatus)". Sattler R, Bishop A, Woodie K, Polasek L. Characterizing estrus by trans-abdominal ultrasounds, fecal estrone-3-glucuronide, and vaginal cytology in the Steller sea lion (Eumetopias jubatus). Theriogenology 120:25-32. https://doi.org/10.1016/j.theriogenology.2018.07.020 Abstract:Theability to monitor the estrus cycle in wild and captive marine species isimportant for identifying reproductive failures, ensuring a successful breedingprogram, and monitoring animal welfare. Minimally invasive sampling methods tomonitor estrus in captive populations have been developed, but results suggestthese tools can be species-specific in their precision and accuracy. Therefore,the minimally invasive sampling methods of trans-abdominal ultrasounds, a fecalsteroid analysis (estrone-3-glucuronide, E1G), and vaginal cytology, wereevaluated for their efficacy to characterize and monitor estrus in a captivebreeding population of Steller sea lions (Eumetopiasjubatus). Three adult females were sampled over five breeding seasons,resulting in six estrus profiles characterized by trans-abdominal ultrasounds, fiveby fecal E1G, and four by vaginal cytology. Animals were trained to allowtrans-abdominal ultrasounds, fecal samples, and vaginal swabs to be collected approximatelydaily. Of the 76 trans-abdominal ultrasound sessions attempted, 8 successfullyvisualized both ovaries. From these scans, the chronology of ovarian changesduring proestrus and estrus was estimated. The time from the detection of developingfollicles to the identification of a dominate follicle occurred in 2-5 days anda corpus hemorrhagicum formed approximately 4 days later. However, becausevisualization of the ovaries was prevented by the gastrointestinal system in 88%of scans, this tool was overall unreliable for monitoring changes associatedwith estrus. To detect fine scale physiological changes associated with estrus,we analyzed changes in fecal E1G (n = 62) and vaginal cytology (n = 157) 15days before and after each female’s single copulation event (Day = 0). Changesin fecal E1G had the highest accuracy at detecting Day = 0. Fecal E1G increasedleading up to estrus, peaked at Day = 0, and then declined. Although we didobserve the characteristic increase in superficial cells associated withimpending estrus, the type of cell which peaked closest to Day = 0 wasintermediate. The uncertainty around the peak in intermediate cells, indicatingestrus, was greater than the uncertainty associated with detecting estrus fromfecal E1G. Collectively, these results suggest that changes in fecal E1G andvaginal cytology are viable tools to detect estrus in Steller sea lions, butrequire daily sampling to detect gradual changes, limiting their applicabilityto studies of wild populations.
Please email me for a copy of the pdf. ren...@alaskasealife.org Thanks! Renae SattlerResearch Associate Alaska SeaLife CenterSeward, AK 99664907-224-6882
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