Precise determination of the time of ovulation will greatly enhance the success rate of artificial insemination and timed breedings of captive marine mammals. Because daily samples are necessary to effectively monitor the estrous cycle, behavioral conditioning of blood and urine collection has greatly facilitated the development of reproductive hormone profiles of the bottlenose dolphin (Tursiops truncatus). Measuring luteinizing hormone (LH) in urine obviates the need for blood collection and increases the frequency with which samples can be obtained. This non-invasive method has the potential to elucidate the temporal associations between the fall of circulating estrogen, the surge of LH, and the time of ovulation. Daily urine samples were collected from one female bottlenose dolphin during an ovulatory estrous cycle. Urine was concentrated and normalized by osmolality before application to an immunochromatographic assay (ICG) designed to detect canine serum LH. Centrifuging urine samples to remove insoluble components enhanced the definition and visibility of LH assay bands, concentrating urine increased the speed and intensity of test band development, and normalization of samples by osmolality ensured the application of a standard concentration of urine to each assay. In this single animal cycle follow-up trial, the urinary LH profile corresponded with serum LH, estrogen, and progesterone profiles, demonstrating the possible efficacy of this method for monitoring LH.

Walrus in US zoos have a very low reproductive rate of 11 births in 80 years, and little is known about Pacific walrus (Odobenus rosmarus divergens) reproductive biology. To address this, we initiated a program in which detailed biological data were recorded on captive walrus. As part of a 7-year study, 1 male and 1 female 16-year-old captive Pacific walrus were carefully monitored with weekly serum hormone analysis, daily glans penis smears for spermatozoa, and abdominal ultrasound for pregnancy. The female ovulated once annually from late December through midJanuary and then exhibited 9 months of sustained elevated progesterone. This nonconceptive estrous cycle profile is consistent with reports from wild walrus females. In contrast, the male's seasonal rut routinely occurred in late February through May with a serum testosterone peak in March. This profile differed from the reported adult male cycle in wild walrus of November through March. During the period of the female's ovulation, the male had nadir testosterone levels and was consistently azoospermic. Likewise, during the male's spermatogenic rut in the spring, the female was anovulatory with elevated progesterone. On this basis, the male was treated for 14 weeks with human chorionic gonadotropin (hCG) in an attempt to increase testosterone levels in synchrony with the female's annual ovulation. The treatment successfully induced rut characterized by sustained elevated serum testosterone levels and production of spermatozoa. The male and female successfully bred, and the female became pregnant. Upon discontinuation of hCG treatment, the male resumed baseline testosterone levels. We theorize that the lack of synchronization of rut and ovulatory cycles is a primary reason for reproductive failure in these captive walrus.

No abstract

No abstract

Characterizing the relationship between ovarian follicular dynamics and the luteinizing hormone (LH) surge in the bottlenose dolphin (Tursiops truncatus) requires detailed daily monitoring due to the transitory nature of LH and ovulation. Utilizing conditioned dolphins and non-invasive sampling techniques, such as urine collection and trans-abdominal ultrasound exams, provides the means to accurately monitor these fleeting processes. Urine samples and ultrasound exams used in this study were originally performed for the purposes of artificial insemination and controlled natural breeding. The LH surge was identified by a rapid immunochromatographic assay (ICG), and real-time B-mode trans-abdominal ultrasound imaging was used to identify pre-ovulatory follicles (POF). Increases in urinary progesterone levels along with the disappearance of the POF verified ovulation. This study found that POF diameters during the LH surge were 1.942 +/-0.098 cm (n = 9), and time to disappearance of the POF from the last recorded LH peak sample was 37.475 +/-12.346 h (n = 6). Peak LH surge levels, based on samples collected 2 to 4 times daily, lasted 6.050 +/-1.332 h (n = 6). Data suggests that bottlenose dolphins, like many other mammals, have brief ovulatory LH surges followed by ovulation within 48 hours.