Analysis of urinary immunoreactive steroid metabolites and gonadotropins for characterization of the estrous cycle, breeding period, and seasonal estrous activity of captive killer whales (Orcinus orca)

Abstract

To increase the basic understanding of killer whale (Orcinus orca) reproductive physiology necessary for the development of artificial breeding programs, we utilized radioimmunoassays (RIA) to detect urinary immunoreactive steroid metabolites (pregnanediol-3~-glucuronide [PdG] and estrone-conjugates [EC]) and gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) in urine samples from six female killer whales. Urine samples were collected from the whales by voluntary presentation behavior over a 2-to 4-year period. All urinary hormone values were corrected for intersample urine concentration variations by indexing with creatinine. Daily urine samples from four whales were collected during two conceptions and 18 complete estrous cycles. LH, FSH, EC, and PdG immunoreactive levels were determined and combined with observed copulatory activity in five cycles, including two conceptive cycles from two whales. Mean luteal phase lengths ranged from 9.7 to 19.2 days. Mean follicular phase lengths ranged from 6.5 to 16.8 days. Mean estrous cycle lengths based on the first detectable PdG levels were 41.6 2 6.72 S.E.M. days. After PdG nadir, immunoreactive FSH levels showed a bimodal pattern with the first peak being greater in size, and both preceding a follicular phase EC increase. LH levels > the 95% confidence interval of the mean were considered significant. Combined LH immunoreactive values from whales 2 and 6 during two and three estrous cycles, respectively, had significant LH peak concentrations on day minus 2. These significant LH peaks were assumed to represent the preovulatory LH surge. Eight copulations during two conceptive cycles were observed between whales 2 and 6 and a breeding male. Six of these copulations (3 with each female whale) occurred within 72 hours of the beginning or the end of the presumptive preovulatory LH surge. Estrous activity was seen throughout the year for the herd. However, individuals had varying periods of anestrus that could not be linked to environmental, social, or nutritional influences. The whales that were reproductively successful had anestrus intervals that were usually influenced by gestation, postparturient period, or lactation. The information obtained during this research enhances the foundation for future artificial reproductive management techniques. 0 1993 Wiley-Liss, Inc.

Study on Reproduction of Captive Marine Mammals

“…Christensen (1984) reported that wild north Atlantic female killer whales were pregnant at from age six to eight [25]. Additionally, Robeck et al (1993) found the first estrous cycle of six captive female killer whales from North Atlantic was 8-9 years old [26]. Our females showed similar ages for sexual maturity as described in these wild and captive female killer whales.…”

Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens)

“…However, methods used in this research were also developed or in some cases evolved simultaneously from research conducted with the killer whale and bottlenose dolphin, the first two cetaceans where the development of AI was successful . As with killer whales and bottlenose dolphins, training of the Pacific white-sided dolphins for daily urine collection was required before endocrinemonitoring techniques could be applied (Walker et al 1988, Robeck et al 1993.…”

“…Analysis of urinary reproductive hormones combined with ovarian ultrasound exams has resulted in describing both follicular dynamics and hormonal profiles during estrous cycles and the periovulatory period in killer whale (Walker et al 1988, Robeck et al 1993, bottlenose dolphin , and beluga . The description of the periovulatory period allowed for the development of methods for consistent prediction of ovulation.…”

Variation of bowhead whale progesterone concentrations across demographic groups and sample matrices

“…However, the bulk of mammalian endocrine literature reports steroid hormone levels from blood (Temte 1991, Kjeld et al 1992, Atkinson et al 1999 and to a lesser degree urine (Robeck et al 1993), feces (Rolland et al 2005(Rolland et al , 2006, and saliva (Atkinson et al 1999, Hogg et al 2005). Other sample materials from which these hormones have been extracted and measured include milk (West et al 2000), muscle (Yoshioka et al 1994), cetacean exhalant or blow (Hogg et al 2005), bone, and ocular secretions (Atkinson et al 1999).…”