152 STUDY OF THREE CONSECUTIVE ELECTROEJACULATIONS IN BROWN BEAR (URSUS ARCTOS)

Abstract

The preservation of threatened species, such as the cantabric brown bear, requires the establishment of genetic resource banks. In these species it is important to increase the efficiency of the electroejaculation techniques so as to collect as many gametes as possible from each collection, and to decrease risks of anesthesia and immobilization. Our objective was to study several characteristics of brown bear semen quality obtained in three consecutive electroejaculations (a, b, and c) in the same anesthetic session. Ejaculates were collected from 11 adult males living in the Cabárceno Nature Park during the breeding season (May–July). Animals were anesthetized by administration of tiletamine + zolazepan (Zoletil 100^®) and ketamine (Imalgene 1000^®) before being subjected to electroejaculation (6 to 10 V; 250 to 300 mA). From each ejaculate we assessed motility (CASA: SCA, Microptic, Barcelona, Spain), osmolality (mOsm k^–1), and viability (VIAB: % viable spermatozoa (spz), SYBR-14 and propidium iodide) and mitochondrial membrane potential (MIT: % spz, JC-1) by flow cytometry. Our results show that total spz (×10⁶ spz) varies widely among individuals depending on the number of electroejaculation. In five males we observe a decreasing pattern (a: 454.50; b: 341.7; c: 138.0); in other two males it is observed an increasing pattern (a: 24.9; b: 70.3; c: 334.3) while in the remaining four males we see a varied pattern, with the sperm production peak in the second electroejaculation (a: 53.4; b: 270.6; c: 107.5). Motility parameters do not show differences among the three electroejaculations, showing a reduction of the progressive motility in the males with increasing pattern with respect to the other patterns. Also, spermatozoa physiology indicators show a relation with the sperm production patterns. For viability (%) it is shown a rising tendency in the increasing pattern (a: 64.0, b: 80.0, c: 79.5) and a reduction tendency in the decreasing pattern (a: 68.7, b: 61.0, c: 58.7). The same is observed in the case of mitochondrial membrane potential (%) (increasing pattern [a: 77.0, b: 89.0, c: 87.0]; decreasing pattern [a: 80.0, b: 76.3, c: 55.7]). Ejaculates of the varied pattern show irregular data for these parameters. On the other hand, osmolality changes depending on the number of electroejaculation (increasing pattern [a: 324.0, b: 289.0, c: 298.3]; decreasing pattern [a: 333.0, b: 297.0, c: 283.0]; varied pattern [a: 264.0, b: 294.6, c: 318.54]) which would determine a change in the spz microenvironment that regulates their physiological activity. Although the high individual variability observed does not lead to solid conclusions, our results indicate that consecutive electroejaculations can be useful for increasing the technique yield in brown bear.

Supported by CICYT (CGL2007-63788/BOS) and Cantur SA. ³Supported by Juan de la Cierva program (MICINN, Spain).