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Fertility control has traditionally been applied in zoos to control captive populations, and reversible contraception is important. However, contraceptive methods for male bears have not been reported. We aimed to establish a reversible contraceptive for male brown bears by investigating the effects of a gonadotropin‐releasing hormone (GnRH) vaccine (Improvac®) that was developed for the immune castration of pigs. We vaccinated six bears with two sequential doses of 400 (n = 2) or 600 μg Improvac® (n = 4) with a 1‐month interval during the pre‐breeding season (February to April). We compared the reproductive parameters (testosterone levels and semen parameters) of the six vaccinated and four non‐vaccinated (control) bears once during the breeding season (May or June). To investigate whether the reproductive performance could be restored in the following year of contraception, we also compared the reproductive parameters once during the breeding season in two bears between the year with GnRH vaccination and the following year without vaccination. Vaccination treatments suppressed reproductive parameters in 5 bears, although vaccination with 400 μg of Improvac® was not effective in one bear. Testosterone levels and the rate of progressive sperm motility were significantly lower, and total sperm count and testis size tended to be lower in vaccinated bears, compared with the controls. Blood biochemical findings and direct observations after Improvac® vaccination did not reveal side effects. Moreover, testosterone levels and spermatogenic scores of two bears were restored in the following year. We confirmed that the Improvac® vaccine elicited a reversible contraceptive effect in male brown bears. [ABSTRACT FROM AUTHOR]

Heat stress reduces the developmental competence of bovine oocytes during the growth phase; however, the detailed mechanisms remain unclear. Amino acids play various critical roles in follicular development, including protein synthesis and as energy sources. We performed in vitro growth (IVG) culture of oocyte--cumulus--granulosa complexes (OCGCs) to assess the amino acid metabolism of small follicles at high temperatures. We isolated OCGCs from early antral follicles (0.5-1.0 mm) and subjected them to IVG culture for 12 days. OCGCs in the heat shock group were cultured under a temperature cycle of (38.5°C: 5 h, 39.5°C: 5 h, 40.5°C: 5 h, and 39.5°C: 9 h) to reproduce the body temperature of lactating cows under a hot environment. OCGCs in the control group were cultured at a constant temperature of 38.5°C for 24 h. Of the surviving OCGCs, those showing similar morphology and size between the groups were selected for amino acid analysis. We analyzed the free amino acids and their metabolites in the culture medium and calculated the depletion or appearance of molecular species. The depletion of three essential amino acids (isoleucine, leucine, and valine), two non-essential amino acids (aspartic acid and glycine), and ornithine was higher in the heat shock group (P < 0.05). Alanine depletion was lower in the heat shock group (P < 0.05). We concluded that heat exposure alters the amino acid metabolism of OCGCs isolated from early antral follicles, which might be involved with the diminished developmental potential of oocytes during summer [ABSTRACT FROM AUTHOR]

Adult male brown bears (Ursus arctos Linnaeus, 1758) display tree-marking behavior to chemically signal their dominance throughout the nondenning period, and this behavior peaks during the breeding season. Within the scent-marking sequence, back rub is a core marking posture. The present study investigated (i) seasonal changes in sebaceous glands in the back skin of brown bears and (ii) the relationship between those changes and testosterone levels. Back skin tissue samples and blood were collected from captive adult intact and castrated males during prebreeding, transitional, breeding, and postbreeding seasons, which were concurrent with back skin observations. In intact males, during the transitional and breeding seasons, an oily secretion from the back skin was observed along with enlarged sebaceous glands. The plasma testosterone concentrations during the transitional and breeding seasons were increased compared with the pre- and post-breeding seasons. Secretions and enlarged sebaceous glands were not found in castrated males, and the plasma testosterone concentrations remained at baseline levels. Oily secretions of the back skin glands that appear more abundant during the breeding season are rubbed against trees. Changes in size and volume of sebaceous glands, and thus their secreting capacity, are likely testosterone-regulated. Key words: brown bear, sebaceous gland, testosterone, tree-rubbing, back skin, scent gland, Ursus arctos. Les ours bruns (Ursus arctos Linnaeus, 1758) males adultes presentent un comportement de marquage des arbres pour signaler chimiquement leur dominance en dehors de la periode de mise bas, et ce comportement atteint un maximum durant la periode de reproduction. Dans la sequence de marquage olfactif, le frottement du dos est une importante posture de marquage. L'etude a examine (i) les variations saisonnieres des glandes sebacees dans la peau du dos des ours bruns et (ii) le lien entre ces changements et les concentrations de testosterone. Des echantillons de tissus de peau du dos et de sang ont ete preleves de males adultes captifs intacts et castres durant les periodes precedant la reproduction, de transition, de reproduction et suivant la reproduction, en meme temps que la collecte d'observations sur la peau du dos. Chez les males intacts, durant les periodes de transition et de reproduction, une secretion huileuse provenant de la peau du dos a ete observee, ainsi qu'une taille accrue des glandes sebacees. Les concentrations de testosterone plasmatique durant les periodes de transition et de reproduction etaient plus grandes que durant les periodes precedant et suivant la reproduction. Les secretions et la plus grande taille des glandes sebacees n'ont pas ete observees chez les males castres, et leurs concentrations de testosterone plasmatique demeuraient egales aux valeurs de reference. Les secretions huileuses des glandes de la peau du dos qui semblent plus abondantes durant la periode de reproduction sont frottees contre les arbres. Les variations de la taille et du volume des glandes sebacees et, donc, de leur capacite de secretion sont vraisemblablement modulees par la testosterone. [Traduit par la Redaction] Mots-cles : ours brun, glande sebacee, testosterone, frottement contre les arbres, peau du dos, glande odoriferante, Ursus arctos., Introduction Olfactory communication is the primary form of communication between individuals in many mammalian species, and it represents a key source of information (Gorman and Trowbridge 1989; Muller-Schwarze 2006). Animals [...]