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Author |
Franceschini, C.; Siutz, C.; Palme, R.; Millesi, E. |
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Title |
Seasonal changes in cortisol and progesterone secretion in Common hamsters |
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Journal Article |
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Year |
2007 |
Publication |
General and Comparative Endocrinology |
Abbreviated Journal |
Gen Comp Endocrinol |
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Volume |
152 |
Issue |
1 |
Pages  |
14-21 |
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Keywords |
Animals; Cortisone/*secretion; Cricetinae/*metabolism; Feces/chemistry; Female; Lactation/physiology; Male; Pregnancy; Progesterone/*secretion; Reproduction/physiology; *Seasons; Sexual Behavior, Animal/physiology |
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Abstract |
In this study, we investigated endocrine factors and behaviour in free-living Common hamsters (Cricetus cricetus) during reproductive and non-reproductive periods of the annual cycle. We applied a non-invasive method to gain information on seasonal changes in adrenocortical activity in male and female hamsters by analysing faecal glucocorticoid metabolite concentrations (FCM). In addition, plasma progesterone concentrations were monitored in females throughout the non-hibernation season. The animals were live-trapped from spring emergence until the onset of hibernation in autumn. Reproductive status was determined at capture and blood and faecal samples were collected. During behavioural observations, agonistic and sexual interactions were recorded. FCM concentrations were significantly higher in males than in females during the reproductive period. In males, a pronounced increase in FCM during the reproductive period coincided with high frequencies of intrasexual aggression. In females, FCM levels remained relatively constant. Aggressive behaviour in females increased during the reproductive period, but was much less frequent than in males. Females, which successfully raised a second litter after a postpartum oestrus and concurrent lactation and gestation had lower FCM levels than individuals, which lost their second litter after parturition. As expected, plasma progesterone concentrations were low before and after the reproductive period. During gestation, levels peaked and remained elevated during lactation. The results of this field study provide insight in critical periods associated with reproduction in male and female Common hamsters. |
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Department of Behavioural Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria. claudia.franceschini@univie.ac.ct |
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English |
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0016-6480 |
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PMID:17408667 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4076 |
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Author |
Bartosova, J.; Komarkova, M.; Dubcova, J.; Bartos, L.; Pluhacek J. |
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Title |
Nursing behaviour in pregnant domestic mares (Equus caballus): Can they cope with dual maternal investment? |
Type |
Conference Article |
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Year |
2012 |
Publication |
Proceedings of the 2. International Equine Science Meeting |
Abbreviated Journal |
Proc. 2. Int. Equine. Sci. Mtg |
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Volume |
in press |
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Keywords |
Suckling behaviour; pregnancy; parent-offspring conflict; domestic horses; Equus caballus |
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Abstract |
Among mammals, lactation is the most energy demanding part of parental care and so parentoffspring conflict should arise over milk provided by the mother. Mother and offspring should disagree over the length and amount of the milk provision. We focused on effect of pregnancy on suckling behaviour variables as indicators of mother-offspring conflict in domestic horses. We presumed shorter suckling bouts and higher rates of rejected and/or terminated suckling in pregnant mares compared to non-pregnant ones. Increasing conflict over amount of maternal investment between mother and her young are to be expected because of her parallel investment into a nursed foal and a foetus. Eight groups of loose housed lactating mares with foals of Kladruby horse were studied at the National Stud Kladruby nad Labem (Czech Republic) from deliveries to abrupt weaning (at the age of 127 to 210 days). We recorded 10 848 suckling solicitations of 79 mare-foal pairs, from which 10 607 resulted in a suckling bout. In 41 cases a nursing mare became pregnant during lactation. We found no significant effect of pregnancy either on probability of the mother rejecting suckling solicitation of her foal or probability that she terminated a suckling bout. However the overall effect of mother’s pregnancy on suckling bout duration was not significant, there were considerable differences in pregnant and non-pregnant mares according to who terminated a suckling bout, whether the mother or the foal (F(1, 9776) = 12.1, P < 0.001). In case it was the mother then the suckling bout was longer if she was pregnant (65.36 ± 1.25 s) than barren (60.55 ± 1.36 s). We found no impact of pregnancy on duration of suckling bouts terminated by the foal. Further, nursing a foal during the first two trimesters of pregnancy had no negative impact on birth weight of the foetus. In conclusion, we found not higher, but a lower mother-offspring conflict in pregnant than in non-pregnant lactating mares while expecting just the opposite. We suggest that pregnant mares compensate their nursed foals during intensive stages of lactation through a relaxed mother-offspring conflict for later decrease in investment due to increasing demands of the foetus and/or for the shorter period of milk supply. Our results (partly published in Bartosova et al. 2011, PLoS ONE 6(8): e22068) are of high importance in horse breeding. One of the main arguments for early weaning of the foals is regeneration of their pregnant mothers before upcoming delivery. Here we present evidence that a pregnant mare “counts” with her dual maternal investment and “employs” evolutionary mechanisms enabling her to rear a vital foetus. From this point of view there is no objective reason for stressful weaning of her nursed offspring practised in conventional breeding. Supported by AWIN, EU FP7 project No. 266213. |
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Corporate Author |
Bartosova, J. |
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Publisher |
Xenophon Publishing |
Place of Publication |
Wald |
Editor |
Krueger, K. |
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978-3-9808134-26 |
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Call Number |
Equine Behaviour @ team @ |
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5501 |
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