5 Abstract This thesis is aimed at spatial variability of population structure of our four most common and the most numerous species of ducks wintering in the Czech Republic. These analysed species are Mallard (Anas platyrhynchos), Tufted duck (Aythya fuligula), Common Merganser (Mergus merganser) and Northern Goldeneye (Bucephala clangula). The field data were collected by January International Waterbird Census in the Czech Republic between 2004 and 2013. Analysed habitat variables include: type of wetland, altitude, population size, level of urbanisation (size of settlement) and mean January air temperature in the investigated site. There was found no significant effect of type of wetland and local population density on population structure in any of these bird species. The next factor, altitude of sites was confirmed as significant only for Mallards, when increasing altitude decreased proportion of males in the population. Furthermore, effect of urbanization was found also in Mallard, when proportions of males increased with level of urbanization, i.e. in larger cities. Finally, , temperature of sites was confirmed to be significant factor affecting population size in the three analyzed species, i.e. in Mallard, Tufted Duck and Northern Goldeneye. Except Common Merganser, ratio of males grew with...

Le virus de l’influenza aviaire hautement pathogène (IAHP) de type H5N1 apparu en Chine en 1996 constitue une menace pour la santé humaine en raison de sa circulation endémique dans les volailles domestiques et de son potentiel zoonotique. La sévérité de l'infection liée à l'IAHP H5N1 est variable selon les espèces d'oiseaux: certains anatidés sont porteurs sains et asymptomatiques du virus tandis que dans les élevages de poulets, l'IAHP est fortement contagieux et caractérisé par des taux de mortalité supérieurs à 90%. Chez les humains, l'impact de l'IAHP H5N1 reste à ce jour modéré (630 cas humains dont 375 morts, World Health Organization Juin, 2013) en raison de la faible transmission du virus des volailles aux humains et d'humain à humain. Cependant, étant donné les taux de létalité élevés (>50%), un changement des modalités de transmission pourrait mener à un impact beaucoup plus élevé.<p>Depuis son émergence, l'IAHP H5N1 a eu un impact économique important dans de nombreux pays d’Asie du Sud-Est. La Thaïlande, pays qui fait partie des principaux exportateurs mondiaux de viande de volaille, a été sévèrement touchée par les multiples vagues épidémiques entre 2003 et 2005. Ces épisodes ont eu un impact sur les revenus des petits et moyens producteurs, mais également causé des pertes économiques importantes dans le secteur de la production intensive de volailles en raison de l'embargo imposé par les principaux marchés d'exportation. <p>L'objectif de ce travail est d’étudier quantitativement l'association entre la production intensive de la volaille et la distribution spatio-temporelle de l'IAHP H5N1 en Thaïlande. Deux approches ont été développées pour aborder cette étude: le développement d’une part de modèles statistiques visant à identifier les déterminants du risque d'IAHP H5N1, et d'autre part, de modèles mécanistiques visant à simuler des trajectoires épidémiques sur base de la connaissance des mécanismes de transmission de l'IAHP H5N1, de la structure du secteur de la production de volaille et des mesures d'intervention mises en place. <p>A l’aide de facteurs environnementaux et anthropogéniques, nous montrons que: (i) la distribution des canards domestiques en Asie peut être prédite en utilisant des modèles de régression non-linéaire, et (ii) la production de volailles peut être désagrégée entre production extensive et intensive sur base du nombre de volailles par éleveur. Enfin (iii), nous montrons en utilisant des arbres de régression boostés ("Boosted Regression Trees", BRT) que les principaux déterminants de la distribution du risque d'IAHP H5N1 sont les canards élevés en systèmes intensifs, le nombre de cycles de culture de riz et la proportion d'eau présente dans le paysage. Finalement, nous illustrons les potentialités des modèles mécanistiques pour évaluer l'efficacité des mesures d'intervention implémentées, tester des scénarios alternatifs d'intervention et identifier des stratégies optimales de prévention et d'intervention contre de futures épidémies<p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

<p>  </p> <p>Heat stress affects breeder ducks raised in North America and other parts of the world, but the effects of such stress on the progenies is not known. Therefore, the objectives of this study were to investigate: 1) The objectives of this thesis were to first investigate the effect of heat stress or exposure to exogenous glucocorticoid (GC) on fertility, production performance, egg biochemistry, egg quality, and welfare of breeder Pekin ducks. 2) the effects of maternal GC on phenotypic plasticity and behavior of the F1 generation. Three studies were carried out to investigate these objectives.</p> <p>The first experiment was conducted to test the hypothesis that chronic treatment with low levels of either corticosterone or cortisol would alter heterophil to lymphocyte ratio (HLR) and immune organ morphometrics. Further, we wanted to determine if chronic treatment with either GC would elicit an increase in cortisol levels in egg albumen. To test our hypotheses, we implanted silastic capsules subcutaneously under the skin of the neck of adult ducks (n = 5/sex/dose) using propofol anesthesia. Capsules contained corticosterone, cortisol, or empty capsules as controls. Over the course of 2 weeks, blood serum, blood smears, body weights, and egg quality data were collected. After 2 weeks, ducks were euthanized using pentobarbital (FatalPlus, 396 mg/ml/kg) and body weight, weights of spleens, livers, and the number of active follicles were recorded. Blood smears were analyzed for HLR by a lab unaware of the treatment groups. Albumen GC levels were assessed using mass spectrometry. Data were analyzed using a 2- or 3-way ANOVA as appropriate and <em>post hoc </em>with Fishers protected least squares difference (PLSD). There were no treatment effects on egg quality measures or body weight. Corticosterone treatment did elicit an increase in serum corticosterone (p < 0.05), but not cortisol levels, compared to controls in both sexes. Both cortisol and corticosterone treatments increased (p < 0.05) serum levels of cortisol compared to controls. Relative spleen weights were higher (p < 0.05) in hens following corticosterone but not cortisol treatment. No other organs showed any differences among the treatment groups. Both GCs elicited an increase (p < 0.001) in HLR in hens at all time-points over the 2-week treatment period compared to controls. Cortisol, not corticosterone, elicited an increase in HLR for drakes (p < 0.05) compared to controls at day 1 after implants. Chronic treatment with cortisol, but not corticosterone, elicited an increase (p < 0.01) in egg albumen cortisol levels compared to other groups. Corticosterone was not detected in any albumen samples.</p> <p>The goal of our second experiment was to test the hypothesis that heat stress (HS) would alter welfare, egg quality, and morphometrics of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen due to recent exciting findings that cortisol, not corticosterone, is isolated in egg albumen. To test our hypothesis, adult Pekin ducks were randomly assigned to two different rooms at 85% lay with 60 hens and 20 drakes per room. Baseline data including body weight, body condition scores (BCS) (such as footpad quality, eyes, nostrils, feather cleanliness, and feather quality scores), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 350C for 10h/day and to 29.50C for the remaining 14h/day for 3 weeks while the control room was maintained at 220C. Eggs were collected daily, and body weights were taken on days 0 and 21 relative to the onset of heat treatment. BCS were collected weekly. Eggs were collected weekly for quality assessment and albumen glucocorticoid (GCs) levels assessment using mass spectrometry. One week before the exposure to HS, 10 hens and 5 drakes were euthanized and the same number again after 3 weeks of HS or control exposures using pentobarbital and birds necropsied. Body weight, weights of the liver, spleen, and the number of maturing follicles were recorded. Data analyses were done by 2- or 3-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p value ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens while there was no significant difference in the circulating levels of corticosterone in drakes compared to the controls. The circulating levels of cortisol increased significantly at week 1 (p < 0.05), week 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at week 2 and 3 only (p < 0.05) in the drakes compared to the controls. Feather quality scores (p < 0.01), feather cleanliness scores (p < 0.001) and footpad quality scores (p < 0.05) increased significantly in the HS group compared to controls, higher BCS indicate a decline in welfare. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3 and a descriptive decrease in the number of fertile eggs upon candling at 10 days of incubation, numeric decrease hatchability and increase in the number of dead embryos in the HS group after the incubation period. Hens in the HS group showed a significantly decreased BW (p < 0.001), and number of ovarian follicles (p < 0.05) compared to controls. Shell weight decreased significantly at week 1 (p < 0.05) compared to controls. Yolk weight decreased significantly at week 3 (p < 0.01) compared to controls. HS elicited a significant increase in albumen cortisol levels at week 1 (p < 0.05) and week 3 (p < 0.05).</p> <p>The third experiment was conducted to determine if parental exposure to heat stress would impair performance, hypothalamic pituitary adrenal (HPA) axis response, welfare, or behavior of their offspring. To achieve these goals, we treated adult drakes and hens at peak lay to heat stress or control temperature for 3 weeks and incubated eggs collected from the last 3 days of the experiment. A total of 76 ducklings were placed into pens from each parental treatment group: control (CON-F1) and heat stress (HS-F1) and raised as grow-out ducks. Weekly data for body weights, body condition scores (BCS), and novel object test (NOT) were collected weekly. At 3 weeks of age, ducks (n = 6 per treatment group) were subjected to adrenocorticotropic hormone (ACTH) (ACTH/cosyntropin, 0.0625 mg/kg) challenge or vehicle as control. Blood samples were collected from the metatarsal vein into serum-separator tubes at 0, 1, 2, 3, and 4 hours relative to treatment for the determination of serum glucocorticoids. Blood smears were also produced from these same samples to determine heterophil to lymphocyte ratios (HLR). All injected birds were euthanized with pentobarbital on the second day relative to ACTH administration, spleen and bursa were removed and weighed immediately. Duck level analyses were completed using 1-, or 2 -way ANOVA as appropriate. BCS were analyzed using a chi-squared test. We observed that HS-F1 had a lower hatch weight (p < 0.05) compared to CON-F1. However, growth rates during the 5-week grow-out period were not significantly different between the two flocks. NOT (N = 4) analyses showed that the HS-F1 had a greater fear response (P< 0.001) compared to CON-F1. Similarly, an ACTH stimulation test showed that the HS-F1 ducks had significantly heightened corticosterone and HLR responses compared to CON-F1 ducks (p < 0.05). The HS-F1 showed altered baseline and ACTH-stimulated levels of cortisol compared to controls.</p> <p>In conclusion, GC elicit differential effects and although corticosterone has been stated to be the predominant GC in avian species, cortisol may provide critical information to further understand and improve welfare. HS decreased performance, fertility, and productivity of breeder ducks. In addition, HS and exogenous GC elicited a selective deposition of cortisol, not corticosterone, in the egg albumen. The maternal cortisol deposited in eggs alter the hypothalamic-pituitary adrenal (HPA) axis and behavioral responses of the F1 generation. This suggests that maternal hormones can alter the phenotypic plasticity of the offspring and can be used to produce offspring that have better adaptation to the rising temperatures as a result of climate change. Finally, the measure of cortisol in egg albumen can be used as a non-invasive marker of stress.</p>