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Disentangling the effects of applying pig slurry or its digestate to winter wheat or a catch crop on dissolved C fluxes
No full textInternational audienceThe anaerobic digestion industry, which is still developing, generates biogas from organic waste products. A co-product of this process, digestate, is increasingly produced and can be recycled on agricultural land as an alternative to mineral fertilizers. Biogas digestate is a recent product whose chemical composition differs from that of its source material, and additional data still need to be acquired on its effects on dissolved carbon fluxes.The objectives of this study were to assess (i) the effects of applying biogas digestate on dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) fluxes with different winter crops, (ii) the dynamics of DOC and DIC concentrations during the drainage season, and (iii) the annual dynamics of DOC and DIC fluxes along the soil profile. The study examined effects of applying biogas digestate, pig slurry, or a mineral fertilizer to winter wheatand two catch crops (mustard and a multispecies crop) on DOC and DIC fluxes in the soil. Lysimeters at 40 cm (topsoil) and 90 cm (subsoil) depths were monitored from 2014 to 2023, from November to March (i.e., 9 winter drainage seasons). During the drainage season, the DOC concentration was highest with digestate, and its timing depended on development of the cover crop: from the beginning of the drainage season for mustard and the multispecies crop and around February for wheat. Applying digestate increased the topsoil DOC fluxes (mean of 35.7 ± 13.7 kg.ha 1 with digestate vs. 21.0 ± 6.7 kg.ha 1 with the other treatments), particularly under mustard. Topsoil DIC fluxes were highest with pig slurry due to higher mineralization than that with digestate(mean of 59.1 ± 22.8 kg.ha 1 with pig slurry vs. 46.2 ± 16.3 kg.ha 1 with the other treatments). In the subsoil, DOC fluxes were low (6.2 ± 4.1 kg.ha 1) and DIC fluxes were high (80.0 ± 45.7 kg.ha 1), with no difference among treatment
Advanced Statistical Modelling of Polarimetric SAR Data for Land Cover Change Detection Analysis
No full textInternational audienceIn this paper, we will present a determinant ratio test (DRT) statistic to measure the similarity of two covariance matrices for unsupervised change detection in polarimetric radar images. The multilook complex covariance matrix is assumed to follow a scaled complex Wishart distribution. In doing so, the distribution of the DRT statistic is analytically derived which is exactly Wilks’s lambda of the second kind distribution, with density expressed in terms of Meijer G-functions. Due to this distribution, the constant false alarm rate (CFAR) algorithm is derived in order to achieve the required performance. More specifically, a threshold is provided by the CFAR to apply to the DRT statistic producing a binary change map. Finally, simulated and real multilook polarimetric radar data are employed to assess the performance of the method and is compared with the Hotelling–Lawley trace (HLT) statistic
The IAHS Science for Solutions decade, with Hydrology Engaging Local People IN a Global world (HELPING)
No full text(IF 2.8;Q2)International audienceThe new scientific decade (2023-2032) of the International Association of Hydrological Sciences (IAHS) aims at searching for sustainable solutions to undesired water conditions - may it be too little, too much or too polluted. Many of the current issues originate from global change, while solutions to problems must embrace local understanding and context. The decade will explore the current water crises by searching for actionable knowledge within three themes: global and local interactions, sustainable solutions and innovative cross-cutting methods. We capitalise on previous IAHS Scientific Decades shaping a trilogy; from Hydrological Predictions (PUB) to Change and Interdisciplinarity (Panta Rhei) to Solutions (HELPING). The vision is to solve fundamental water-related environmental and societal problems by engaging with other disciplines and local stakeholders. The decade endorses mutual learning and co-creation to progress towards UN sustainable development goals. Hence, HELPING is a vehicle for putting science in action, driven by scientists working on local hydrology in coordination with local, regional, and global processes
Hormonal and nutritional regulations of lactation persistency in dairy ruminants
No full textInternational audienceIntroductionIt has long been recognized that the lactation curve in dairy ruminants is shaped by the regulation of mammary tissuecell numbers throughout lactation1,2. However, the precise hormonal and nutritional factors driving lactation persistencyare not been fully elucidated. Therefore, a set of experiments was conducted to investigate the effects of hormonal andnutritional challenges on cell turnover in the mammary tissue.Materials and MethodsInitially, experiments on dairy cows were conducted to assess the effects of hormonal challenges. The effect of inhibitingprolactin release was assessed by administering daily injections of a dopamine agonist (quinagolide) to cows for 8 weeks,compared with control group receiving no injections. Additionally, the effect of sex steroids was studied by performingeither ovariectomy or sham surgery on dairy cows, followed by a monitoring period of 52 weeks. Furthermore, theeffects of feeding level were investigated in dairy cows assigned to either a basal diet or a severe feed restriction from 2wks before calving to wk 11 postpartum, or during a 4-wk moderate feed restriction (-20% DMI). The effects of differenttypes of diets were investigated by supplementing 32 dairy cows with either by pass starch or amino acids (rumenprotected lysine, methionine, and histidine) from 8 wks to 26 wks postpartum. Similarly, 2 levels of NEL (1.48 vs. 1.65Mcal/ kg DM) through concentrates and amino acid supply (rumen protected methionine) were tested on 24 midlacI14tatinggoats for 4 wks. Mammary tissue cell turnover was assessed through immunohistochemical analyses in allexperiments, and the exfoliation of mammary epithelial cells (MEC) into milk was examined in some cases.ResultsThe impacts on milk yield (MY) resulting from hormonal challenges (-14% during prolactin inhibition or +10% afterovariectomy) were associated with alterations in apoptosis/proliferation balance in the bovine mammary tissue and adecrease of MEC exfoliation (only for ovariectomy). The decreases in MY due to feed restriction (- 38 % and - 8%respectively with a severe and a moderate feed restriction) in cows were associated with either a higher level ofapoptosis or an increase in MEC exfoliation with no effect on cell proliferation. The increase in MY (+ 11%) induced bystarch supplementation in cows was accompanied by enhanced cell proliferation. AA supplementations did not affectmilk yield but resulted in increased cell proliferation in both dairy cows and goats and reduced cell apoptosis in dairygoats.ConclusionsTaken together, these experiments support the hypothesis that the regulation of lactation persistency in dairy cows andgoats, subjected to hormonal or nutritional challenges, involves changes in the number of mammary cells, mediated byadjustments in the apoptosis/proliferation balance and the rate of mammary cell exfoliation into milk. AAsupplementation can also affect cell turnover
Large potential impacts of marine heatwaves on ecosystem functioning
No full textInternational audienceOcean warming is driving significant changes in the structure and functioning of marine ecosystems, shifting species' biogeography and phenology, changing body size and biomass and altering the trophodynamics of the system. Particularly, extreme temperature events such as marine heatwaves (MHWs) have been increasing in intensity, duration and frequency. MHWs are causing large-scale impacts on marine ecosystems, such as coral bleaching, mass mortality of seagrass meadows and declines in fish stocks and other marine organisms in recent decades. In this study, we developed and applied a dynamic version of the EcoTroph trophodynamic modelling approach to study the cascading effects of individual MHW on marine ecosystem functioning. We simulated theoretical user-controlled ecosystems and explored the consequences of various assumptions of marine species mortality along the food web, associated with different MHW intensities. We show that an MHW can lead to a significant biomass reduction of all consumers, with the severity of the declines being dependent on species trophic levels (TLs) and biomes, in addition to the characteristics of MHWs. Biomass of higher TLs declines more than lower TLs under an MHW, leading to changes in ecosystem structure. While tropical ecosystems are projected to be sensitive to low-intensity MHWs, polar and temperate ecosystems are expected to be impacted by more intense MHWs. The estimated time to recover from MHW impacts is twice as long for polar ecosystems and one-third longer for temperate biomes compared with tropical biomes.This study highlights the importance of considering extreme weather events in assessing the effects of climate change on the structures and functions of marine ecosystems
Reproductive modes in populations of late-acting self-incompatible and self-compatible polyploid Ludwigia grandiflora subsp. hexapetala in western Europe
No full textInternational audienceReproductive mode, i.e., the proportion of individuals produced by clonality, selfing and outcrossing in populations, determines how hereditary material is transmitted through generations. It shapes genetic diversity and its structure over time and space, which can be used to infer reproductive modes. Ludwigia grandiflora subsp. hexapetala (Lgh) is a partially clonal, polyploid, hermaphroditic, and heteromorphic plant that recently colonized multiple countries worldwide. In western Europe, individuals are either self-incompatible caused by a late-acting self-incompatibility (LSI) system developing long-styled flowers, or self-compatible (SC), with short-styled flowers. In this study, we genotyped 53 long- and short-styled populations newly colonizing France and northern Spain using SNPs to estimate rates of clonality, selfing and outcrossing. We found that populations reproduced mainly clonally but with a high diversity of genotypes along with rates of sexuality ranging from 10% up to 40%. We also found evidence for local admixture between long- and short-styled populations in a background of genetic structure between floral morphs that was twice the level found within morphs. Long- and short-styled populations showed similar rates of clonality, but short-styled populations presented significantly higher rates of selfing, as expected considering their breeding system and despite the small rates of failure of the LSI system. Within the 53 studied populations, the 13 short-styled populations had fewer effective alleles, lower observed heterozygosity, and higher inbreeding coefficients, linkage disequilibrium and estimates of selfing than what was found in long-styled populations. These results emphasize the necessity to consider the variation of reproductive modes when managing invasive plant species. The overall maintenance of higher genetic diversity with the possibility of maintaining populations clonally in the absence of compatible partners may explain why long-styled individuals seem to be more prevalent in all newly expanding populations worldwide. Beyond Lgh, our methodological approach may inspire future studies to assess the reproductive modes in other autopolyploid populations
Stratégies nutritionnelles pour optimiser le statut immunitaire et antioxydant de la vache laitière
No full textMastitis is an inflammatory disease of the mammary in dairy cows, most commonly caused by bacteria. The incidence of mastitis is high in early lactation, probably due to the oxidative stress and inflammation characteristic of this period. The aim of this thesis was to evaluate preventive strategies based on dietary supplementation with vitamin E or plant extracts by assessing their effects on redox and immune status, both at the systemic and local mammary levels in dairy cows. Two studies were performed: a longitudinal study in healthy cows and an inflammatory study using LPS infusion in a mammary quarter. First, the thesis showed that the antioxidant metabolism of multiparous cows was higher than that of primiparous cows, associated with a lower functional capacity of circulating immune cells. In healthy cows, the supplementations reduced the inflammatory response to prevent hyperinflammation. In both studies, vitamin E tended to reduce lipid peroxidation and increase glutathione peroxidase activity. Plant extracts tended to increase the expression of antioxidant transcription factors. During the inflammation study, antioxidant supplemented cows had higher local immune capacity, in addition with a more preserved mammary epithelium integrity. Epidemiologic studies are now needed to confirm the preventive effect of vitamin E and plant extracts under field conditions.Les mammites sont des pathologies inflammatoires de la mamelle chez les vaches laitières, le plus souvent liées à une bactérie. L’incidence des mammites est importante en début de lactation, sans doute du fait d’un stress oxydant et d’une inflammation caractéristique de cette période. Cette thèse avait pour objectif d’évaluer des stratégies de prévention basées sur des supplémentations nutritionnelles en vitamine E ou en extraits de plantes en objectivant leurs effets sur le statut redox et immunitaire, aussi bien au niveau systémique que locale à l’échelle de la glande mammaire. Deux essais ont été réalisés, un essai longitudinal chez des vaches en bonne santé, et un essai en épreuve inflammatoire par infusion de LPS dans un quartier de mamelle. Dans un premier temps, la thèse met en évidence que le métabolisme antioxydant des vaches multipares était plus important que celui des primipares, et associé à une moindre capacité fonctionnelle de leurs cellules immunitaires circulantes. Chez des vaches en bonne santé, les supplémentations en antioxydant ont diminué la réponse inflammatoire, pour éviter une hyper inflammation. Dans les deux essais, la vitamine E a eu tendance à réduire la peroxydation des lipides et augmenter l’activité de la glutathion peroxydase. Les extraits de plantes ont eu tendance à augmenter l’expression du facteur de transcription antioxydant. Lors de l’épreuve inflammatoire, les vaches supplémentées ont eu des capacités immunitaires locales plus élevées et une intégrité de l’épithélium mammaire préservée. Des études épidémiologiques sont maintenant nécessaires pour confirmer l’effet préventif de la vitamine E et des extraits de plantes en conditions de terrain
Analyse des Chaînes de Valeur Mondiales dans les industries Agroalimentaires
No full textOver the last thirty years, there has been a significant increase in global value chain (GVC) trade. The challenge is to measure the importance of GVCs in the agrifood sector from a microeconomic perspective and identify the determinants and motivations of firms to participate in this process, in order to better account for GVCs in the design of countries' trade and industrial policies. Specifically, the thesis analyses the GVC participation premium of retailers' suppliers the role of product quality on firms' boundary choices in GVCs; and how these choices affect their bargaining power. Theoretical elements, based on a model with heterogeneous firms, make it possible to analyze these mechanisms in detail. The empirical analyses use detailed data on French companies in the agri-food industry tohighlight the importance of intra-industry analysis of GVCs. The results show the GVC participation premium for retailers' suppliers. Secondly, it is documented that quality upgrading enables firms to participate more intensively in GVCs by performing a greater number of production stages. This leads increased input costs and higher profits and value added. Thirdly, it is demonstrated that firms' specialization in further upstream stages of GVCs, as well as expansion along GVCs of firms producing closer to final demand, increase the division of surplus in GVCs, and that these effects are mainly due to higher quality production. Additionally, the effect of specialization is stronger when firms actually and solely undertake processing activities in GVCs, and because it reduces the hold-up problem for firms, otherwise the two effects cancel each other out.Au cours des trente dernières années, le commerce des chaînes de valeur mondiales (GVCs) a considérablement augmenté. Le défi est de mesurer l’importance des GVCs dans le secteur agroalimentaire d'un point de vue microéconomique et à identifier les déterminants et les motivations des entreprises à participer à ce processus, afin de mieux les prendre en compte dans l'élaboration des politiques commerciales et industrielles des pays. Spécifiquement, la thèse analyse la prime de participation aux GVCs des fournisseurs des détaillants ; le rôle de la qualité des produits sur les choix de frontières des firmes dans les GVCs ; et comment ces choix affectent leur pouvoir de négociation. Des éléments théoriques, basés sur le modèle des firmes hétérogènes, permettent d'analyser ces mécanismes en détail. Les analyses empiriques utilisent des données détaillées sur les firmes françaises de l'industrie agroalimentaire pour souligner l'importance de l'analyse intra- branche des GVCs. Les résultats démontrent la prime de participation aux GVCs des fournisseurs des Détaillants. Ensuite, il est démontré que l'amélioration de la qualité permet aux firmes de participer de manière plus intensive aux GVCs en réalisant un plus grand nombre d'étapes de production. Il en résulte une augmentation des coûts des intrants, des bénéfices et de la valeur ajoutée. Enfin, il est démontré que la spécialisation des firmes dans des étapes plus en amont des GVCs, ainsi que l'expansion le long des GVCs des firmes produisant plus près de la demande finale, augmentent la division du surplus dans les GVCs, et que ces effets sont principalement dus à une production de meilleure qualité. En outre, l'effet de la spécialisation est plus fort lorsque les firmes entreprennent effectivement et uniquement des activités de transformation dans les GVCs, et parce qu'elle réduit le problème du hold-up, sinon les deux effets se neutralisent
Application de Lacticaseibacillus paracasei sur la peau du trayon: Quels impacts sur la santé animale et sur les procédés de transformation du lait?
No full textInternational audienceLa mammite bovine constitue une preoccupation majeure pour l'industrie laitiere. Les approches actuelles, incluant les traitements antibiotiques, sont partiellement efficaces et peuvent contribuer au risque de dissemination d’antibioresistance, ce qui justifie le developpement de traitements alternatifs.L’objectif de ce projet est de developper une strategie microbienne visant à renforcer l'effet barriere du microbiote naturellement present sur le trayon par l'application de Lacticaseibacillus paracasei CIRM BIA 1542 (Lp1542). Le traitement (Lp1542, iode ou aucun traitement) a ete applique apres la traite deux fois par jour pendant 15 jours sur les 4 trayons de 20 vaches Holstein en bonne sante, en milieu de lactation (n = 6 a 8 par traitement). Des echantillons de sang, de lait de premier jet et de lait citernal ainsi que des ecouvillonnages de la peau de trayon ont ete preleves a J1, J8, J15 et J26 avant la traite du matin et a J15 avant la traite du soir (J15S) afin d’evaluer l'impact de Lp1542 aux niveaux microbien, immunitaire et physiologique. Le traitement avec Lp1542 a entraine une augmentation de la population de bacteries lactiques et des populations microbiennes totales sur la peau du trayon et dans le lait avant la traite a J15S par rapport au traitement a l'iode. L'analyse metagenomique a revele des changements dans la composition du microbiote de la peau du trayon et du lait, au-dela de la presence de la souche de Lacticaseibacillus appliquee, avec notamment une plus grande abondance d'Actinobacteriota, y compris Bifidobacterium, et une plus faible abondance de Pseudomonadota sur la peau des trayons des vaches traitees avec Lp1542 par rapport aux quartiers traites a l'iode. En outre, le traitement avec Lp1542 n'a pas declenche de reaction inflammatoire majeure dans la glande mammaire et n'a pas eu d'effet negatif sur la fonctionnalite et l'integrite de l'epithelium mammaire. Des essais complementaires ont permis d'evaluer l’impact de Lp1542 sur les procedes de transformation du lait. Premierement, la thermosensibilite de Lp1542 a ete demontree pour des conditions representatives de traitement thermique du lait. Deuxiemement, il a ete demontre que Lp1542 n’interferait pas avec les proprietes d'acidification ou proteolytique d’un ferment commercial.En conclusion, l’ensemble de ces resultats semblent indiquer qu'un traitement topique avec Lp1542 dans un contexte sain ne semble pas impacter la sante animale, ni les procedes de transformation du lait. Ces resultats nous invitent donc a explorer davantage l’efficacite de Lp1542 dans la prevention de la mammite bovine