Ethanol vapours limit Botrytis development over the postharvest life of table grapes

The application of ethanol vapours has been optimised over two seasons in order to prevent rot development, caused by Botrytis cinerea, and stem browning in 'Chasselas' table grapes. At a dose rate of 2 ml per kg of grapes, ethanol vapour was as effective as sulphur dioxide pads. Consumer panels detected no significant difference in sensory perception between controls and treated grapes. The ethanol vapour treatment could be easily implemented by the table grape industry since the technology is similar to sulphur dioxide treatment

Effect of cow diet on the ruminal microflora and its in vitro fatty acid production

The objective of this study was to investigate the effects of donor’s cow diet (hay or maize silage plus concentrates) on ruminal bacteria count, flora diversity and fatty acids profile (FA) of ruminal fluid and in vitro biohydrogenation (BH) of C18:2. Two dry cows fitted with a ruminal canula were used in a 2x2 design. Each period included three weeks of diet adaptation and two weeks of sampling. The cows were fed twice daily either a diet (H) composed of grass (38%) and alfalfa hay (62%) or an acidogenic diet (A) composed of maize silage (38%), wheat (57%) and soybean (5%) meal. Ruminal fluid was sampled and centrifugated (150g, 5min., 39°C). The ruminal fluid (80mL) was mixed with 80mL of buffer, a fermentative substrate and grape seed oil as source of C18:2 before being incubated during 6 hours at 39°C in anaerobic and dark conditions. Biodiversity was estimated by the Simpson index modified by Haegeman et al.1 after SSCP analysis, and FA were analysed by GLC. Bacteria counting was realised according to Oblinger and Koburger2 (1975). Total and cellulolytic bacteria contents were higher in inoculum A than in inoculum H (9.3.109 vs. 2.4.108/mL for total bacteria and 2.4.108 vs. 1.6.107/mL for cellulolytic bacteria). No difference in the biodiversity of the inoculums was noticed according to the cow or the diet, but diversity during period 1 tended to differ (P=0.09) from period 2, suggesting a time variation of flora biodiversity. Before incubation, the ruminal fluid from the cow receiving diet A contained significantly (P<0.01) more C18:2, trans-10 and trans-11 C18:1, and odd-chain FA than inoculum from the cow receiving diet H. After incubation, inoculum A resulted in a significantly (P<0.01) greater BH of C18:2 than inoculum H, and produced more trans-10C18:1, trans-11C18:1 and odd-chain FA (P<0.01) Trans-10 and odd-chain FA are known to be increased by a high concentrate diet, which explains that inoculum A was richer in these FA than inoculum H. The ruminal flora selected in vivo by diet A continued the production of these FA in vitro. The greater content of trans-11C18:1 and of C18:2 in the inoculum A could be explained by the greater content in C18:2 of the diet A. During incubation with added C18:2, inoculum A continued to produce more trans-11 along with a higher C18:2 BH than inoculum H, which could be due to the higher concentration of cellulolytic bacteria in the inoculum A

Random changes in the heifer rumen in bacterial community structure,physico-chemical and fermentation parameters, and in vitro fiber degradation

The variability over time of several main ruminal characteristics was studied in heifers over 15 consecutive weeks. Three heifers were assigned to a low-fiber diet (27% NDF) and three to a high-fiber diet (44% NDF). The physico-chemical (pH and redox potential) and fermentation(volatile fatty acids and ammonia contents) parameters were determined on 1 day per week for 15 consecutive weeks. On the same days the bacterial community structure was studied using a molecular fingerprint technique and the ruminal fiber degradation was studied by in vitro incubation of a withdrawn ruminal content sample. Numerous random changes were observed from week to week for all physico-chemical and fermentative parameters and in vitro fiber degradation. The redox potential was the only parameter to show a significant interaction between diet and week. Except for the ammonia content, the amplitudes of fluctuations observed were higher for the low-fiber diet. The bacterial community structure did not differ between diets or weeks. The in vitro fiber degradation was similar for both diets, with numerous random changes throughout the study. The findings of this study indicated that most of the parameters of the ruminal ecosystem had time-related changes with random fluctuations around a mean value which reflect an unstable equilibrium. This conclusion was valid for both low- and high-fiber diets

Etude par pyroséquençage haut débit (454) de l’implantation des bactéries au niveau du rumen du veau laitier, de sa naissance au sevrage

Objectif : Décrire la séquence temporelle d'implantation de la population bactérienne au niveau du rumen chez le veau, de la naissance jusqu'au sevrage, via des outils de microbiologie moléculaire

Mesure in vitro de l'activité de la communauté bactérienne ruminale

Les techniques modernes de biologie moléculaire permettent une description de la micropopulation ruminale. L’étude de l’activité de cette population sur les principaux constituants de la ration est souvent réalisée in vitro. L’objectif de cette étude était de vérifier si la population bactérienne est active mais n’évolue pas pendant une courte incubation in vitro, ce qui permettrait de mettre en relation le profil et l’activité des bactéries. La communauté bactérienne mise à incuber in vitro n’a pas évolué, ni en quantité, ni en structure ou en diversité, ce qui suggère que les conditions de culture n’entraînent pas une sélection de certaines espèces au cours des 6 premières heures. Cette communauté est restée active, puisque capable de dégrader les différents substrats : matières azotées, glucides et lipides. Une mesure in vitro de l’activité microbienne est donc possible, et pourrait s’avérer intéressante à associer aux techniques de biologie moléculaire afin de mieux caractériser la communauté bactérienne d’un prélèvement

Education and economic growth: endogenous growth theory test ; the French case

Die Diskussion über die verschiedenen Determinanten des Wirtschaftswachstums hat für beträchtliche Aufmerksamkeit gesorgt, sowohl wegen ihrer wirtschaftspolitischen Implikationen als auch wegen der theoretischen und empirischen Analysen, die diese Diskussion hervorgebracht hat. So wird oft argumentiert, das langfristige Wirtschaftswachstum ließe sich mit endogenen Wachstumsmodellen erklären. Vor allem wird angenommen, dass die Produktion von Wissen mittels Bildung selbsttragendes Wirtschaftswachstum induziere. Einer Vielzahl theoretischer Entwicklungen zum Trotz weisen die empirischen Ergebnisse jedoch in eine andere Richtung. Dies ist für die Verfasserin Anlass zu einer kritischen Auseinandersetzung mit den neuen Wachstumstheorien. Das behauptete, bildungsinduzierte endogene Wirtschaftswachstum soll zudem am Beispiel Frankreichs für das 19. und 20. Jahrhundert überprüft werden. Dabei handelt es sich um einen empirischen Test von Lucas' Modell (1988). Die Ergebnisse sind überraschend und stehen in vollständigem Gegensatz zu den Hypothesen der neuen Wachstumstheorien. Die Humankapitalrenditen entwickeln sich rückläufig, sodass durch Bildung produziertes Wissen nicht der Motor selbsttragenden Wirtschaftswachstums sein kann. (ICEÜbers)'The debate concerning the various determinants of economic growth has attracted considerable attention, due to both the importance of its implication in terms of economic policy and the number of theoretical and empirical analyses engendered by it. Thus, the argument according to which endogenous growth models explain long-term economic growth is often put forward. Particularly, it is held that the production of knowledge by education induces self-sustained economic growth. However, in spite of numerous theoretical developments, attempts at empirical verification give contradictory conclusions. The aims of this article are therefore to undertake a critical reading of the theoretical contribution of new growth theories and to present an empirical testing for France in the 19th and 20th centuries to justify or invalidate the probable endogenous nature of economic growth induced by education. In short, it is an empirical test of Lucas' model (1988). The results are surprising and so in contradiction with the hypothesis of new growth theories: human capital returns are decreasing and thus knowledge produced by education cannot be the engine of self-maintained economic growth.' (author's abstract

The new growth theories: a survey of theoretical and empirical contributions

In den 80er Jahren kam es zu einer Renaissance der neo-klassischen Theorie des Wachstums mit dem Ziel, die Schwächen der neokeynesianisch orientierten Modelle zu überwinden. Erneut wurde nach den entscheidenden Determinanten eines nachhaltigen wirtschaftlichen Wachstums gefragt: Ist es der technische Fortschritt allein, der den 'Wohlstand der Nationen' mehrt oder führt in letzter Instanz Kapitalakkumulation zu dem gewünschten Effekt? Welche weiteren Produktionsfaktoren müssen hinzukommen (materielle Infrastruktur, Umweltkapital und -ressourcen, Humankapital oder der Stand des technologischen Wissens) und mit welcher Gewichtung sind sie zu berücksichtigen? Welches ist die günstigste Marktstruktur, die Wachstum garantiert? Der vorliegende Beitrag resümiert die Diskussionen um diese theoretischen Fragen, um dann im zweiten Teil ihre empirische Triftigkeit zu prüfen. (ICA)'The debate concerning the various determinants of economic growth has attracted considerable attention, both through the importance of its implications in terms of economic policy and through the number of theoretical and empirical analyses that it has engendered. This being so, the aim of this article is (I) to undertake a critical reading of the contribution of the 'new growth theories' and (II) to review the empirical assessments of its endogenous nature.' (author's abstract

Analyse comparée des écosystèmes digestifs du rumen de la vache et du caecum du lapin

Dans cette revue nous avons synthétisé les données obtenues dans notre équipe et celles de la bibliographie afin de contribuer à une meilleure connaissance de l’écologie des communautés bactériennes et archées des fermenteurs digestifs des mammifères herbivores. L’analyse a porté sur la comparaison des deux principales stratégies digestives rencontrées chez les mammifères herbivores actuels : un fermenteur en position proximale, le rumen, et un fermenteur en position distale, le caecum. Parmi les espèces d’intérêt agronomique,la vache et le lapin on été choisis comme animaux modèles. Après avoir rappelé les caractéristiques anatomiques et physicochimiques de ces fermenteurs digestifs, nous avons analysé les spécificités de leurs communautés procaryotiques liées à l’hôte, la variabilité individuelle, la structuration spatiale (inter- et intra- fermenteurs digestifs) et la dynamique temporelle (journalière et hebdomadaire) avec ou sans perturbation nutritionnelle induite

A new method to measure the redox potential (Eh) in rabbit caecum: relationship with pH and fermentation pattern

[EN] This study aimed to assess the anaerobic status of the caecal biotope in the rabbit through the measurement of its redox potential (Eh). Since the caecal content has a high viscosity, the duration of the Eh measurement is high (10 to 20 min) and two methods were compared in 10 week- old rabbits: in vivo vs. post-mortem. In addition, Eh, pH and temperature of the caecal digesta were analysed according to caecotrophy and three periods in the day (soft faeces production: 08:00-10:00 h and 12:00-14:00 h; hard faeces production: 17:00-19:00 h) were compared, using 34 rabbits aged 65 d and weighing 2.3 kg. Caecal Eh decreased 2 min after measurement began, and then stabilised from 20 min onwards (from -152 to 221 mV, P<0.001), in contrast to caecal pH which remained constant over time. Mean values for Eh (at 20 min) and pH were - 219 mV and 6.2 respectively, and did not change according to method or collection period. Only the caecal temperature was 2°C higher (P<0.001) for the in vivo (39°C) than for the post-mortem (37°C) method. Average caecal dry matter and total volatile fatty acid were on average 22 % and 106 mmol/L, and were affected neither by the method nor by the collection period. Caecal Eh was negatively correlated to caecal pH (R²=0.22; P=0.006, n=34), but not to other biotope traits. The Eh measurement in rabbit caecal content could be performed with a minimum recommended duration of 20 min, under anaesthesia or post-mortem. We confi rmed that the rabbit caecal ecosystem is highly anaerobic.This work was partly funded by a grant from Lesaffre Feed Additives (France)Kimsé, M.; Monteils, V.; Bayourthe, C.; Gidenne, T. (2009). A new method to measure the redox potential (Eh) in rabbit caecum: relationship with pH and fermentation pattern. World Rabbit Science. 17(2):63-70. https://doi.org/10.4995/wrs.2009.659637017