Appétence et valeur alimentaire de foins de fétuque indemnes ou infestés par le champignon endophyte Acremonium coenophialum

International audienc

Mise au point et etude d'un test enzymatique de la digestibilite de fourrages pauvres ou riches en amidon

Un test enzymatique de digestibilité des fourrages à partir d’enzymes (amylase, pepsine, cellulase) a été mis au point ; son protocole est détaillé. Sur maïs ensilage, ce test est assez bien corrélé avec la méthode classique qui utilise du jus de rumen et il est plus précis et plus fidèle. D’autres essais ont montré que ces résultats étaient également valables sur des fourrages pauvres en amidon comme le sorgho ou la fétuque élevée. Sur maïs, ce test permet de mettre en évidence des différences nettes de digestibilité, également mises en évidence par des mesures avec moutons, alors que la corrélation entre ces deux mesures n’est pas bonne quand les différences variétales ne sont pas significatives. Il semble directement utilisable pour la sélection des fourrages pour la qualité si l’on souhaite soit faire des gains notables de qualité, soit éliminer des génotypes à trop faible digestibilité, soit vérifier que l’on ne perd pas en qualité au cours de cycles d’amélioration du rendement ou de la précocité.An in vitro enzymatic test of forage digestibility is described, using amylolytic, proteinolytic and cellulolytic enzymes. The detailed method is given in an appendix. With maize silage, this APC method gave results correlated with those of the classic rumen juice method, and was more precise and reproducible. Other trials showed that this method also gave good results with low starch-content forages such as tall fescue or sudangrass or sorghum x sudangrass hybrids. With maize, correlations between the APC test of digestibility and digestibility measured by sheep were not good if the variability between test varieties was not significant. The test could be used in breeding programmes if the aim is either to increase digestibility significantly, or to discard low digestibility genotypes or to test that there is no decrease in digestibility during breeding cycles for yield or earliness

In-vivo assessment of different breeding strategies for improving quality in tall fescue

International audienc

Textures, water content and degassing of silicic andesites from recent plinian and dome-forming eruptions at Mount Pelee volcano (Martinique, Lesser Antilles arc

Previous petrological and phase-equilibrium experimental studies on recent silicic andesites from Mount Pelée volcano have evidenced comparable pre-eruptive conditions for plinian and dome-forming (pelean herein) eruptions, implying that differences in eruptive style must be primarily controlled by differences in degassing behaviour of the Mount Pelée magmas during eruption. To further investigate the degassing conditions of plinian and pelean magmas of Mount Pelée, we study here the most recent Mount Pelée's products (P1 at 650 years B.P., 1902, and 1929 eruptions, which cover a range of plinian and pelean lithologies) for bulk-rock vesicularities, glass water contents (glass inclusions in phenocrysts and matrix glasses) and microtextures. Water contents of glass inclusions are scattered in the plinian pumices but on average compare with the experimentally-deduced pre-eruptive melt water content (i.e., 5.3– 6.3 wt.%), whereas they are much lower in the dominant pelean lithologies (crystalline, poorly vesicular lithics and dome samples). This indicates that the glass inclusions of the pelean products have undergone strong leakage and do not represent pre-eruptive water contents. The water content of the pyroclast matrix glasses are thought to closely represent th

I/S and C/S mixed layers, some indicators of recent physical-chemical changes in active geothermal systems: The case study of Chipilapa (El Salvador)

I/S and C/S mixed layers from the geothermal field of Chipilapa (El Salvador) have been studied in details in order to reevaluate their potential use as indicator of the thermodynamic conditions in which they were formed. It is funded that overprinting of clay bearing alteration stages is common. For a given alteration stage, the spatial variation of I/S and C/S mixed layer ininerals is controlled by kinetics of mixed layer transformation and not only by temperature. Clay geo-thermometers cannot give reliable results because the present crystal-chemical states of the I/S and C/S mixed layers is not their initial state, it was aquired during the overall hydrothermal history which post dated the nucleation of smectitic clay material at high temperature. Occurrences of smectites or smectite-rich mixed layers at high temperature in reservoirs is a promising guide for reconstruct the zones in which boiling or mixing of non isotherinal fluids occurred very recently or still presently

MASCOTTE, a research test facility for high pressure combustion of cryogenic propellants

Communication to : 12th European aerospace conference (3rd European conference on space transportation systems), Paris (France), November 29 - December 01, 1999SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2000 n.15 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Experimental validation of stability assessment methods for segmented solid propellant motors

Communication to : AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibit, Monterey, CA (USA), June 28-30, 1993SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1993 n.89 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

MASCOTTE : a test bench for cryogenic combustion research

Communication to : 47th International astronautical congress, Beijing (China), October 7-11, 1996SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1997 n.216 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc