Effects of inorganic nitrogen and amino acids on the degradation of ammonia-treated barley straw and proteosynthesis in a continuous culture of rumen microbes

International audienc

Optimisation of DNA extraction from rumen bacteria

International audienc

Influence des apports d'azote alpha acide aminé et inorganique sur la dégradation in vitro de la paille de blé traitée à l'ammoniac par les micro-organismes du rumen

National audienceLe traitement à l’ammoniac de la paille de céréale améliore nettement la valeur alimentaire de ce sous-produit (Cottyn et al, 1989). Le présent travail a eu pour but de préciser, in vitro, l’action d’une complémentation en azote sur I’utilisation, par les micro-organismes du rumen, de la paille de blé traitée à l’ammoniac par voie humide, en distinguant niveau d’apport (MAT de 0 à 5 % de la MS) et nature de l’azote (inorganique ou a-aminé)

Optimisation of DNA extraction from rumen bacteria

International audienc

Optimisation of headspace solid-phase microextraction for quantitative analysis of monoterpenes in caprine blood

In order to follow the metabolic fate of alpha-pinene, beta-pinene, p-cymene and linalool, four monoterpenes characteristic of the spring diet of dairy goats in the Basilicata region (Southern Italy), we have investigated the use of headspace solid-phase microextraction (HS-SPME) on a 100 mu m polydimethylsiloxane coated fibre as a preparation technique for their analysis by gas chromatography in blood. The effects on terpenes recovery yields of exposure temperature, between 25 and 45 degrees C, exposure time, between 5 and 25 min, and sample ionic strength, between 0 and 250 g/L NaCl, were modelled by second order polynomials parameterised with data from a Hoke experimental design of 13 runs. HS-SPME of alpha- and beta-pinene was mostly favoured by low temperatures and, to a lesser extent, by short extraction times in a linear way. The model fitted to p-cymene data was characterised by a curvilinear effect of extraction time (main effect, P = 0.04; quadratic effect, P=0.10) and quadratic effect of salting (P = 0.04) generating a saddle-shaped surface response. Peak areas of p-cymene were lowered by intermediate NaCl concentrations and short extraction times. For linalool, all the main effects (P < 0.04) and the quadratic effect of extraction time (P = 0.02) generated a hill-shaped response surface. The largest linalool peaks resulted from relatively low extraction times and high temperatures. The best set of operative conditions was an exposure temperature of 35 degrees C. an exposure time of 22 min and a NaCl concentration of 250 g/L. With limonene as an internal standard, the linearity, intra-assay precision and quantification limits were estimated for each terpene determination. The proposed HS-SPME method allowed fast, simple and sensitive determination of terpenes in goat blood samples by conventional equipment. (C) 2012 Elsevier B.V. All rights reserved

Maintenance of rumen protozoa populations in a dual outflow continuous fermenter

International audienc

Stoechiométrie des fermentations ruminales en culture continue, effet de la nature de la céréale et de la teneur en parois de la ration

National audienc