The effect of varying hay/barley-proportions in the feed ration on biotin metabolism of rumen microbes was studied by means of the rumen simulation technique RUSITEC. The stepwise replacement of hay by barley decreased dietary biotin and the net output of biotin by the microbial metabolism. It is concluded that rumen microbes utilise more and/or synthesize less biotin with increasing proportions of dietary barley. These results indicate that a critical reconsideration of current views with regard to the supply and requirement of the high yielding dairy cow for biotin is necessary.
. Methane emissions from the rumen of sheep fed a mixed grass-clover pasture at two fertilisation rates in early and late season. Can. J. Anim. Sci. 82: 69-77. In vivo CH 4 production from four rumen-fistulated sheep fed fresh ryegrass-white clover (Lolium perenne -Trifolium repens) diets ad libitum was monitored using C 2 H 6 as a tracer gas. Treatments comprised mixed pastures at two different fertilisation rates (0 vs. 150 kg N ha -1 yr -1 ) and at two periods in the growing season (early, June-July vs. late, August-September). Higher crude protein (CP) [22.5% dry matter (DM)] in late vs. early season (13% DM) was associated with increased importance of protein fermentation, as suggested by higher rumen concentrations of iso-acids [3.7 ± 1.0 vs. 2.4 ± 0.9% total volatile fatty acids (VFA)]. However, rumen CH 4 production (25.8 ± 5.0 L kg -1 DMI) was not affected, probably because of compensatory seasonal changes in the chemical composition of the pasture, su0 as reduced water-soluble carbohydrates (WSC) (13.0 ± 2.6 vs. 4.9 ± 1.4% DM) or increased neutral detergent fibre (NDF) (48.5 ± 6.1 vs. 57.4 ± 4.6% DM). Although clover saponins might have a defaunation and CH 4 inhibitory effect, considerable seasonal or fertiliser-induced changes in clover proportion did not affect rumen protozoal concentrations (8.8 ± 1.6 × 10 5 mL -1 rumen contents, early season), rumen methanogenesis or microbial growth as suggested from urinary excretion of purine derivatives (6.7 ± 1.7 mmol d -1 ). In contrast, however, a clear animal effect was found: on average, one animal produced less CH 4 than the three others (20.3 vs. 27.6 L kg -1 DMI).Key words: Ryegrass, clover, N fertilisation, season, rumen, methane Mbanzamihigo, L., Fievez, V., da Costa Gomez, C., Piattoni, F., Carlier, L. et Demeyer, D. 2002. Les émissions ruminales de méthane par des moutons alimentés avec un pâturage mixte de rye grass-trèfle blanc à deux niveaux de fertilisation et au début et à la fin de l'été. Can. J. Anim. Sci. 82: 69-77. La production de CH 4 in vivo était mesurée sur 4 moutons fistulés au niveau du rumen et alimentés ad libitum avec de l'herbe fraîche en utilisant l'C 2 H 6 comme gaz traceur. Des pâturages mixtes (rye grass, Lolium perenne / trèfle blanc, Trifolium repens) à deux niveaux de fertilisation (0 vs. 150 kg N ha -1 an -1 ) ont été étudiés au début (Juin-Juillet) et à la fin (Août-Septembre) de l'été. Le pourcentage de PB plus élevé à la fin qu'au début de la saison estivale (22.5 % vs. 13 % matière sèche) était associée avec une fermentation protéique plus importante, comme le suggèrent les pourcentages plus élevés des iso-acides dans le rumen (3.7 ± 1.0 vs. 2.4 ± 0.9 % AGV totaux). Néanmoins, la production ruminale de CH 4 (25.8 ± 5.0 L kg -1 matière sèche ingérée) n'a pas changé, probablement à cause des effets compensatoires, de la diminution du taux de WSC (13.0 ± 2.6 vs. 4.9 ± 1.4 % matière sèche) ou de l'augmentation du NDF (48.5 ± 6.1 vs. 57.4 ± 4.6 % matière sèche) observées à la fin de la saison. Malgré la defaunation potent...
Inhaltsverzeichnis 1 Einleitung _____________________________________________________________________ 2 Fragestellung _________________________________________________________________ 3 Material und Methoden 3.1 Versuchsplan_________________________________________________________________ 3.2 in-vitro-Methoden 3.2.1 Fütterung der Spendertiere __________________________________________________ 3.2.2 Pansensaftentnahme _______________________________________________________ 3.2.3 Defaunierung des Pansensaftes ______________________________________________ 3.2.4 Gewinnung der Bakteriensuspension __________________________________________ 3.2.5 batch-culture-Methode ______________________________________________________ 3.2.6 Pansensimulationstechnik (RUSITEC) _________________________________________ 3.3 Analytische Methoden 3.3.1 Messung von pH-Wert und Redoxpotential _____________________________________ 3.3.2 Bestimmung der Protozoenzahl_______________________________________________ 3.3.3 Messung der Fermentationsgase _____________________________________________ 3.3.4 Messung der flüchtigen Fettsäuren ____________________________________________ 3.3.5 Berechnung der Wasserstoffwiederfindung _____________________________________ 3.3.6 13 C-Kernresonanzspektroskopie (NMR) ________________________________________ 3.4 Statistische Auswertung_____________________________________________________ 4 Versuchsergebnisse 4.1 batch-culture-Untersuchungen mit nicht defauniertem Pansensaft ___________ 4.1.1 Einfluß der Ration des Spendertieres __________________________________________ 4.1.2 Einfluß der Nüchterungsdauer des Spendertieres ________________________________ 4.1.3 Einfluß des in-vitro-Substrates ________________________________________________ 4.1.4 Einfluß der Wechselwirkungen zwischen den Faktoren Ration, Nüchterungsdauer und in-vitro-Substrat ________________________________________________________ 4.2 batch-culture-Untersuchungen mit defauniertem Pansensaft _________________ 4.2.1 Einfluß der Ration des Spendertieres __________________________________________ 4.2.2 Einfluß der Nüchterungsdauer des Spendertieres ________________________________ 4.2.3 Einfluß des in-vitro-Substrates ________________________________________________ 4.2.4 Einfluß der Wechselwirkungen zwischen den Faktoren Ration, Nüchterungsdauer und in-vitro-Substrat ________________________________________________________ 4.3 Zusammenfassung der Ergebnisse aus den batch-culture-Untersuchungen___ 4.4 in-vitro-Untersuchungen zum Nachweis der reduktiven Acetogenese mit Hilfe von 13 C-CO 2 ________________________________________________________ 4.4.1 Nachweis der reduktiven Acetogenese durch Mikroben des Schweinedarms _________ 4.4.2 Untersuchungen zum Nachweis einer reduktiven Acetogenese im Pansensaft ________ 4.4.3 Untersuchungen zum Nachweis einer reduktiven Acetogenese durch pansenstämmige Mikroorganismen aus dem RUSITEC-System ___________________________________ II 5 Diskussion 5.1 Versuchsplan und Versuchskritik ____________________________...
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