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The gas-test technique as a tool for predicting the energetic value of forage plants

2001; EDP Sciences; Volume: 50; Issue: 5 Linguagem: Inglês

10.1051/animres

1627-3591

M. Chenost, Jocelyne Aufrère, Didier Machebœuf,

Bioenergy crop production and management

Seventy-nine forages of known in vivo organic matter digestibility (OMD) out of which 45 of known voluntary dry matter intake (DMI) all measured with sheep, were submitted to the in vitro gas production (GP) technique.The aim was to study the prediction accuracy (R 2 , RSD) of the nutritive value of the main components of forages that is, OMD, DMI and voluntary digestible organic matter intake (DOMI).This accuracy was compared with that obtained with the pepsin cellulase method (Cellulase).It appeared necessary to consider the forages by category (grasses or legumes and green forages or hays) in order to obtain a better accuracy in OMD prediction.The "(a + b)" value of the GP model = a + b (1-e -ct ) used to fit the data did not appropriately predict OMD, which was much better predicted from the "c" value (related to the rate of fermentation) or by Cellulase.For grass hays, the OMD was already well predicted by GP 24 h × CP (gas produced after 24 hours × crude protein content).The accuracy of digestibility prediction was improved by adding CP as a complementary variable except with lucerne hays.The relationships between DMI and gas production (at a given time or at the end of fermentation) were fair and not really improved by adding CP content.However, the accuracy of DOMI prediction was slightly better with "c" × CP than with Cellulase for green grasses and grass hays, although Cellulase was better for DOMI prediction of whole lucerne.Although the gas production technique was less efficient than Cellulase to predict OMD it is an interesting technique for predicting voluntary DOMI, that is the global nutritive value of forages.prediction / organic matter digestibility / ingestibility / in vitro gas production / Cellulase / forages / ruminant Résumé -Utilisation de la technique du gaz-test comme outil de prévision de la valeur énergétique des fourrages.L'objectif de cette étude a été de mesurer la précision de la méthode de la production de gaz (GP) in vitro pour prévoir la valeur énergétique des fourrages et de comparer celle-ci à la méthode pepsine-cellulase (Cellulase).Soixante-dix-neuf fourrages dont la digestibilité in vivo de la matière organique (OMD) était connue ont été utilisés comme substrats.Les valeurs des quantités volontairement ingérées (DMI) étaient connues pour 45 des fourrages.Les substrats étaient fermentés dans des seringues avec le fluide ruminal et la production de gaz était relevée 3, 6, 12, 24, 48, 72, 96 heures après inoculation.Il est apparu nécessaire de considérer les fourrages par catégories