Portal de Periódicos da CAPES

Effect of wilting and ensiling on ruminal degradability of temperate grass and legume mixtures

2005; EDP Sciences; Volume: 54; Issue: 2 Linguagem: Francês

10.1051/animres

1627-3591

José Luis Repetto, Cecilia Cajarville, Jorge D’Alessandro, A. Curbelo, C. Soto, Daniel Garín,

Botanical Research and Chemistry

Changes in chemical nitrogen fractions and ruminal degradability of wilted and ensiled temperate forages were studied.Seven cultivated pastures from Uruguayan farms were sampled for their study in each of the following silage-making steps: fresh forage (F), wilted forage (W), and silage (S).Samples were analysed for crude protein (CP), soluble protein in buffer phosphate (SP), and neutral and acid detergent insoluble nitrogen (NDIN and ADIN).The degradability of dry matter (DM) and nitrogen (N) were measured in situ in three cows, and the effective degradability (ED) was calculated using outflow rumen rates of 3 and 6% per h (ED03 and ED06).Wilting reduced both ED06 of DM (F = 56.29%,W = 54.25%;P = 0.033) and N (F = 71.65%,W = 68.03%;P < 0.001).However, wilting did not produce significant changes in the chemical fractions.Forage fermentation produced an increase in SP (Average value of fresh and wilted forages (F + W) = 27.35%,S = 44.25% of CP; P < 0.001) and ADIN (F + W = 9.90%, S = 13.56% of CP; P = 0.014).Ensiling increased the soluble fraction (a) (F + W = 43.15%,S = 59.68%;P < 0.001), the undegradable fraction (u) (F + W = 16.52%,S = 18.45%;P = 0.007) and decreased the non-soluble degradable fraction (b) (F + W = 40.34%,S = 21.87%;P < 0.001) of N. Thus, fermentation produced significant changes in the chemical N fractions and ruminal degradability of DM and N in temperate regions, while wilting affected only the latter.forage / wilting / fermentation / silage / rumen degradability Résumé -Effect du préfanage et de l'ensilage sur la dégradabilité ruminale des fourrages de prairies tempérées.Les variations des paramètres de la dégradation ruminale de la matière sèche (DM) et de l'azote ont été étudiées sur le fourrage vert sur pied (F), préfané (W) et ensilé (S).Ces fourrages provenaient de sept prairies tempérées en Uruguay.Les teneurs en matières azotées totales (CP), en azote soluble (SP) et en azote lié aux parois végétales (NDIN et ADIN) ont été déterminées.Les dégradabilités ruminales de la DM et de l'azote (N) ont été déterminées par la méthode in situ sur 3 vaches et la dégradabilité théorique (ED) a été calculée en utilisant un taux de sortie des particules du rumen, respectivement, de 3 et 6 % par h (ED03 et ED06).Le préfanage a entraîné une