Efecto de la composición botánica de los henos y del nivel de ingestión sobre su digestibilidad y ritmo de paso a través del tracto digestivo

Zusammenfassung

Sixteen mature ewes were used to investigate the effects of type of hay and level of intake on digestibility and rate of passage. Two levels of intake -maintenance (NB) and 90% of the "ad libitum" intake (NA)- and two hays -alfalfa hay (HA) and grass hay (HG)- were compared. Chromium-mordanted hay (ground through a 2 mm. screen) was used as marker. Apparent digestibility coefficients for organic matter (DMO) and neutral (DFND) and acid detergent fibre (DFAD) were not affected (P > 0.05) by level of intake. DFND and DFAD were higher (P < 0.05) for sheep fed grass hay than for those fed alfalfa hay. Digestibility of crude protein (DPB) was greater (P < 0.05) for sheep fed alfalfa hay than for those fed grass hay. The retention time of marker in the reticulo-rumen was lower (P < 0.05) for the higher level of intake (NA), but the retention time in the post-ruminal tract was essentially identical for both levels (NA and NB). A tendency (P < 0,10) for a greater total mean retention time of marker (TMRT) in the digestive tract (47,14 and 56,48 h. for the NA and NB level intake) was found.