In sacco Dry Matter and NDF Degradability of Grass Silage Harvested at Three Stages of Maturity
Abstract
The objective of this experiment was to study the effects of grass maturity at harvest on the nutritive value of grass silage in relation to chemical composition and in sacco degradability of dry matter (DM) and neutral detergent fiber (NDF). Grass sward was harvested at transition phase (P1), early reproductive phase (P2) and late reproductive (P3) growth stage of orhardgrass (Dactylis glomerata L.) as a dominant grass (70% over other grasses). Four fistulated Charolais sheep were used to measure silage DM and NDF degradability characteristics over 0, 3, 6, 12, 24, 48 and 72 h of in sacco incubation. As the crop matured, the NDF and acid detergent fiber (ADF) concentration decreased significantly (P<0.05). The DM degradability and the effective degradability significantly decreased (P<0.05) with increasing grass maturity at harvest. The effective degradability (ED) of DM and NDF was calculated considering a rumen passage rate of 4% hour-1 and the following values were found: 62.6, 51.2, 50.7 for DM and 46.9, 39.3, 38.0 for NDF, respectively. It was concluded that decreased in sacco DM and NDF degradability was a result of lower nutritive value of grass silage harvested at advanced grass maturity.
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