Evaluation of Dry-Matter Loss, Nutritive Value, and In Situ Dry-Matter Disappearance for Wilting Orchardgrass Forages Damaged by Simulated Rainfall

摘要

'Benchmark' orchardgrass (Dactylis glomerata L.) was wilted to moisture concentrations of 61.4% (WET), 15.3% (IDEAL), and 4.1% (DRY) and subjected to 0, 0.5, 1.0, 1.5, 2.0, 2.5, or 3.0 in of simulated rainfall with a custom-built rainfall simulator. When simulated rainfall was applied to IDEAL orchardgrass, dry matter (DM) loss, total N, and all fiber components except hemicellulose increased with rainfall amount, exhibiting a significant (P < 0.048) polynomial effect or multiple effects in each case. Excluding the 0-in control, substantial DM loss (> 5.0%) was observed at all rainfall increments, and a maximum of 8.8% was reached when 3.0 in of simulated rainfall was applied. For DRY orchardgrass forage, DM losses increased to a maximum of 10.7% inlinear (P < 0.0001), quadratic (P = 0.001), and cubic (P = 0.033) patterns with rainfall amount. For WET orchardgrass forage, DM loss increased linearly (P = 0.006) with rainfall amount, but the maximum DM lost was only 1.9% for this wetter forage. Simulated rainfall affected (P <= 0.044) concentrations of N, NDF, ADF, hemicellulose, cellulose, lignin, and 48-h in situ digestibility for this wet forage, but polynomial effects were varied and the range of concentrations across rainfall amounts was generally quite narrow. Over the entire study, DM loss and deleterious changes in nutritive value were increased with simulated rainfall amount. Although not compared statistically, orchardgrass forages that were wilted substantially prior to applying simulated rainfall appeared to be more sensitive to DM loss and negative changes in nutritive value than were forages that were subjected to rainfall soon after mowing was-completed.