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

Abstract

Throughout much of the southeastern USA, hay harvest can be complicated by a high probability of rainfall events that may cause damage to the resultant hay crop. The objectives of this study were to investigate the effects of simulated rainfall and two postrainfall drying methods on losses of dry matter (DM) and changes in nutritive value for wilting orchardgrass ( Dactylis glomerata L.) and bermudagrass [ Cynodon dactylon (L.) Pers.] forages. Orchardgrass was wilted to moisture concentrations of 674 (WET), 153 (IDEAL), and 41 (DRY) g kg −1 and subjected to 0, 12, 25, 38, 51, 64, or 76 mm of simulated rainfall from a custom‐built rainfall simulator. For IDEAL orchardgrass, DM loss reached a maximum of 88 g kg −1 when 76 mm of simulated rainfall was applied. Dry matter loss, total N, and all fiber components except hemicellulose increased with rainfall amount, exhibiting single or multiple polynomial effects ( P ≤ 0.048) in each case; however, responses were not consistent across these response variables. A second study was conducted with bermudagrass using similar techniques, except that the forage contained 761 (WET), 400 (MID), and 130 (IDEAL) g kg −1 of moisture when simulated rainfall was applied. For IDEAL bermudagrass forage, DM losses increased in linear ( P = 0.001) and quadratic ( P = 0.003) relationships with simulated rainfall, but the maximum DM loss was only 21 g kg −1 . For both forages, DM loss and deleterious changes in nutritive value generally increased with rainfall amount, but these responses appeared to be much greater for orchardgrass.