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Title: EVALUATION OF DRY MATTER LOSS, NUTRITIVE VALUE, AND IN SITU DRY MATTER DISAPPEARANCE FOR WILTING ORCHARDGRASS AND BERMUDAGRASS FORAGES DAMAGED BY SIMULATED RAINFALL

Author
item SCARBROUGH, DEAN - UNIVERSITY OF ARKANSAS
item COBLENTZ, WAYNE - UNIVERSITY OF ARKANSAS
item HUMPHRY, J - UNIVERSITY OF ARKANSAS
item COFFEY, KEN - UNIVERSITY OF ARKANSAS
item DANIEL, TOMMY - UNIVERSITY OF ARKANSAS
item Sauer, Thomas
item JENNINGS, JOHN - UNIVERSITY OF ARKANSAS
item TURNER, JOHN - UNIVERSITY OF ARKANSAS
item KELLOGG, D - UNIVERSITY OF ARKANSAS

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2004
Publication Date: 4/1/2005
Citation: Scarbrough, D.A., Coblentz, W.K., Humphry, J.B., Coffey, K.P., Daniel, T.C., Sauer, T.J., Jennings, J.A., Turner, J.E., Kellogg, D.W. 2005. Evaluation of dry matter loss, nutritive value, and in situ dry matter disappearance for wilting orchardgrass and bermudagrass forages damaged by simulated rainfall. Agronomy Journal. 97:601-614.

Interpretive Summary: Grass is often cut, dried, and baled to be used as animal feed during the winter when there is not enough grass growing in pastures. Growers try to schedule grass mowing to avoid rainfall as rain slows the drying time of the cut grass and also reduces the quality of the hay as animal feed. In this study, samples of two grasses (orchardgrass and bermudagrass) were collected at different stages of drying and subjected to simulated rainfall. Samples of the forages were then analyzed to determine the effects of rainfall on hay quality. It was found that the quality of the hay was reduced with increasing amount of rainfall (up to about 3"). The decrease in hay quality was generally greater for orchardgrass than for bermudagrass and for drier than for wetter grass samples of each type. This research is important to forage growers as it shows the importance of getting hay baled and into storage before rainfall to protect the quality of the hay as animal feed.

Technical Abstract: Orchardgrass, (Dactylis glomerata L.) was wilted to moisture concentrations 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, dry matter (DM) loss, total nitrogen, and all fiber components except hemicellulose increased with rainfall amount, exhibiting significant (P ' 0.048) linear, quadratic, cubic, and/or quartic effects in each case; however, there was no consistent pattern of effects across these response variables. Excluding the 0-mm control, substantial DM loss (' 50 g kg-1) was observed at all rainfall amounts, and a maximum of 88 g kg-1 was reached when 76 mm of simulated rainfall was applied. A second study was conducted with bermudagrass [Cynodon dactylon (L.) Pers.] 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, which occurred at the 64-mm application level. For both orchardgrass and bermudagrass forages, DM loss and deleterious changes in forage nutritive value generally increased with rainfall amount. Generally, deleterious changes in nutritive value and DM loss appeared to be much greater for orchardgrass than for bermudagrass forages; in addition, these changes were greater for forages that were wilted substantially prior to applying simulated rainfall compared to forages that were subjected to simulated rainfall immediately after mowing.