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This article in AJ

  1. Vol. 98 No. 1, p. 85-93
     
    Received: Mar 28, 2005


    * Corresponding author(s): coblentz@uark.edu
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doi:10.2134/agronj2005.0091

Nitrogen Partitioning and Estimates of Degradable Intake Protein in Wilting Orchardgrass and Bermudagrass Hays Damaged by Simulated Rainfall

  1. D. A. Scarbrougha,
  2. W. K. Coblentz *b,
  3. R. K. Ogdenb,
  4. J. E. Turnerc,
  5. J. B. Humphryb,
  6. K. P. Coffeyb,
  7. T. C. Danield,
  8. T. J. Sauere,
  9. J. A. Jenningsf and
  10. D. W. Kelloggb
  1. a Dep. of Animal Science, Univ. of Arkansas, Fayetteville, AR 72701 (current address: 126 Jessie Dunn, Northwestern Oklahoma State Univ., Alva, OK 73717)
    b Dep. of Animal Science, Univ. of Arkansas, Fayetteville, AR 72701
    c Dep. of Animal Science, Univ. of Arkansas, Fayetteville, AR 72701 (current address: North Carolina State Univ. Mountain Res. Stn., Waynesville, NC 28786)
    d Dep. of Crop, Soil, and Environmental Sciences, Univ. of Arkansas, Fayetteville, AR 72701
    e USDA-ARS, National Soil Tilth Lab., Ames, IA 50011
    f Animal Science Section, Arkansas Coop. Ext. Service, Little Rock 72203. Contribution of the Arkansas Agric. Exp. Stn

Abstract

This study investigated the effects of simulated rainfall on N partitioning and concentrations of degradable (DIP) or undegradable (UIP) intake protein for wilting orchardgrass (Dactylis glomerata L.) and bermudagrass [Cynodon dactylon (L.) Pers.] hays. Orchardgrass forage was wilted to 674, 153, or 41 g kg−1 of moisture (WET-O, IDEAL-O, and DRY-O, respectively) in the field before applying the simulated rainfall (0, 13, 25, 38, 51, 64, or 76 mm). For WET-O, DIP (g kg−1 crude protein [CP]) increased cubically (P = 0.020) with simulated rainfall, but the overall range of response was small (653–673 g kg−1 CP). Estimates of DIP (g kg−1 CP) for IDEAL-O and DRY-O decreased by 46 and 25 g kg−1 CP, respectively, between the 0- and 76-mm rainfall increments; for IDEAL-O, these decreases occurred in a linear (P < 0.0001) pattern, whereas quadratic (P = 0.009) and linear (P = 0.029) effects were observed for DRY-O. Bermudagrass forage was field wilted to 761, 400, or 130 g kg−1 of moisture (WET-B, MID-B, and IDEAL-B, respectively) and evaluated similarly. For WET-B and MID-B, DIP (g kg−1 CP) was not affected (P > 0.05) by simulated rainfall. In contrast, quartic (P = 0.019) and linear (P = 0.002) effects were observed for IDEAL-B, but these responses were confined primarily to changes between the undamaged (0-mm) control and the initial 13-mm rainfall increment. On a practical basis, concentrations of DIP were, at most, altered only moderately in response to simulated rainfall and relatively little when forages were still too wet to bale.

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