| Abstrakt: |
Four spring barley cultivars (Steptoe, Colter, Lud, and Gallatin) were grown under two planting dates and two post-flowering irrigation levels to determine the source of differences in fiber composition, starch, and ruminal in situ disappearance. Planting date and irrigation level generated few differences in the chemical composition of barley grain, hull, or straw. Steptoe grain contained less (P<0.05) starch and greater (P<0.05) acid detergent fiber (ADF) and neutral detergent fiber (NDF) than other varieties, which was associated with lesser (P<0.05) in situ disappearance. Hull percentage differed (P<0.05) between all varieties and ranged from 16.3 to 19.5% of kernel DM. Steptoe had a greater percentage of hulls, and Steptoe hulls contained more (P<0.05) ADF and NDF and were less (P<0.05) degradable than hulls from other varieties. Colter, Gallatin, and Lud grain did not differ (P>0.05) in grain starch content or in situ disappearance; however, in situ disappearance of the hulls was different (P<0.05) with values of 35.2 > 33.2 > 30.5% for Colter, Gallatin, and Lud, respectively. Similar to the responses observed for grain and hulls, Steptoe straw contained greater (P<0.05) NDF, ADF, and lignin, and was less ruminally degradable (P<0.05) than other varieties. Lud had straw with lesser (P<0.05) fiber content than Gallatin straw and greater (P<0.05) ruminal DM disappearance than Colter straw; however, these differences did not appear to be associated with hull characteristics. Hull percentage and chemical composition differed among barley sources which was associated with differences in ruminal degradability. |
