Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/5/2006
Publication Date: 4/1/2007
Citation: Burns, J.C., Fisher, D.S. 2007. Dry matter intake and digestibility of coastal, tifton 44, and tifton 85 bermudagrass hays grown in the upper south. Crop Science. 47:95-810. Interpretive Summary: The bermudagrasses are the major warm-season grass that can be grown across the Southern US. In the Upper South, however, some cultivars lack acceptable winter hardiness and frequently experience stand losses. Such cultivars do not serve as reliable perennials for the region. Coastal has been grown across the region with acceptable results. Although winter injury and subsequent stand losses occur across the Upper Piedmont, Coastal recovers rapidly in the spring with stand fill in occurring by late spring. The major limitation to Coastal, however, is its modest dry matter digestibility which generally leads to only modest daily animal gains during the growing season. Both T44 and T85 were selected to have greater dry matter digestion and their apparent survival in the upper South warrants their evaluation as a stored feed. In general, Coastal hays are consumed as well or greater, whereas, dry matter digestion is inferior to either T44 or T85, and T85 is often superior to T44. The data indicate that T85 has the potential to be of greater nutritive value than either Coastal or T44 for the Upper South.
Technical Abstract: Coastal bermudagrass [Cynodon dactylon (Pers.) L.] is the major warm-season grass grown across the upper south. More recent hybrid releases of Tifton 44 (T44) and Tifton 85 (T85) offer potential of improved nutritive value. This experiment compares the dry matter intake and digestion of Coastal bermudagrass (Coastal), T44, and T85 when grown in the upper South. One preliminary and three experiments were conducted with steers comparing Coastal and T44, and two experiments comparing all three hybrids were conducted with sheep. Hays from these cultivars were grown under different soil and climate conditions and harvested at different maturities. In the comparison of Coastal and T44 with steers, dry matter intake was greater for Coastal in one of the three experiments, whereas intakes were similar in the other two. Greater intake for Coastal was associated with greater dry matter digestion and digestible intakes. In the other two experiments, T44 had greater dry matter digestion than CB in one but similar in the other. Masticates of T44, evaluated in two experiments, consistently had a greater proportion of large particles and the least proportion of small particles compared with Coastal. In one experiment, comparing a July and August hays, the masticate large, medium, and small particle-size classes of T44 had greater in-vitro dry matter disappearance than Coastal and the July hays were greater in in-vitro dry matter disappearance for each particle-size class. When harvest made in June, July, and August were compared for Coastal and T44, considerable interaction occurred between cultivar and harvest data. Comparing Coastal, T44, and T85 with sheep in two experiments showed Coastal to have greatest intake in one experiment with the other two cultivars similar, whereas all three were consumed similarly in the second experiment. Coastal was digested consistently less compared to T44 and T85 and T85 had highest dry matter digestion in one of the two experiments. The masticate of Coastal, compared with T44 and T85 had smallest particle size and least in-vitro dry matter disappearance, whereas T85 had greatest particle size and IVDMD. Coastal also had the least large particles and the most medium and small particles. Tifton 85 generally had the greatest IVDMD for all particle-size classes with T44 intermediate and Coastal least. The data indicate that any one of the three bermudagrass hybrids can be used as stored feeds for ruminants. Tifton 85 however, appears to have greater digestible fiber than either Coastal or T44 and offers the potential for greater dry matter digestion and digestible intake compared with Coastal.