113<i>In Situ</i> Digestive Kinetics of Four Bermudagrass Cultivars

Abstract While much effort has been devoted to both the characterization of ruminal fermentation dynamics and evaluation bermudagrass production, independently, there is a lack information regarding digestive kinetics using beef cattle in southern forage systems. Thus, objective our study was evaluate situ four (Cynodon dactylon [L.] Pers.) cultivars heifers consuming typical forages. (Coastal, Tifton 44, 85, Russell). Ruminally fistulated (n = 4) were assigned randomly one (Coastal [COS], Russell [RUS], 44 [T44], or 85 [T85]) for 30-d vivo periods (21-d adaptation 9-d collection). On d 31 2 3, an in-situ experiment conducted as randomized complete block design with 3-factor factorial treatment structure. The first factor diet consumed by animal (described above). second incubated (same experiment). third incubation timepoint 19; 0, 0.25, 0.50, 0.75, 1, 2, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144, 168 h). Four bags each at timepoint; two used NDF, ADF, ADL, CP determination. Data analyzed SAS v. 9.4. There decreased (P &amp;lt; 0.05) potentially degradable fraction from COS (30.0%) compared T85 (55.1%), T44 (48.1%), RUS (47.1%). Similarly, presented greatest undegradable (37.0%) least (15.9%), intermediate (25.0 21.9%, respectively). no effect cultivar, however, on rate constant digestion (0.94%/h; P 0.26) lag time (3.2 h; 0.38). A visual appraisal degradation curve suggests that asymptote not reached measured h. Results are interpreted mean preferable followed RUS, while favorable. Further, given visible asymptote, we speculate likely passes rumen before full realized.