In vitro digestion kinetics of neutral detergent fiber extracted from Tifton 85 and Coastal bermudagrasses

Hays used to compare the digestion kinetics of neutral detergent fiber (NDF) were Tifton 85 bermudagrass (T85) harvested after 3.5 or 7 weeks of growth, a second cutting of T85 harvested after 3.5 weeks of regrowth, and Coastal bermudagrass (CBG) harvested after 4 weeks of growth. Neutral detergent fiber extracted from the hays was exposed to in vitro digestion and the digesta analyzed for their NDF content. The in vitro dry matter disappearance for the first (63.6%) and second (59.9%) cutting of 3.5-weeks old T85 was similar but higher than that for T85 harvested after 7 weeks of growth (48.7%) or CBG harvested after 4 weeks of growth (52.0%). In vitro NDF digestion at 72 h of incubation for T85 harvested at 3.5 week (74.5%) was similar to that of 3.5-weeks T85 regrowth (67.4%), but higher than that of CBG (63.7%) or 7-weeks T85 (53.7%). After fitting a nonlinear model to the data, T85 harvested at 3.5 week had a higher (P<0.05) potentially digestible fraction of NDF. Extraction of NDF from the hays increased the potentially digestible fraction of NDF. In summary, Tifton 85 bermudagrass harvested at 3.5 week had a higher NDF concentration, and higher NDF digestion than did Coastal bermudagrass harvested at 4 week.