Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/1998
Publication Date: N/A
Interpretive Summary: Dairy producers in the lower South depend heavily on imported forages, primarily alfalfa, as a source of high quality fiber. Use of regionally adapted, locally grown forages, such as bermudagrass, could substantially reduce costs of dairy cattle feeding. Research was conducted to evaluate the fiber digestion of Tifton 85 bermudagrass, harvested after 3 1/2 or 7 weeks of regrowth, as a portion of a total mixed ration. Corn silage served as a standard for comparison. Both rate and extent of digestion of Tifton 85 fiber was greater than corn silage fiber. However, digestion of immature bermudagrass was much more favorable. Results demonstrate the feasibility of including high quality Tifton 85 bermudagrass in total mixed rations for high producing dairy cows.
Technical Abstract: Total mixed rations based on corn silage, Tifton 85 (T85) bermudagrass hay harvested at 3.5 wk and 7 wk of growth and with low or high NDF were used to study the effects of hay maturity, forage source, or level of dietary NDF on in situ digestion kinetics for TMRs. Among hays and corn silage, NDF and lignin concentrations decreased in the order of: T85 bermudagrass harvested at 7 wk of growth, T85 bermudagrass harvested at 3.5 wk of growth, T85 harvested at 3.5 wk of growth, and corn silage, which in vitro and in situ DM digestion showed the opposite trend. The extent of in situ NDF digestion decreased in the order or: T85 bermuda harvested at 3.5 wk of growth, T85 bermuda harvested at 7 wk of growth and corn silage (42.5%). Increase in bermuda maturity decreased in vitro NDF disappearance for TMRs at 48 hr of incubation from 44.7 to 38.8%. Forage source or level of dietary NDF had no effect on extent of in situ DM digestion for TMRs. Increase in bermuda maturity decreased the extent of in situ digestion of DM and NDF respectively for TMRs by 3 and 9%. After fitting the nonlinear model to the disappearance data, the TMR in which corn silage was used as the forage source had higher readily digestible fraction of DM than T85 based TMRs. Digestion profiles for 3.5 wk bermuda based TMRs were similar to those for corn silage based TMR.