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Title: IN VITRO DIGESTION KINETICS OF NEUTRAL DETERGENT FIBER OF TIFTON 85 AND COASTAL BERMUDAGRASSES

Author
item MANDEBVU, P - UNIVERSITY OF GEORGIA
item WEST, J - UNIVERSITY OF GEORGIA
item Gates, Roger
item HILL, G - UNIVERSITY OF GEORGIA

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The yield potential and forage quality of Tifton 85 bermudagrass is high compared to many cultivars currently used in the southern U.S. Capitalizing on the potential of this new feed resource for ruminant livestock requires a thorough understanding of nutritional attributes. Studies were conducted to compare the rate and extent of cell wall digestion of two sources of 3-1/2 week old Tifton 85, 7 week Tifton 85, 4-week old Coastal and corn silage. Extracted cell wall (NDF) was also delignified with potassium permanganate. NDF concentration of 3-1/2 week old Tifton 85 was higher than 4-week old Coastal. Rate and extent of digestion of 3-1/2 week old Tifton 85 was greater than Coastal which was slightly higher than 7-week old Tifton 85. Delignification increased digestion rate and extent of all cell wall preparations. Delignified cell walls of 7-week old Tifton 85 were digested more rapidly than 7-week old Coastal. Although Tifton 85 is inherently high in cell wall content, this fraction is more rapidly and completely digested than comparable material derived from Coastal bermudagrass, contributing to the high forage quality of Tifton 85.

Technical Abstract: The NDF digestion kinetics of Tifton 85 harvested after 3« wk of growth (F3W), second 3« wk of regrowth (S3W) or 7 wk of growth (7W), and 4-wk old Coastal bermudagrass (CBG) were studied. NDF was extracted from the forages (F3WNDF, S3WNDF, 7WNDF, and CBGNDF), and delignified using potassium permanganate (dF3WNDF, dS3WNDF, d7WNDF, and dCBGNDF). Thus treatments were : 1) F3W, 2) S3W, 3) 7W, 4) CBG, 5) F3WNDF, 6) S3WNDF, 7) 7WNDF, 8) CBGNDF, 9) dF3WNDF, 10) dS3WNDF, 11) d7WNDF, and 12) dCBGNDF. The concentrations of ash-free NDF, ash-free ADF, and permanganate lignin (% DM) for F3W, S3W, 7W, and CBG respectively were 78.1, 77.2, 82.3, 77.6; 35.9, 35.5, 40.8, 35.0; and 4.9, 6.0, 7.0, 4.7. The IVDMD at 48 h of incubation for treatments 1-12, respectively were 63.6, 59.9, 48.7, 52.0, 61.4, 58.5, 46.0, 47.5, 68.2, 66.7, 61.3, and 60.3. Extent of NDF digestion (%) at 96 h of incubation for treatments 1-12, respectively was 74.5, 67.4, 53.7, 63.7, 75.9, 71.4, 59.3, 64.7, 73.5, 69.4, 66.0, 64.4; rate of digestion (%/h) for the potentially digestible fraction (PDF) of NDF was 4.63, 4.16, 4.19, 3.89, 5.42, 5.38, 4.79, 4.13, 5.69, 6.30, 6.06, 5.12; and lag time of digestion (h) was 1.88, 2.46, 3.13, 1.98, 1.88, 2.02, 2.75, 1.46, 1.43, 2.24, 2.08, 1.43.