Date of this Version
J. Animal Science 67:1418‑1424
Animal selectivity and digestibility differences among switchgrass strains selected for different in vitro dry matter digestibilities (IVDMD) were measured in a grazing trial with esophageally fistulated steers and a sheep digestion trial. Extrusa selected by esophageally fistulated steers grazing high-IVDMD (Trailblazer), Pathfinder and Iow-IVDMD strains of switchgrass were compared, as were top and whole plant hand-clipped samples from each strain. Trailblazer extrusa had higher (P < .1) in vitro organic matter disappearance (IVOMD) and lower (P < .1) NDF and ADF than Pathfinder extrusa. Extrusa from all three strains appeared to be of higher quality than top or whole plant hand-clipped samples. In vitro organic matter disappearance tended to be highest for Trailblazer top hand-clipped samples. Composition of hand-clipped samples among strains was not significantly different. Mature crossbred wethers were used to compare Trailblazer and P ~ switchgrass hay in a digestion trial. No differences (P > .1) were detected between slrains for DMI or apparent digestibility of DM, NDF, ADF and CP. Extrusa from Trailblazer switchgrass that had been selected for whole plant IVDMD had higher IVOMD; however, there was no indication that steers selected a differentially higher IVOMD for one strain than another.