Trabue et al. (2007) suggest that ruminal metabolism of glycerol is approximately 80% after 24 h, resulting in a decreased acetate:propionate ratio (P < 0.05; Schröder and Südekum, 2007). Re- searchers in our laboratory estimate that glycerin is almost entirely converted to propionate, which would support a reduction in the acetate:propionate ratio [J. S. Drouillard and J. Heidenreich (Kansas State Univer- sity, Manhattan), unpublished data]. Previous research suggests glycerin is an effective feed source in multiple species, but limited data show the effect of glycerin on beef cattle performance and carcass characteristics.