Dried distillers grains with solubles (DDGS) are commonly used as a protein source in finishing cattle diets; however, increased availability of canola meal (CM) from biodiesel production has increased interest in CM as an alternative protein source. This study evaluated the effects of replacing DDGS with CM on nutrient and amino acid (AA) intake, flow, and digestibility. Three finishing diets were evaluated: 1) A diet that contained DDGS at 20.0% (DM basis) inclusion (CON); 2) A diet where CM replaced 50% of DDGS (CM50); 3) A diet where CM replaced 100% of DDGS (CM100). Complete replacement of DDGS with CM resulted in greater intake of arginine, lysine, tryptophan, and glycine. However, post-ruminal AA flow, apparent digestibility, or nitrogen retention were unaffected by protein source. These results indicate that despite differences in protein source, ruminal microbes compensated for the different AA profiles between DDGS and CM, thus delivering comparable metabolizable AA supplies to the animal. Finally, CM100 resulted in greater gluconeogenic precursors for ruminants. Therefore, CM can serve as an effective alternative to DDGS. Protein source selection should be based on availability and cost rather than expected differences in nutrient utilization.

Read the full article in the Journal of Animal Science.