Brassica carinata is a newly developed oilseed for bio-fuel production in Canada. The bio-fuel processing results in a large amount of co-products (carinata meal), which could potentially be utilized as a protein source for animal feed. However, there is little research on metabolizable protein characteristics of carinata meal for dairy cattle. The objectives of this study were to determine differences among carinata meal, extruded carinata meal and canola meal for dairy cattle in terms of (1) rumen protein degradation, (2) intestinal digestion of protein, (3) total truly digestible protein supply, and (4) feed milk value. The animal trial was carried out in University of Saskatchewan dairy research facility. Statistical analyses were performed using PROC MIXED procedure of SAS 9.3 with significance declared at P ≤ 0.05. The results indicated that extruded carinata meal had higher rumen degraded protein than canola meal (P ≤ 0.05). Intestinal digestible protein was the highest in canola meal but the lowest in extruded carinata meal (P < 0.0001), while total digestible protein was the highest in extruded carinata meal but the lowest in canola meal (P < 0.0001). Extruded carinata meal had the most truly absorbed rumen-synthesized microbial protein in the intestine and degraded protein balance, but had the least truly absorbed rumen undegraded feed protein and truly digested protein in the small intestine (P ≤ 0.05). The canola meal was the highest in truly absorbed rumen undegraded feed protein in the small intestine but the lowest in truly absorbed rumen-synthesized microbial protein in the intestine and degraded protein balance (P ≤ 0.05). Feed milk values had no significant difference in carinata meal and canola meal using the Dutch DVE/OEB model. In NRC model, canola meal was the highest in FMV. The results indicated that carinata meal could be used as a potential protein supplement. Extrusion processing seems to have a negative effect on protein utilization and production in dairy cattle.