Effects of Solvent- or Mechanically Extracted-Brassica Carinata Meal on Performance of Cows.

Brassica carinata is an oilseed that requires a relatively short growing season and allows for good yields of aviation-based fuels. Further, B. carinata contains large amounts of glucosinolates that precludes use of B. carinata as food to humans. Synthesis of aviation-based fuels from B. carinata results in residues (carinata meal) not destroyed by fuel manufacture. We placed 56 cows (beginning BW = 482.4 ± 9.5 kg) blocked by BW into 8 pens and allowed ad libitum access to either long-stem or ground cornstalks for 56 d. Subsequently, 2 cows within each pen were provided canola meal, solvent- or mechanically-extracted carinata meal daily in amounts designed to meet DIP requirements; 1 cow in each pen served as a negative control (no supplement). Intake of the daily protein supplement was complete among cows provided either solvent-extracted carinata meal and canola meal, but intake of cold-pressed carinata meal was small (14.3 ± 1.0% of daily supplement). Overall, ΔBCS was -0.6 ± 0.06 with no interaction between forage processing and supplemental protein (P > 0.37). Differences among ΔBCS in response to supplemental protein were apparent after 14 d, and overall ΔBCS was less (P < 0.01) among cows fed canola meal and solvent-extracted carinata meal compared to negative control cows; however, ΔBCS among cows fed mechanically-extracted carinata meal was similar to the negative control. Forage processing had no effect (P > 0.13) on ΔBCS. Changes in BW were apparent after 42 d. Overall ΔBW was greatest (P < 0.01) among cows fed canola meal, least among cows fed mechanically-extracted carinata meal or no protein, and solvent-extracted carinata meal was intermediate. Additionally, cows fed ground cornstalks had less ΔBW compared to cows fed long-stem cornstalks. Because glucosinolates can effect thyroid function we measured circulating T3 and T4 at the beginning, middle (d 28) and end (d 56) of our study. As expected neither T3 or T4 differed at the beginning of the experiment; however, at d 56 T3 was greater (P = 0.05) among cows fed canola meal compared to negative control and cows fed solvent- or mechanically-extracted carinata meal were intermediate. Protein supplementation had no effect on T4, but T3 and T4 were less (P < 0.04) at d 28 and d 56 among cows fed ground cornstalks compared to cows fed long-stem cornstalks. Apparently, solvent- but not mechanically-extracted carinata meal may be useful as a source of supplemental protein to cows.