Can Solvent-or Mechanically-Extracted Carinata Meal Be Used as an Effective Source of Supplemental Protein to Cows Fed Poor Quality Forages?

Abstract

Brassica carinata is an oilseed crop that requires a relatively short growing season and produces high crop yields. It is a great source for aviation biofuel, however it produces a large amount of waste that may be used as a protein supplement for cattle. We tested the effects of solvent- or mechanically-extracted carinata meal as a protein supplement to ad libitum ground or long-stem corn residue (i.e., corn plant left over from grain harvest) had on cow performance and digestibility. Fifty-six non-pregnant cows in 8 pens had ad libitum access to either long-stem or ground corn residue in addition to mechanically- or solvent-extracted carinata meal, canola meal (positive control), or no supplemental protein (negative control). Overall, change in body condition score (ΔBCS) was -0.6 ± 0.06 and was not affected by forage length or supplemental protein (P = 0.37). However, change in body weight (ΔBW) was greatest (P \u3c 0.01) among cows fed canola meal, least among cows fed supplemental mechanically-extracted carinata meal or no protein, and intermediate among cows fed solvent-extracted carinata meal. Cows fed ground corn residue had less ΔBW (P \u3c 0.02) cows fed long-stem corn residue. Carinata meal has a high concentration of glucosinolates, however the value of these chemical compounds can vary from processing methods. Due to the high level of glucosinolate concentration in mechanically- and solvent-extracted carinata meal (72.34 μmol/g DM and 16.51 μmol/g DM, respectively), which can impair thyroid function and cause other negative effects, levels of T3 and T4 were tested in cows. At d 56, T3 was greater (P = 0.05) in cows fed canola meal compared to negative control cows and carinata meal was different. Protein supplement type had no effect on T4, but T3 and T4 were less (P \u3c 0.04) at d 28 and d 56 among cows fed ground corn residue compared to cows fed longstem corn residue. Total DMI was less among cows fed no supplemental protein, intermediate for cows fed mechanically- or solvent-extracted carinata meal, and a tended (P = 0.10) to be greatest among cows fed canola (positive control) meal. Furthermore, forage intake was greater (P \u3c 0.01) in cows fed long-stem corn residue compared to cows fed ground corn residue. However, measures of total-tract DM, OM, NDF, and ADF digestibility were increased (P \u3c 0.01) by more than 23% among cows fed longstem compared to ground corn residue. Carinata meal could potentially serve as a source of supplemental protein for cows as a solvent-extracted form, but apparently not mechanically-extracted