Evaluation of the Effective Cowpea [Vigna unguiculata (L.) Walp] Sprouting or Roasting for Pig Feeding

Background: The study investigated the effective roasting or sprouting of cowpeas (Vigna unguiculata) based on effects on in vitro digestibility (IVDMD), supported by measurement of key chemical components and trypsin inhibitor activity (TIA). Methods: The in vitro dry matter digestibility (IVDMD) of raw and all processed cowpeas were evaluated using standard, 3-step (gastric-ileal-colon) simulation of porcine digestion, modified for micro (0.5 g) sample digestion. Standard methods were employed to track processing effects on Ash, CP, Fat, ADF, NDF and trypsin inhibitor activity (TIA) at key processing points. Result: Sprouting for 2 and 3 days significantly decreased (p less than 0.05) gastric-ileal IVDMD while increasing (p less than 0.05) colon IVDMD. Total (steps 1-3) IVDMD increased (p less than 0.05) in 2-day (0.911) and 4-day (0.902) sprouts. The 20-minute cowpea roasting to 105°C terminal grain temperature resulted in high (p less than 0.05) step 3 and total IVDMD coefficients. The lowest (p greater than 0.05) total IVDMD was recorded in 15-minute (0.883) (95°C terminal grain temperature) roasts. In both experiments 1 and 2, quantitative changes in IVDMD were consistent with the changes in the chemical components (ADF, NDF, fat, CP, minerals) and trypsin inhibitor activity. In conclusion, the compartmental and total IVDMD and quantitative change in chemical components and TIA indicated 4 days sprouting and 20-minute (105°C) roasting were respectively most effective for cowpea processing.