Scientific Study

Background: The industrial de-hulling of fresh pistachio generates a large quantity of pistachio by-products (PBP). This study was carried out to investigate the effects of treating soybean meal (SBM) and canola meal (CM) with tannin extracts derived from PBP on the protein fractions according to Cornell Net Carbohydrates and Protein System (CNCPS), rumen degradability and ruminal and post-ruminal crude protein (CP) disappearance in an in situ trials using 3 fistulated steers. The extracts of PBP were obtained via different solvents and then added to SBM and CM, so that the final concentrations of added tannins were 0, 5 and 10 g kg-1 dry matter basis. Results: The CNCPS soluble proteins (fractions A + B1 ) of CP and B1 fraction of CP were lower (P < 0.01) in SBM and CM treated with PBP extracts than untreated meals. Treating SBM with different PBP extracts (except 5 g kg-1 tannin water extract) and CM with 5 g kg-1 tannin water extract and 10 g kg-1 tannin ethanol extract decreased (P < 0.01) ruminal disappearance of CP. From the in situ results, the rapidly degradable fraction (a) of CP decreased (P < 0.01) by treating SBM with different PBP extracts and CM with 5 and 10 g kg-1 tannin water extracts; whereas the slowly degradable fraction (b) of CP remained unchanged in SBM. Treatment of SBM and CM with PBP extracts decreased (P < 0.01) the effective degradability of crude protein (EDCP) estimated with different outflow rates. Conclusion: Some of the tannin extracts derived from PBP by water, ethanol and methanol could be effective on protein protection of SBM and CM from degradation in the rumen; however, the use of tannin from water extracts can be more economical and practical.