two experiments were conducted to evaluate the crude protein fractionation, in vitro gas production and the biological effects of tannins in alfalfa silage treated with different levels of pistachio by-products (pb) extract. pb was soaked in water with a ratio of 1:5 (w/v) for 12 h. after filtering and concentrating, the crude extract was added to fresh alfalfa to a final concentration of 1%, 2...