Ruminal fermentation, microbial protein synthesis and nitrogen balance in sheep fed pistachio by-product silage

This study was conducted to evaluate the effect of feeding several levels of pistachio by-product silage (PBS) on feed intake, nitrogen metabolism, protozoa population and purine derivative excretion in sheep. The isoenergetic and isonitrogenous diets were: 1) control (without PBS), 2) 7% PBS, 3) 14% PBS, and 4) 21% PBS. Eight rams (40±2.5 kg live weight) were used in a replicated Latin square design with four diets and four periods of 35 days each. Feeding 14% of PBS enhanced significantly (P 0.05) dry matter intake, nitrogen intake and nitrogen retention in sheep. Purine derivative excretion and microbial protein synthesis increased (P 0.05) when diets contained PBS. Ruminal pH increased and Holotrich protozoa population decreased linearly with increasing levels of PBS in the diets (P 0.05). By increasing PBS in the experimental diets, total protozoa population and Entodinium sp. changed quadratically (P 0.05). The results showed that PBS up to 14% can be used as a dietary ingredient for sheep, especially when conventional feeds are in short supply.