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 different levels of Pistachio pulp silage (PPS) on feed intake, nitrogen metabolism, protozoa population and purine derivative excretion in sheep. Experimental diets were different in amount of PPS. The compositions of diets given to the different treatments were as follow: (1) control (without PPS), (2) 7% PPS, (3) 14% PPS and (4) 21% PPS. Eight rams (40±2.5 kg) were used in a replicated Latin square design with four diets and four periods of 35 days each. Animals were fed with isocaloric and isonitrogenous diets. Feeding 14% of PPS enhanced significantly (p <0.05) dry matter intake, nitrogen intake and nitrogen retention in sheep. Purine derivatives excretion and so microbial protein synthesis increased (p <0.05) with adding PPS to experimental diets. Ruminal pH increased linearly with adding of PPS in this study. the Holotrich protozoa population decreased linearly by increasing level of PPS in diets (p <0.05). By increasing PPS in the experimental diets, total protozoa population and Entodinium sp., were changed quadratically (p <0.05). The highest number of protozoa population was related to 14% PPS in experimental diet. These results showed that PPS up to 14% can be used as proper source of feed for small ruminants to overcome the shortage of animal feedstuffs.