مقایسه دفع مشتقات پورینی و سنتز پروتیین میکروبی در گوساله های نر نژاد سیستانی و هلشتاین

Background: purine derivatives can be used for measuring of microbial protein synthesized in the rumen. objectives: the aim of research was compare of purine derivatives excretion and microbial protein synthesis in two breeds of sistani and holstein. methods: the rations were prepared in a completely randomized design in maintenance level and were fed to animals in 2 breeds that each composed of 7 calves as replicate. the urine was collected with spot sampling method to measure of purine derivatives for 10 days and 5 times every day. the blood samples was prepared for measuring of blood parameters (glucose, triglycerides and blood urea nitrogen) in all of calves of two breeds from jugular vein too. results: results showed the amount of microbial protein synthesis in sistani calves was 42.87mmol/day that was more significantly than holstein calves (16.38 mmol/day) (p < 0.01). the amount of allantoin and uric acid in both breeds was not significantly different. the concentration of glucose, nitrogen of blood urea nitrogen and triglycerides was significantly different in both breeds (p < 0.01). the amount of glucose, nitrogen of urea blood and triglyceride was more in the sistani breed compare to holstein breed (respectively 77.4, 23.07 and 36.57 mg/dl in sistani breed and 67.51, 16.27 and 24.42 mg/dl in holstein breed). conclusions: generally, the results of this experiment showed that efficiency of microbial protein synthesis in sistani breed was more significantly than holstein breed with feeding the equal ration.