Estimation of microbial protein flow from the rumen of sheep using microbial nucleic acid and urinary excretion of purine derivatives

alantoina allantoin biosynthese biosynthesis contenido proteico diet dieta duodenum energy content energy value intestin intestines intestinos methode methodology methods microorganisme microorganismos microorganisms nucleic acids orina ovin ovinos protein content proteine proteins purinas purine purines rumen sheep urine