THE INFLUENCE OF PROTEIN LEVEL ON THE NITROGEN ABSORPTION IN THE GASTRO-INTESTINAL TRACT OF DAIRY COWS FED GRASS SILAGE FERTILIZED WITH TWO LEVELS OF NITROGEN

Increased recycling of nitrogen to the forestomachs on low nitrogen rations was found. On high CP rations the AAN at duodenum was greater than or equal to the N intake. Apparently absorbed TN in the small intestine was increased on the SBM supplemented ration. No significant difference was found for absorbed AAN fractions. Key words: Nitrogen, cattle, metabolism, gastro-intestinal tract