title: Acid-soluble purine and pyrimidine derivatives in cow's milk produced on normal feed and almost protein-free-feed with urea as the main nitrogen source.
abstract: In two groups of Ayrshire cows (group I normal feeding with protein, group II got mostly urea as N-source), the TCA-soluble purine and pyrimidine derivatives of the milk were determined quantitatively. The O.D. [U/I] at pH 7-5 and 260 nm was higher in group II than in group I. The difference in N-nutrition of the animals has no influence on the composition of the purine and pyrimidine fractions investigated, especially with regard to orotic acid, uric acid, and CMP. At early stages of lactation the contents of CMP and uric acid were relatively high, but decreased with longer time of lactation. In opposition to this the orotic acid content increased in the same period. These tendencies could be registered in both groups. Besides CMP, uric acid, and orotic acid the minor nucleotides, NAD, AMP, GMP, UMP and others have been determined quantitatively. Their maximum has been found at the beginning of the lactation period and, in general, their contents were higher in group II than in group I.
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle; D003597:Cytosine Nucleotides / Q000378:metabolism; D004044:Dietary Proteins; D005260:Female; D007774:Lactation; D008892:Milk / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism; D009963:Orotic Acid / Q000378:metabolism; D011247:Pregnancy; D011488:Protein Deficiency / Q000378:metabolism*; D011687:Purines / Q000378:metabolism*; D011743:Pyrimidines / Q000378:metabolism*; D014508:Urea; D014527:Uric Acid / Q000378:metabolism
chemical_list: D003597:Cytosine Nucleotides; D004044:Dietary Proteins; D009711:Nucleotides; D011687:Purines; D011743:Pyrimidines; D014527:Uric Acid; D009963:Orotic Acid; D014508:Urea