Investigations on the N-metabolism in lactating cattle by means of urea applied orally: XII. Utilization of urea fed for the synthesis of milk-and body protein in dairy cows

Wetzel, K.; Gebhardt, O.; Hubner, G.

Archiv für Tierernährung 16(4-5): 425-435

1966


ISSN/ISBN: 0003-942X
Accession: 024901260

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Abstract
In experiments on 2 dairy cows the levels of urea-N utilization obtained by use of a mathematical model were as follows: 19% of the amount of urea-N fed were utilized for the synthesis of lactoproteins, 56% and 59% of the quantity of urea supplied were excreted in the urine while 25% and 22% were discharged with the feces. Additionally, the levels of utilization were calculated by integration techniques (independent of the concept employed for the above-mentioned model). The percentages of urea-N utilized for the formation of milk were calculated to be 16% and 18%, the percentages excreted in the urine were 48% and 60%, the amounts of urea-N discharged in the feces were calculated to be 21% and 22%. Moreover, analyses of the experiments showed that the level of fodder-N utilization in lactoprotein synthesis was only slightly higher than that found for urea-N.