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The appearance of re-cycled urea in the digestive tract of goats during the final third of a once daily feeding of a low-protein ration

Published online by Cambridge University Press:  09 March 2007

Y. Obara  and
K. Shimbayashi
Y. Obara
Affiliation:
National Institute of Animal Health, Yatabe, Tmkuba, Ibaraki 305, Japan
K. Shimbayashi
Affiliation:
National Institute of Animal Health, Yatabe, Tmkuba, Ibaraki 305, Japan
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Abstract

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1. An experiment was carried out with goats fed on a low-protein ration to clarify the importance of the rumen and significance of saliva in the appearance of re-cycled urea in the digestive tract during the final third of a once daily feeding regimen. The isotope-dilution method with [15N]urea and 15NH4Cl was used.

2. When the serum urea level was 58 mg N/l, the amount of urea transferred from the blood urea pool to the rumen ammonia pool was 48.6 mg N/l, which was estimated to be approximately 43% of the total amount of urea having appeared in the NH3 pool of the digestive tract. When the serum urea level was 106 mg N/l, the corresponding amount of NH3 was 77.7 mg N/h, which was estimated to be approximately 46% of this total amount.

3. The amount of saliva secreted was measured directly by the oesophageal fistula method. Salivary secretion serves as a mode of transfer of blood urea to the rumen NH3 pool. Then the ratio, salivary secretion:diffusion through the rumen wall during the final third of the cycle was calculated to be 1:4–1:6.

4. In goats fed on a low-protein diet, the rumen is an important site of appearance of blood urea in the digestive tract. It was verified that the principal mode of transfer of blood urea to the rumen was the direct diffusion through the wall of the rumen.

Information

Type
Papers on General Nutrition
Information
British Journal of Nutrition , Volume 44 , Issue 3 , November 1980 , pp. 295 - 305
Copyright
Copyright © The Nutrition Society 1980

References

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