The Journal of Agricultural Science

Research Article

Fractionation of nitrogen isotopes by animals: a further complication to the use of variations in the natural abundance of 15N for tracer studies

K. W. Steelea1 p1 and R. M. Daniela1

a1 University of Waikato, Hamilton, New Zealand

SUMMARY

A study of the fractionation of nitrogen isotopes in the diet by cattle is described and the results discussed.

Compared with the diet, urine had a lower ratio of 15N to 14N, but faeces, blood and milk all had a higher ratio.

It is argued that the use of natural 15N as a tracer in grazed ecosystems is more complicated than was at first thought.

(Received May 03 1977)

Correspondence:

p1 Present address: Kuakura Agricultural Research Centre, Private Bag, Hamilton, New Zealand.

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