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Faecal N excretion as an approach for estimating organic matter intake by free-ranging sheep and cattle

  • G. V. Kozloski (a1), E. M. C. Zilio (a1), F. Ongarato (a1), B. C. Kuinchtner (a1), A. G. Saccol (a1), T. C. M. Genro (a2), L. Oliveira (a3), B. M. Faria (a3), I. M. Cezimbra (a3) and F. L. F. Quadros (a1)...
  • Please note a correction has been issued for this article.


The current study aimed to test whether organic matter intake by free-ranging ruminants could be estimated from the amount of nitrogen (N) excreted in faeces and to compare this approach to conventional techniques. An equation describing the relationship between excreted N and nutrient intake was developed in indoor digestibility trials conducted with male sheep (n = 36) and cattle (n = 24) housed in metabolism cages and solely fed hay harvested from a local rangeland. Faecal N excretion was linearly related to organic matter (OM) intake without a significant animal species effect. To evaluate the linear equation, data from free-ranging trials conducted with sheep and cattle were used. The faecal N approach was compared with either in situ digestibility plus external marker (n = 123) or n-alkanes (n = 272) to estimate OM intake and digestible OM intake. Estimates obtained through the faecal N approach did not closely fit those obtained with either conventional technique for any variable. Averaging all individual values, the supply of metabolizable energy (ME) estimated through faecal N was similar to the required level, whereas both the in situ and n-alkanes techniques overestimated ME supply. In conclusion, OM intake by free-ranging sheep and cattle can be estimated based on the amount of N excreted in faeces with some advantages over conventional techniques: knowledge about herbage attributes is not required and it accounts for individual variability on selectivity and digestion processes.


Corresponding author

Author for correspondence: G.V. Kozloski, E-mail:


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A correction has been issued for this article: