Adequacy of equations used to calculate urinary nitrogen contribution to total nitrogen excreted by ruminants

Authors

  • Ronaldo Eduardo Vibart AgResearch
  • David Pacheco New Zealand Agricultural Greenhouse Gas Research Centre

DOI:

https://doi.org/10.33584/jnzg.2024.86.3695

Abstract

Nitrogen (N) concentration in the diet is the best sole predictor of the contribution of urinary N to total N in excreta. A large database was compiled containing feed and excreta variables from dairy cattle, beef cattle, sheep and deer, to evaluate the predictive ability of five linear models and four non-linear models to calculate the contribution of urinary N to total N in excreta. Species-specific linear models for beef cattle and sheep did not result in better predictions than those obtained from a generic linear model developed for all ruminant species. The predictive ability of a non-linear dairy cattle model was noticeably better than that of a linear model. The poor performance of a linear model along with a smaller number of observations from deer studies points to the merit of the construction of a new deer-specific model. This study provides support for the robustness of N partitioning towards urinary N in the animal sub-model of OverseerFM™ for a comprehensive range of diets with varying N concentration for beef cattle and sheep. In the future, the use of more sophisticated modelling approaches that involve partitioning of data for model development and evaluation may be required.

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Published

2024-10-31

How to Cite

Vibart, R. E., & Pacheco, D. (2024). Adequacy of equations used to calculate urinary nitrogen contribution to total nitrogen excreted by ruminants. Journal of New Zealand Grasslands, 86, 179–187. https://doi.org/10.33584/jnzg.2024.86.3695

Issue

Section

Vol 86 (2024)

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