Evaluating the predictive ability of a mechanistic model of nitrogen partitioning applied to lactating dairy cows consuming ryegrass-based diets

Authors

  • R.E. Vibart
  • F.Y. Li
  • I. Vogeler
  • R. Cichota

DOI:

https://doi.org/10.33584/jnzg.2013.75.2915

Abstract

The ability to understand and predict ruminant nitrogen (N) partitioning has become important as concerns over the environmental impact of pastoral agriculture increase. A mechanistic model of N partitioning from dairy cows consuming ryegrass was used to quantify the amount of N secreted in milk, urine, and faeces, and retained in body tissues. Data from lactating dairy cows (13 N balance experiments) were used to evaluate the model. Predictions for milk, urinary, faecal, and total excreta N were in agreement with observed values. Empirical models have been successful in predicting N partitioning from ruminants, but such approaches lack the underlying biological processes and may not apply to all observed values. An improved representation of the underlying mechanisms of N partitioning and the possibility of identifying areas where knowledge is lacking was achieved by the use of the current mechanistic model. Keywords: Nitrogen, milk N, urinary N, faecal N, empirical, mechanistic.

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Published

2013-01-01

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Section

Articles