Sheep urination frequency, volume, N excretion and chemical composition: Implications for subsequent agricultural N losses

A - Papers appearing in refereed journals

Marsden, K. A., Lush, L., Holmberg, J. A., Whelan, M. J., King, A. J., Wilson, R. P., Charteris, A. F., Cardenas, L. M., Jones, D.L. and Chadwick, D. R. 2020. Sheep urination frequency, volume, N excretion and chemical composition: Implications for subsequent agricultural N losses. Agriculture, Ecosystems & Environment. 302, p. 107073. https://doi.org/10.1016/j.agee.2020.107073

AuthorsMarsden, K. A., Lush, L., Holmberg, J. A., Whelan, M. J., King, A. J., Wilson, R. P., Charteris, A. F., Cardenas, L. M., Jones, D.L. and Chadwick, D. R.
Abstract

Ruminant urine patches are potential sites of reactive nitrogen (N) loss to the environment. Quantification of N
losses from grazed grasslands requires measurement of the frequency of urine deposition, as well as its volume
and chemical composition. However, studies to date are typically restricted to analyses of few replicate animals
and urination events, especially for sheep. Here, we present data on urine frequency, volume, chemical composition
(n=193 events from n=6 sheep) and metabolomic profile (n=4–5 events from n=4–5 sheep) from
penned sheep. Differences in urine parameters and chemical composition data were compared seasonally and
between two sites (improved and semi-improved pasture). Sheep urinated 8–11 times d−1, assuming time within
pens represented a 24 h period. The mean urine event volume recorded was 289±14 mL, from which we
estimated a daily urine production value of 2.77±0.15 L urine sheep−1 d−1. Daily urine N excretion and
individual urine N concentrations were greater from sheep in improved pasture (26.7±2.3 g N sheep−1 d−1;
7.0±0.2 g N L−1) compared to those in semi-improved pasture (16.7±1.2 g N sheep−1 d−1; 5.5±0.4 g N
L−1), but this did not equate to greater individual urine patch N loadings due to site differences in the urine-tosoil
surface area influenced (17.5 L m-2 at the semi-improved site and 8.9 L m-2 at the improved site). Urine
chemical composition varied seasonally and by site. Site- and season-specific urine should, therefore, be used in
studies assessing N losses from urine patches. Based on the urine chemical composition data, we provide an
updated artificial sheep urine ‘recipe’ which could be utilised to replicate natural sheep urine. The urine metabolomic
profile clustered according to pasture quality, while clustering according to season was less evident.
Our results provide important information for experimental and modelling studies assessing the scale and nature
of N pollution arising from sheep-grazed pastures.

KeywordsNitrogen cycle; Ruminant; Grazing; Livestock; Excreta; Metabolome
Year of Publication2020
JournalAgriculture, Ecosystems & Environment
Journal citation302, p. 107073
Digital Object Identifier (DOI)https://doi.org/10.1016/j.agee.2020.107073
Web address (URL)https://www.sciencedirect.com/science/article/pii/S0167880920302590
Open accessPublished as ‘gold’ (paid) open access
FunderNational Environmental Research Council
Funder project or codeGrazing behaviour, urine composition and soil properties are key controls of N2O emission factors in the uplands
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online21 Jul 2020
Publication process dates
Accepted01 Jul 2020
PublisherElsevier Science Bv
ISSN0167-8809

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