DOI: 10.5285/127afd24-d2cd-457f-b837-2dd5d328f101
title: Welsh Mountain ewe urine frequency and volume data measured from tri-axial accelerometers on ewes grazing two upland pastures in North Wales

description: This dataset contains urine frequency and volume data measured from tri-axial accelerometers on Welsh mountain ewes free-grazing two contrasting upland field sites (semi-improved and unimproved pasture) in North Wales, across two seasons each (spring and autumn). 

The data, were collected using tri-axial accelerometers glued to the hind of Welsh Mountain ewes to study the urination behaviour of free-grazing sheep. Using a Boolean algorithm,  the characteristic squatting position that ewes exhibit upon urination was detected in the accelerometer data. Initially the performance of the accelerometers with sheep in urine collection pens was assessed. Data were collected  on the volume of each urination event and recorded the time of each observed urination event. This initial data was used to assess whether the accelerometers and Boolean algorithm were successful in identifying urination events, but also to ascertain whether the time spent in the squatting position would correlate with the volume of urine produced (thus allowing the technique to be able to estimate urine volume from squatting time only in subsequent field deployments).  Information on when, where and how often livestock urinate are key data to be able to assess the scale and nature of nitrogen pollution arising from grazed agroecosystems.  Urine patches deposited by grazing livestock are large sources of emissions of the greenhouse gas, nitrous oxide, due to high concentrations of nitrogen deposited over relatively small areas. 

 These data were collected in the NERC funded Uplands-N2O project (grant award: NE/M015351/1).
description: The initial study was undertaken with Welsh Mountain ewes (n=5) housed in urine collection apparatus, equipped with tri-axial accelerometers glued to their hind. The time of ewes exhibiting the urination squatting posture was recorded and the volume of each individual urine event was also recorded. The data form this trial were analysed blind with the Boolean algorithm and we recorded no records of false positive or negatives in the dataset, suggesting the technique would work well for the field deployments. We regressed the data for squat time with urine volume, and obtained a linear relationship. This linear relationship was subsequently used to estimate urine volume from squat time only in the field campaigns. 

For the field campaigns Welsh Mountain ewes (n=30) were equipped with accelerometers glued to their hinds and deployed to a semi-improved upland 11.5 ha field (240-340 m asl) at the Henfaes Research Centre (53°13′N, 4°0ʹW) in spring (12th May 2016 to 16th June 2016) and autumn (28th September 2016 to 3rd November 2016). The following year a different set of sheep (n=30) from the same flock were deployed to an area of common grazing land (495 ha) on the Carneddau mountain range (322 - 943 m asl) within the Snowdonia National Park (53°22′N, 3°95′W), Wales, UK.

Sheep were deployed in spring (31st May 2017 to 5th July 2017) and autumn (18th September 2017 to 28th October 2017) at the second study site. This resulted in a large dataset for the time, squatting duration, frequency and estimated volume of individual sheep urine events while free-grazing. Data for rainfall and temperature across the four study periods are also provided. For specific quality control procedures and further details please read the supporting documentation associated with each deposited data file.