Urine distribution and grazing behaviour of female sheep and cattle grazing a steep New Zealand hill pasture

Abstract

Much of the nitrogen (N) excreted by grazing animals is within highly concentrated urine patches. The N that is not used by plants is likely to be lost through leaching, emitted as N gases or added to the soil organic N pool. The present study used custom-made global positioning system (GPS) and urine sensors on 20 non-lactating ewes and 20 non-lactating beef heifers grazing steep hill country to determine potential critical source areas for N loss to the environment. Bite counters on four sheep and five heifers showed when and where animals were eating. Animals were monitored simultaneously on 0.5 ha adjacent paddocks over 8 days. Sheep and cows urinated a mean (±s.d.) of 21.2 ± 6.1 and 9.0 ± 3.0 times/day, respectively. Eating started soon after sunrise and increased during the day to reach a maximum in the hour before sunset, after which the eating activity of both species was near zero for most of the night, except for a short feeding period at around 0300 hours. The urination frequency of sheep increased as eating activity increased during the day, but this relationship was not seen in heifers. Land classified as easy hill country (≤12°) comprised 31% of the sheep paddock and contained 23% of the urination events. In contrast, although the easy hill country comprised 33% of the cattle paddock, 46% of the urine patches were in this area. Although aerial application of N mitigation products to whole paddocks or farms is uneconomic, the results of the present study suggest that mitigation products could possibly be cost-effectively targeted to easy contoured, cattle-grazed hill country areas accessible by farm vehicle.

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

“…Urine volume is mainly influenced by water intake and the mineral load ingested by the animal (Selbie et al 2015), and can be high when the moisture content of the diet is high, or when the herbage leaves are wet with rain water or dew (Doak 1952). Urine volume can also vary as a response to coping with changes in ambient temperatures (Betteridge et al 2010a). Data for sheep urine volume and frequency are scarce, but typically individual sheep urine events range between 100 and 200 mL (Doak 1952;Haynes and Williams 1993).…”

“…Daily sheep urine volume ranged from 0.5 to 3 L in Ledgard et al (2008) and the frequency of urination events has been reported to range between 13 and 20 times per day (Doak 1952;Betteridge et al 2010aBetteridge et al , 2010b.…”

A Geo-Visual Analytics Approach to Biological Shepherding: Modelling Animal Movements and Impacts

“…In the case of gathering areas for excretion by sheep and cows, there is a distinction between urination sites and defecation sites (Betteridge, 2010a). By knowing their relative areas and locations, the estimated mass of excreta can be used to support computer models for the prediction of CSAs and, therefore, nitrogen (N) emissions.…”

“…This would contribute to a mitigation strategy related to N emissions arising from grazing livestock, especially if mitigations are targeted at CSAs (Betteridge et al 2011). The N losses are mainly in the form of gaseous losses to the atmosphere and leaching into the groundwater (Betteridge et al 2010a). Farmers require information on N losses in order to reduce emissions to meet local and international N leaching and greenhouse gas target levels.…”

“…Using data from southern Hawkes Bay, New Zealand, Figure 6(a) shows a 2-D plot of urination and defecation events, normalised by time, for monitored cows in a paddock in steep hill country (Betteridge et al, 2010a;Betteridge, 2010b). A sampling grid for the 0.5 ha paddock was used based on GPS data for urine sensor output and defecation data.…”