Do sheep access riparian zones to drink or graze?
For this weeks summary we take a look at the behaviour of sheep around water. This has been the only paper/brief communication published from New Zealand looking at this topic.
Why should we be interested in sheep accessing waterways and riparian areas?
Cattle having free access to waterways such as streams has been shown to be a cause of poor water quality, due to urination, defecation and pugging in and around the waterway. Cattle can also pug the banks of waterways and, thus, cause sediment loss. The same has not been shown for sheep and the question here is, do they even visit the waterway?
Although government-imposed regulations to fence waterways currently only applies to dairy cattle in New Zealand, it is likely that some exclusion restrictions will apply to sheep and beef in the future.
This is a concern, as there is very little research examining the behaviour of sheep around natural waterways in NZ. The paper summarised here is the first of its kind and hopefully there will be follow up research to determine if sheep have a negative impact on water quality or not.
Ewes access riparian zones to graze during the cooler months.
Having access to a water trough had no effect on the drinking behaviour of ewes.
The ewes that accessed the riparian areas did so at a similar time of day across the two-week study period.
This brief study monitored a flock of sheep for their behaviour and movements using GPS devices and motion activated trial cameras.
Video recordings were made to observe the interaction of 40 mixed-age Romney ewes with a natural waterway at Massey University’s hill-country farm Tuapaka.
Ewes were single-bearing and managed in a 1.6 ha paddock (Figure 1) that contained a discrete natural stream. The stream was 1 m wide and less than 30 cm deep. The pasture was maintained above 1000 kgDM/ha.
Ewes were offered reticulated water (week 2) in the form of a trough or were restricted from accessing the water trough (week 1). It rained lightly once each week.
The below image shows an aerial view of the paddock that the sheep were in and all the little dots are the location markers of ONE ewe over the two week period. It shows that this ewe spent little time next to the water way and most of their time on the upper flatter parts of the paddock.
This means there will likely be minimal to no urination and defecation directly into or next to the stream and a low risk for additional erosion to be caused by the sheep. This is just an indication and more research would be required to confirm this.
Riparian zones were accessed by some ewes (n=20) whose behaviours observed appeared to be influenced by time of day and environmental temperature.
The average time of day that the ewes accessed the waterway was at 2:45pm and the average temperature was 13°C when accessed.
Restricted access to the water trough had no effect on ewe drinking behaviour.
There were instances where some of the ewes did not visit the trough or stream throughout the week. This indicates that sheep could fulfil their water requirements from pasture in cooler months which has been shown in older studies (Macfarlane et al. 1958)
The average drinking water requirements for sheep have been reported as 3 L per sheep per day and during the drier months 4.5 L per sheep per day (Horizons 2007).
These water requirements are used for resource consent purposes so may be higher than actual intake.
The study summarised here confirms that sheep can fulfil their water requirements from pasture alone, as even when sheep were restricted from using the trough for a week (the drinking trough was covered) the sheep did not visit the trough.
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The graph below shows the proportion of time the ewes spent doing each activity when they were in the riparian area.
When in the riparian areas, ewes spent 68% of their time grazing, around 16% stationary, so just standing in the riparian zone and around 2% of their time drinking.
There was only ONE ewe that was observed to walk into the stream. The other ewes that drank from the stream attempted to keep their feet dry and away from the water by kneeling beside the stream to drink or standing on the bank to drink out of the stream.
For the week that the trough access was restricted, these behaviours were not significantly different from one another. Therefore, access to the water trough had no effect on the drinking behaviour of ewes.
It was concluded that, during winter, although only a small number of sheep drank from waterways, ewes accessed riparian zones to mostly graze. Showing that majority of ewes get their water requirements from grazing pasture.
The authors don't state why they completed the study in winter and not in summer when water requirements would likely be greater. However, as this study was the first in New Zealand to look at the behaviour of sheep around waterways, it was likely completed in winter to be used as a baseline or control water requirements of sheep. It would definitely be interesting to see if the behaviours change in summer.
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Bunyaga AS, Corner-Thomas RA, Burkitt LL, Draganova I, & Kenyon PR. (2020). BRIEF COMMUNICATION: The behaviour of sheep around a natural waterway. New Zealand Journal of Animal Science and Production, 80, 124-127.