The behaviour of sheep around a hill country stream and impacts on freshwater quality : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science, School of Agriculture and Environment, Massey University, Palmerston North
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Date
2021
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Massey University
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Abstract
Recent amendments by the New Zealand Government to the Resource Management Act (RMA) regulations proposed that fencing and a 3m setback were required for streams more than 1 m wide and the exclusion of farmed cattle, deer and pigs from these waterways (Ministry for the Environment, 2020). Currently, sheep are not required to be excluded from waterways. Furthermore, there is no literature on the behaviour of sheep in New Zealand around hill country streams or their impacts on water quality. During the Summer of 2021 (February), a crossover design trial was conducted with forty mixed aged ewes in a hill country paddock transected by a fifth order stream on Massey University’s Tuapaka farm. During the study, ewes had access to a trough for the first week and did not have access to the trough on the second week. Ewes were monitored using motion activated cameras, accelerometers attached to a halter, and GPS units attached to a collar. Water sampling was conducted for two days of each week during each treatment and analysed for suspended sediment, total phosphorus, dissolved phosphorus, total nitrogen, ammonia, nitrate, and E. Coli. The results from the summer trial showed that the behaviour of sheep around the stream was not influenced by the availability of a drinking trough. When sheep had no access to the trough, however, they spent more time within areas of the stream that were easy to access and were observed to drink from the stream. Total phosphorus concentration was lower in the first week (unrestricted access to the trough, p = 0.020) were as suspended sediment, total nitrogen, and E. Coli loads (p = 0.0002, 0.0374 and 0.029 respectively) were higher compared to the second week (restricted access to the trough). There were no recorded instances were sheep defecated into the stream and two occurrences of urination near the stream. This study suggests that sheep had a minimal influence on water quality and any effects were likely due to rainfall events. A follow-up trial following the same methodology was conducted in Autumn (April) within the same paddock and with the same sheep. The behaviour of sheep around the stream during Autumn was not influenced by the availability of a drinking trough. Access to the trough had an inconsequential impact on the behaviour of the ewes within the stream zone. It is probable that the moisture content of the pasture was sufficient to satisfy the water requirements of the sheep during the trial and negated the need to drink from the stream. Indicators of water quality were elevated during and immediately after rainfall events and highlights the sediment loss that can occur from a grazed pasture during a rainfall event. There was no association between sheep activity and a decline in water quality. Suspended sediment loads were greater when during the first week (restricted trough access, p = 0.002) whereas total nitrogen, total phosphorus and E. Coli loads did not differ between treatments (p = 0.629, 0.989 and 0.528 respectively) There were no recorded instances were sheep defecated into the stream. These experiments showed that sheep interaction with a natural waterway during summer and autumn on a Manawatu Hill country farm had an insignificant influence on the water quality metrics measured. Therefore, it is unlikely that excluding sheep from accessing natural waterways would result in improvements to water quality.