Executive Summary
Goal: To establish beef cattle defecation frequency and distribution on hill country in New Zealand and quantify the effects of a number of environmental factors. This information is likely to be used in a model to predict the effect of factors influencing stream water quality.
Context of the project: Livestock farming has been suggested to be one of the major causes of deterioration of riparian areas and water quality. Microbes and nutrients from manure enter streams by several potential pathways. One direct deposition from the animals as they drink, graze, or otherwise spend time in and along the stream. It has been suggested that the impact of defecation on aquatic ecosystems may be resolved by excluding stock from streams by fences. However, fencing would be economically prohibitive in the United States (Platts & Wagstaff, 1984) and in New Zealand (Bettjeman, 1997). There have been few studies on the effect of cattle defecation in streams under New Zealand farming conditions. The aims of this project were to establish beef cattle defecation frequency and distribution on hill country in New Zealand and quantify the effects of season; an alternative water source to the stream; other resources near the stream (shade); size of the field; and pasture availability.
Approach: In a study examining factors influencing the use of streams by cattle (Bagshaw, 2001),three experiments were carried out. During the course of these experiments the location and timing of defecation for each animal was recorded. The defecation data from the three experiments were amalgamated.
Outcomes:
- Beef cattle on hill country in New Zealand defecate in the riparian zone at a rate of 0.2 faeces per cow per day. Half of the faeces were deposited in the water and the other half were deposited within the 2m stream bank (demarcated as the riparian zone in this study).
- There was an indication that the number of faeces deposited by a cow in the riparian zone is related to the amount of time the individual spends in that area.
- Beef cattle in this study spent on average 4 percent of the day in the riparian zone and cows voided about 4 percent of the expected number of faeces in this time. Despite the relatively low number of faeces deposited in the riparian area, the impact may be high on water quality.
- The numbers of defecations in the riparian zone were not affected by season, the presence of a trough, other resources next to the stream, field size, or pasture availability.
- If management rather than exclusion techniques are to be used to prevent cattle from defecating in streams then we need to understand how to control animals by manipulating resources in the environment.
- Previous study by Bagshaw (2001) investigated the relative importance of resources in the riparian zone. The stream was found to be used daily and all the resources investigated were used (water to drink, water to cool, shade, and forage specific to the riparian area). The relative importance of these resources to cattle is still unclear.
- Amelioration methods to reduce the amount of faeces deposited in riparian zones could include: 1) the manipulation of the availability of the factors near the stream (such as water to drink, water for cooling, shade or forage specific to the riparian area); 2) reducing the availability of resting sites; 3) presenting combinations of attractive resources distant from the stream.
- Further studies are required to determine behavioural techniques to reduce the amount of faecal material deposited directly in riparian zones.
Publications:
Bagshaw, C.S. (2001) Factors influencing cattle (Bos Taurus) use of streams, PhD. Thesis (Psychology Department, University of Auckland).
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