2. General Method
Location
The study site was located on a hill country farm at the Whatawhata research station, near Hamilton, New Zealand.
Behavioural Observations
Observations were undertaken in the same way for each experiment. Observations were recorded by a team of trained observers assigned to each field, one observer per field. Each observer was located in a hide on a field opposite to the study field. In the Experiment 1, cattle were observed between 8 am to 5.30 pm every second day. In Experiment 2 and 3, the cattle were observed from dawn (approximately 5.30 am) until dusk (approximately 8 pm). Two different behavioural recording schedules were used. The behaviour and location in the field of each individual was recorded every 10 minutes (10 minute scan sampling data) (due to the requirements of a separate experiment) using the behavioural categories and definitions shown in . In addition, for all cattle within 2 m of the riparian zone, the behaviour of the individuals (location and defecations) was recorded every minute. A cow was recorded as defecating when the base of the tail was raised and arched away from the body, the hind legs were placed slightly forward and apart, and the back was arched and faeces expelled.
Fields
The dimensions of the fields, and zones within the fields, were calculated using laser-range finder binoculars with azimuth and inclinometer (Leica Vector GIS, Leica, Heerburg, Switzerland). Each field was divided into four zones from top to stream (top, middle, bottom, and riparian zones). The top, middle and bottom zones were each approximately one third of the field, and were indicated by 50-cm high white stakes placed across the field. The riparian zone was defined as the area within one cow’s body length (2 metres) of the stream. A stream flowed along the valley floor of each field. The channels of the stream were approximately 2 m wide, the water width was approximately 1 m, and the depth of the water was approximately 9 cm.
Pasture Cover
In Experiments 1 and 2 a trained observer measured pasture availability, immediately before (pre-trial) and after (post-trial) the trial. Pasture was recorded as kilograms of dry matter per hectare (kg DM/ha). In Experiment 3 a trained observer measured pasture cover in each zone, before grazing of each replicate, at mid-replicate (on Day 7), and after each replicate.
Weather
Weather data were collected throughout the trial using a nearby weather station. Hourly measures included: maximum and minimum air temperature; rainfall; and relative humidity.
Experimental procedure
Experiment 1 examined the behaviour of beef cattle in the fields in each of the four seasons. Experiment 2 examined the behaviour of cattle when there was high pasture availability in the summer. In addition, both Experiments 1 and 2 examined the effect on provision of an additional water source on cattle behaviour. Experiment 3 examined the effect of specific factors in the stream environment on cattle use of the stream area (and the rest of the field). In all experiments, individuals were identified with large numbered ear tags and large numerals painted on both sides of their bodies with pink stock paint. A description of the method for each experiment will be given below.
Experiment 1
Animals
In the Autumn and Winter replicates, 30 pregnant Angus cows of mixed age were allocated at random to two groups (15 cows in each group). These animals had been together as part of a larger group of cows since calving. In the Summer and Spring replicates, 20 or 40 Angus cows of mixed age, with calves at foot, were allocated at random to either two or four groups (10 cows and 10 calves in each group), respectively.
Field Description
Four fields were used in the study, with the same aspect, and of similar size (on average 1.1 ha). The fields were paired according to size; field 1 and 2, and field 3 and 4. The slopes within each of the fields varied from 7o to 35o. The average height of the fields from the stream to the top of the hill was 150 m. The pairs of study fields were separated from each other by a field and a gully to minimise social interaction between groups. The field characteristics are summarized in Table 1.
Table 1. Size of each zone in each field
|
Field 1 |
Field 2 |
Field 3 |
Field 3 |
|
|
Zone |
Size |
Size |
Size |
Size |
|
Top |
1428 m2 |
2620 m2 |
6667 m2 |
2562 m2 |
|
Middle |
2679 m2 |
1815 m2 |
5384 m2 |
4291 m2 |
|
Bottom |
3889 m2 |
2753 m2 |
4896 m2 |
3428 m2 |
|
Riparian |
1012 m2 |
217.6 m2 |
1142 m2 |
1126 m2 |
|
Total |
8 844 m2 |
7 406 m2 |
18 089 m2 |
11 407 m2 |
Trial Design
Replicates were conducted in each season over two consecutive years, except for Spring where one trial only was conducted (Table 2). Fields 1 and 2 were used for all replicates. In addition, during one Summer replicate, and the Spring replicate, fields 3 and 4 were used. In each pair of fields, a 50 l water trough was located at the top of one field, and not in the other. Water for the troughs was pumped from a stream in the catchment supplying the stream water. The experimental design was a cross-over design. For each pair of fields, the trough was placed in one field for a particular season, and in the opposite field in the same season the following year (Table 2). Cattle resided in the fields for 6 days. On the first day of the trial, cattle were moved into the fields in the late afternoon. Observations were recorded on the 2nd, 4th and 6th day of each trial (referred to as Day 1, 2 and 3 in the results). However, in the second Autumn trial, the animals were kept in the fields for three days only, as there was not enough pasture to feed the animals for 6 days. Therefore, observations in this trial were recorded on 1st, 2nd and 3rd days of the trial.
|
Season |
Field 1 |
Field 2 |
Field 3 |
Field 4 |
|
Autumn 1 |
Trough |
No Trough |
Not Measured |
|
|
Winter 1 |
No Trough |
Trough |
Not Measured |
|
|
Spring 1 |
Not measured |
|||
|
Summer 1 |
No Trough |
Trough |
Not Measured |
|
|
Autumn 2 |
No Trough |
Trough |
Not Measured |
|
|
Winter 2 |
Trough |
No Trough |
Not Measured |
|
|
Spring 2 |
Trough |
No Trough |
Trough |
No Trough |
|
Summer 2 |
Trough |
No Trough |
Trough |
No Trough |
1 indicates the first year of the trial, and 2 indicates the second year of the trial. Trough indicates that a trough was located in the top zone.
Experiment 2
Animals
In both trials, 60 lactating Angus cows of mixed age, each with a suckling calf, were allocated at random to four groups (15 cows with calves in each group). Stocking density was maintained at a similar level as Experiment 1 (average 9.1 cow-calf pairs per ha). These animals had been together as part of a larger group of cows since calving.
Field Description
It was important that the fields had a stream at the bottom and a ridge at the top. In order to achieve this, there was some variation in field size (1.1 to 2.2 ha) (Table 3).
Table 3. Size of each zone in each field
|
Field 1 |
Field 2 |
Field 3 |
Field 4 |
|
|
Zone |
Size |
Size |
Size |
Size |
|
Top |
3611 m2 |
1391 m2 |
2947 m2 |
1629 m2 |
|
Middle |
6264 m2 |
1979 m2 |
3162 m2 |
2254 m2 |
|
Bottom |
7602 m2 |
4746 m2 |
5981 m2 |
7303 m2 |
|
Riparian |
189 m2 |
148 m2 |
176 m2 |
250 m2 |
|
Total |
1 7666 m2 |
8264 m2 |
1 3402 m2 |
1 1436 m2 |
Trial Design
The experiment was conducted in early summer (December) and late summer (March), with each period including two replicates. Each replicate comprised a pair of fields. A trough was positioned at the top of one of the fields. Cows and calves grazed the fields for six days, and observations were conducted every second day. The procedure was similar for both the early and later summer periods, except that the troughs were alternated between the pairs of fields (change over design) (Table 4).
Table 4. Experimental Design
Trough indicates that a trough was located in the top zone.
|
|
Field 1 |
Field 2 |
Field 3 |
Field 4 |
|
Early summer |
||||
|
Replicate 1 |
Trough |
No Trough |
- |
- |
|
Replicate 2 |
- |
- |
No trough |
Trough |
|
Late Summer |
||||
|
Replicate 1 |
- |
- |
Trough |
No trough |
|
Replicate 2 |
No Trough |
Trough |
- |
- |
Experiment 3
Animals
Seventy-nine Angus cows of mixed age with calves were used in the experiment. These animals had been running together as part of a large group of cows since calving. There was also a separate group of 30 first-calvers (2 year old cows who had produced their first calves) with calves who were joined to the mixed age group during the experiment. All calves were 5 months old at the beginning of the study.
Animals were allocated randomly to four fields. One group of four fields constituted one replicate. There were four replicates, conducted consecutively over the summer period January to March. The allocation of the 109 cow-calf pairs for each replicate is shown below.
Replicates 1 and 2
Four groups of 10 cows with calves were drawn at random from two groups of cattle, mixed age cows and first-calvers. The 40 animals consisted of 35 mixed age cows and 5 first-calvers with calves. Each group was placed in a separate field. One cow died in the first replicate in Field 1, and a naïve mixed-age cow with calf was added to this group.
Replicate 3
Four groups of 10 naïve cows with calves were drawn at random from the remaining group of mixed-age cows with calves. The first-calvers group was not available as the cows and calves in this group had been weaned and removed from the experiment.
Replicate 4
Four groups of 10 cows with calves were drawn at random from the five naïve cows with calves remaining in the mixed age group, and 35 mixed age cows with calves were drawn from those used in Replicate 1 and 2.
Four different fields were allocated to each replicate. An unused field and a gully separated each field from another to minimise social interactions between groups. The field characteristics are summarised in Table 5. Field size varied from 0.4 ha to 1.6 ha and the average height from the bottom to top of the field was 133 m. A single 50 l trough was located within 2 m of the stream. The animals entered the fields via gates at the top of the hills.
Table 5. Size of each zone and slope of each field in each replicate
The size and inclination of the three areas of the field used in fields 1 to 16. B + R = bottom plus riparian zones
|
Rep. 1 |
Field 1 |
Field 3 |
Field 5 |
Field 7 |
||||
|
Size m2 |
Slope (o) |
Size m2 |
Slope (o) |
Size m2 |
Slope (o) |
Size m2 |
Slope (o) |
|
|
Top |
4092 |
21 |
3906 |
24 |
2313 |
25 |
3310 |
19 |
|
Middle |
3039 |
33 |
4003 |
34 |
2525 |
36 |
1099 |
31 |
|
B + R |
2128 |
33 |
2980 |
23 |
2009 |
24 |
1606 |
37 |
|
Total |
9259 |
28 |
10889 |
27 |
6847 |
26 |
6015 |
27 |
|
Rep. 2 |
Field 2 |
Field 4 |
Field 6 |
Field 8 |
||||
|
Top |
1536 |
23 |
1317 |
25 |
1823 |
20 |
2955 |
21 |
|
Middle |
3609 |
33 |
1894 |
29 |
2423 |
32 |
2707 |
23 |
|
B + R |
3734 |
26 |
4638 |
19 |
2145 |
38 |
2244 |
32 |
|
Total |
8879 |
28 |
7849 |
23 |
6391 |
29 |
7906 |
25 |
|
Rep 3 |
Field 9 |
Field 11 |
Field 12 |
Field 13 |
||||
|
Top |
6101 |
21 |
2873 |
25 |
895 |
16 |
2670 |
25 |
|
Middle |
4987 |
19 |
2346 |
19 |
2011 |
22 |
2136 |
19 |
|
B + R |
4310 |
25 |
3205 |
19 |
5426 |
28 |
4130 |
23 |
|
Total |
15398 |
23 |
8424 |
25 |
8332 |
23 |
8332 |
23 |
|
Rep. 4 |
Field 10 |
Field 14 |
Field 15 |
Field 16 |
||||
|
Top |
5280 |
19 |
2433 |
22 |
849 |
25 |
3600 |
15 |
|
Middle |
5818 |
20 |
3456 |
28 |
1094 |
33 |
2676 |
31 |
|
B + R |
5007 |
24 |
3009 |
26 |
2060 |
30 |
2188 |
36 |
|
Total |
16105 |
22 |
8898 |
25 |
4003 |
28 |
8404 |
26 |
Treatments
Four factors were identified from the literature that may attract cattle to the riparian zone. They were: water to drink; water for cooling; shade; and forage that grows in the riparian zone. In order that Treatments could be given in a systematic manner, the following arrangements were devised.
Shade
Shade structures were erected in each field. Each structure was assembled using 6 poles (10 cm diameter) placed near the stream bank, in a rectangular shape, 6 m long by 3.6 m wide by 2.5 m high. The structures were orientated with the longest length parallel to the stream, and positioned on the flattest ground available as close as possible to the stream bank. They were situated 2 m from the stream bank edge (i.e., outside the riparian zone). Black shade cloth (80 percent shade cover) was placed on the top of the structure when shade was made available to the cows, and otherwise rolled back.
Water to Drink
In this treatment, electric fences along the stream bank prevented cattle having direct access to most of the stream. Cows were given two easy access points to the stream, up stream and down stream, where drinking areas were created using the electric fence. In these specified areas, cattle could stand on the stream bank and drink from the stream. There was enough room for a cow to place her head and front two feet in the water.
Complete Access to the Stream
When cattle were provided complete stream access, they had the opportunity to enter the stream along its length. Cows were not able to cross the stream to the opposite bank as an electric fence on the opposite bank prevented this.
Forage
Particular species of plants near the water may attract cattle to the riparian zone. Forage in and near the stream was available to be grazed during the first 4 days of a replicate. On Day 5 of each replicate forage was removed within a 2 m radius of the stream. This was achieved by intense grazing of the designated stream area. Electric fences were used to hold the experimental cattle from each field within the specified area for approximately 2 hours. This will later be referred to as forage treatment.
Design for Allocating Treatments
Each replicate was carried out over 12 days. The 12 days were divided into 2-day periods (i.e., there were 6 periods during each replicate). The Treatments were changed between 8.00 am and 10.00 am on the first day of each period. It was thought that this would give cattle time to adjust to the change prior to being observed on the second day of each period.
Stream Treatments
There were four possible Treatments in the stream area:
- A control condition, where cattle had access to the shade structure and the stream. The remaining three Treatments each had at least one factor removed.
- No shade, removal of the shade, where the shade cover was rolled back. The animals still had complete access to the stream.
- No paddle, removal of access to walking in the stream (paddling), where the animals were able only to drink from the stream, and shade in the shade structure was available.
- No stream, removal of access to the stream so animals did not have access to walking in the stream (paddling) or to drinking in the stream. Shade in the shade structure was available.
In all Treatments, a Trough was always available near the stream.
Latin Square Design
There were two phases to the design of each replicate, Phase I and Phase II. There was forage available at the stream in Phase I but not during Phase II (forage treatment).
Phase I was the first four days of the replicate (2.2-day periods). During these days forage was available in the riparian zone. The order in which the Treatments were allocated to the fields in Phase I was based on the last 2 rows of the four field by four Treatment, Latin square design (Phase II). This allowed an assessment of the effect of forage in the riparian zone on each Treatment. Phase II was carried out over the following 8 days (4 x 2-day periods). On the first day of Phase II (Day 5 of the replicate), forage was removed from the riparian zone. This allowed a test of each Treatment, without forage at the stream, in Phase II. The order in which the Treatments were allocated to the fields in Phase II was based on a 4 x 4 Latin square design. Each Treatment is donated by either A, B, C, or D (Table 6).
Table 6. Experimental design for each replicate
Phase II treatments were based on a Latin square design. Phase I treatments were the same as the last 2 rows of the Latin square of Phase II. The same procedure was followed for each replicate, although the four Treatments (A, B, C and D) were allocated in a different order across periods.
|
Period |
Field i |
Field ii |
Field iii |
Field iv |
|
|
Phase I |
1 |
C |
D |
A |
B |
|
2 |
D |
A |
B |
C |
|
|
Forage was removed in the riparian zone |
|||||
|
Phase II |
3 |
A |
B |
C |
D |
|
4 |
B |
C |
D |
A |
|
|
5 |
C |
D |
A |
B |
|
|
6 |
D |
A |
B |
C |
|
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