4. Results

Numbers of defecations in the riparian zone

Random Effects

There were no random sources of variation. Daily defecations per cow supported a common Gamma distributed variation for each of the following (1) in the water, (2) on the bank and (3) in the riparian zone (in the water plus on the bank). Each Gamma distribution had a coefficient of variation close to 100 percent, which was compatible with an exponential distribution. The total numbers of defecations for each mob each day in the riparian zone (in the water plus on the bank) can be modelled (within short grazings) as a Poisson variate. In this case the average is based on a number per cow per day arising independently for each mob from the same exponential distribution.

Fixed Effects

The numbers of defecations deposited in the water, on the bank or in the riparian zone (in stream plus on bank) per cow per day were not significantly effected by Season, Trough, Shade, or Field.

The average number of defecations per cow per day in the water, on the bank and in the riparian zone are shown in Table 7.

Table 7. Average number of defecations per cow per day

	Average per cow per day
Defecations in the water	0.11
Defecations on the bank	0.09
Defecations in the riparian zone	0.2

Since the number of hours cattle were observed each day varied between experiments (from 9 to 16 hours) the average number of defecations was analysed per hour. Within this measure, the average number of defecations per cow per hour in the water, on the bank and in the riparian zone were also not significantly effected by Season, Trough, or Shade.

The average number of defecations per cow per hour in the water, on the bank and in the riparian zone are shown in Table 8.

Table 8. Average number of defecations per cow per hour

	Average per cow per hour
Defecations in the water	0.009
Defecations on the bank	0.007
Defecations in the riparian zone	0.016

Pasture Availability

There was no effect of pasture in the riparian zone on the numbers of defecations in the riparian zone.

Time Spent in the Riparian Zone

Cattle spent on average 4 percent of their day in the riparian zone Table 9. The amount of time spent in the riparian zone varied across experiments from 1.5 to 6.7 percent.

Table 9. The average proportion of time spent in the riparian zone across three Experiments

	Average number of minutes in the riparian zone (mins/cow/day)	Average number of minutes observed (min)	Percent of time spent in the riparian zone (% per cow per day)
Experiment 1	8.3	540	1.5
Experiment 2	25.3	600	4.2
Experiment 3	57	840	6.7
Average time across studies spent in the riparian zone			4.1

Percent of total defecations in the riparian zone

Random Effects

There were no random sources of variation.

Fixed Effects

The percent of total defecations in the water, on the bank or in the riparian zone (in water plus on bank) were not significantly effected by Season, Trough, or Shade (Table 10).

Table 10. The average percentage of cattle defecation in the water, on the bank, and in the riparian zone (in water plus on the bank)

	Average percentage
Defecations in the water	8.3
Defecations on the bank	6.3
Defecations in the riparian zone	14.6

Numbers of defecations in the whole field

Random Effects

There were no random sources of variation. The observed daily defecations per cow supported a Gamma distribution.

Fixed Effects

The total numbers of defecations in the field was not significantly effected by Trough, or Shade.

Season

There were significantly more total defecations in the field during the Summer and Autumn compared to Winter and Spring, which arose independently each day for each group of cows in a particular field (mob).

There was variations in the length of time animals were observed each day between seasons, therefore the numbers of defecations in the whole field were analysed per hour. However, the length of time animals were observed did not account for the significant difference in the numbers of defecations between seasons.

The average total number of defecations per cow per day was 1.2 and the average total number of defecations per cow per hour was 0.1.