124 H
.A.M. Spoolder et al. Livestock Production Science 63 2000 121 –129
2.3.2. Skin damage housing system. Tukey’s HSD was used for pair-
Skin damage was assessed on focal animals on the wise comparison of the means of the treatments
day before each of the two mixing moving treat- Minitab, 1993. Strong tendencies 0.05
, P , ments were applied, on the day after mixing, at day 7
0.10 have also been indicated in the tables. after Mix 1 and on day 5 after Mix 2. The assess-
ment consisted of a count of the number of skin lesions bruises, scratches and wounds per area:
3. Results
front from snout to middle of back, rear from middle of back to tail and tail. Skin damage was
3.1. Behaviour recorded using the Husky Hunter16 portable com-
puter. The frequency and average duration of a number
of behavioural parameters were higher in groups 2.3.3. Performance
which were mixed and moved, compared to groups All pigs on the experiment were weighed on entry
which were only moved Table 3. However, during to the treatments, at Mix 1, two weeks after Mix 1, at
Mix 1 the incidence of minor aggressive interactions Mix 2 approximately one week before slaughter
such as knocks and threats were higher in the groups and at slaughter. A record was kept of all food added
which were moved only, compared to groups which to the single space hoppers in both buildings to give
were mixed as well as moved. total food consumption of the group. From these data
There was some indication that the intensity of the the food conversion ratio FCR, the voluntary food
aggressive interactions was greater during Mix 1 intake VFI, as well as average daily live weight
compared with Mix 2. During Mix 1 there was a gain DLWG could be calculated.
higher frequency of one-sided fights across all four treatments Mix 1 vs. Mix 2: 0.600 vs. 0.198;
2.4. Statistical analyses F
5 6.81; P 5 0.010, and a higher frequency of
1,182
knocks threats Mix 1 vs. Mix 2: 12.53 vs. 8.41; For the analysis of the behavioural data, the four
F 5 7.72; P 5 0.006 compared to Mix 2.
1,182
randomly chosen focal pigs were the experimental Prior mixing experience did not appear to affect
units, with a correction for group effects in the the aggressive behaviour of pigs during the 2 h
analyses of variance through blocking Genstat 5 following a subsequent mix. The only indication that
Committee, 1987. The performance data were ana- mixing at 55 kg may have had an effect on behaviour
lysed for each separate time period in between during mixing at 75 kg was found in the frequency
weighings, and across the whole of the finishing of biting: move at Mix 1 vs. moving
1 mixing at period. As experimental unit the pen was used when
Mix 1: 3.2 vs. 4.8 bites at Mix 2, respectively; comparing within time periods or the individual
F 5 3.3; P 5 0.073.
1,88
when comparing across the whole finishing period, The behaviour of the pigs was affected by the
as pen composition changed as a consequence of layout of the pen Table 4. However, the effects of
most treatments. Transformations were used where housing system on aggression immediately post-mix-
data did not meet the requirements of the analysis of ing was not the same during Mix 1 and Mix 2.
variance in the following order: angular, square root During Mix 1, the incidence of aggressive interac-
and logarithmic transformation. Data which could tions and the duration of fights appeared to be lower
not be normalised, were analysed using non-paramet- in the K compared with the S treatment. Further-
ric techniques. The two treatment factors were more, the average duration of one-sided fights was
mixing treatment and housing system. There were no longer in K pens. The frequency of aggression after
blocking factors. Interactive effects of mixing treat- the second Mix was greater in the K pens, although
ment at 55 kg and mixing just before slaughter were the average duration of two-sided fights was still
tested for by using Mix 1 at 55 kg and Mix 2 at longer in the S pens Table 4.
one week before slaughter as treatment factors. The percentage of aggressive interactions which
These effects were tested for separately for each resulted in a change of location i.e., a move from
H .A.M. Spoolder et al. Livestock Production Science 63 2000 121 –129
125 Table 3
Levels of aggression per focal pig, per 2-h observation period and general activity in groups of finishers which were mixed and moved, compared to pigs which were only moved
Behaviour Treatment
Move Mix
1 move P-value
a a
Mean 95 C.I.
Mean 95 C.I.
Mix 1
Knock threat freq. 17.1
12.3–22.7 8.7
6.7–10.9 , 0.001
Biting freq. 4.2
2.7–6.1 5.8
4.6–7.1 NS
One-sided fights freq. 1.5
0.8–2.5 3.2
1.8–5.1 0.030
Two-sided fights freq. 2.5
1.5–3.8 2.7
1.4–4.5 NS
b
One-sided fights av. duration 16.3
10.9–22.8 14.4
10.0–19.6 NS
b
Two-sided fights av. duration 20.0
7.3–54.9 27.6
19.8–38.4 0.094
b
Inactivity duration 2887.0
2437–3337 3646.0
3268–4023 0.007
c
Mix 2
Knock threat freq. 9.3
7.2–11.6 7.5
5.2–10.2 NS
Biting freq. 2.0
1.3–2.9 6.5
4.8–8.4 , 0.001
One-sided fights freq. 0.1
0.09–0.14 0.6
0.4–0.9 , 0.001
Two-sided fights freq. 0.1
0.08–0.14 3.7
2.6–5.3 , 0.001
b
One-sided fights av. duration 14.8
7.6–24.4 14.1
10.4–18.4 NS
b
Two-sided fights av. duration 18.0
12.7–25.6 27.1
19.1–38.4 0.060
b
Inactivity duration 3343.0
2882–3803 3374.0
2975–3772 NS
a
As most variables had to be transformed prior to analysis, standard errors could not be calculated. The back transformed 95 confidence interval is therefore presented here.
b
All durations are in seconds.
c
Please note that at Mix 2 half the groups which were ‘‘mixed and moved’’, had only been ‘‘moved’’ at Mix 1 i.e., treatment B groups. Conversely, half the groups which were ‘‘moved’’ at Mix 2 had been ‘‘mixed and moved’’ at Mix 1 treatment A groups.
the kennel into the dunging area or vice versa was kg appeared to have less skin damage immediately
higher immediately after pigs had been mixed and after mixing at 75 kg day 1 after Mix 2: 15.2 vs.
moved compared with pigs which had only been 22.9 lesions per pig for mixing
1 moving at Mix 1 moved e.g., one-sided fights: 10.0 vs. 32.5 for
vs. moving only at Mix 1; F 5 9.99; P 5 0.004.
1,90
moved vs. mixed 1 moved respectively; F
5 13.9; This effect had disappeared five days after the
1,36
P , 0.001; Table 5. Differences in this parameter
second mix. The effects of treatments on changes in between the two housing systems were not signifi-
skin lesion scores are presented in Table 6. cant e.g., one-sided fights: 26.3 vs. 16.2 for K vs.
The increase in skin lesions differed between the S, respectively; F
5 2.83; P 5 0.101.
two housing systems. After Mix 1, K pigs had a
1,36
higher increase in skin lesions between day 2 1 and
3.2. Skin damage day 7 than S pigs. After Mix 2 this was reversed,
with S pigs showing a greater increase in lesions There was a significant effect of the mixing
between days 2 1 and 1, as well as between days
treatment at Mix 1 on the level of skin lesions after 2 1 and 5 Table 7.
Mix 1 e.g., day 1 after Mix 1: 20.3 vs. 12.7 lesions Aggressive behaviour during the first 2 h after Mix
per pig for mixing 1 moving vs. moving only;
1 was not related to the increase in skin lesions F
5 11.13; P 5 0.001. Similarly, mixing and measured on day 1 after Mix 1, nor was it associated
1,92
moving as opposed to moving only at Mix 2 with changes measured at day 7. Following Mix 2
resulted in a higher number of skin lesions after Mix there was a high degree of correlation between the
2. A significant effect of Mix 1 was found on skin increases in skin damage from day
2 1 to day 1 and lesions after Mix 2: pigs which had been mixed at 55
the total duration and frequency of two-sided fights
126 H
.A.M. Spoolder et al. Livestock Production Science 63 2000 121 –129 Table 4
Effects of housing system on duration in seconds and frequency of aggressive behaviours per focal pig during the first 2 h after mixing Behaviour
Building Kennelled
Sloping floor P-value
a a
Mean 95 C.I.
Mean 95 C.I.
Mix 1
Knock threat freq. 10.6
8.3–13.2 15.9
10.9–21.8 0.059
Biting freq. 5.9
4.4–7.4 7.0
5.1–8.9 NS
One-sided fights freq. 2.2
1.3–3.4 2.3
1.3–3.6 NS
Two-sided fights freq. 1.4
0.8–2.2 4.5
2.9–6.4 , 0.001
b
One-sided fights av. duration 12.0
7.9–16.9 19.5
11.8–29.2 0.003
b
Two-sided fights av. duration 3.0
1.1–8.5 3.3
1.4–7.6 NS
b
Inactivity duration 3154.0
2766–3541 3402.0
2901–3902 NS
Mix 2
Knock threat freq. 12.3
9.3–15.8 5.3
4.2–6.5 , 0.001
Biting freq. 3.9
2.8–5.2 4.0
2.6–5.8 NS
One-sided fights freq. 0.3
0.1–0.7 0.1
0.0–0.2 0.092
Two-sided fights freq. 1.1
0.5–2.3 0.4
0.2–1.0 0.053
b
One-sided fights av. duration 15.6
10.7–21.5 12.9
8.5–18.2 NS
b
Two-sided fights av. duration 16.6
11.8–23.5 36.5
26.2–50.8 , 0.001
b
Inactivity duration 3400.0
2986–3813 3273.0
2819–3726 NS
a
As most variables had to be transformed prior to analysis, standard errors could not be calculated. The back transformed 95 confidence interval is therefore presented here.
b
All durations are in seconds. Table 5
Percentage of interactions which resulted in a change of location lying area vs. dunging area for one or both of the animals involved Behaviour
Building Kennelled
Sloping floor P-value
Moved Mixed
Moved Mixed
S.E.D. Housing
Mixed Interact.
a
Knock threat 0.16
0.41 0.15
0.20 –
NS NS
NS
a
Biting 0.09
0.45 0.03
0.79 –
NS 0.009
NS One-sided fights
17.0 35.7
3.0 29.3
8.6 NS
, 0.001 NS
Two-sided fights 13.4
32.0 11.1
42.1 5.5
NS , 0.001
NS
a e
An log transformation had to be used prior to data analysis. Means are back transformed values. S.E.D.s could not be calculated.
during the first 2 h after mixing and moving e.g., ing. In the kennelled building, both after Mix 1 and
correlation between total duration of two-sided fights after Mix 2, DLWG was lower in the groups which
and skin lesion score: r 5 0.620; n 5 96; P , 0.001.
were mixed compared to the groups which had only No such relationship was found between skin lesions
been moved. No such effect was found in the sloping at day 1 and other behavioural variables such as
floor building see Table 8. In both buildings biting and knocks or threats.
however, food intakes did not differ in the periods immediately following mixing e.g., food intake in
3.3. Performance kennelled building during two weeks following Mix
1: 2.42 vs. 2.46 kg per day, for mixing 1 moving vs.
Treatment effects on daily live weight gain ap- moving only; F
5 0.28; NS. As a result food
1,8
peared to differ between the two housing systems, conversion ratios were poorer under the mixing
1 but only in the periods immediately following mix-
moving treatment in the kennelled accommodation
H .A.M. Spoolder et al. Livestock Production Science 63 2000 121 –129
127 Table 6
a
Increase in levels of skin damage recorded between days 2 1 and 1, and days 2 1 and 7 or 5 all relative to day of mixing during the first
b
Mix 1 and second Mix 2 mixing moving treatment, per treatment group Mix
Day Treatments
P-value C
A B
D S.E.D.
First mix Second mix
Interaction 1
2 1 to 1 2 1.3
12.0 0.7
10.3 2.98
, 0.001 NS
NS 1
2 1 to 7 2 5.5
7.2 3.1
7.9 3.78
0.002 0.086
NS 2
2 1 to 1 5.6
2.6 26.6
13.9 4.52
0.016 , 0.001
NS
c
2 2 1 to 5
9.4 13.0
26.1 29.9
– NS
, 0.001 NS
a
Data are the average number of wounds or scratches.
b
Treatments are: C: No mixing on either occasion, A: mixing at 55 kg, not at 75 kg, B: mixing at 75 kg, not at 55 kg, D: mixing both at 55 kg and at 75 kg.
c
Data were transformed using square root transformation. Back transformed values are presented. S.E.D.s could not be calculated.
4. Discussion
