kid was caught the day after its birth for marking and weighing. The identity of its mother was recorded. Weight was recorded again when it was 1 month old.
2.4. Analysis BMDP statistical software was used for the statistical analysis.
The stability of the hierarchic order during the study was determined by Friedman Ž
. variance analysis, applying an arcsine transformation Cohen and Cohen, 1983 to
Ž .
standardize the dominance rates D . The Appleby index was used to test the linearity of the hierarchy.
The comparisons between aggressiveness and dominance rank were made in two Ž .
Ž .
ways. 1 An analysis of variance ANOVA of the relationship between social rank and the rate of aggressions initiated and received. The aggression rates were reclassified as
Ž . high, medium and low. 2 The differences in agonistic behaviour shown developed by
Ž .
Ž .
the animals during grazing free feeding and in the stable milking and forced feeding Ž
were tested by the chi-square method with one degree of freedom Sokal and Rohlf, .
Ž .
1969 , that is, the active dominance rate threat and aggression
and non-active Ž
. avoidance, displacement and supplanting
were compared in these two situations Ž
. shepherding–stable .
Ž ANOVA was used to test for the effect of individual characteristics age, length of
. animals, and horns on social rank. Both age and size were reclassified as high, medium
and low. Age was standardized by a logarithmic transformation according to Sokal and Ž
. Rohlf
1969 to make variance independent of the mean and to make frequency
distribution skewed to the right more symmetrical. ANOVA was also done for the relationship between hierarchy and intake of the most
Ž .
important plant groups in the diet shrub and herbaceous . Intake of each plant group was expressed as a percentage of the total intake, an arcsine transformation was used to
Ž .
standardize the dominance rates Cohen and Cohen, 1983 . Ž
. An ANOVA of the relationship between social rank and productivity milk and meat
was performed. Milk production is influenced by the age of the goat; goats from 4 to 6 Ž
. years 3rd and 5th lactation of age produce the most milk. This age group was the one
observed for the effect of dominance on milk production, because it has the most homogeneous milk production.
3. Results
3.1. Social hierarchy The study confirmed the existence of a well-defined hierarchy in a flock of domestic
goats. Dominance relationships showed considerable stability throughout the period of Ž
2
. investigation Friedman variance analysis, X s 0.60, p s n.s. .
r
Ž Results show a linear, although not perfect, hierarchy in female goats Appleby
2
. index, K s 0.62, d s 388.8, gl s 35, X s 203.1, p - 0.001 , with a few dyadic
relationships that did not fit this pattern. Of 364 relationships obtained from the
Table 1 Ž
. Effect of the aggression rate on the dominance index D
Ž .
Ž . In each group low, medium or high all the individuals with similar aggression have been grouped n .
Ž .
n D mean
Standard error Aggressions initiated
Low 10
0.50 0.09
Medium 16
0.82 0.07
Ž Ž .
. High
6 1.10
0.12 F 2,29 s8.61, ps 0.0012
Aggressions receiÕed Low
5 1.12
0.12 Medium
14 0.91
0.07 Ž Ž
. .
High 13
0.49 0.07
F 2,29 s13.96, P s 0.0001
Ž .
Ž .
individual dyads, 335 92 continued the linearity of the hierarchy, and 29 8 of these relationships were contrary to this social rank.
3.2. Aggression–dominance relationship There was a positive relationship between the individual index of dominance and the
Ž Ž
. .
rate of initiated aggression ANOVA, F 2,29 s 8.61, p s 0.0012 , whereas with the Ž Ž
. . Ž
. rate of received aggression it was negative F 2,29 s 13.96, p s 0.0001
Table 1 . Goats compete more for scarce resources. This is reflected in the difference between
Ž .
their interaction when competition is slight on pasture and that in highly competitive Ž
. Ž .
situations stable: e.g., milking, food supplement and place of rest Table 2 . The type
Ž
2
of dominance shown by the goats in these two areas is very different X s 60.7,
. Ž
. p - 0.001 ; the greatest part of their behaviour in the pasture is ‘‘passive’’ 75.5 , with
only 24.5 of the interactions ‘‘actively’’ dominating. In the stable, on the contrary, the Ž
. proportion of passive dominance was much lower 52 , with a notable increase in
Ž .
threats and aggression 48 . 3.3. Influence of physical characteristics on social rank
In this study, the length of the animal was measured, since measurement of the thorax is affected by the state of pregnancy, and height varies greatly with breed. The
Table 2 Ž
. Ž
. Differences of behaviour with slight competition on pasture and high competition on stall
X
2
s60.7, p-0.001. n indicates the total number of interactions observed in the pasture and in the stall.
Shepherding Stall
n n
Non-active dominance 369
75.5 278
52.0 Active dominance
120 24.5
257 48.0
characteristics of the goats observed and their indices of dominance are indicated in Table 3.
Ž Ž .
. Rank is strongly determined by age
F 2,23 s 21.46, p s 0.0000 , and by size Ž Ž
. . Ž
. F 2,23 s 13.17, p s 0.0002
Table 4 . The oldest and largest animals occupy the topmost positions in the social hierarchy.
Horns greatly affects rank. Horns determined the efficiency of the individual in competitive interaction, both threatening and in a fight. Animals with horns were
Ž Ž .
invariably found in the topmost positions in the herd hierarchy F 1,24 s 0.0003,
. Ž .
p s 0.0003 Table 4 .
3.4. The effect of dominance on feeding Ž
Shrub consumption was significantly related to rank in those seasons spring and .
Ž .
summer when more vegetation was available Table 5 . Goats from the low-ranking
Table 3 Dominance index and physical characteristics of the studied goats
‘‘Goat’’ indicates the number that identifies each animal, D indicates dominance index. Horns: A, absence, P, presence.
Ž .
Ž .
Goat D
Age years Length cm
Horns 107
2 121
A 5
5.3 4
136 A
106 8.3
2 130
A 110
15.8 2
123 A
3 17.4
3 115
A 7
17.4 5
133.5 A
11 21.7
4 131
A 1
26.7 4
126 A
8 28.6
4 126
A 9
31.6 5
124 A
73 33.3
6 134
A 74
33.3 8
134 A
2 44.4
4 132
A 70
48 7
139 A
151 56
q8 135
A 181
56.5 q8
142 A
96 57.1
7 135
A 83
57.9 7
135 A
72 62.5
7 147
A 154
69.6 q8
132 A
71 72
6 139
A 80
75 6
145 A
12 76.9
7 125.5
P 90
76.9 6
135 A
156 78.6
q8 146
P 182
78.6 q8
131 P
91 92.6
7 139
P 95
93.1 8
141 P
152 100
q8 138
P
Table 4 Ž
. Effect of the physical characteristics on the dominance index D
n indicates the total number of interactions. Ž
. n
D average ANOVA
Ž .
Age years 3–4
4 0.26
5–6 6
0.56 Ž
. 7 to 8
16 0.98
F 2,23 s 21.46, ps 0.0000 Ž
. Length cm
115–125 4
0.30 126–136
14 0.73
Ž .
137–147 8
1.07 F 2,23 s13.17, ps 0.0002
Horns No
22 0.68
Ž .
Yes 4
1.30 F 1,24 s18.11, ps 0.0003
group consumed fewer shrubs than goats in the middle ranks, and goats in the highest ranks had the maximum intake.
The consumption of forbs, like shrubs, was also influenced by position in the social Ž
. hierarchy Table 6 , but the higher the rank, the lower the intake of forbs. This result
was also found in the spring and summer seasons as with shrubs.
Table 5 Effect of the rank on the intake of shrubs
n indicates the number of animals; ‘‘mean’’ indicates shrubs intake expressed in of the total intake, normalised with the arcsine transformation.
Ž .
Ž .
Season Rank D
n Mean
Standard Season
Rank D n
Mean Standard
error error
Spring 1987 Low
9 0.52
0.041 Spring 1988
Low 9
0.69 0.044
Medium 3
0.51 0.071
Medium 5
0.69 0.058
High 8
0.67 0.044
High 6
0.90 0.053
Ž .
Ž .
F 2,17 s 3.78, ps 0.0439 F 2,17 s 4.99, ps 0.0198
Summer 1987 Low
9 0.41
0.058 Summer 1988
Low 9
0.77 0.042
Medium 3
0.58 0.101
Medium 5
0.97 0.056
High 8
0.65 0.062
High 6
1.01 0.051
Ž .
Ž .
F 2,17 s 4.25, ps 0.0318 F 2,17 s 7.96, ps 0.0036
Autumn 1987 Low
9 0.89
0.063 Autumn 1988
Low 7
0.80 0.057
Medium 4
0.97 0.094
Medium 7
0.82 0.057
High 7
0.88 0.071
High 6
0.83 0.062
Ž .
Ž .
F 2,17 s 0.36, ps n.s. F 2,17 s 0.06, ps n.s.
Winter 1987 Low
9 0.73
0.088 Medium
4 0.83
0.132 High
7 0.85
0.100 Ž
. F 2,17 s 0.41, ps n.s.
Table 6 Effect of the rank on the intake of forbs
n indicates the number of animals; ‘‘mean’’ indicates forbs intake expressed in of the total intake, normalised with the arcsine transformation.
Ž .
Ž .
Season Rank D
n Mean
Standard Season
Rank D n
Mean Standard
error error
Spring 1987 Low
9 0.83
0.041 Spring 1988
Low 9
0.87 0.043
Medium 3
0.85 0.071
Medium 5
0.88 0.058
High 8
0.76 0.043
High 6
0.67 0.053
Ž .
Ž .
F 2,17 s1.01, ps n.s. F 2,17 s 5.12, ps 0.0182
Summer 1987 Low
9 1.14
0.061 Summer 1988
Low 9
0.79 0.043
Medium 3
0.97 0.105
Medium 5
0.60 0.058
High 8
0.86 0.064
High 6
0.54 0.053
Ž .
Ž .
F 2,17 s 5.12, ps 0.0182 F 2,17 s 7.33, ps 0.0051
Autumn 1987 Low
9 0.34
0.047 Autumn 1988
Low 7
0.66 0.053
Medium 4
0.47 0.070
Medium 7
0.54 0.053
High 7
0.25 0.053
High 6
0.55 0.058
Ž .
Ž .
F 2,17 s 3.19, ps 0.0664 F 2,17 s1.63, ps n.s.
Winter 1987 Low
9 0.80
0.092 Medium
4 0.74
0.138 High
7 0.69
0.104 Ž
. F 2,17 s 0.28, ps n.s.
3.5. Effect of dominance on production The dominance of the individual significantly influences its production, with middle-
ranking goats the most productive, and those of lower rank, as well as high-status Ž
. animals, less productive Table 7 .
Table 7 Effect of the social rank in the production of milk and of meat
n indicates the number of animals. Ž
. Production
Rank D n
Mean Standard error
Production of milk Low
8 1.52
0.106 Ž
. lrdayrgoat
Medium 31
1.74 0.054
High 9
1.49 0.099
Ž .
F 2,45 s 3.35, ps 0.0439 No. kids
Low 18
0.23 0.038
Medium 16
0.31 0.041
High 12
0.21 0.047
Ž .
F 2,43 s1.53, ps n.s Ž
. Weight of all kids kg
Low 18
4236 341
first day of life Medium
16 5616
362 High
12 4575
418 Ž
. F 2,43 s 4.05, ps 0.0244
Ž .
Weight of all kids kg Low
18 10 385
794 first month of life
Medium 12
13 792 972
High 10
12 035 1065
Ž .
F 2,37 s 3.58, ps 0.0379
Ž .
Production of meat was also affected by the social hierarchy Table 7 . Middle-rank- Ž
. ing goats produced more meat adding the weight of all their breedings per birth
Ž .
Ž .
5615.6 kgrgoat , followed from a distance by the high-ranking goats 4575.0 kgrgoat , Ž
. and finally those of lower rank 4236.1 kgrgoat . Similar results were observed in
1-month-old suckling kids, with the kids of the middle-status goats again weighing more Ž
. Ž
. 13729.2 kgrgoat , followed by those of uppermost rank 12035.0 kgrgoat , and finally
Ž .
those lowest in the hierarchy 10384.7 kgrgoat . Though the middle-ranking goats also have the greatest number of kids per birth, the difference is not significant.
4. Discussion
