on the feeding of animals and consequently in their production. This will allow taking of measures to improve the management of the flock, and therefore to increase their
production and profitability.
2. Materials and methods
2.1. Research area The study was conducted at the ‘‘Los Pajares’’ experimental plot, a 130-ha area
located in the Filabres mountain range, in the province of Almerıa, in southern Spain.
´
The area is a small valley with elevations ranging from 735 to 1025 m. The climate is semi-arid Mediterranean with a mean annual precipitation of about 324 mm. The
Ž .
vegetation climax is a ‘‘coscojal’’ Quercus coccifera , but the ‘‘Los Pajares’’ land- Ž
. scape shows the influence of agriculture. Robles 1990 distinguished six different kinds
Ž .
Ž of shrublands: ‘‘Albaidar’’
Anthyllis cytisoides , ‘‘Albaidar-Espartal’’ Stipa tenacis- .
Ž .
Ž sima and Anthyllis cytisoides , ‘‘Espartal’’ Stipa tenacissima ‘‘Romeral’’ Rosmarinus
. Ž
. Ž
. officinalis , ‘‘Tomillar’’ Thymus baeticus , and ‘‘Aulagar’’ Ulex parÕiflorus .
2.2. Animals The experimental flock was 90 head of ‘‘Granadina’’, ‘‘Malaguena’’ and ‘‘Serrana’’
˜
goats and their respective crossbreeds. Management was semi-extensive. The animals were released to graze during the day and returned to a closed shed at night. On
returning from grazing, the animals were fed in a manger with a small amount of supplement.
All the animals in the herd were earmarked with a numbered metal tag and measured Ž
. length, height and thorax . A sample of 20 goats made up of animals from each age
Ž .
from 2 years until more than 8 was chosen for observation. 2.3. Data compilation
Social behaviour was recorded between March 1988 and September 1989 using an Ž
. ‘‘all-occurrences’’ sampling method Altmann, 1974 . Most interaction data were col-
Ž .
lected during direct observation of grazing 7 hrday . Additional observations were Ž
. made during morning milking 1 hrday and during afternoon feeding with concentrate
Ž .
in the manger 0.5 hrday . All animals had the same probabilities of being observed. The approximate total observation time during this experiment was 500 h. Every time an
Ž interaction occurred, both the goats involved actor — the goat provoking the interac-
. tion, and reactor — the goat subjected to the provocation were noted, and the type and
the outcome of the interaction were recorded. Ž
. Ž
. Ž
. Ž
. Following Rowell 1966 , Struhsaker 1967 , Seyfarth 1980 and Lee 1983 , the
assessment of interindividual competition was based on the direction of dyadic ap- proach–retreat interactions. The approach–retreat hierarchies were considered to be
Ž dominancersubordination hierarchies Bernstein and Sharpe, 1966; Kaufmann, 1967;
. Rowell, 1974; Bernstein, 1976; Deag, 1977 , and an individual’s rank order was called
its dominance rank. Ž .
The antagonistic interactions considered were a ‘‘retreat’’: one animal moves away Ž
. Ž
. Ž .
at the approach of another avoid or runs away when chased by another flight , and b Ž .
‘‘approach’’: any of the following interactions: 1 ‘‘displacement’’: one animal walks Ž .
steadily toward another, which retreats; 2 ‘‘supplant’’: one animal takes away another’s Ž
. Ž . resources e.g., food or resting place ; 3 ‘‘threat’’: one animal directs its nose or horns
Ž . towards another; 4 ‘‘aggression’’: one animal pokes its nose or horns towards another.
An approach not accompanied by an antagonistic interaction was not considered in the Ž
. determination of approach–retreat hierarchies Alados and Escos, 1992 .
The usual individual ranking method is to order the members of a group so as to Ž
minimize the number of wins under the diagonal of an interaction matrix Schein and .
Forhman, 1955; Brown, 1975; Lott, 1979 . This practice increases the overall impression Ž
. of linearity by obscuring irregularities in hierarchies Beilharz and Mylrea, 1963 ,
Ž .
Ž .
Appleby 1983 suggests a test adapted from Kendall 1962 , in which a significant result indicates that dominance among the animals studied is transitive more often than
would be expected by chance. That is to say that if an animal ‘‘A’’ dominates another ‘‘B’’, and this ‘‘B’’ dominates ‘‘C’’, it is probable that ‘‘A’’ dominates ‘‘C’’.
Ž .
Ž .
Dominance D was calculated for each individual, following Lamprecht 1986 : D s number of individuals subdominantr number of individuals dominant
Ž
qnumber of individuals subdominant = 100
.
as the percent of animals dominated to all animals with which it has interacted. This Ž
. method, previously used by Scott 1980 , establishes the rank of each individual better
than the simple ‘‘number of individuals dominated’’. The rank of an individual depends Ž
. on its performance in all the dyads contested Chase, 1985 , but dominance depends on
Ž .
its attributes relative to those interacting with it Barrette and Vandal, 1986 , the animals were grouped into three categories: high-ranking females with D 0.66, medium-rank-
ing females with D between 0.33 and 0.66 and low-ranking females with D - 0.33 to compute the effect of rank on feeding and production.
In order to study the relationship between the aggressive behaviour and the stress Ž
situation, all the interactions were grouped in ‘‘active dominance’’ threats and aggres- .
Ž .
sive interactions and in ‘‘non-active dominance’’ retreat, supplant and displacement . The individual rate of aggression was calculated as the total number of threats and
aggressions recorded for the subject divided by the total number of threats and aggressions recorded for the group.
The animals were observed directly to determine what they ate. The following Ž .
Ž . Ž .
information was recorded: a plant species, b part of the plant, c number of bites, Ž .
and d type of shrubland where it occurred. Afterwards, approximately 300 bites of the most important species were cut by hand simulating the goat’s feeding habit. This was
dried at 50 8C to determine the dry weight of a bite and analyze its nutritional intake.
Milk production was measured daily for each animal during sampling. The milking was carried out by hand by the shepherd in the stable; at that very moment the
interactions taking place inside the shed were written down from a remote place. Each
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
