Social interactions and cortisol levels in blood of dairy goats (Capra hircus) housed in three different densities during pregnancy
MetadataVis full innførsel
- Master's theses (IHA) 
Domesticated goats (Capra hircus) are social species that live in groups. Throughout the world goats are kept in different systems, and on different densities when housed indoors. There is no Norwegian requirement stating the amount of space accessible for each goat, except in the ecological driven farms, where 1.5 m2/goat is required by law. Usually, 0.6 m2/goat is considered sufficient in Norwegian dairy goat husbandry. High levels of displacements from resources, chasing, threats and physical encounters can be an indication of social stress in a group and can be induced by among other aspects high density. The aim of this study was to investigate whether there is any effect of different stocking densities on social interactions and cortisol level in blood of pregnant goats modeling common densities applied in different countries. We used fifty-four pregnant goats divided in nine groups to investigate these questions. The group size was kept constant of six goats, but the area available for each individual varied from 1 m2, 2 m2 or 3 m2, meaning that they were housed in 3 different group densities: 6 m2, 12 m2 or 18 m2. The experiment was carried out in three replicates of observations of social interactions (November, December and January), and three replicates of blood sampling to determine the cortisol level (October, December and January). Both basal levels of cortisol, (collected before the experiment started) and two samples during the actual treatment were conducted. The results showed that only the behaviour “threat” was affected by density, which increased in the highest density of 1 m2 per goat. Time period had an effect on most of the behaviours tested, meaning a change in the rate from one observational period to another. Density and time period together affected one behaviour, namely butting. Different groups that were housed within different densities affected the number of “clashing” and the number of “displacements from rest”. The level of cortisol was not affected by density, the opposite of what we predicted. Cortisol level correlated negatively with positive behaviours. Total amount of agonistic behaviours declined over time, while positive behaviours increased over time. The cortisol level was highest at the beginning of the treatment period. We concluded that cortisol in blood plasma might not be the best indicator of long-term stress. Housing goats in relatively high densities can lead to increased amounts of aggressive interactions, but within the range of densities 1- 3 m2 per goat, as tested in the present project, the effects were only moderate.