The aim of our proposed study is to evaluate different management schedules of separation of breeding does in terms of (social) stress, agonistic behaviour, and injuries. As explained in section 6.2, establishing a dominance hierarchy through agonistic interactions including fights is part of the natural behaviour of rabbit does. Confining does to an exclusive territory (i.e., solitary housing) during part of the reproductive cycle when the incentive to defend their litter is strongest could alleviate fighting and reduce social stress and injuries. For that purpose, does will be separated two to eight days longer after parturition than is presently done in Switzerland using three varying management schedules. The first one is the control, where the does are kept separately for 12 days as currently the case. In the first modification, artificial insemination will be delayed by two days (regrouping will take place two days later at 14 days).The second modification consists of separating the does six days longer than previously. Plainly shifting the agonistic interactions to a time later in the breeding cycle will be considered a failure of the management schedule. Likewise, restricting agonistic interactions to fewer days due to a shorter period of group housing is not desired.
As stated before, reproductive and maternal behaviour are strongly controlled by hormones (Neumann and Steinbeck, 1971; González-Mariscal, 2001), detailed behavioural observations will be combined with the assessment of correlated hormonal changes under the different management schedules. This will help us predict more precisely during which period the isolation of does is advisable to improve their welfare.
We also want to assess the stress that individual does experience under variations in group housing. Previously, measuring stress in rabbits by glucose levels in the blood and corticosterone metabolites in the faeces has yielded results which were difficult to interpret. Large portions of the variation in blood glucose level and concentrations of corticosterone metabolites in the faeces could not be explained and did not correlate with lesions and the level of aggression (Andrist et al., 2012; Andrist et al., 2014). Therefore, we intend to assess stress by the measurements of (core) body temperature using an implanted body temperature recording device. For feasibility see the attached report. Stress induced hyperthermia (emotional fever) has been used as an assessment tool of stress in various species like rodents (Eberli et al., 2011), cows (Proctor and Carder, 2016), humans (Oka, 2015), and even birds (Moe et al., 2017). Real-time monitoring of stress of the rabbits will be performed around the time of grouping.
For the project, the following hypotheses and associated predictions will be tested:
Hypothesis (1): Isolation of does to days 14 (Treatment 1) or 18 (Treatment 2) postpartum decreases the extent of aggression, lesions, and stress compared with does isolated only 12 days (Control) after postpartum. On day 6 after regrouping, does that were isolated for 14 or 18 days will have fewer lesions, a prediction based on agonistic behaviour being (mainly/partly) linked to the defence of the nest and litter.
Alternative (Null) hypothesis: Agonistic behaviour and stress are of the same magnitude and just delayed in groups with longer isolation phases. The number of lesions on day 6 after regrouping is the same for all groups. This scenario is plausible if agonistic behaviour is (mainly/partly) linked to the establishment of a hierarchy.
Hypothesis (2): Agonistic behaviour is correlated with the course of the hormonal secretions and decreases as testosterone decreases during lactation. The course of the hormonal secretions (partly) explains the variation among the groups with different lengths of isolation.
Alternative (Null) hypothesis: Agonistic behaviour is not correlated with the hormonal secretions but is correlated with the time after regrouping.
