The effects of early olfactory experience and inter-species cross-fostering on the sexual preferences of mice

This study on the effects of early experience in mice consists of two different sets of experiments. The first part is an investigation on the role of odours in the ontogeny of sexual preferences. It is preceeded by a review of the state of our knowledge of the role of odours in the social behaviour of rodents. MAINARDI et al. found in 1965 that female mice, reared with artificially perfumed parents, spent more time with males scented with the same perfume when sexually mature. The aims of my study were to repeat these investigations using better. controlled conditions and with a new experimental set-up, and to extend' the research by testing the hypothesis of "sensitive periods" for olfactory stimuli in mice. Two strains were used ~ Balb/C and c₅₇ /Black. Experimental animals were scented by daily spraying with geraniol (c₁₀H₁₈O) on the mother, litter and nest using an aerosol spray. A first group was scented from birth till the 10th day of life, a second from day 11 to day 20, a third from day 21 to day 30. The animals were tested for their preference between normal conspecifics and a geraniol- scented one, when they were between 3 and 4 months of age. The improvements on MAINARDI's Technique consisted of, 1°) a more reliable apparatus which offered a wider range of choice between 5 stimulus animals, 2°) better control of the "spontanous response of the mice towards the experimental odour, 3°) a control of the spontaneous responses of the mice in choice of compartments within the apparatus itself and towards the individual stimulus mice without the presence of geraniol, 4°) the use of two strains as control for genetic variability. I have not been able to replicate MAINARDI's results. Two alternative conclusions are suggested. First there is nd effect of early experience on the attitude of these strains towards geraniol. The odour is mildly aversive to them and remains so even if they are exposed to it early in life. Secondly, if taking a trend into account: exposure to geraniol for the first 10 days of life accentuates aversiveness in adult life. The second ,part of the experimental work consists of an investigation of the effects of cross-fostering mice (Balb/C) and voles (Clethrionomys glareolus britan, nicus). Two control groups were employed, one of mice and voles reared normally, the others of mice and voles cross-fostered within the ir own species. All vole pups fostered to mice died but 55% of the mice fostered to voles survived although they were significantly lighter than controls at weaning. Intraspecific fostering of mice did not affect their mortality rate or body weight. The following code will be used: control (normal) Balb (NB), Balb-fostered Balbs (BFB), vole-fostered Balbs (VFB), control voles (NV), vole-fostered voles (VFV). The animals were submitted to various tests. 1) Small field test (between day 21 and 28): recording of various activities in a small breeding cage. The general trend in the fostered animals was an increase of more "sedentary" activities (grooming, pausing, chewing) and digging, and a corresponding decrease of activities such as sniffing/walking and rearing. 2) Open field test (between day 45 and 52): the main trend was a drop in ambulation in BFB and VFB compared to NB, and in VFV compared to NV. The rearing scores for the open field showed less significant differences, but the trends were the same as in the ambulation scores. Urination, defecation and grooming seemed to be unaffected by fostering. The test demonstrates that changes produced are mainly due to the act of fostering itself. 3) Emergence test (various ages): this test measures the time taken to emerge from a hide beneath which the animals could shelter. BFB and VFB males are significantly more reluctant to leave the hide than NB. The females showed no significant differences. 4) Social preference test (between day 60 and 67): NB prefer Balbs, NV prefer voles, and VFB prefer voles (their foster-species). However, BFB and VFV show a strong drop in their preference for their own species, revealing again an effect due to the act of fostering itself, and thus forcing one to qualify a simple interpretation in terms of sexual imprinting for the changed behaviour of VFB

Assessing ridden horse behavior: professional judgment and physiological measures

The assessment of ridden horse behavior by 12 equestrian professionals (riding instructors n ¼ 4, riders n ¼ 4, veterinarians n ¼ 4) was compared with observed behavior and physiological measures (salivary cortisol and eye temperature). Horses (n ¼ 10) were ridden at walk, trot, and canter in a predefined test of approximately 2-3 minutes. Video footage of the ridden test (RT) was analyzed using Observer XT 10 and duration of behavioral states/events recorded. Saliva was collected in the stable, after the warm-up (WU) and at 0, 5, 15, 30, and 60 minutes after the RT. The saliva was analyzed for cortisol (enzyme-linked immunosorbent assay) and the difference between minimum and maximum concentration (ng/mL) and associated sample times recorded. Eye temperature was measured using an infrared thermal camera (MobIR M8), static images (stable, after WU, after RT), and video footage (WU and RT) with maximum eye temperatures derived from set intervals. Mean maximum eye temperatures during ridden work were calculated. Video footage of the RT was observed by the 12 equestrian professionals who each scored the horses on 7 performance parameters derived from the Fédération Equestre Internationale rules for dressage events and the training scale of the German National Equestrian Federation (relaxation, energy, compliance, suppleness, confidence, motivation, and happiness). These scores were compared with behavioral and physiological measures and correlations investigated (Spearman's rank order correlation). Higher percentage durations of high head carriage (ranging from 0 to 50.75% of RT) and the nose carried at an angle in front of the vertical (0%-74.29% of RT) correlated with overall less favorable assessment by the equestrian professionals (P < 0.05) and only the instructors associated neutral head carriage (32.76%-91.92% of RT) and vertical nasal angle (0.97%-68.90% of RT) as a positive sign (P ¼ 0.03 and P ¼ 0.04, respectively). Increases in salivary cortisol positively correlated with the duration of low head carriage (P < 0.05), suggesting that this way of going increased the demands placed on the horse. Increased eye temperature positively correlated with duration of nose carried behind the vertical when ridden (P ¼ 0.02) and negatively correlated with duration of nose carried in front of the vertical (P ¼ 0.01). Some discrepancy between physiological evidence and professional assessment of ridden horse behavior was evident as were differences between groups of professionals. Further evaluation of the association between behavioral signs and physiological measures is now required to ensure that the assessment of ridden horse performance is based on valid and consistent measures

Could Work Be a Source of Behavioural Disorders? A Study in Horses

Stress at work, as shown by a number of human studies, may lead to a variety of negative and durable effects, such as impaired psychological functioning (anxiety, depression…). Horses share with humans this characteristic of working on a daily basis and are submitted then to work stressors related to physical constraints and/or more “psychological” conflicts, such as potential controversial orders from the riders or the requirement to suppress emotions. On another hand, horses may perform abnormal repetitive behaviour (“stereotypies”) in response to adverse life conditions. In the present study, we investigated whether the type of work the horses are used for may have an impact on their tendency to show stereotypic behaviour (and its type) outside work. Observations in their box of 76 horses all living in the same conditions, belonging to one breed and one sex, revealed that the prevalence and types of stereotypies performed strongly depended upon the type of work they were used for. The stereotypies observed involved mostly mouth movements and head tossing/nodding. Work constraints probably added to unfavourable living conditions, favouring the emergence of chronic abnormal behaviours. This is especially remarkable as the 23 hours spent in the box were influenced by the one hour work performed every day. To our knowledge, this is the first evidence of potential effects of work stressors on the emergence of abnormal behaviours in an animal species. It raises an important line of thought on the chronic impact of the work situation on the daily life of individuals

Diabetes in Danish Bank Voles (M. glareolus): Survivorship, Influence on Weight, and Evaluation of Polydipsia as a Screening Tool for Hyperglycaemia

BACKGROUND: Previous studies have concluded that the development of polydipsia (PD, a daily water intake ≥ 21 ml) among captive Danish bank voles, is associated with the development of a type 1 diabetes (T1D), based on findings of hyperglycaemia, glucosuria, ketonuria/-emia, lipemia, destroyed beta cells, and presence of autoantibodies against GAD65, IA-2, and insulin. AIM AND METHODS: We retrospectively analysed data from two separate colonies of Danish bank voles in order to 1) estimate survivorship after onset of PD, 2) evaluate whether the weight of PD voles differed from non-PD voles, and, 3), evaluate a state of PD as a practical and non-invasive tool to screen for voles with a high probability of hypeglycaemia. In addition, we discuss regional differences related to the development of diabetes in Scandinavian bank voles and the relevance of the Ljungan virus as proposed etiological agent. RESULTS: We found that median survival after onset of PD is at least 91 days (lower/upper quartiles = 57/134 days) with a maximum recording of at least 404 days survivorship. The development of PD did not influence the weight of Danish bank voles. The measures of accuracy when using PD as predictor of hyperglycaemia, i.e. sensitivity, specificity, positive predictive value, and negative predictive value, equalled 69%, 97%, 89%, and 89%, respectively. CONCLUSION: The relatively long survival of Danish PD bank voles suggests potentials for this model in future studies of the long-term complications of diabetes, of which some observations are mentioned. Data also indicates that diabetes in Danish bank is not associated with a higher body weight. Finally, the method of using measurements of daily water intake to screen for voles with a high probability of hyperglycaemia constitutes a considerable refinement when compared to the usual, invasive, methods

Evolving protocols for research in equitation science

Within the emerging discipline of Equitation Science the application of consistent methodology, including robust objective measures, is required for sound scientific evaluation. This report aims to provide an evaluation of current methodology and to propose some initial guidelines for future research. The value of research, especially that involving small sample sizes, can be enhanced by the application of consistent methodology and reporting enabling results to be compared across studies. This paper includes guidelines for experimental design in studies involving the ridden horse. Equine ethograms currently used are reviewed and factors to be considered in the development of a riddenhorse ethogram are evaluated. An assessment of methods used to collect behavioral and physiological data is included and the use of equipment for measurements (e.g., rein-tension and pressure-sensing instruments) is discussed. Equitation science is a new discipline, subject to evolving viewpoints on research foci and design. Technological advances may improve the accuracy and detail of measurements, but must be used within appropriate and valid experimental designs

Investigating anhedonia in a non-conventional species: Do some riding horses Equus caballus display symptoms of depression?

International audienceInvestigating depression-like conditions in animals is methodologically challenging, but potentially important for welfare. Some riding horses display ‘withdrawn’ states of inactivity and low responsiveness that resemble the reduced engagement with the environment shown by certain depressed patients. To assess whether these animals are experiencing a depression-like state, we investigated anhedonia – the loss of pleasure, a key symptom of human depression – in 20 withdrawn and non-withdrawn horses from the same stable. The time horses spent being withdrawn appeared unrelated to age or sex, but correlated with time devoted to stereotypic behaviour, a possible marker of lifetime stress. Comparison with data collected 5 years earlier also revealed that horses scored as withdrawn then remained significantly likely to display the behaviour. We measured sucrose intake, a classic measure of anhedonia never previously applied to horses. Flavoured sugar blocks, novel to these subjects, were mounted in each stall and weighed 3, 8, 24 and 30 h after provision. We predicted that if affected by depression-like states, the most withdrawn horses would consume the least sucrose. This prediction was met (F1,18 = 4.65, two tailed p = 0.04). This pattern could, however, potentially reflect general appetite levels and/or food neophobia. To control for these confounds, hay consumption was measured over 5 days, as were subjects’ latencies to eat a meal scented with a novel odour. Although low hay consumption and long latencies to eat scented food did predict low sucrose consumption, statistically controlling for these confounds did not eliminate the relationship between being withdrawn and consuming less sucrose (although reducing it to a strong trend): F1,15 = 4.28, two-tailed p = 0.056. These data thus suggest long-lasting depression-like states in certain riding horses, which correlate with stereotypic behaviour and are characterised by anhedonia and bouts of ‘withdrawn’ unresponsiveness

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Godkänd; 2008; 20080828 (ysko