Frank Odberg

Factors affecting behavioural disturbances in race-horses

The aim of the present study was to identify relations between stereotyped behaviours (cribbing, weaving and box-walking) and wood-chewing in thoroughbred flat-racing horses (TB) and standardbred trotters and the different management, feeding and training factors to which these horses are exposed. This was obtained by inquiries to all the professional trainers of TB and trottinghorses used for racing in Sweden. The usable response rates were 61% for trotters and 72% for TB representing 4597 trotters from 234 stables and 644 TB from 38 stables. A small field study was carried out to control the validity of the main study which gave results similar to those in the main study. There was a large difference between the two horse categories in the occurrence of behavioural disturbances. The TB had significantly more stereotypies than the trotters (P < 0·001) but there were no differences in the occurrence of wood-chewing. There were several differences in external factors between the horse categories, e.g. trotters had more opportunities for social contacts with other horses, they also had more free time outside the stable and they were trained a shorter time per week than the TB. The TB were given larger amounts of concentrate than the trotters. Wood-chewing within each horse category was explained by the amount of roughage (P < 0·05 in trotters and P < 0·001 in TB) together with other factors. Stereotypies in the TB were explained by: amount of concentrate (positive relation), number of horses per trainer (positive relation) and amount of roughage (negative relation).

Limitations on the effectiveness of environmental improvement in reducing stereotypic behaviour in bank voles (Clethrionomys glareolus)

Abstract Bank voles (Clethrionomys glareolus) from three age groups were transferred from conditions in which stereotypic behaviour reliably developed to conditions in which stereotypies rarely developed, to test if environmentally induced stereotypies become independent of their causal factors. Forty-eight voles were used, aged 2 months (Young: n = 18); 6 months (Mid: n = 14); and 14 months (Old; n = 16) at the start of the experiment. All had been bred and housed in conventional laboratory cages, in which roughly half of each age group had developed locomotor stereotypies. Half of the voles were housed in a small cage with no vegetation (barren) and half the voles in a larger cage, containing hay and twigs (enriched). After 60 days, the voles were swapped from one treatment cage to the other. Their behaviour was recorded on three occasions in each cage (after 5 days, 30 days and 55 days) on video for 30 min following an unfamiliar stimulus (ball point pen rattled along roof of cage). Voles usually ran or dug in the barren cage, and remained motionless in the enriched cage, immediately following the rattle. There was no evidence of habituation to the rattle. Eight Young, six Mid and 12 Old voles performed stereotypies in the barren cage and three Mid and ten Old voles also performed stereotypies in the enriched cage. No Young voles performed stereotypic behaviour in the enriched cage, so stereotypies were harder to disrupt through environmental enrichment in older voles. Voles that performed stereotypies had a shorter latency to move and spent less time inactive than voles that did not perform stereotypies, in all age groups and both environments, except for Young voles in the enriched cage. These moved later and spent more time inactive in the enriched cage if they had been found to stereotype in the barren cage. This suggests that young stereotyping voles are more responsive to aversive stimuli than non-stereotyping voles, but that their specific behavioural response to the rattle is context specific. In an environment with plenty of cover, young stereotyping voles remain immobile, whereas they respond more actively when little cover is available.

Design of laying nests in furnished cages: influence of nesting material, nest box position and seclusion

1. Preferences for three nesting materials and nest box positions were investigated simultaneously in two trials using a furnished cage: one with 18 individual laying hens and one with 18 groups of 5 hens. Following a habituation period in pre-test cages, every hen or group of hens was tested for 2 d: once without and once with plastic flaps at the entrance of the nest boxes. 2. Hens preferred peat and artificial turf to coated wire mesh for egg laying. 3. One nest box position was clearly preferred to both other nest boxes. The hens’ choice of nest box position was influenced by the pre-test cage in which they had been habituated. 4. The presence of plastic flaps at the entrance of the nest boxes had no influence on the proportion of eggs laid on the different nesting materials or on the proportion of floor eggs. 5. Individual and group testing resulted in the same overall results despite the presence of a distinct group effect.

Perching behaviour and perch height preference of laying hens in furnished cages varying in height.

1. The objective was to investigate the effect of cage height on perch height preference and perching behaviour in laying hens. Twelve groups of two hens and 12 groups of 14 hens were tested in furnished cages equipped with two wooden perches. These stepwise perches were designed such that hens could choose between 7 different heights (6, 11, 16, 21, 26, 31 and 36 cm). Day- and night-time perching behaviour was observed on 4 consecutive days with a different cage height each day: 150, 55, 50 and 45 cm. 2. Given that a minimum perch–roof distance of 19 to 24 cm was available, hens preferred to roost on the highest perches at night. 3. Lowering cage height not only forced hens to use lower perches, but also reduced time spent on the perches during the day (two-hen and 14-hen test) and night (14-hen test). Moreover, it affected daytime behavioural activities (more standing and less preening) on the perches in the two-hen tests (but not in the 14-hen tests). 4. During the day lower perches were used more for standing and walking, higher perches more for sitting and sleeping. This behavioural differentiation was most pronounced in the highest cages. 5. Perch preference and perching behaviour depend on both the floor–perch distance and the perch–roof distance. Higher cages provide more opportunity for higher perches (which hens prefer), for better three-dimensional spacing (and consequently reduced density at floor level) and for behavioural differentiation according to perch height.

Effect of Apomorphine on the Conflict-Induced Jumping Stereotypy in Bank Voles

In conventional laboratory cages, bank voles (Clethrionomys glareolus) develop a jumping up-and-down stereotypy already before the age of one month. Central DA systems are thought to be involved in the expression of these conflict-induced stereotypies (CIS). Stereotypies can also be elicited pharmacologically, most commonly by amphetamine and apomorphine. Hence, administration of apomorphine to jumping bank voles provides the opportunity to compare pharmacologically-induced stereotypies (PHIS) and CIS in that species. A pilot study showed that apomorphine induced stereotyped licking that is qualitatively different from the CIS elicited by captivity. The present study investigated whether apomorphine has an effect on CIS-levels. The lowest dose (0.625 mg/kg) did not elicit licking but neither influenced jumping levels. Higher doses (0.938 and 1.094 mg/kg) lead to the occurrence of licking but also suppressed CIS-levels. However, the discordance in time profiles of licking and jumping argues against a shift from jumping to licking due to further stimulation of already activated DA systems. Therefore, expression of jumping seems to depend on stimulation of other DA receptor subtypes or jumping may even be DA independent.

Heart rate and behavioural responses of crib-biting horses to two acute stressors

The heart rate and behaviour of 14 adult saddle horses, eight crib-biters and six normal controls, were investigated. Initially, the relationship between crib-biting and heart rate was investigated while the horses were undisturbed. The horses were tested when restrained with a lip twitch, and assessed when they were exposed suddenly to the rapid inflation of a balloon. The heart rate of the crib-biters during crib-biting was lower than during other behaviour. The crib-biters had a higher overall mean heart rate (P<0.05) suggesting that they may have had a higher basal sympathetic activity. After the application of the twitch, all the horses had a transient increase in heart rate which returned to basal values more rapidly in the crib-biters. The crib-biters were less reactive to the lip twitch, five of the six investigated remaining calm, and after the release of the twitch, they spent more time nibbling (P<0.05) than the control horses. The crib-biters reacted more strongly to the inflation of the balloon (three of the six reacted), and after it had been inflated they spent more time walking in the box.

Effect of manual imitation of grooming on riding horses' heart rate in different environmental situations.

S. Normando1*, A. Haverbeke2,4, L. Meers2, F.O. Ödberg2, M. Ibáñez Talegón3 and G. Bono1 1Dipartimento di Scienze Sperimentali Veterinarie, Università di Padova, V iale dell’Università 16, Agripolis, I-35020 L egnaro PD, Italy; 2Department of Animal Nutrition, Genetics, Production and Ethology, Universiteit Gent, Heidestraat 19, B-9820 Merelbeke, Belgium; 3Departamento de Producción Animal, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, España; 4Present address: FUNDP, Department of Veterinary Medicine, rue Muzet, 4 B-5000 Namur, Belgium *Correspondence: Dipartimento di Scienze Sperimentali Veterinarie, Università di Padova, Strada Romea 16, Agripolis, I-35020 L egnaro PD, Italy E-mail: simona.normando@unipd.it

Perch width preferences of laying hens

1. In order to investigate the effect of perch width on perching behaviour of laying hens, two experiments in which hens could choose between 7 different perch widths (1·5, 3·0, 4·5, 6·0, 7·5, 9·0 and 10·5 cm) were conducted. In one experiment (EXP-2P) test cages contained two long perches gradually broadening and narrowing stepwise, in the other experiment (EXP-7P) 7 separate short perches differing in width were placed in the test cages. In each experiment 12 groups of 4 hens were filmed during day and night. The behaviour and location of the hens were recorded and whether the nest box affected hen distribution over the perches was investigated. 2. During daytime, in EXP-2P, there was an increase in perch use with increasing perch width. Hens spent less time on perches of 1·5 cm wide compared to perches of 9·0 and 10·5 cm wide. In EXP-7P, the 1·5-cm wide perch was also used the least (but only the difference with 4·5-cm wide perches was statistically significant) but perch use did not increase linearly with perch width. During the night, there were no significant perch width preferences in either experiment. 3. The percentage of active behaviours (preening, walking, drinking, pecking at hen) versus passive behaviours (standing, sitting, sleeping) did not differ significantly according to perch width. 4. In EXP-7P, there was a trend for perch use to decrease with greater distances to the nest box in the morning. 5. A perch width of 1·5 cm is not recommended for laying hens. For wider perch widths, results were equivocal: they tend to support rather than challenge the widespread use of 4·5-cm wide perches in commercial units.

Dissociation between MK-801- and captivity-induced stereotypies in bank voles

Abstract Pharmacologically induced stereotypies (PHIS) following dopamine agonists and, more recently, the non-competitive NMDA antagonist dizocilpine (MK-801), are used to study human psychopathology and for screening potential neuroleptic drugs. On the other hand, bank voles (Clethrionomys glareolus) spontaneously develop stereotyped jumping in barren cages, already before the age of 1 month (= captivity-induced stereotypies or CIS). Large inter-individual differences in the level of jumping exist. In this study, the effect of MK-801 on various behaviours of bank voles, and in particular the relationship between CIS and PHIS, was investigated by repeated administration of MK-801 to stereotyping (ST) and non-stereotyping (NST) voles. The animals received nine daily SC injections of, respectively, saline and 0.3 mg/kg MK-801, with a 48-h break between both treatments. Their behaviour was visually recorded every 4 days. The results showed that jumping was neither evoked in NST, nor intensified in ST. Instead, in both ST and NST, PHIS consisting of intensive sniffing and locomotor stereotypy characterised by running in unidirectional circles were elicited. Furthermore, ST showed behavioural sensitisation for locomotor stereotypy, while in NST intensive sniffing was progressively enhanced. These results suggest that CIS and PHIS induced by MK-801 in bank voles are regulated, at least in part, by different neuronal mechanisms and that ST and NST could be predisposed to develop more easily one given PHIS than the other.

Paradoxical rate-dependent effect of fluoxetine on captivity-induced stereotypies in bank voles

Treatment of stereotypies in human and animal clinics is still empirical due to our incomplete understanding of underlying mechanisms. As a consequence, experimental studies in controlled laboratory conditions are necessary. Bank voles (Clethrionomys glareolus), housed in barren laboratory cages, often develop stereotyped up-and-down jumping even before the age of 1 month. The aim of this study was to investigate how captivity-induced stereotypies respond to fluoxetine (Prozac), a selective serotonin reuptake inhibitor. During a control period of 10 days saline was administered daily s.c. to 6-month-old bank voles (n=24). In the subsequent 30 days, 16 animals received a dose of 10-mg/kg s.c. daily while 8 other animals were injected a dose of 20-mg/kg fluoxetine. Stereotypies, general activity, food intake and body weight were measured. Dose-related and paradoxical rate-dependent effects were found on stereotypies. After 10 days of treatment, the stereotypy levels of the animals with high pre-drug stereotypy rates decreased in contrast with those of low stereotypers which increased. No effect was found on general activity and food intake. Weekly weighing revealed an increase of weight during the total drug period and a return to pre-drug levels during the week thereafter.