V01.6(!997i: 183-191. Effects of cage size and obstructed view from cage on use of resting platforms by farmed silver foxes Jaakko Mononen, Mikko Harri and Leena Ahola University ofKuopio, Department ofApplied Zoology and Veterinary Medicine, PO Box 1627, FIN-70211 Kuopio, Finland, email: mononen@uku.fi The effects of cage size and an obstructed view from the cage on the use of wooden nonwalled resting platforms by juvenile male (n=10) and female (n=ls) silver foxes (Vulpes vulpes) were assessed in a 10 week experiment. The degree of the view and the free floor area of the cage varied between the five types of cage used. Each animal spent 2 weeks in each type of cage and their behaviour was videorecorded for a 24-h period in each 2-week period. The foxes spent 59 ± 13% of their daily time on the platforms. Use declined from 72 ± 13% in September to 35 ± 21% in November. Males used the platforms more than did females. In late October and early November, the foxes in cages with an obstructed view from the floor made more use of the platforms for both active behaviour and resting than did those in cages with an unobstructed view from the floor. The larger the free floor area of the cage, the less the silver foxes used the platforms during activity in mid-August and mid-September. One probable function of the platform is to offer the foxes an observation and resting place with an open view in all directions. Key words: fur farming, animal behaviour, preference, animal welfare, housing ntroduction According to the European Convention (1991), not all biological needs of farmed silver foxes (Vulpes vulpes) and blue foxes (Alopex lagopus) are met in the current commercial husbandry sys- tems. As a minimum requirement, the Conven- tion recommends that a suitable nest box or plat- form should be available for each fox. If a plat- form only is available, it should have solid sides. These structures should be placed as high as possible. The Convention lists the needs as a solid floored resting site, an observation place, a hiding place, and the possibility to stay on a higher level than the cage floor. Of these four needs, only the latter is systematically support- ed by the results of previous platform studies on silver foxes (see a review by Mononen et al. 1996c). It may be connected with the need of an animal for an observation place providing an unobstructed view. Height and/or unobstructed view may be key features of the cage environ- ment (Mononen et al. 1995, 1996a, b) that mod- © Agricultural and Food Science in Finland Manuscript received October 1996 183 AGRICULTURAL AND FOOD SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=DEyXVifKOK_VC1qp.0ePvCwEO_zkVOxfMR9uyXw.YXKeblHK2rPFi7YUk6apCZMudM9P7Xb5n41QAKW9UXAebHB4qhkvnhIiT7fSSK1qLanie-zjXOnH6DsBh7vnSW_jeEQflzZL5RLAwYA7LxZV6tG9_S-jmEqzvihQRwkYhQuczLjHQQR_VixQxM5EeKzfORZb1cmiP2ssQaXGLtqruLlK2Y59UbT1NM_rvEaP-CKdZp9AKPfCpAUdJo_2JFKgNQKGuh_v8ymhnVfJYeyMHur-czIoCF2khoYqTCkEOJ5sC4yAT6P2IpZWBVqB-9_poPk8E8IkEjHKAEYerQ Mononen, J. et al. Effects of cage size and obstructed view on use ofresting platforms ify foxes’ behaviour in experimental and real cage environments and may thus confuse our understanding of what the animal really prefers and why. On the other hand some discrepancies between results from different studies may also be due to differences in experimental set-ups, e.g. in size of cages and size and type of platforms. For example, a nest box inside the cage reduces the free floor area of the cage; the foxes may then use the roofof the box, i.e. one type ofplat- form, more than platforms that do not restrict the free floor area (Mononen et al. 1995). In the present study, two hypotheses present- ed by Mononen et al. (1995) were tested on farmed silver foxes. According to ‘the view hy- pothesis’, more use is made ofplatforms in cages with an obstructed view from the cage floor, but according to ‘the reduced space hypothesis’ the platforms offer extra space which is used more in cages with restricted floor area. The size and height of the platforms were kept constant and all the experimental animals were exposed to all five types of experimental cage, i.e. they acted as their own controls. Material and methods The experiment was conducted at the Fur Ani- mal Research Station of the University of Kuo- pio in Juankoski, eastern Finland. The experi- mental silver foxes were raised according to the normal Finnish commercial practice. They were given fresh feed once a day, and water was avail- able ad libitum or was made available twice a day. Cages and platforms The experimental wire mesh cages were in a two- row shed. The cage floor was 50 cm above the level of the corridor floor of the shed and about 75 cm above the ground. In each cage there was a woodenresting platform (45x70 cm). The plat- forms were hung 25 cm from the cage ceiling. Four platform types and two cage sizes were combined to provide five cage types (Figure 1): A. The standard cage (105 x 115 x7O cm, Wx- LxFI) with a box type platform. The fox could not go under the platform, and the view from the cage floor was obstructed. B. The standard cage with a platform and walls below it obstructing the view. The fox could go under the platform but the view from be- neath the platform was obstructed by hard- board walls attached to the cage wall. C. The standard cage with a platform. The fox could go under the platform and had an un- obstructed view from beneath the platform. D. The standard cage with a platform without access under the platform. The fox could not go under the platform, as access was prevent- ed by wire mesh walls, but the view from beneath the platform was not obstructed. E. Abig cage (105 x 240 x 70 cm, WxLxH) with a box type platform. The fox could not go under the platform and the view from beneath the platform was partly obstructed in that di- rection. There were five cages of each type. The dif- ferent types of cage were in series such that a cage with an unobstructed view (C and D) was always next to another cage with an unobstruct- ed view, i.e. Type C cage, Type D cage, the half of the Type E cage without the platform or a cage without a platform with a non-experimental an- imal. Likewise a cage with an obstructed view (A or B) was always next to another cage with an obstructed view, i.e. Type A cage, Type B cage, the half of the Type E cage with the box- type platform or a Type A cage with a non-ex- perimental animal. Thus, in Type C and D cages the view was unobstructed for at least about one metre in both directions in the cage row and in Type A and B cages the view was always partly obstructed in both directions in the cage row. In Type E cages the view was partly obstructed in the direction of the box type platform and unob- structed in the other direction. Thus, in Type E cages an area was available, the half of the cage 184 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6 (1997): 183-191, without the nest box, from which the view was almost as good as from Type C and D cages, and substantially better than from Type A or B cages. Therefore, the Type E cage was classified as a cage with an unobstructed view. Both series of cages, with and without the obstructed view, were in two cage rows in the shed. Hence, a fox (especially when lying) on the floor of a cage in which the platform obstructed the view, i.e. Type A and B cages, was severely hindered from seeing either the foxes in the neighbouring cages or anyone approaching its cage along the aisle of the shed. In these cages the platform structures also narrowed the sector in which the foxes could see the foxes in the other cage row of the shed and the area outside the shed. On the left side of the shed there was a 30- m-wide open area and beyond that farm build- ings with plenty of human activity. On the right side there was a shed housing raccoon dogs (Nyc- tereutes procyonoides) at a distance of 5 m. The view from the Type C and Type D cages and from the half of the Type E cage without the nest box was minimally obstructed in all directions. Animals, procedure and observations The experimental silver foxes (15 females, 10 males) were born in May 1994 and weaned at about 8 weeks. Thereafter they were housed sin- gly in standard fox cages (105 x 115 x 70 cm, WxLxH) without any platforms or nest boxes. The foxes were from 11 litters. Five experimen- tal groups were formed. Each group was com- posed of three females and two males. The coef- ficient of relatedness of the foxes within each group was less than 0.25. The experiment comprised five 2-week peri- ods. Each individual fox was housed alone in each type ofcage for 2 weeks. The differentcage types were introduced to the different groups in the following order: Group 1, ACEDB; Group 2, BEDCA; Group 3, CDABE; Group 4, DABEC and Group 5, EBCAD. On the first day of Peri- od 1 (sth September 1994) two or three foxes from each group were allocated to the left cage row and two or three to the right cage row. Ow- ing to the arrangement of the cages the individ- uals in each group were thus distributed along longitudinal axis of the shed. On the first day of Periods 2-5 each fox was transferred to a new cage. To reduce any effects due to cage location, each individualwas exposed to both the left and right cage rows and to the front, middle and rear sections of the shed during the experiment. The platforms remained fairly clean, but due to oc- casional defecating and urinating on the plat- forms they were cleaned by scraping, if neces- sary, on the first day ofeach period before a new animal was transferred to the cage. The behaviour of each animal was video re- corded for 24 hours during the second week of each period. The video system is described in Mononen et al. (1996a). During dark hours dim red lights (Philips E27ES, 60 W) were used. Oth- erwise the lighting was natural. Ambient tem- perature was recorded at 0800 each morning. The behaviour of the foxes was analysed from Fig. I. Schematic drawings of the five cage types. See text for details. 185 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Mononen, J. et al. Effects ofcage size and obstructed view on use ofresting platforms Table 1.Categories ofrecorded behavioural states and their combinations, i.e. the behavioural variables. Lying in a curled or stretched-out posture wasrecorded as resting and all otherbehaviour as active behaviour. BehaviourCategory AP Active on the platform RP Resting awake or asleep on the platform AF Active on the wire mesh floor RF Resting awake or asleep on the wire mesh floor TA=AP+AF Total activity TP=AP+RP Total time on the platform PAP=AP/(AP+AF) Proportion of active time on the platform PRP=RP/(RP+RF) Proportion of resting time on the platform the video tapes using an instantaneous sampling method (Martin and Bateson 1993) with a 5-min sampling interval. The behavioural categories used are presented in Table 1. Statistics and presentation of data The behavioural results were calculated as per- centages of observations and are hereafter called ‘percentages of time’ or ‘percentages of active/ resting time’. The results are presented in the text as mean ± standard deviation, but in figures only as means. The effects of cage types (i.e. cage size and platform type), advancing time(i.e. ex- perimental period) and sex on platforms use were analysed by using the variables TP (proportion of total time on platform), PAP (proportion of total active time on platform) and PRP (propor- tion of total resting time on platform) (Table 1). The variables PAP and PRP were used instead ofAP (active time on platform) and RP (resting time on platform) because the daily percentage of active time varied between the periods and also tended to vary between the sexes. Many behavioural variables were neither nor- mally distributed nor transformable. Therefore, non-parametric statistics were used. Due to the lack of suitable nonparametric methods the in- teractive effects of the independent variables (cage type, sex and advancing time) on behav- iour could not be directly analysed but had to be deduced from separate analyses. The number of animals in each analysis varied, because some data were lost due to dysfunction of the video recorder during Period 2. The view hypothesis predicts that the plat- forms are used more in cages with an obstructed view from the cage floor. Thus, the platforms should be used more in Type A and B cages than in Type C, D or E cages. To allow for the possi- ble effects of cage size (big cage vs standard cage) the comparison AB vs CD was included. According to the reduced space hypothesis the platforms offer extra space which is used more in cages where the floor area is restricted. Thus, the rate of platform use in different cage types should be in the order: A=D>B=C>E. To test these two hypotheses, the behaviour of each in- dividual was pooled by calculating the mean for each behavioural state for two or more cage types as required by each hypothesis. For example, to compare platform use in the cages with an ob- structed view (AB) with that in cages with an unobstructed view (CDE), the mean platform use in cages AB was calculated for each individual and compared with the mean use in cages CDE calculated similarily. The Wilcoxon matched- pairs signed-ranks test and the Page test for or- dered alternatives were used to compare two and three pools, respectively (Siegel and Castellan 1988). The effect of advancing time (i.e. the differ- ences between the periods) was analysed by com- paring the five periods with Friedman two-way ANOVA. The effect of sex was studied by pool- ing the data from all periods within each indi- vidual and comparing the behaviour between the sexes with the Mann-Whitney U-test (Siegel and Castellan 1988). The interactions between the cage types and advancing time were studied by pooling the an- imal groups within each period according to the two hypotheses and comparing the groups with- in each period with the Mann-Whitney U-test 186 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Vol. 6 (1997): 183-191. Fig. 2. The behaviour of silver fox- es (n=l 8) during the five periods. The differences between the peri- ods are significant forall four var- iables (p<0.05, Friedman two-way ANOVA). The dates are the days of the 24-hour video recordings during the second week of each period. Below the dates are the temperature ranges (°C) of morn- ing temperatures (at 0800) and mean day lengths (h.min) for the video recording days of each pe- riod. (two pools) or the Jonkheere test for ordered al- ternatives (three pools) (Siegel and Castellan 1988). The interactions of sex with cage type and advancing time were studied by analysing the effects of cage type and advancing time for both sexes separately. The results of these analyses were compatible with those of the analyses with both sexes. Thus, for briefness, only the results of the sex-pooled data are presented. In the case of the differences between two pools of cage types, one-tailedprobabilities were used, since the a priori hypotheses determined the order of the pools. Note that the Page test and Jonkheere test are also considered to be one- tailed tests. Otherwise two-tailed probabilities were used (Siegel and Castellan 1988). Results The silver foxes were active 41 ±3% of their daily time (pooled result for five periods). The percentage of daily activity varied in the course of the experiment, being 33 ± 5%, 41 ±4%, 49 ± 4%, 43 + 5% and 44 ± 6% of time (N= 18, P