In-cage sandbox as a ground substitute for farmed blue foxes (Alopex lagopus): Effects on digging activity and welfare

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1 In-cage sandbox as a ground substitute for farmed blue foxes (Alopex lagopus): Effects on digging activity and welfare H. T. Korhonen 1, L. Jauhiainen 2, and T. Rekilä 1 MTT Agrifood Research Finland, 1 Animal Production Research, Fur Animals FIN Kannus, Finland; 2 Data and Information Services, FIN Jokioinen, Finland. Received 9 December 2002, accepted 2 July Korhonen, H. T., Jauhiainen, L. and Rekilä, T In-cage sandbox as a ground substitute for farmed blue foxes (Alopex lagopus): Effect on digging activity and welfare. Can. J. Anim. Sci. 83: A study on the behavioural and welfare effects of in-cage sandboxes was carried out on juvenile farm-bred blue foxes (Alopex lagopus) with special reference to digging behaviours and time spent on sand substrate. Twelve juvenile male blue foxes were used in each of two experimental groups: (1) a test group and (2) a control group. Animals were raised singly in cages measuring 120 cm long 105 cm wide 70 cm high, from weaning in July to pelting in December. All experimental animals were housed conventionally but cages of the test group contained in-cage sandboxes (80 cm long 40 cm wide 14 cm high). Various physiological, behavioural, health and productionrelated variables were measured during the study. Final body weights of test animals were significantly (P = 0.05) lower than controls. Occurrence of endoparasites (Toxascaris leonina, Isospora sp.) did not substantially differ between groups. Open field activity was greater (P = 0.02) and latency to touch novel objects shorter (P = 0.02) in the test group compared with the control. Cortisol-creatinine ratio, incidence of stereotypes, size of adrenals or other organs, blood screen and fur quality parameters were not significantly different. Sandbox hygiene deteriorated rapidly during the experimental period. Fur coats of test animals were dirtier than those of controls at pelting. Claw length of test animals was significantly shorter (front foot; P < 0.005, back foot, P < 0.001) than in controls only in October. Altogether nine different sandbox behaviours were observed in the test foxes. Digging was the fifth most common behavior, comprising 5.8% of total sandbox use. Amount of time spent in the sandbox peaked in July, averaging 117 min/24 h, and declined towards winter. The most common sandbox behaviours observed were walking (24.3% of total time), sitting (22.0%) and resting (17.5%). Results indicated low motivation to use in-cage sandboxes as a digging substrate. On the other hand, the presence of in-cage sandboxes may provide opportunities for foxes to engage in other species-specific activities and/or seek sensory comfort through contact with the sand. The effects of in-cage sandboxes on animal welfare need further study. Key words: Alopex lagopus, sand floor, digging, motivation, welfare, fur farming Korhonen, H. T., Jauhiainen, L. et Rekilä, T Utilisation d un carré de sable comme succédané du sol avec les renards arctiques (Alopex lagopus) : incidence sur le creusage et le bien-être des animaux. Can. J. Anim. Sci. 83: Les auteurs ont étudié le comportement et le bien-être de jeunes renards arctiques (Alopex lagopus) d élevage disposant d un carré de sable dans leur cage pour préciser notamment leur comportement au niveau du creusage et le temps passé dans le sable. Douze jeunes renards arctiques mâles ont été divisés en deux groupes : (1) un groupe expérimental et (2) un groupe témoin. Les animaux ont été élevés séparément dans des cages de 120 cm de longueur par 105 cm de largeur et 70 cm de hauteur du sevrage, en juillet, à la récolte des peaux en décembre. Les sujets du groupe expérimental disposaient de cages ordinaires, mais celles de l autre groupe contenaient un carré de sable (80 cm de longueur par 40 cm de largeur et 14 cm de profondeur). Durant l étude, les auteurs ont mesuré plusieurs variables associées à la physiologie, au comportement, à la santé et à la production des animaux. Les sujets expérimentaux étaient sensiblement plus maigres (P = 0,05) que les témoins. La présence d endoparasites (Toxascaris leonina, Isospora sp.) ne varie pas sensiblement entre les deux groupes. Les sujets expérimentaux étaient plus actifs sur le terrain (P = 0,02) et prenaient moins de temps à toucher les objets nouveaux (P = 0,02) que les témoins. On ne note pas d écart appréciable entre les deux groupes pour ce qui est du rapport cortisol/créatinine, de l incidence des stéréotypes, de la taille des surrénales et d autres organes, de l analyse du sang et de la qualité de la fourrure. L hygiène du carré de sable s est vite détériorée durant l expérience. La fourrure des sujets expérimentaux était plus sale que celle des témoins à la récolte. Leurs griffes étaient aussi sensiblement plus courtes (pattes avant, P < 0,005; pattes arrière, P < 0,001), mais en octobre seulement. Neuf comportements ont été observés chez les sujets expérimentaux disposant d un carré de sable. Creuser se classe cinquième parmi les comportements les plus fréquents et explique 5,8 % de l utilisation du carré de sable. Les animaux passent le plus de temps dans le sable en juillet, soit 117 minutes en moyenne par période de 24 heures, puis de moins en moins à mesure que l hiver approche. Les comportements les plus fréquents sont marcher (24,3 % du temps total), s asseoir (22,0 %) et se reposer (17,5 %). Ces résultats indiquent que les animaux sont peu enclins à utiliser le sable pour creuser. La présence d un carré de sable dans la cage pourrait toutefois amener les renards à entreprendre d autres activités propres à l espèce ou à chercher un certain réconfort dans le contact avec le sol. Il conviendrait d entreprendre des recherches plus poussées sur le bien-être que les animaux retire d un carré de sable dans la cage. Mots clés: Alopex lagopus, sol en sable, creuser, motivation, bien-être, élevage d animaux à fourrure 703

2 704 CANADIAN JOURNAL OF ANIMAL SCIENCE The two farmed foxes species, the blue fox (Alopex lagopus) and the silver fox (Vulpes vulpes), have traditionally been raised in wire-mesh cages that provide few opportunities to engage in species-typical behaviour. Recently, open wirenetting platforms have been provided for resting and surveillance, and wooden blocks for chewing. Whelping nestboxes made of board are provided as shelter for breeding vixens during April June. The floors of farm cages are made of wire-netting exclusively. In the wild, earthen substrate is a predominant component of foxes living environment. As terrestrial carnivores wild foxes regularly perform digging behaviour while caching or digging up food (Henry 1977; Jeselnik and Brisbin 1980), or when making a whelping den or a resting place (Weber 1985; Meia and Weber 1993). These activities are not possible under intensive wire-netting confinement. Recently, animal welfare concerns have been expressed about the housing conditions of farmed foxes. It has been emphasized that foxes are not given chances for species-typical characteristics like digging or feet contact with earthen substrate. These natural features presumably are beneficial for wellbeing in general, but also rewarding, i.e., providing positive sensory feedback from feet and claws. Lack of their performance may thus compromise animal welfare. This assumption has yet to be scientifically demonstrated, however (European Convention 1999). Previous studies have investigated motivation to dig and use an earthen floor under experimental conditions where foxes have either had free access from a wire-netting cage to the ground (Korhonen and Niemelä 1997; Korhonen et al. 1999; Korhonen et al. 2001a), or were housed in earthen pens exclusively (Kronholm 1994; Pyykönen et al. 1997; Korhonen et al. 2001b, c). The main findings from those studies are that there are large individual and seasonal variation in digging motivation, and that motivation for digging might arise from several different reasons. Furthermore, the effect of depriving foxes of the opportunity to dig have not revealed a clear rebound effect for digging. The above-cited studies indicate the need to obtain more reliable data before final conclusions can be made about farmed foxes need for digging and ground contact. Further research is also needed in terms of clarifying the welfare implications (Korhonen et al. 2001a,d) An alternative set up compared to previous studies would be to provide foxes with a ground substitute directly within the home cage. The present study on farmborn blue foxes employed a customized in-cage sandbox for that purpose. It was predicted that blue foxes would be sufficiently flexible to accept and utilize such a substitute. Furthermore, it was postulated that sandboxes would give the experimental animals opportunities to: (1) perform digging behaviour per se; (2) dig for a certain purpose; and, (3) obtain immediate sensory feedback through physical contact with the earthen substrate. The main aims of this study were to investigate (1) to what extent sandboxes motivate juvenile blue foxes to dig and spend time on a sand floor, and (2) the consequences of in-cage sandboxes on some measures of animal welfare. In this context, welfare indicators included evaluation of various physiological, behavioural, health and production-related parameters (Korhonen et al. 2001a,b,d). Furthermore, in-cage novel object and open field tests were Fig. 1. Layout of experimental set-up in test group: (a) wire-mesh platform; (b) sandbox; and (c) wooden block. Control animals had an otherwise similar set-up except without a sandbox. used to evaluate effects of sandboxes on exploratory behaviour, and a feeding test was used to evaluate temperament (fearful vs. confident). MATERIALS AND METHODS Subjects, Management and Body Measures The study was carried out at the Fur Farming Research Station (MTT) in Kannus Finland, (63.54 N, E) during July December Experimental animals were born in May. They were housed until weaning with their mothers and littermates in conventional wire-mesh floor cages measuring 120 cm long 105 cm wide 70 cm high. At weaning (age 8 wk) on 18 July, foxes were divided into two experimental groups: (1) a control group without in-cage sandboxes and (2) a test group with in-cage sandboxes. Each group comprised 12 juvenile male blue foxes housed singly. Cage size was 120 cm long 105 cm wide 70 cm high for both groups. Each cage contained a wire-mesh platform (105 cm long 25 cm wide) located at about 23 cm from the ceiling. Birchwood blocks (7 cm long 5 cm diameter) were available in the cages of both groups. A sandbox, measuring 80 cm long 40 cm wide 14 cm high, was placed below the platform of each test group cage (2) (Fig. 1). The sandbox contained 25 kg of crushed gravel (0 18 mm) and a sand layer approximately 10 cm deep. Animals were fed by a commercial feeding machine. Freshly mixed fox feed was supplied twice a day during July September and once a day thereafter. Main ingredients of the feed were slaughterhouse offal, fish, fish offal and cereals, in accordance with the standard Finnish recommendations (Berg 1986). No vermifuges were added into the

3 KORHONEN ET AL. IN-CAGE SANDBOX FOR BLUE FOXES 705 Table 1. Behaviour categories, and short description of behavioural elements Category Description Sitting Sitting on hind legs, motionless Standing Standing on four legs, motionless Locomotor activity In locomotion/walking; non-stereotypic Stereotype Repetitive pacing/circling around Self-biting Biting of body Scratching Scratching something with forepads Self-grooming Licking, pulling at body/pelage Jumping Jumping up; hind legs leave the floor Resting Sleeping, lying awake Digging Digging at sandfloor with forepads Eating Eating food Defecating Defecating (faeces) On platform Sleeping, lying or sitting on platform Block contact Having a nose/foot contact with block feed. Daily feed ration was the same for each group, varying from a minimum of 500 g (July) to a maximum of 1000 g (October) per animal daily. Leftovers were divided among other members of the same experimental group. Fresh water was available ad libitum from automatic watering devices. Body weights were measured with an accuracy ± 20 g on a Vaakakoskinen AD-4326A balance (Helsinki, Finland). The fourth claw from the left (phalanx IV) was measured from the cuticle to the claw tip with a slide gauge. The animals were sacrificed on 3 December. Heart, liver and thymus were weighed separately on a Mettler PM 400 (GWB)( Zurich, Switzerland) balance to the nearest 0.1 g and adrenals on a Sartorius Instrulab balance (Germany, Gottingen) accurate to 0.1 mg. The health of the experimental animals was checked daily. Animals were cared for according to guidelines comparable to those of the Canadian Council on Animal Care (1993). Furthermore, the authors had obtained legal permission from Finnish welfare/veterinary authorities to perform this experiment. Behavioural Measurements The behaviour of the foxes was continuously videorecorded for 24-h periods on four separate occasions. The video recording system comprised eight black-white video cameras (Computer FC-55; Milano, Italy) equipped with wide-angle lenses, two quad splitters (Computer QS-MX; Milano, Italy), enabling transmission of each simultaneous recording from the four cameras into a time-lapse video recorder (Hitachi VT-L2000E; Talyo, Japan), and two black-white monitors (Computer CEM-12; Milano, Italy). Videograms were recorded at a frequency of 1.25 per second. During the hours of darkness each cage was lit by two dim red lights (Philips E27ES, 60 W). Recording schedule was as follows: July, Aug., 3 4 Oct., Nov. Fourteen different behaviour patterns (Table 1) were quantified from the video tapes by the instantaneous sampling method (Martin and Bateson 1986) with a sampling interval of 2 min (Jauhiainen et al. 2003). The exception was stereotypic behaviour for which all occurrances were recorded. Stereotypies were based on the definition/classification of Korhonen et al. (2001a). Different forms of stereotypic Table 2. Summary of physiological, haematological, production-related as well as open field test results. Data are given as estimate means and standard error of means (SE) for other parameters except for fur mass, colour purity, cover and quality class they are as medians. NS = not significant Variable Control Sandbox SE P Body weight (kg) 18 Jul NS 4 Sep NS 30 Oct Dec Body weight gain (kg) Heart (g) Spleen (g) NS Liver (g) NS Thymus (g) NS Adrenals (mg) NS Claw length/front foot (cm) 18 Jul NS 4 Sep NS 30 Oct < Dec NS Claw length/back foot (cm) 18 Jul NS 4 Sep NS 30 Oct < Dec NS Open field activity z Latency to novel object y Cortisol:creatinine 23 Aug NS 11 Oct Haemoglobin (g L 1 ) NS Red blood cells (10 9 L 1 ) NS White blood cells (10 9 L 1 ) NS Haematocrit (%) NS Skin length (cm) NS Skin weight (g) NS Fur mass x 4 4 NS Colour purity x 6 6 NS Cover (guard hair) x 5 5 NS Quality class x 6 5 NS z Number of lines crossed in test arena. y Time (s) when 50% of tested animals touched the object. x Evaluated according to a scale of 1 10 where: 1 = poorest, 10 = best. behaviour were not recorded separately, however. All behavioural analyses were performed using the data from video tape recorders (JVC video casette recorder HR-D560E) and TV monitors (Philips). After initial examination of the video data, behaviours shown in Tables 4 and 5 were selected for the analysis. Behaviour Tests The following standardized test (ball test) was used to test response to an in-cage novel object. A baseball (diameter 7 cm) was placed in the cage, close to the door opening, after which the cage door was closed. Latency to make physical contact with the ball, and number of contacts with the ball were recorded for 1 min. The ball was cleaned with paper after each test (Rouvinen et al. 1999). The test was performed three times: 18 July, 5 Sept. and 10 Nov. The feeding test began with the experimenter giving the fox a feed portion and then withdrawing 50 cm from the cage door. If the fox did not begin eating it within 60 s, the fox was considered fearful (Rekilä et al. 1997). Before the test,

4 706 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 3. Number of animals having clean, dirty, moderately dirty and very dirty furs at pelting Control Sandbox Hip Clean Slightly dirty 0 1 Moderately dirty 0 0 Very dirty 0 0 Abdomen Clean 12 9 Slightly dirty 0 2 Moderately dirty 0 1 Very dirty 0 0 Buttock Clean 11 4 Slightly dirty 0 7 Moderately dirty 0 1 Very dirty 0 0 Tail Clean 12 6 Slightly dirty 0 3 Moderately dirty 0 3 Very dirty 0 0 feed was withheld from the animals for 24 h. The feeding test was carried out on the same days as the in-cage ball test. An open field test was conducted on 28 Nov. The open field arena was constructed of wire-mesh, forming a runway 4 m long 2 m wide 1.5 m high. The arena had an earthen floor. The open field arena was divided into eight equally sized fields by marks drawn lightly on the ground. Field eight contained a large red bucket, which served as the novel object in the test. Each test animal spent 5 min in the open field arena. Number of fields crossed was calculated for open field activity (Korhonen et al. 1997). Latency to make physical contact with the novel object was also recorded. The floor of the open field was always cleared of manure before the entrance of another fox. Cortisol and Haematology Plastic trays were placed below the cages for the collection of 24-h urine samples. Trays were covered with gauze to separate faeces from urine. Urine was collected twice: on 23 Aug. and 11 Oct. After collection, samples were weighed, bottled and stored immediately at 20 C. Urinary cortisol concentration (nmol L 1 ) was analysed by a competitive immunoassay technique (Coat-A-Count Cortisol Assay by Diagnostic Products Corporation, Los Angeles, CA). Urinary creatinine concentration was determined by kinetic Jaffe s reaction. Urinary cortisol was finally expressed as the cortisol:creatinine ratio to correct for variation in the dilution of urine (Lasley and Kirkpatrick 1991; Rekilä et al. 1997). For the blood screen, each fox was caught with neck tongs, and a blood sample was drawn from the cephalic vein into 5-mL sampling tubes. All samples were taken within 2.5 min from the start of capture. Blood was collected on 3 Dec. Blood stabilized with K-EDTA was used for analyses of haemoglobin, erythrocyte count, white blood cell count and haematocrit by a Cell-Dyn 400 counter (Sequoia-Turner Corp., USA). Conditions of Sandboxes and Furs Dirtiness of sandboxes was visually evaluated once a week on a scale of 1 4 where: 1 = clean, 2 = slightly dirty (occasional dirty spots, including faeces, feed remains, hairs, etc.), 3 = moderately dirty (several dirty spots) and 4 = very dirty (most of nestbox covered by faeces, feed remains, hairs, etc.). Evaluations were always made by the same person. Plastic trays were placed below the cages for the collection of 24-h faecal samples on 1 Oct. and 26 Nov. Sand samples from sandboxes of the test group were also collected. All samples were analysed by the flotation method (Ewing 1986) as applied to endoparasite recognition in farmed foxes (Reinisalo 2001). About 10 g of faeces were mixed into 50 ml of saturated sugar fluid (550 g saccarose, 443 ml distilled water, 7 ml of 37% formalin). The sample was allowed to stand for 5 min, after which it was strained through gauze into a test tube, then covered with test glass (24 24 mm). After 30 min, the test glass was removed and placed onto an object glass for microscopic analyses (100 and 400 magnification). The dirtiness of furs was evaluated on a scale of 1 4 where: 1 = clean, 2 = slightly dirty (few dirty spots), 3- moderately dirty (several dirty spots) and 4 = very dirty (most of fur covered by dirty spots). Body parts that were scored were: hip, tail, buttock and abdomen. Pelts were evaluated for fur mass, colour purity, cover of guard hair, and fur quality. Evaluation was based on the scoring used by the Finnish Fur Breeders Association for experimental pelt grading, on a scale of 1 10 where: 1 = poorest, 10 = best (Korhonen and Niemelä 1994). Statistical Methods Experimental design was a randomised complete block design, where the litter was used as a block effect. Therefore, organ weights, open field activity, skin length and blood parameters were analysed by the analysis of variance for randomised complete block design (Gomez and Gomez 1984). In addition, final body weight was used as a covariate in the analysis of organ weights. Behaviour, body weights, claw lengths and cortisol:creatinine ratios were measured at two to four different times during the study period. Analysis of claw length had two repeated measures factors: time and front/back foot. Possible correlation of repeated measures taken from the same fox was taken into account in following model: y ijk = block k + group i + error 1 + time j + error 2 + group time ij + ε ijk where group i, time j and group time ij represent the fixed effects of groups, time and their interaction, respectively. Block k, error 1, error 2 and ε ijk represent the normally distributed random effects of litter, between subject error, between time error and residuals, respectively. This model and the assumptions it is based upon have been presented by Gumpertz and Brownie (1993). Assumptions of the two previous models were checked by graphical methods: a box-plot for normality of errors and plots of residuals for homogeneity of error variance. Assumptions were achieved after

5 KORHONEN ET AL. IN-CAGE SANDBOX FOR BLUE FOXES 707 square-root transformation in the statistical analysis of resting behaviour. Fur properties (mass, colour purity, cover, quality class, and dirtiness of furs) and endoparasites were not normally distributed and therefore Friedman s non-parametric test and sign test, respectively, were used to compare groups. Parameters of the models were estimated by the REML estimation method, using the SAS system for Windows, release 8.2, and MIXED procedure (SAS Institute, Inc. 1999). Survival analyses were used to analyse data from in-cage behavioural tests and open field novel object test. These tests were performed by the LIFETEST procedure (SAS Institute, Inc. 1999). RESULTS Growth and Fur Properties Initially, body weights of the animals did not differ significantly between the experimental groups (Table 2). Nor were there any significant differences in body weights between experimental groups on 4 Sept. or 30 Oct. At final weighing, on 3 Dec., body weights of test foxes were significantly lower (P = 0.05) compared to control animals. Body weight gain, i.e., final body weight-initial body weight, was significantly higher (P = 0.02) in controls than test animals. Lengths of forefoot and hindfoot claws were initially similar in both groups, but on 30 Oct. claw length of both the forefeet (P < 0.005) and hindfeet (P < 0.001) of control animals was significantly longer compared to test animals (Table 2). However, differences between the groups were not significant at final measuring time on 3 Dec. Claw length was significantly longer in the forefoot than hindfoot in both control (P < 0.005) and test (P = 0.02) groups. Furthermore, difference between length of forefoot and hindfoot claws was the same for both groups (P = 0.60) at each measurement time. Dirtiness of furs at pelting is given in Table 3. Significant differences were detected in the dirtiness of the tails (P < 0.01), buttocks (P < 0.005) and abdomens (P = 0.07) between experimental groups. Significant differences were not revealed in skin length or skin weight between the experimental groups (Table 2). Furthermore, no differences were found in fur mass, colour purity, cover of guard hair or quality class between the experimental groups (Table 2). Health Status Significant differences were not found in cortisol:creatinine ratio between experimental groups on 23 Aug. or 11 Oct. (Table 2). Nor were any differences found for haemoglobin level, red blood cell count, white blood cell count or haematocrit between the groups (Table 2). Test animals tended to have heavier heart weights (P = 0.09) than control animals. Weights of other organs did not differ significantly between the study groups (Table 2). Figure 2 shows that the dirtiness of the sandboxes increased rapidly after the start of the experiment. During the second test week only 8% of sandboxes were clean, but from the fourth week onwards none remained clean. Correspondingly, during the third week 8% of sandboxes became very dirty, and during the eighth week over half of the sandboxes (67%) were classified as very dirty. Two different types of endoparasite were detected from the sampled sandboxes, namely Toxascaris leonina and Isospora sp. On 1 Oct., the numbers of animals carrying T. leonina were 5 and 4 in the control and test groups (P = 0.99), respectively, and the number of animals infected with Isospora sp. was 7 in both groups (P = 1.00). Furthermore, the sand samples revealed that six sandboxes contained T. leonina and four Isospora sp. On 26 Nov., animals infected with T. leonina numbered 5 and 8 in control and test groups (P = 0.45), respectively. Correspondingly, the number of animals infected with Isospora sp. were 1 and 6 in control and test groups (P = 0.06), respectively. Four sand samples contained T. leonina and one sample had Isospora sp. Behavioural Responses Analysis of videorecordings revealed only a few differences in time budgets between the study groups (Table 4). Test animals were found to stand (P < 0.005) and jump (P = 0.03) more frequently than controls. Control animals, on the other hand, tended to have more contacts with wooden block (P = 0.08) than test animals. Significant differences between video recording dates were found for all parameters except standing, jumping and block contact (Table 4). However, these differences were not exclusively systematic or age-related. A significant interaction effect of group and recording date was found for stereotypies, self-grooming and jumping. On 26 July, there were significantly (P = 0.02) more stereotypies in the control (19.2 min/24 h) than in the test group (12.4 min/24 h). On 29 Aug., however, the situation was quite the opposite (12.7 vs min/24 h; P = 0.04). On 3 Oct., no differences were found (9.3 vs. 9.1 min/24 h). On 21 Nov., more stereotypies were encountered in test (15.0 vs. 9.6 min/24 h; P = 0.05) than in control animals. On 26 July, control animals tended to selfgroom more (115.4 vs min/24 h; P = 0.07) than test foxes. During the other recording dates, however, no differences were observed. Test animals jumped significantly more often than controls on 26 Aug. (46.5 vs min/24 h; P = 0.02), 3 Oct. (48.2 vs min/24 h; P < 0.005) and 21 Nov. (53.2 vs min/24 h; P = 0.02). On 26 July, no significant differences were evident (32.5 vs min/24; P = 0.18). Significant differences were found for time spent in the sandbox (P = 0.02) for the different video recording dates (Table 5). Most time spent in the sandbox was in late July, declining markedly in late August (P < 0.05). A constant lower level was recorded in October and November. Foxes were found to perform nine different behaviours when in the sandboxes (Table 5). Significant seasonal changes were found for digging and scratching behaviours (P < 0.005), being highest during July August and gradually lower from early October onwards. Scratching was lowest in October, whereas sitting, standing and eating in a sandbox remained constant throughout the study. A clear peak in sandbox behaviours such as self-grooming, resting and walking was observed in July. Circadian differences were not detected for time spent in the sandbox. During the hours , and time spent in the sandbox was 21.9, 25.8 and 21.1 min/8 h, respectively (P = 0.42). Nor were there any circadi-

6 708 CANADIAN JOURNAL OF ANIMAL SCIENCE Fig. 2. Distribution of dirtiness of sandboxes for four categories (clean, slightly dirty, moderately dirty, very dirty) during the course of the experiment. Table 4. Estimated means (min/24 h) and standard error of means (SE) for analyzed behaviours. P 1 = main effect of group; P 2 = main effect of recording date; P 3 = interaction effect of group and recording date. NS = not significant Variable Control Sandbox SE P 1 P 2 P 3 Sitting NS <0.001 NS Standing <0.005 NS NS Loc. activity NS <0.005 NS Stereotype NS 0.06 <0.005 Self-biting NS <0.01 NS Scratching NS <0.005 NS Self-grooming NS < Jumping NS <0.005 Resting NS <0.001 NS On platform NS 0.02 NS Block contact NS NS an differences in digging activity (0.7, 2.0 and 1.4 min/8 h, respectively; P = 0.12). Contacts with the birch block, however, occurred most commonly during (17.6 min/ 8h) (P < 0.001). Corresponding values for and were 6.9 and 8.3 min/8h, respectively. Significant circadian differences in block contacts were evident also for control animals during the periods of , , and (P < 0.001). These were 8.2, 18.2 and 11.5 min/8h, respectively. Test foxes were more active (P = 0.02) than control animals in the open field test arena (Table 2). Furthermore, latency to touch the novel object was significantly shorter (P = 0.02) in test animals than controls. Significant differences were not found in number of animals that touched the ball and number of contacts with ball during the ball test. Nor were there any significant differences in number of animals that came to eat during the feeding test (Table 6). For all test dates, latency to touch the ball was similar in both groups, i.e., 50% of animals touch the ball within 2 6 s from the start of the test. DISCUSSION Our results revealed that foxes spent most of their time on the wire-mesh floor. However, an in-cage sandbox may be of some importance to foxes as they stayed in it 117 min/24 h in July, and even the lowest 24 h-value observed in October was 37 min. This finding is actually in good agreement with our previous studies (Korhonen and Niemelä 1997; Korhonen et al. 1999) in which foxes spent most of their time in the wire mesh cage, but used available earthen floor of the pen also. The preference tests (Harri et al. 2000; 2001), in which wire mesh, sand, dry wood and wet wood were compared, additionally support the assumption that farmed foxes do not choose only one floor material, but use each one that is available, but with variable preference. This is because different floors and resources serve different behaviours and needs. Principally, there can be two underlying reasons for explaining the foxes motivation to engage in digging behaviour. First, digging might be goal-directed, i.e., making a den as well as caching or digging up a food or making an occasional resting hole (Korhonen et al. 2001c). Second, they might dig because species-specific digging performance per se is rewarding, i.e., sensory feedback from feet and muscles (c.f. Hughes and Duncan 1988; Harri et al. 1999). These two explanations may not necessarily be mutually exclusive, however. In the present study, we were able to distinguish from our video tapes two features of digging activity, namely, (1) digging the sand, and (2) scratching the sandbox walls. The former is more digging for a certain purpose whereas the latter better reflects digging-like performance

7 KORHONEN ET AL. IN-CAGE SANDBOX FOR BLUE FOXES 709 Table 5. Estimated means (min/24 h) and standard error of means (in parentheses) for various behaviours in sandboxes. NS = not significant Variable 26 Jul. 29 Aug. 3 Oct. 21 Nov. P In sandbox Digging 6.7 (1.3) 5.7 (3.1) 1.1 (0.5) 2.0 (1.6) <0.005 Scratching 6.0 (1.1) 2.7 (0.9) 1.3 (0.9) 3.7 (1.2) 0.04 Loc. activity 37.3 (5.7) 14.2 (3.2) 4.7 (1.1) 6.7 (2.4) <0.01 Sitting 15.3 (3.2) 13.2 (3.4) 13.9 (3.7) 14.5 (6.4) 0.02 Standing 3.2 (0.9) 4.1 (1.4) 2.6 (1.5) 2.8 (0.6) NS Self-grooming 9.8 (3.3) 3.5 (1.2) <1.0 z <1.0 z Resting 31.2 y 5.7 y 3.4 y 5.0 y <0.001 Eating 4.9 (1.5) 9.2 (1.7) 7.0 (2.5) 12.0 (4.1) NS Defecating 3.0 (0.4) 1.8 (0.4) 0 0 <0.001 Total (26.2) 60.0 (10.7) 37.6 (7.4) 65.7 (9.5) 0.02 z Only few observations, not possible for statistical analyses. y Standard error of means not available because of square root transformation. without a clear observable goal. Frequencies of both digging forms were about the same in test animals. We also tried to distinguish caching and digging up a food item from video tapes. Such goal-directed digging was not observed, however. Two opposite explanations for this result can be found. One is methodologial, i.e., we were unable to reliably distinguish from our video tapes food caching/digging up a food. This concept is partly supported by the fact that some food remains were seen in sandboxes when evaluating their dirtiness. The second explanation is that the occurrence of food caching behaviour was very infrequent indeed. Farmed foxes are accustomed to a regular, rather excessive food supply, and therefore, expectations of animals for scanty or lack of food are slight, and they may not consider any need for food caching. The situation is quite different in the wild where Arctic (blue) foxes have adapted to substantial fluctuations in the abundance of food (Frafjord 1993). It appears that in-cage sandboxes, likewise earthen flooring in pens (Korhonen et al. 2001c), may serve several functions for farm-bred blue foxes. This assumption is based on our result that animals were found to perform as many as nine different behaviours in the sandboxes. The most common of these was walking, which averaged 24.3% of total sandbox use. Next common behaviors were sitting, resting and eating. Digging was the fifth most common behaviour, amounting to 5.8% of the total sandbox use. Thus, not only did sandboxes serve as a digging substrate, but also as a place for locomotion and rest. In our previous studies digging behaviour amounted to 11 min/24 h in a under-cage earthen floor (Korhonen et al. 2001a) and to 15 min/24 h in an earthen floored pen (Korhonen et al. 2001b). In the present study, average time spent for digging the sand was lower, namely 4 min/24 h. However, if scratching the sandbox is considered a form of digging, then calculated total digging-like performance amounted to 7.3 min daily. Despite this, our results suggest that an in-cage sandbox is less attractive for digging than is an actual earthen substrate located on the ground. Total time spent in the sandbox significantly declined as the experiment proceeded. Separate sandbox behaviours which also declined over time were walking, resting, defecating, self-grooming and digging. At least four explanations for the decline in sandbox use can be proposed. The first is a novel object effect; novelty of sandboxes activated foxes to use them, particularly in July. Consequently, with declining novelty foxes interest diminished (Jeppesen and Falkenberg, 1990). Second, there may be an age effect; sandboxes interested young foxes more than older ones because of the more exploratory and recreational nature of young animals (Korhonen et al. 2002). A seasonal effect may also explain a reduction in sandbox use; towards autumn/winter foxes interest in sandboxes declined. Finally, there may be an increase in discomfort; increased dirtiness of sandboxes made them less inviting. In the present study, the proportion of digging of total sandbox use was highest in August, after which it clearly declined. Previous studies (Korhonen et al. 1999, 2001b) are in good agreement with our finding. According to them the significant decline in digging motivation from August to November appears to be typical for blue foxes, and also occurs when they are raised in penned conditions. Additionally, a long-term study on penned foxes showed that motivation to dig varies year-round, and is not actually affected by novelty of substrate, but rather by season (Korhonen et al. 2001c). Furthermore, in October November ambient air temperatures were already occasionally below zero, causing the sandboxes to became colder and/or slightly frozen and therefore uncomfortable. It is difficult to say which of these four alternatives, individually or in some combination, explains the reduction in digging over time. Video recordings revealed only a few systematic differences in time budgets between control and test animals. Significant differences were found for jumping and sitting, both of which occurred more frequently in the test group. Higher jumping frequency can be explained by the fact that foxes have to jump from sandbox to the cage floor and vice versa. Higher standing activity of test foxes is more difficult to explain. However, one form of staying in a sandbox clearly was standing, and half of total standing occurred in the sandbox. It is possible that the reason for standing on sand was due to foot comfort from the sand floor (Harri et al. 1999). Wooden blocks are typically provided to foxes as environmental enrichment on farms. This is done because the animals do interact with them frequently (Korhonen and Niemelä 2000; Korhonen et al. 2002). In this way blocks have a significant enrichment value. The present results revealed that sandboxes may also serve as an enrichment for blue foxes. However, the finding that animals spent a lot

8 710 CANADIAN JOURNAL OF ANIMAL SCIENCE Table 6. Number of animals that touched the ball, number of contacts with ball during the ball test, and number of animals that came to eat within 60 s during the feeding test. Sifnificant differences were not found between the groups in any case Control Sandbox No. of animals touched the ball 18 Jul Sep Nov. 8 9 No. of contacts with ball 18 Jul Sep Nov No. of animals that came to eat 18 Jul Sep Nov. 9 9 more time making contact with blocks than digging or scratching in the sandbox may be interpreted as a sign that they prefered the blocks over the sandbox as environmental enrichment. Open field tests typically measure exploratory behaviour of animals in relation to emotionality and fear. Typically, high emotionality (or fear) inhibits exploration whereas low emotionality facilitates it (Archer 1973; Harri et al. 1995). A major function of exploratory behaviour is to provide animals with information about their environment in order to cope with it. Thus, exploration is a high-priority behaviour. The present open field test results indicated that foxes having a sandbox in their cage engaged in more exploratory behaviour in a novel environment compared to controls. This was reflected both as higher open field activity as well as shorter latency to touch the novel object in the arena. This may be partly explained by different structure of the home environment, i.e., the cage with the sandbox resembled the openfield arena with the red bucket more than the cage without sand. The in-cage ball test, however, did not reveal any differences in exploratory behaviour between the groups. This may be due to different sensitivity and validity of the tests. Open field tests might be considered more reliable because they are conducted in a novel arena-located outside of the home cage. So, they more effectively expose animals to a conflict of exploration and fear compared to the familiar home cage. The other of our in-cage tests, the feeding test, did not reveal any differences between the groups. This test typically exposes experimental animals to a conflict of two competing factors, namely fear of humans and hunger (Harri et al. 1995). Typically this test is considered very valid in measuring fear (Rekilä et al. 1997). The present results led us conclude that a sandbox in a home cage does not affect fear of humans in farmed blue foxes, but causes foxes to be more inquisitive of their environment. During a period of stress, the hypothalamic-pituitaryadrenal (HPA) axis is activated via the hypothalamus, leading to corticotrophin-releasing hormone secretion, which, in turn, induces the release of adrenocorticotrophin hormone (ACTH) from the anterior pituitary. Finally, ACTH stimulates the release of glucocorticoids such as cortisol from the adrenal cortex (Svendsen and Carter 1984). The two most common indicators used to demonstrate stress in farmed foxes are cortisol:creatinine ratio and size of adrenals (Rekilä et al. 1997; Korhonen et al. 2001a,d). Both of these variables were analysed in the present study. The results did not reveal significant differences between the groups. Furthermore, our cortisol:creatinine values are in good agreement with the prior values measured for farmed blue foxes housed in conventional and less intensive housing environment (Korhonen et al. 2001a,d). Thus it appears that the animals in the present study did not suffer from pronounced long-term stress. This finding is also supported by the low frequency of stereotypies, which were even less common in both our groups than previously documented for foxes under penned conditions (Korhonen et al. 2001b). The results revealed that both the test animals and controls were infected by parasites, indicating that parasites are spread via routes other than sand. Most likely they came from the feed, because no vermifuges were added to it (Reinisalo 2001). Our results revealed that infection from sand may be more pronounced if sandboxes are used over a long period. This was seen as a tendency for higher occurrence of Isospora sp. in our test foxes compared to controls in November. Previously, Reinisalo (2001) found that occurrence of parasites was higher in foxes housed in earthen pens than in wire-mesh cages. Parasite species found in the study of Reinisalo (2001) were the same as those in our studies, i.e. T. leonina and Isospora sp. There is previous evidence showing that the thymus is reduced in size by stresses such as inanition and diseases. For example, the thymus glands of adult red foxes with mange were smaller than those of healthy animals (Twigg and Harris 1982). Similarly, malnourished raccoon dogs were found to have smaller thymus glands than animals with a normal body condition (Korhonen and Harri 1984). In the present study, significant differences were not found in size of thymus between experimental groups. Two explanations for this are proposed: (1) parasites did not affect thymus size, or (2) they affected it similarly in both groups. Actually, thymus size of our animals appears to be very comparable to that measured previously in non-affected animals (Korhonen et al. 2000a,d). This would favour the latter explanation. Furthermore, present results did not reveal any differences in the blood screen (haemoglobin, erythrocyte count, white blood cell count, haematocrit) between experimental groups. Typically, the blood screen is considered to be a general indicator of animal health. Thus, it appears that parasite infection did not substantially or at least measurably affect the health status of the experimental foxes. One point that may be related to parasite infection is our result that final body weights of test animals were significantly lower compared to controls. In theory, other reasons for lower weights might be that test animals either were more active or ate less. Our measurements do not directly support these two explanations because (1) no significant differences in the amount of locomotor activity between the groups were found; and (2) animals in each group were fed the same amount of feed. However, we discovered that heart weight tended to be greater in test animals. It is known that cardiac

9 KORHONEN ET AL. IN-CAGE SANDBOX FOR BLUE FOXES 711 hypertrophy is encountered in animals subjected to physical exercise (Östman-Smith 1979; Hirada 1982). Thus although test animals did not move more than controls, possibly they exercised/jumped more intensively, which tended to cause increased heart weight. This higher intensity of activity thus resulted in a higher energy consumption, which, in turn, could explain the lower body weight of test animals. It is also possible that test animals tended to eat less than controls because of some food caching. Dirtiness of sandboxes was found to increase rapidly over the course of the experiment. This was mainly because foxes defecated/urinated on sand, but also because some feed remains and hair were left on the sand floor, too. Fur coats and feet of foxes having a sandbox were dirtier than those of control animals at pelting in December. Since pelts were dried, detailed pelt analyses were carried out later. These did not reveal any substantial differences in fur quality, colour purity or fur mass, however. So, dirtiness in fur coat observed at pelting did not significantly affect fur quality parameters according to our later analyses. This is a little surprising and not in accordance with our previous results from blue foxes kept on earth flooring (Korhonen et al. 2001a,d). The question as to whether or not the opportunity to dig is crucial for foxes under farm conditions requires further clarification. To answer to this we need a better understanding of the underlying motivations for foxes digging by identifying factors that elicit the behaviour, and by determining how strongly it is motivated by internal versus external factors. As well, long and short-term consequences of digging deprivation should be studied in more detail. CONCLUSIONS It can be concluded that in-cage sandboxes principally provide foxes with the opportunity to dig and stay on earthen substrate. The rather low frequency of digging performance found suggests that farm-bred foxes are not strongly motivated to dig. The physiological, behavioural, health and production-related variables employed to evaluate welfare implications did not reveal any consistent result either in favour of or against the use of in-cage sandboxes. However, the sandboxes appear to be enriching to the foxes, based on the increased open field activity in the test group, and the greater diversity of behaviours these foxes could perform. ACKNOWLEDGEMENTS This study was mainly funded by the Oiva Kuusisto Foundation. The staff of the Fur Farming Research Station of Kannus (MTT) are gratefully acknowledged for their help in carrying out these experiments. Special thanks to Pekka Siirilä for computer assistance and Tiina Huuki for the video analyses. Archer, J Tests for emotionality in rats and mice: a review. Anim. Behav. 21: Berg, H Rehutietoutta turkiseläinkasvattajille. Turkiseläintutkimuksia 23. 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