Blue Fox Research Articles

Systemic AA amyloidosis in the red fox (Vulpes vulpes).

Amyloid A (AA) amyloidosis occurs spontaneously in many mammals and birds, but the prevalence varies considerably among different species, and even among subgroups of the same species. The Blue fox and the Gray fox seem to be resistant to the development of AA amyloidosis, while Island foxes have a high prevalence of the disease. Herein, we report on the identification of AA amyloidosis in the Red fox (Vulpes vulpes). Edman degradation and tandem MS analysis of proteolyzed amyloid protein revealed that the amyloid partly was composed of full-length SAA. Its amino acid sequence was determined and found to consist of 111 amino acid residues. Based on inter-species sequence comparisons we found four residue exchanges (Ser31, Lys63, Leu71, Lys72) between the Red and Blue fox SAAs. Lys63 seems unique to the Red fox SAA. We found no obvious explanation to how these exchanges might correlate with the reported differences in SAA amyloidogenicity. Furthermore, in contrast to fibrils from many other mammalian species, the isolated amyloid fibrils from Red fox did not seed AA amyloidosis in a mouse model.

Prevalence of Pentatrichomonas hominis infections in six farmed wildlife species in Jilin, China

Pentatrichomonas hominis is an anaerobic flagellated protozoan that primarily parasitizes the gastrointestinal tract and is a conditional pathogen. It has an extensive host range and is well known as a potential causative agent of zoonotic disease. The objective of this study was to provide the first findings of the prevalence of P. hominis in six farmed wildlife species, sika deer (S.D.), Rex rabbits (R.R.), blue foxes (B.F.), silver foxes (S.F.), raccoon dogs (R.D.) and minks (M.), that are commercially important in Jilin Province, China. In this study, 450 faecal samples were tested for P. hominis infection by culturing and nested PCR assays. The average prevalence of P. hominis infections were as follows: S.D. 20% (26/130), R.R. 16.25% (13/80), B.F. 45% (27/60), S.F. 43.33% (26/60), R.D. 53.33% (32/60) and M. 48.33% (29/60). The prevalence in herbivores (18.57% for S.D. and R.R.) was significantly lower than that in non-herbivores (47.5%). PCR product sequencing indicated that infections were mainly caused by the P. hominis strain Changchun Canine 1, and we found a P. hominis strain with a mutated sequence, Changchun-RR, which had three mutations compared with the referenced homologous P. hominis sequences. Morphological observations of the Changchun-RR strain showed that it was similar to P. hominis. Our study suggests that P. hominis is widespread in six farmed wildlife species in Jilin Province and provides baseline information for the presence of this parasite in these animals.

Sperm kinematic, head morphometric and kinetic-morphometric subpopulations in the blue fox (Alopex lagopus).

This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component (PC) analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations: SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed: SP1: large oval cells; SP2: medium size elongated cells; and SP3: small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations – SP1: high oscillatory motility, large and short heads; SP2: medium velocity with small and short heads; SP3: slow motion small and elongated cells; and SP4: high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans.

Risk aversion affects economic values of blue fox breeding scheme.

The profit and production of an average Finnish blue fox farm was simulated using a deterministic bio-economic farm model. Risk was included using Arrow-Prat absolute risk aversion coefficient and profit variance. Risk-rated economic values were calculated for pregnancy rate, litter loss, litter size, pelt size, pelt quality, pelt colour clarity, feed efficiency and eye infection. With high absolute risk aversion, economic values were lower than with low absolute risk aversion. Economic values were highest for litter loss (18.16 and 26.42 EUR), litter size (13.27 and 19.40 EUR), pregnancy (11.99 and 18.39 EUR) and eye infection (12.39 and 13.81 EUR). Sensitivity analysis showed that selection pressure for improved eye health depended strongly on proportion of culled animals among infected animals and much less on the proportion of infected animals. The economic value of feed efficiency was lower than expected (6.06 and 8.03 EUR). However, it was almost the same magnitude as pelt quality (7.30 and 7.30 EUR) and higher than the economic value of pelt size (3.37 and 5.26 EUR). Risk factors should be considered in blue fox breeding scheme because they change the relative importance of traits.

The isozyme spectra of lactate dehydrogenase in the tissues of the raccoon dog Nyctereutes procyonoides in the autumn

An electrophoretic assay of lactate dehydrogenase (EC 1.1.1.27) isozymes in the tissue homogenates of cardiac and skeletal muscles, kidney, lungs, spleen, and liver of the raccoon dog Nyctereutes procyonoides from two different geographic zones, viz., northwestern Russia and Poland, as well as the Arctic blue fox Alopex lagopus L. and the red fox Vulpes vulpes L. was performed during the preparatory period to the winter season. Raccoon dogs, which hibernate under natural conditions, differ from other canids (the red fox and Arctic blue fox) to which they are close taxonomically by their body weight and by the higher proportion of aerobic H subunits of lactate dehydrogenase in all organs except for the heart. A higher content of “fast” anode fractions, lactate dehydrogenase-1 and lactate dehydrogenase-2, in the heart, kidney, lungs, liver, and spleen was detected in the raccoon dogs from the northern region compared to those from the southern geographic zone. The shift in the reaction catalyzed by lactate dehydrogenase towards the production of pyruvate indicates that this metabolite is necessary for the synthesis of fatty acids during lipogenesis in the autumn.

Genetic variations of the coding region of the melanocortin receptor 1 (MC1R) gene in the fox.

The melanocortin 1 receptor (MC1R) gene plays an important role in the control of coat colour in mammals. Genetic variation of the MC1R gene and the relationship between genotype and coat colour are not well understood. Studies in the fox may improve our understanding of gene influence on coat colour in dogs and cats. To investigate coat colour associated mutations in the coding region of MC1R gene in foxes. A total of 118 foxes, comprising 70 red foxes (Vulpes vulpes) (19 red, 10 white silver, 29 silver and 12 chocolate foxes) and 48 arctic foxes (Vulpes lagopus) (9 dominant white blue foxes and 39 normal blue foxes) were included in the study. Evaluation of the DNA sequence of the coding region of MC1R gene and its polymorphisms. Eight polymorphic sites (single nucleotide polymorphisms, SNPs) distributed throughout the 954-bp coding region of the fox MC1R gene were detected. Among them, c.13G>T, c.124A>G, c.289G>A, c.373T>C and c.839 T>G were mis-sense mutations, which resulted in codon change of p.G5C, p.N42D, p.V97I, p.C125R and p.F280C, respectively. Mutation and haplotype analysis indicated that c.373T>C was associated with black and brown pigmented phenotypes in foxes, and c.13G>T and c.839T>G were important in distinguishing V. lagopus and V. vulpes. SNP c.373T>C in the coding region of the MC1R gene is probably associated with the brown phenotype of chocolate foxes.

Influence of dietary copper concentrations on growth performance, serum lipid profiles, antioxidant defenses, and fur quality in growing-furring male blue foxes (Vulpes lagopus).

A 75-d experiment was conducted to evaluate the influence of dietary Cu concentrations on growth performance, serum lipid profiles, antioxidant defenses, and fur quality in growing-furring male blue foxes. Seventy-five male blue foxes (5.78 ± 0.09 kg BW) were selected and randomly allocated to 1 of the following 5 dietary treatments: 1) control (basal diet without supplemental Cu; 7.78 mg Cu/kg), 2) 12.22 mg/kg supplemental Cu (Cu20), 3) 32.22 mg/kg supplemental Cu, 4) 72.22 mg/kg supplemental Cu (Cu80), and 5) 152.22 mg/kg supplemental Cu (Cu160). A dry feed that consisted of animal meals, soybean meal, extruded corn, and soybean oil was used as the basal diet and Cu was supplemented as reagent grade CuSO∙5HO. The results showed that Cu supplementation increased the ADG ( < 0.05) and fat digestibility ( < 0.01) and tended to improve G:F ( = 0.09). The ADFI, however, was not affected by dietary Cu ( > 0.10). Additionally, Cu supplementation linearly increased the concentration of fecal Cu, liver Cu, serum total protein, and albumin ( < 0.01). Foxes in the Cu160 group had higher serum Cu concentration than those in the control and Cu20 groups ( < 0.05). The concentration of serum cholesterol decreased with dietary Cu supplementation ( < 0.05). Serum high-density lipoprotein, on the contrary, tended to increase with Cu supplementation ( = 0.09). Copper supplementation increased the activity of glutathione peroxidase ( < 0.05) and tended to increase the activity of serum ceruloplasmin ( = 0.07). For fur quality, skin length in the Cu80 group was greater than that in the control and Cu20 groups. In addition, hair color tended to deepen with the increasing of dietary Cu concentrations ( = 0.08). In conclusion, this study demonstrates that Cu supplementation can promote growth and increase fat digestibility and fur length. Additionally, dietary Cu supplementation can enhance antioxidant capacity and reduce serum cholesterol in growing-furring blue foxes.

Comparative studies on testicular and epididymal morphology, and serum hormone concentrations in foxes and the hybrids during the breeding season

The silver fox and the blue fox belong to different genera, and the hybrid males are fully or partially sterile. In the present study, the objective was to evaluate the causes of hybrid male sterility, and therefore analyze the differences in testicular, and epididymal morphology and serum hormone concentrations among silver foxes, blue foxes, and the hybrids during the breeding season. Samples were collected from 20 male silver foxes, 20 male blue foxes, 15 male HSBs (silver fox female×blue fox male hybrids) and 14 male HBSs (blue fox male×silver fox female hybrids), respectively. Seminal evaluation showed large numbers of sperm present in the semen of blue foxes and silver foxes, but no sperm present in the hybrids. Mean testicular volume and the diameter of seminiferous tubules in silver foxes and blue foxes were greater than in the hybrids; and there were many Sertoli cells, spermatogenic cells, and sperm in silver foxes and blue foxes, while spermatogenic cells decreased with no sperm in the hybrids. Mean serum LH and prolactin concentrations in silver foxes and blue foxes were less and testosterone was greater than in the hybrids (P<0.05). The results indicate that germ cell meioses in the hybrids were arrested at the prophase stage of meiosis, and that lesser concentrations of testosterone and greater concentrations of LH and prolactin can inhibit the completion of spermatogenesis.

Blue foxes’ (Vulpes lagopus) motivation to gain access and interact with various resources

We analysed the willingness of blue foxes (Vulpes lagopus) to work for and utilise five resources: a platform, wooden block, sand floor, nest box and empty space. Ten juvenile blue fox males were housed singly in apparatus consisting of three cages connected with one-way doors through the walls in between the cages and subjected to work for each of the five resources, one at a time. The resource was placed in one of the outermost cages of the apparatus. Force needed to open the door leading to the resource cage was increased daily by 0.25 or 0.5kg. The number of daily entries, visit durations and interaction with the resource were recorded on workloads of 0, 0.5, 1.5, 2.5, 3.5, 5, 6.5, and 8kg of extra weight. The latency to start interacting with the resource after entering the resource cage was measured on a workload of 3.5kg. The mean number of daily entries in the resource and the other outermost, i.e. control cage varied from 7 to 28 and from 17 to 44, respectively. The increasing workload decreased the number of entries in the resource cage, increased those in the control cage (Linear Mixed Model: F1,638=79.5, P<0.001) and lengthened the visit durations in both cages (F1,642=7.2, P<0.01). The foxes made most (F4,643=9.0, P<0.001) and shortest (F4,641=2.8, P<0.05) visits to the outermost cages when the available resource was either a platform or empty space. The visit durations were longest when the available resource was a nest box. The foxes interacted regularly with the wooden block, but five foxes were not observed interacting with the platform. The nest box was utilised approximately 50% of the time spent in the resource cage, while the platform was utilised only 1–6% and wooden block 2–17% of the time. The mean latency to start interacting with the resource after entering the resource cage was shortest for the sand floor (8s) and longest for the platform (113s, F3,335=26.3, P<0.001). The results show that the foxes re-scheduled their activities on increasing workloads in the apparatus. Based on the number of entries and visit durations, blue foxes valued the wooden block, nest box and sand floor more than the platform or an empty cage. After entering the resource cage, the foxes started interacting fastest with the sand floor, showing high motivation to interact. After entering the resource cage, the foxes make use of the roof of the nest box more urgently than the interior of the nest box. Long bouts in the cage with nest box indicate resting behaviour.

Isolation and characterization of polymorphic microsatellite markers for blue fox (Alopex lagopus).

The blue fox, belonging to the family Canidae, is a coat color variant of the native arctic fox (Alopex lagopus). To date, microsatellite loci in blue fox are typically amplified using canine simple sequence repeat primers. In the present study, we constructed an (AC)n enrichment library, and isolated and identified 17 polymorphic microsatellite markers for blue fox. The number of alleles per locus is from two to seven based on 24 examined individuals. The expected and observed heterozygosities were in the range of 0.3112 to 0.8236 and 0.2917 to 0.8750, respectively. The polymorphic information content per locus ranged from 0.2583 to 0.8022. These polymorphic markers can be useful for future population genetic studies of both farmed blue foxes and wild arctic foxes.

De novo assembly and characterization of farmed blue fox (Alopex lagopus) global transcriptome using Illumina paired-end sequencing.

The blue fox (Alopex lagopus), a coat-color variant of the Arctic fox, is a domesticated fur-bearing mammal. In the present study, transcriptome data generated from a pool of nine different tissues were obtained with Illumina HiSeq2500 paired-end sequencing technology. After filtering from raw reads, 32,358,290 clean reads were assembled into 161,269 transcripts and 97,252 unigenes by the Trinity fragment assembly software. Of the assembled unigenes, 37,967 were annotated in the National Center for Biotechnology Information (NCBI) Non-Redundant (NR) protein database and 26,264 in the Swiss-Prot database. Among the annotated unigenes, 24,839 and 24,267 were assigned using the Gene Ontology (GO) and euKaryotic Orthologous Groups (KOG) databases, respectively. Altogether, 17,057 unigenes were mapped onto 227 pathways using the Kyoto Encyclopedia of Genes and Genomes database. In addition, 6394 simple sequence repeats were identified by examining 12,965 unigenes (>1 kb), which could contribute to the development of molecular markers. This study generated transcriptome data for the blue fox that will promote further progress in expression profiling studies, and provide a good annotation basis for genomic studies.

First report of Toxoplasma gondii Seroprevalence in Farmed Arctic Foxes (Vulpes lagopus) in Eastern and Northeastern China

Until now, no information on Toxoplasma gondii seroprevalence in Arctic foxes (Vulpes lagopus) was available in China. A serological survey was undertaken to assess T. gondii seroprevalence in farmed Arctic foxes in eastern and northeastern China. Antibodies to T. gondii were examined in 1346 farmed Arctic foxes using the modified agglutination test (MAT). A total of 113 (8.39%, 95% confidence interval [CI] 6.91-9.87) serum samples were positive to T. gondii at a 1:25 cutoff. Seroprevalence of T. gondii infection in male Arctic foxes was 8.68% (95% CI 6.75-10.6), which was higher than that in the female Arctic foxes (7.95%, 95% CI 5.65-10.26). The prevalence in polar foxes was 7.07% (95% CI 5.14-8.99), which was lower than that in the blue foxes (9.75%, 95% CI 7.49-11.99). T. gondii seroprevalence in Arctic foxes in Heilongjiang, Jilin, Liaoning, and Shandong Provinces was 9.85% (95% CI 5.75-13.95), 9.21% (95% CI 5.54-12.87), 7.37% (95% CI 5.22-9.51), and 8.68% (95% CI 5.66-11.70), respectively. There were no statistically significant differences between T. gondii seroprevalence and morphs, sex, or regions of Arctic foxes in logistic regression analysis (p < 0.05). The results of the present survey indicated that T. gondii infection in farmed Arctic foxes is prevalent in China. To our knowledge, this is the first report of T. gondii seroprevalence in Arctic foxes in China.

Genotyping of Enterocytozoon bieneusi in Farmed Blue Foxes (Alopex lagopus) and Raccoon Dogs (Nyctereutes procyonoides) in China.

Enterocytozoon bieneusi is the most common species of microsporidia found both in humans and animals. Farmed animals, particularly closely associated to humans, may play an important role of zoonotic reservoir in transmitting this disease to humans. The fur industry is a major economic component in some parts of China. To understand the prevalence, genotype variety and zoonotic risk of E. bieneusi in farmed foxes and raccoon dogs, two species of fur animals, fecal specimens of 110 blue foxes and 49 raccoon dogs from Heilongjiang and Jilin provinces in China were examined by internal transcribed spacer (ITS)-based PCR. E. bieneusi was detected in 16.4% (18/110) blue foxes and 4.1% (2/49) raccoon dogs. Altogether, four genotypes of E. bieneusi were identified, including two known genotypes D (n = 13) and EbpC (n = 5), and two novel genotypes named as CHN-F1 (n = 1) in a fox and CHN-R1 (n = 1) in a raccoon dog. Phylogenetic analysis revealed that all the four genotypes were the members of zoonotic group 1. Genotypes D and EbpC were found in humans previously. The findings of zoonotic genotypes of E. bieneusi in the foxes and raccoon dogs suggest these animals infected with E. bieneusi may pose a threat to human health.

Effects of dietary methionine supplementation on growth performance of cubs, nutrient digestibility, nitrogen metabolism and serum biochemical indicators of female blue foxes (Alopex lagopus).

The objective of the present study was to investigate the effects of methionine (Met) supplementation on growth performance of cubs, nutrient digestibility, nitrogen metabolism and serum biochemical parameters of female blue foxes. One hundred primiparous female blue foxes that were similar in breeding date, pedigree, age, and weight were selected for the trial. The foxes were randomly assigned to four groups (n = 25 each group) and fed diets supplemented with Met at 2 (Met2), 4 (Met4), 6 (Met6) and 8 g/kg (Met8), respectively, for 40 days. Our data showed that body weights at 20 and 40 d were significantly higher in the Met4 group than in the Met2 group (P < 0.05). The Met4 group also had the highest apparent digestibility of dry matter and crude protein compared with either the Met2, Met6, or Met8 group (P < 0.05). The serum Met and isoleucine (Ile) concentrations were significantly higher in the Met4 group than in the Met6 or Met8 group (P < 0.05). In summary, these data indicate that supplementary Met improves growth performance of cubs likely due to increased crude protein and dry matter and increased nitrogen retention of female blue foxes. The optimal amount of Met supplementation is 10 g/kg basal diet.

Breeding for better eye health in Finnish blue fox (Vulpes lagopus).

The frequency of eye infections in the Finnish blue fox population has increased during the past decade. Eye infection may incur economic losses to producers due to reduced selection intensity, but ethical aspects need to be considered as well because eye infection can be quite painful and reduce animal well-being. The purpose of this study was to determine the potential for genetic selection against susceptibility to eye infection. The data were collected from 2076 blue foxes at the MTT fur animal research station. Genetic parameters were estimated using single- and multiple-trait animal models. The heritability estimate for eye infection was analysed as a binary trait (EYE) and was moderate (0.24±0.07). EYE had a moderate antagonistic genetic correlation (-0.49±0.20) with grading density (thick underfur). The genetic correlation of EYE with grading size or body condition score was estimated without precision, but all size traits had a low antagonistic phenotypic correlation with EYE. Our results suggest that there is genetic variance in susceptibility to EYE, indicating that eye health can be improved through selection. The current recommendation is that the sick animals should be culled immediately. If more efficient selection is needed, the selection index and multiple-trait animal models can be applied in breeding for better eye health.

Effects of Dietary Copper and Zinc Supplementation on Growth Performance, Tissue Mineral Retention, Antioxidant Status, and Fur Quality in Growing-Furring Blue Foxes (Alopex lagopus).

A 4×2 factorial experiment with four supplemental levels of copper (0, 20, 40, or 60 mg copper per kg dry matter) from copper sulfate and two supplemental levels of zinc (40 or 200 mg zinc per kg dry matter) from zinc sulfate was conducted to investigate the effects of dietary copper and zinc supplementation on growth performance, tissue mineral retention, antioxidant status, and fur quality in growing-furring blue foxes. One hundred and twenty healthy 15-week-old male blue foxes were randomly allocated to eight dietary treatments with 15 replicates per treatment for a 70-day trial from mid-September to pelting in December. The average daily gain and feed conversion ratio were increased with copper supplementation in the first 35 days as well as the overall period (P<0.05). In addition, copper supplementation tended to increase feed intake during the first 35 days (P<0.10). Diets supplemented with 200 mg/kg zinc did not affect body gain (P>0.10) and feed intake (P>0.10) but improved feed conversion (P<0.05) compared with those supplemented 40 mg/kg zinc throughout the experiment. No copper×zinc interaction was observed for growth performance except that a tendency (P=0.09) was found for feed intake in the first 35 days. Supplementation of copper or zinc improved crude fat digestibility (P<0.01) but had no effects on the digestibility of other nutrients. Fecal copper was increased with both copper (P<0.01) and zinc addition (P<0.05). However, fecal zinc was affected only by dietary zinc addition (P<0.01). Mineral contents in serum and kidney were not affected by dietary treatments (P>0.05). However, the level of copper in the liver was increased with copper supplementation (P<0.05) and tended to decrease with zinc supplementation (P=0.08). Dietary zinc addition tended to increase the activity of alkaline phosphatase (P=0.07). The activities of copper-zinc superoxide dismutase and catalase tended to increase by copper (P=0.08) and zinc addition (P=0.05). Moreover, a copper×zinc interaction was observed for catalase in the experiment (P<0.05). Serum malondialdehyde concentration decreased with the increasing of dietary copper and zinc levels (P<0.05). The activity of glutathione peroxidase tended to increase by copper addition (P=0.09). For fur quality, foxes fed diets supplemented with high copper had larger skin length and darker pelts than those fed the basal diet without copper addition (P<0.05). In conclusion, this study demonstrated that dietary copper and zinc supplementation can improve growth by increasing feed intake and improving fat digestibility. Additionally, copper and zinc can enhance the antioxidant capacity of blue foxes. This study also indicates that additional zinc up to 200 mg/kg did not exert significant adverse effects on the copper metabolism of growing-furring blue foxes.

Application of Sequence-Characterized Amplified Regions to the Detection of Self-biting Behavior in the Blue Fox

Application of Sequence-Characterized Amplified Regions to the Detection of Self-biting Behavior in the Blue Fox

The complete mitochondrial genome sequence of Alopex lagopus (Caniformia: Canidae)

The phylogenetic and taxonomic positions of the blue fox (Alopex lagopus) have long been unclear. In this study, we determined and described the complete mitogenome sequence of A. lagopus for the first time, which is 16,629 bp in length and contains 37 genes, including 13 protein-coding genes, 2 rRNAs, 22 tRNAs, 1 origin of replication on the light-strand and a putative control region. The overall base composition is A: 31.3%, T: 27.8%, C: 26.1% and G: 14.8%, with a slight AT bias (59.1%). Most of them have TAA as the stop codon, except ND2 uses TAG, ND4 uses AGG, Cytb uses AGA and COX3 and ND3 use an incomplete stop codon TA. This information could not only contribute to provide useful molecular data for the species identification, but also to further taxonomic and phylogenetic studies of Alopex and Canidae.

A Study on Multi-Enriched Housing Environment in Blue Foxes

A traditional fox cage was furnished with both activating environmental enrichments (EE) (a bone, a scratching plate, a hockey buck, a ceiling rope and a wall rope and straw) and EEs enabling resting or observation (a wire-mesh platform and a top nest box). The aim was to find out to which extent blue foxes (Vulpes lagopus) utilized these EEs, and to collect practical experiences of the EEs. The experimental animals were 12 adult blue fox vixens that had been housed in cages furnished with a platform and a bone for about 1.5 years before they were transferred to the multi-enriched cages. The frequency and duration of the active contacts with the EEs were measured with continuous recording on Days 1, 2, 7 and 16 after the transfer, with three hours (13:30 - 14:30, 18:00 - 19:00 and 2:00 - 3:00) on each day. The total use of the EEs was 15 times per hour and more than 20% of the time. For most EEs both the time spent in contact and the frequency of contacts with the EEs declined steeply after Day 1, reflecting a novelty effect of the EEs. This decline was not so evident for the platform, top nest box and wall rope. These three EEs were also the ones used the most by the foxes. The ropes were badly damaged during the experiments, whereas other EEs remained in good condition. Explorativity markedly increased when animals were transferred from home cage to enriched cages. Explorativity remained high during entire study period when foxes were kept in enriched enrichment. Furthermore, it remained high also after transferring of animals back to home cages. Capture reaction was quite similar in home and enriched cages. The amount of stereotypy varied among recording days (P < 0.05). When foxes were transferred from home cages to multi-enriched cages, no change was found in the amount stereotypy during Days 1 and 2. Thereafter, the amount of stereotypy showed a declined trend. Stereotypy tended to increase when foxes were transferred back to home cages. Our results indicated that foxes used readily the opportunities for more diverse behaviours.

Foreleg Bending in Blue Foxes (&amp;lt;i&amp;gt;Vulpes lagopus&amp;lt;/i&amp;gt;) as Evaluated by Radiography

The aim was to compare radiographic X-ray data to foreleg bending, moving difficulties and body size in juvenile blue foxes. Experimental groups were: 1) restricted feeding, Ca:P ratio 1.5:1 (R 1); 2) restricted feeding, Ca:P ratio 2.9:1 (R 2); 3) restricted feeding Ca:P ratio 2.0:1 control level (R 3); 4) ad libitum feeding, Ca:P ratio 1.5:1 (AL 1); 5) ad libitum feeding, Ca:P ratio 2.9:1 (AL 2); 6) ad libitum feeding Ca:P ratio 2.0:1 control level (AL 3). Moving difficulties and foreleg bending were evaluated in live animals. At pelting, left foreleg was removed. X-ray pictures were taken from lateral views. Dimensions of ulna and radius were measured from the X-ray pictures. Conditions of carpal joint and elbow joint were visually evaluated. The results showed that final body weight was affected by feeding intensity (P = 0.001). Ad libitum fed animals had more moving difficulties compared to restricted ones (P = 0.001). The Ca:P ratio tended (P = 0.06) to have an effect on feet bending. Bending was greatest in low Ca:P ratio (1.5:1) and, correspondingly, least in high Ca:P ratio (2.9:1). Moving difficulties were most common in heaviest animals. The moving difficulties tended (P = 0.07) to be positively related to feet bending. Maximum width of ulna was lowest in low Ca:P ratio diet (1.5:1). Bending was negatively correlated with maximum width of ulna. It can be concluded that low Ca:P ratio in the diet (1.5:1) increases foreleg bending in juveniles. Moving difficulties are related to foreleg bending and high body weight.