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28
DARZI et al.
As the coccidial oocysts are shed with the faeces contaminating the environment, food and water
the rabbitʼs cages, food dishes and water containers need to be routinely disinfected. Avoidance of
stress and strict sanitary measures are thought to reduce or prevent clinical disease (Fox et al., 1984).
REFERENCES
Barriga O.O. 1997. The class Apicomplexa or Sporozoa. In:
Veterinary Parasitology for Practitioners, 2nd edition, Edina,
Minn: Burgess International Group, 76.1-26.4.
Benjamin M.M. 1981. Outline of Veterinary Clinical Pathology,
the Iowa State University Press Ames, Iowa, USA, 30.
Bhatia B.B. 2000. Textbook of Veterinary Protozoology. 1st edition.
Directorate of Information and Publication of Agriculture,
Indian Council of Agricultural Research, Krishi Anusandhan
Bhavan, Pusa, New Delhi, 178-180.
Chen C.M.C., Tsai L.C., Chung C.F., Han, S.H. 1972. Basement
membrane in hepatic coccidiosis of rabbits. 1. Camp. Pathol.
82, 59-63.
Flynn R.J. 1973. Protozoans and neosporans. In: Parasites of
Laboratory Animals, Ames, Iowa, Iowa State University Press,
54-56.
Fox J.G., Cohen B.J., Loew F.M. 1984. Laboratory Animal Medicine.
Academic Press Inc. (London) Ltd., 222-224.
Frebourg T., Delpech B., Bercoff E., Senant J., Bertrand P., Deugnier
Y., Bourreille J. 1986. Serum hyaluronate in liver diseases:
study by enzymoimmunological assay. Hepatology 6, 392-405.
Gardiner G.H., Fayer R., Dubey J.P. 1998. Apicomplexa. In: An Atlas
of Protozoan Parasites in Animal Tissues, 2nd edition, Armed
Forces Institute of Pathology, Washington, DC., 20-30.
Georgi J.R., Georgi M.E. 1990. Protozoans. In: Parasitology for
Veterinarians, 5th edition, W.B. Saunders, Philadelphia, 34-
87.
George J., Tsutsumi M., Takase S. 2004 Expression of hyaluronic
acid in N-nitrosodimethylamine induced hepatic fibrosis in
rats. Int. J Biochem. Cell Biol. 36, 307-319.
Giacometti L., Parakkal P.F. 1969. Skin transplantation:
Orientation of epithelial cells by the basement membrane.
Nature, 223, 514-515.
Gupta V.K. 2005 Pathology of naturally occurring rabbit diseases
in Himachal Pradesh. In: Souvenir-XXII Annual Convention
of Indian Association of Veterinary Pathologists and
National Symposium on Newer Concepts in Animal and Avian
Disease Diagnosis-A Farmer, Industry and Institutional
Dialogue and a satellite Seminar on Principles of
Histological Basis of Gross Pathology of CL Davis DVM
Foundation, USA. November. 193-204.
John N.M., Zea M.E., Kawano T., Omata Y., Saito A., Toyoda Y.,
Milkano T. 1999. Identification of carbohydrates on Eimeria
stiedae sporozoites and their role in the invasion of cultured
cells in vitro. Vet. Parasitol, 81, 99-105.
Levine N.D. 1985. Apicomplexa- The Coccidia Proper. In:
Veterinary Protozoology, Iowa State University Press, Ames,
Iowa, 130-138, 178, 221-222.
Luna L.G. 1968. Manual of Histologic Staining Methods of the
Armed Forces Institute of Pathology, 3rd edition. McGraw-Hill
Book Company, New York, USA, 38-39, 94-95, 168-169.
Mc Manus J.F.A. 1946. Histopathological demonstration of mucin
after periodic acid. Nature (London), 158, 202, in: BANCRAFT,
JD. and GAMBLE, M (ed), 2002.Theory and practice of
histopathological techniques, 5th edn, Churchill Livingstone,
London, Edinburgh, New York, Philadelphian, St. Louis,
Sydney, Toronto, 175.
Murawaki Y., Ikuta Y., Koda M., Nishimura Y., Kawasaki H. 1996.
Clinical significance of serum hyaluronan in patients with
chronic viral liver disease. J Gastroenterol. Hepatol. 11, 459-
465.
Peres A., Deulofeu R., Gimenez A., Caballeria L., Bruguera M.,
Caballeria J., Ballesta A.M., Rodes J. 1996. Serum hyaluronate
reflects hepatic fibrogenesis in alcoholic liver disease and is
useful as a marker of fibrosis. Hepatology 24, 1399-1403.
Urquhart G.M., Armour J., Duncan J.L., Dunn A.M., Jennings F.W.
1987. Phylum Protozoa. In: Veterinary Parasitology,
Churchill Livingstone, New York, 218-220.
Varga I. 1982. Large scale management systems and parasite
populations: coccidian in rabbits. Vet. Parasitol. 11, 69-84.
29
World Rabbit Sci. 2007, 15: 29 - 36
© WRSA, UPV, 2007
Received July 2006 - Accepted December 2006.
ABSTRACT:Four experiments are described relating to gnawing sticks application in rabbit housing. In experiment 1
and 2, Pannon White rabbits, weaned at the age of five weeks, were placed into pens with wire net floor. In
experiment 1, every pen (180 animals in 12 pens, surface per head: 571 cm2) was provided with three gnawing
sticks randomly chosen from White locust, Black elder, White willow, Little-leaf linden, European larch, Black poplar,
European white birch, White buckeye and White mulberry species. In experiment 2 (150 animals in 10 pens, surface
per head: 571 cm2), only those tree species ingested by rabbits in the first experiment were used (White locust,
White willow, Little-leaf linden, Black poplar and White buckeye). In the second experiment, rabbits showed the
highest preference towards gnawing sticks of Little-leaf linden, while similar White willow and White buckeye
consumption was observed. In the experiment 3, rabbits’ preference to different types of wood and the influence
on rabbits’ behaviour of added wooden sticks as environmental enrichment was studied. At the age of 38 days,
48 male SIKA rabbits were housed individually in wire cages (surface per head: 1500 cm2). According to the type
of wood placed in the cage, rabbits were equally allotted to four groups: control, Common oak, Little-leaf linden and
Norway spruce. Rabbits’ preference to type of wood was studied on all the animals with wooden stick, while
rabbits’ behaviour was studied on 16 focus animals at the age of 5 and 13 weeks using continuous 24 hours video
recordings. Rabbits preferred gnawing Little-leaf linden and Norway spruce compared to Common oak. Addition of
gnawing sticks had no significant influence on duration of rabbits’ behaviour, except for eating feed and gnawing
wooden stick time. In experiment 4, the effect of housing and environmental enrichment on the performance and
behaviour of growing rabbits was tested. 72 hybrid rabbits were housed after the weaning period in standard
fattening cages at 2, 3, 4 animals per cage (surface per head: 1045 cm 2, 697 cm2, 522 cm2
,respectively). Half cages
were enriched using a wood stick (Robinia pseudoacacia) dangling from the ceiling of the cage. The environmental
enrichment decreased the stereotypies (gnawing the bars of the cage). A tendency to lower aggressive behaviours
in enriched caged rabbits was also found compared to the conventional caged rabbits. This might indicate a better
satisfaction of the behavioural needs for the enriched caged rabbits.
Key words: Growing rabbits, gnawing sticks, tree species, performance, behavioural traits.
WW
WW
WO R L DO R L D
O R L DO R L D
O R L D
RR
RR
RABBITABBIT
ABBITABBIT
ABBIT
SS
SS
SCIENCECIENCE
CIENCECIENCE
CIENCE
APPLICATION OF GNAWING STICKS IN RABBIT HOUSING
Princz Z.*, Orova Z.*, Nagy I.*, Jordan D.†, Štuhec I†, Luzi F.‡, Verga M.‡, SzendrőZs.*
*Univ. of Kaposvar, Faculty of Animal Science, KAPOSVÁR, Hungary.
†Univ. of Ljubljana, Biotechnical Faculty, Dep. of Animal Science, DOMžALE, Slovenia.
‡Univ. of Milan, Faculty of Veterinary Medicine, Animal Husbandry Inst., MILANO, Italy.
INTRODUCTION
During the recent years increasing importance was attached to the analysis of the rabbitsʼ welfare.
Several forms of environmental enrichment were tested in the conventional low level of stimulus
cage system. Gnawing sticks were frequently placed into the rabbit cages (Hansen et a l., 2000; Luzi
et al., 2003; Princz et al., 2005) and their effect on the performance and behaviour was recorded.
Several authors (Lidfors, 1997; Jordan and Štuhec, 2003; Verga et al., 2004) defined the species of the
applied gnawing sticks, but the exact tree species are not always given. Some suggestions were
published about the recommended tree species by Ernte (www.ernte.at): apple, ash, willow, spruce,
oak, however, they suggest the placement of leafy branches. In the present study some consequences
when placing gnawing sticks in rabbit housing are shown.
30
PRINCZ et al.
MATERIALS AND METHODS
Experiment 1 and 2 were carried out at the University of Kaposvár using Pannon White rabbits.
Animals were placed into pens (1.71×0.50 m2; 15 rabbits per pen; surface per head: 571 cm2) with wire
net floor in closed air-conditioned rabbitry. Experiments lasted between the age of 5-11 weeks. During
the experiments the room temperature was 18 °C and the daily lighting was 16 hours. Rabbits were fed
a commercial pellet ad libitum between the age of 5-9 (10.3 MJ digetible energy (DE)/kg, 14.5% crude
protein, 2.0% fat, 17.5% crude fibre, 50 ppm Tiamulin, 500 ppm Oxitetracycline, 1 ppm Diclazuril) and
9-11 (10.6 MJ DE/kg, 16.0% crude protein, 3.0% fat, 16.0% crude fibre) weeks. Water was available ad
libitum from nipple drinkers. The feeder was placed on the wall of the cage; the two drinkers were put
on the opposite side (1.71 m from the feeder). After stripping the bark off, the gnawing sticks were
placed horizontally 20 cm high on the wall of the adjacent pens (Figure 1).
In experiment 1 (n=180 rabbits in 12 pens) every pen was provided with three gnawing sticks randomly
chosen from White locust (Robinia pseudoacacia), Black elder (Sambucus nigra), White willow
(Salix alba), Little-leaf linden (Tilia cordata), European larch (Picea abies), Black poplar (Populus
nigra), European white birch (Betula pendula), White buckeye (Aesculus hippocastanum) and
White mulberry (Morus alba) species (with a diameter of 3 cm and length of 20 cm). During the trial
the preference of the rabbits (ingested vs. rejected species) was monitored to choice the main accepted
species for examing their ingestion.
In experiment 2 (n=150 rabbits in 10 pens) only those gnawing sticks (tree species) were used that
were ingested by the rabbits in the first experiment (White locust, White willow, Little-leaf linden,
Black poplar and White buckeye). Every pen was applied with 3 gnawing sticks of different species
(using all possible combinations). Size of the stick was the same as in the preceding trial. Prior to
their placement into the cages the volumes of the gnawing sticks were determined by inserting them
into a glass cylinder filled with water. Gnawing sticks fully ingested during the experiment were
replaced. Gnawing stick consumption was determined (in cm3) from the volume differences measured
at the beginning and at the end of the experiment. The data of gnawing stick ingestion per pen
(experiment 2) were evaluated by one way analysis of variance using SPSS 10.0 software package
(SPSS, 1999).
Experiment 3 was carried out at the University of Ljubljana and lasted nine weeks, namely between
the rabbitsʼ age of 38 to 94 days. It included 48 male New Zealand White rabbits of Slovenian male
line SIKA. Animals were housed individually in wire cages sized 37.5×40×30 cm, equipped with a
feeder and nipple drinker. The rabbits were fed ad libitum with the complete feed mixture for fattening
rabbits (10.4 MJ DE/kg, 17% crude protein, 14% crude fibre, 2% fat). 12 hours light:12 hours dark
Figure 1. Placement of gnawing stick on the wall of pen (experiment 1 and 2).
31
GNAWING STIC K FOR RABBITS
schedule was used, with the lights on from 6:00 am to 6:00 pm. During the experiment ambient
temperature and relative humidity varied from 21 to 25°C and 35 to 57%, respectively. Right after the
individual housing animals were allotted to four groups, each containing 12 rabbits, according to the
type of wooden stick (dimensions: 2.1×4.4×50.3 cm) fixed horizontally right under the upper side of
the rabbitʼs cage. For gnawing material the first group received Common oak (Qercus robur), the
second Little-leaf linden (Tilia cordata), and the third Norway spruce (Picea abies) sticks. The
control group was left without wooden sticks.
To establish the amount of gnawed wood, wooden sticks were weighed once a week. During the
experiment it was observed that the relative humidity of the wood was changing with regard to
relative humidity of the air in the rabbitry, which caused oscillation in the weight of wooden sticks.
For this reason it was impossible to determine the amount of gnawed wood from the weight of the
wooden stick, therefore it was determined on the basis of 5 grades of visual evaluation (1 - visible
marks of teeth or completely intact, 2 – slightly gnawed, 3 – moderately gnawed, 4 – severely gnawed,
5 – extremely gnawed).
To determine the influence of different type of wooden stick on rabbitsʼ behaviour, 16 focus animals
(4 from each group) were recorded for 24 hours by infrared video camera (WV-BP330/Panasonic) in
the first and the last experimental week. Recordings were analysed by two observers with the
“Observer 4.1” program (Noldus), during which the duration of the behavioural elements was
continually registered. Activities of rearing up (sitting with forepaws lifted from the floor), eating
feed, drinking, caecotrophy, biting wire and feeder, wood gnawing, grooming, sniffing, hopping,
stretching, inactivity, and contact with the neighbour rabbit were observed, but in this study only
the results for behaviours important from the rabbitsʼ welfare point of view (biting wire and feeder)
and those, where there was a trend or significant difference between groups (inactivity, eating feed,
wood gnawing) are presented in detail. Statistical data analysis was conducted using statistical
program package SAS (2001). Data were not normally distributed and were therefore analysed with
nonparametric Wilcoxon rank-sum test with Bonferroni-Holms correction for multiple comparison of
groups.
Experiment 4 was carried out in a commercial farm located in North West of Italy. Over the trial, the
room temperature was about 15 °C and the daily lighting was 16 hours. 72 hybrids rabbits were
housed in standard cages with the same dimension during the gnawing period from 35 to 75 days of
age. The animals were housed in 2, 3 or 4 per cage (surface per head: 1045 cm2, 697 cm2 and 522 cm2,
respectively). Half cage were enriched using a Black locust stick (Robinia pseudoacacia) 24 cm
length and 8 cm of diameter, hanging from the ceiling of the cage, to study the effect of the
environmental enrichment. Animals were fed ad libitum a commercial feed (9.62 MJ DE/kg, 15.8%
crude protein, 3.0% fat, 16.5% crude fibre from 35 till 50 days of age; 10.25 MJ DE/kg, 16.5% crude
protein, 3.5% fat, 16.0% crude fibre from 50 days of age till slaughtering). Weight and daily weight
gain were recorded at weaning (35 days of age), at 53 days of age and at slaughter (75 days of age).
Behaviours were video recorded at the beginning (1st period) and at the end of the fattening period
(2nd period), for 24 hours each period, using 3 cameras connected to a Multiplexer and VCR tape
recorder. Thus each cage was observed for 48 hours in total. Behaviour was recorded using a scan
sampling method (Martin and Bateson, 1993) every 10 min during the whole observation time (288
scans per image). The following behaviours were recorded: lying, lying stretched, sniffing another
rabbit, sniffing the object, self and allo-grooming, movement, drinking, eating feed, caecotrophy,
hopping, standing, gnawing the bars of the cage, gnawing the wood stick, motor stereotypies,
aggressive behaviours. The following behaviours were performed very seldom, so they were excluded
form the analysis: lying, lying stretched, sniffing the object, self-grooming, movement, drinking,
30
PRINCZ et al.
MATERIALS AND METHODS
Experiment 1 and 2 were carried out at the University of Kaposvár using Pannon White rabbits.
Animals were placed into pens (1.71×0.50 m2; 15 rabbits per pen; surface per head: 571 cm2) with wire
net floor in closed air-conditioned rabbitry. Experiments lasted between the age of 5-11 weeks. During
the experiments the room temperature was 18 °C and the daily lighting was 16 hours. Rabbits were fed
a commercial pellet ad libitum between the age of 5-9 (10.3 MJ digetible energy (DE)/kg, 14.5% crude
protein, 2.0% fat, 17.5% crude fibre, 50 ppm Tiamulin, 500 ppm Oxitetracycline, 1 ppm Diclazuril) and
9-11 (10.6 MJ DE/kg, 16.0% crude protein, 3.0% fat, 16.0% crude fibre) weeks. Water was available ad
libitum from nipple drinkers. The feeder was placed on the wall of the cage; the two drinkers were put
on the opposite side (1.71 m from the feeder). After stripping the bark off, the gnawing sticks were
placed horizontally 20 cm high on the wall of the adjacent pens (Figure 1).
In experiment 1 (n=180 rabbits in 12 pens) every pen was provided with three gnawing sticks randomly
chosen from White locust (Robinia pseudoacacia), Black elder (Sambucus nigra), White willow
(Salix alba), Little-leaf linden (Tilia cordata), European larch (Picea abies), Black poplar (Populus
nigra), European white birch (Betula pendula), White buckeye (Aesculus hippocastanum) and
White mulberry (Morus alba) species (with a diameter of 3 cm and length of 20 cm). During the trial
the preference of the rabbits (ingested vs. rejected species) was monitored to choice the main accepted
species for examing their ingestion.
In experiment 2 (n=150 rabbits in 10 pens) only those gnawing sticks (tree species) were used that
were ingested by the rabbits in the first experiment (White locust, White willow, Little-leaf linden,
Black poplar and White buckeye). Every pen was applied with 3 gnawing sticks of different species
(using all possible combinations). Size of the stick was the same as in the preceding trial. Prior to
their placement into the cages the volumes of the gnawing sticks were determined by inserting them
into a glass cylinder filled with water. Gnawing sticks fully ingested during the experiment were
replaced. Gnawing stick consumption was determined (in cm3) from the volume differences measured
at the beginning and at the end of the experiment. The data of gnawing stick ingestion per pen
(experiment 2) were evaluated by one way analysis of variance using SPSS 10.0 software package
(SPSS, 1999).
Experiment 3 was carried out at the University of Ljubljana and lasted nine weeks, namely between
the rabbitsʼ age of 38 to 94 days. It included 48 male New Zealand White rabbits of Slovenian male
line SIKA. Animals were housed individually in wire cages sized 37.5×40×30 cm, equipped with a
feeder and nipple drinker. The rabbits were fed ad libitum with the complete feed mixture for fattening
rabbits (10.4 MJ DE/kg, 17% crude protein, 14% crude fibre, 2% fat). 12 hours light:12 hours dark
Figure 1. Placement of gnawing stick on the wall of pen (experiment 1 and 2).
31
GNAWING STIC K FOR RABBITS
schedule was used, with the lights on from 6:00 am to 6:00 pm. During the experiment ambient
temperature and relative humidity varied from 21 to 25°C and 35 to 57%, respectively. Right after the
individual housing animals were allotted to four groups, each containing 12 rabbits, according to the
type of wooden stick (dimensions: 2.1×4.4×50.3 cm) fixed horizontally right under the upper side of
the rabbitʼs cage. For gnawing material the first group received Common oak (Qercus robur), the
second Little-leaf linden (Tilia cordata), and the third Norway spruce (Picea abies) sticks. The
control group was left without wooden sticks.
To establish the amount of gnawed wood, wooden sticks were weighed once a week. During the
experiment it was observed that the relative humidity of the wood was changing with regard to
relative humidity of the air in the rabbitry, which caused oscillation in the weight of wooden sticks.
For this reason it was impossible to determine the amount of gnawed wood from the weight of the
wooden stick, therefore it was determined on the basis of 5 grades of visual evaluation (1 - visible
marks of teeth or completely intact, 2 – slightly gnawed, 3 – moderately gnawed, 4 – severely gnawed,
5 – extremely gnawed).
To determine the influence of different type of wooden stick on rabbitsʼ behaviour, 16 focus animals
(4 from each group) were recorded for 24 hours by infrared video camera (WV-BP330/Panasonic) in
the first and the last experimental week. Recordings were analysed by two observers with the
“Observer 4.1” program (Noldus), during which the duration of the behavioural elements was
continually registered. Activities of rearing up (sitting with forepaws lifted from the floor), eating
feed, drinking, caecotrophy, biting wire and feeder, wood gnawing, grooming, sniffing, hopping,
stretching, inactivity, and contact with the neighbour rabbit were observed, but in this study only
the results for behaviours important from the rabbitsʼ welfare point of view (biting wire and feeder)
and those, where there was a trend or significant difference between groups (inactivity, eating feed,
wood gnawing) are presented in detail. Statistical data analysis was conducted using statistical
program package SAS (2001). Data were not normally distributed and were therefore analysed with
nonparametric Wilcoxon rank-sum test with Bonferroni-Holms correction for multiple comparison of
groups.
Experiment 4 was carried out in a commercial farm located in North West of Italy. Over the trial, the
room temperature was about 15 °C and the daily lighting was 16 hours. 72 hybrids rabbits were
housed in standard cages with the same dimension during the gnawing period from 35 to 75 days of
age. The animals were housed in 2, 3 or 4 per cage (surface per head: 1045 cm2, 697 cm2 and 522 cm2,
respectively). Half cage were enriched using a Black locust stick (Robinia pseudoacacia) 24 cm
length and 8 cm of diameter, hanging from the ceiling of the cage, to study the effect of the
environmental enrichment. Animals were fed ad libitum a commercial feed (9.62 MJ DE/kg, 15.8%
crude protein, 3.0% fat, 16.5% crude fibre from 35 till 50 days of age; 10.25 MJ DE/kg, 16.5% crude
protein, 3.5% fat, 16.0% crude fibre from 50 days of age till slaughtering). Weight and daily weight
gain were recorded at weaning (35 days of age), at 53 days of age and at slaughter (75 days of age).
Behaviours were video recorded at the beginning (1st period) and at the end of the fattening period
(2nd period), for 24 hours each period, using 3 cameras connected to a Multiplexer and VCR tape
recorder. Thus each cage was observed for 48 hours in total. Behaviour was recorded using a scan
sampling method (Martin and Bateson, 1993) every 10 min during the whole observation time (288
scans per image). The following behaviours were recorded: lying, lying stretched, sniffing another
rabbit, sniffing the object, self and allo-grooming, movement, drinking, eating feed, caecotrophy,
hopping, standing, gnawing the bars of the cage, gnawing the wood stick, motor stereotypies,
aggressive behaviours. The following behaviours were performed very seldom, so they were excluded
form the analysis: lying, lying stretched, sniffing the object, self-grooming, movement, drinking,
32
PRINCZ et al.
eating feed, caecotrophy, hopping, standing, gnawing the wood stick and motor stereotypies. Data
were evaluated by Analysis of Variance using SAS package (2001)placing environmental enrichment
and housing as main effects. Behaviours were also analysed by the Principal Component Analysis
(PCA, Todeschini, 1998), and by their frequencies, according to the considered independent variables.
An overview about the experiments is presented in Table 1.
RESULTS
Based on the results of experiment 1 rabbits showed preference towards White locust, White willow,
Little-leaf linden, Black poplar and White buckeye as they consumed the gnawing sticks of these
species in various amount. Black elder, European larch, European white birch and White mulberry
species were rejected as no ingestion of these species could be observed (regardless of the different
combinations).
Table 1: Overview of the experiments
Experiment
1 2 3 4
Country Hungary Hungary Slovenia Italy
Breed Pannon White Pannon White SIKA Hybrid
Age (days) 35-77 35-77 38-94 35-75
No. of rabbits 180 150 48 72
No. of rabbits per
placing unit 15 12 1 2-3 or 4
Surface per head (cm2) 571 571 1500 522-1045
Temperature (ºC) 18 18 21-25 15
Daily lighting (hours) 16 16 12 16
Applied gnawing stick
species
White locust, Black
elder, White willow,
Little- leaf linde n,
European larch, Black
poplar, Europen white
birch, White buckeye,
White mulberry
White locust, White
willow, Little -lea f
linden, Black poplar,
White buckeye
Co mmon oak, Little-
leaf lind en, Nor wa y
spruce
Black locust
Examined behaviour Preference Consumption
Biting wire and feeder,
Inactivity, Eating feed,
Stick gnawing
Sniffing another rabbit,
A l l o - g r o o m i n g ,
Gna wing th e ca ge ,
Aggressive behaviour
Statistical method Analysis of variance Analysis of variance Wilcoxon rank-sum test Principal component
analysis
Table 2: Consumption of gnawing stick depending on the tree species (Experiment 2)
Consumption Species SE P-value
Little-leaf linden White willow White buckeye Black popular White locust
Per pen, cm3(35-77 d) 278c132b128b7a3a23.9 0.001
Per rabbit, cm3(per day) 0.44 0.21 0.20 0.01 0.005 - -
Means in a row with different superscripts indicate significant differences (P<0.05).
33
GNAWING STIC K FOR RABBITS
According to experiment 2 (Table 2) the rabbits showed the highest preference towards Little-leaf
linden gnawing sticks, while similar amount of White willow and White buckeye ingestion was
experienced. The gnawing stick consumption of White locust and Black poplar was relatively small.
In experiment 3 rabbits showed significantly higher preference to Little-leaf linden and Norway
spruce sticks than to Common oak sticks (Table 3). The average score of gnawed wood was almost
the same for Little-leaf linden and Norway spruce gnawing sticks (2.95 and 2.77) although Little-leaf
linden sticks received more often grade 5 (extremely gnawed) than Norway spruce sticks (Figure 2),
where the amount of gnawed wood was most often evaluated with grade 3 (moderately gnawed).
Common oak sticks were almost all intact. Enrichment of cages with different types of wooden sticks
had no significant influence on duration of observed behaviours, except eating feed and wood
gnawing (Table 3). Rabbits with Norway spruce sticks ate feed significantly less time than rabbits in
Common oak group. Rabbits spent significantly greater percentage of time gnawing Little-leaf linden
and Norway spruce sticks in comparison with Common oak sticks. Difference in duration of wood
gnawing between Norway spruce and Little-leaf linden group was not significant, although mean
Frequency (%)
Figure 2: Distribution of the grade
of gnawed wood (Experiment 3)
0
10
20
30
40
50
60
70
80
90
100
1 1.5 2 2.5 3 3.5 4 4.5 5
Grade
Common oak
Little - leaf linden
N
o
Table 3: Grade of gnawed wood and the influence of environmental enrichment on mean duration
(percentage per hour) of rabbits' behaviours (Experiment 3)
Group P-value
Control Common oak Little-leaf linden Norway spruce
Grade of gnawed wood1- 1.0a2.95b2.77b0.0021
Behaviour, %
Inactivity 60.15 56.37 55.69 59.79 0.0580
Eating feed 7.99ab 8.49a7.86ab 6.91b0.0342
Biting wire and feeder 1.62 2.16 1.15 1.21 0.8759
Wood gnawing - 0.00a0.01b0.21b0.0005
Means in a row with different superscripts indicate significant differences (P<0.05). 1Five grades of visual evaluation from
1=visible marks of teeth or completely intact to 5=extremely gnawed.
32
PRINCZ et al.
eating feed, caecotrophy, hopping, standing, gnawing the wood stick and motor stereotypies. Data
were evaluated by Analysis of Variance using SAS package (2001)placing environmental enrichment
and housing as main effects. Behaviours were also analysed by the Principal Component Analysis
(PCA, Todeschini, 1998), and by their frequencies, according to the considered independent variables.
An overview about the experiments is presented in Table 1.
RESULTS
Based on the results of experiment 1 rabbits showed preference towards White locust, White willow,
Little-leaf linden, Black poplar and White buckeye as they consumed the gnawing sticks of these
species in various amount. Black elder, European larch, European white birch and White mulberry
species were rejected as no ingestion of these species could be observed (regardless of the different
combinations).
Table 1: Overview of the experiments
Experiment
1 2 3 4
Country Hungary Hungary Slovenia Italy
Breed Pannon White Pannon White SIKA Hybrid
Age (days) 35-77 35-77 38-94 35-75
No. of rabbits 180 150 48 72
No. of rabbits per
placing unit 15 12 1 2-3 or 4
Surface per head (cm2) 571 571 1500 522-1045
Temperature (ºC) 18 18 21-25 15
Daily lighting (hours) 16 16 12 16
Applied gnawing stick
species
White locust, Black
elder, White willow,
Little- leaf linde n,
European larch, Black
poplar, Europen white
birch, White buckeye,
White mulberry
White locust, White
willow, Little -lea f
linden, Black poplar,
White buckeye
Co mmon oak, Little-
leaf lind en, Nor wa y
spruce
Black locust
Examined behaviour Preference Consumption
Biting wire and feeder,
Inactivity, Eating feed,
Stick gnawing
Sniffing another rabbit,
A l l o - g r o o m i n g ,
Gna wing th e ca ge ,
Aggressive behaviour
Statistical method Analysis of variance Analysis of variance Wilcoxon rank-sum test Principal component
analysis
Table 2: Consumption of gnawing stick depending on the tree species (Experiment 2)
Consumption Species SE P-value
Little-leaf linden White willow White buckeye Black popular White locust
Per pen, cm3(35-77 d) 278c132b128b7a3a23.9 0.001
Per rabbit, cm3(per day) 0.44 0.21 0.20 0.01 0.005 - -
Means in a row with different superscripts indicate significant differences (P<0.05).
33
GNAWING STIC K FOR RABBITS
According to experiment 2 (Table 2) the rabbits showed the highest preference towards Little-leaf
linden gnawing sticks, while similar amount of White willow and White buckeye ingestion was
experienced. The gnawing stick consumption of White locust and Black poplar was relatively small.
In experiment 3 rabbits showed significantly higher preference to Little-leaf linden and Norway
spruce sticks than to Common oak sticks (Table 3). The average score of gnawed wood was almost
the same for Little-leaf linden and Norway spruce gnawing sticks (2.95 and 2.77) although Little-leaf
linden sticks received more often grade 5 (extremely gnawed) than Norway spruce sticks (Figure 2),
where the amount of gnawed wood was most often evaluated with grade 3 (moderately gnawed).
Common oak sticks were almost all intact. Enrichment of cages with different types of wooden sticks
had no significant influence on duration of observed behaviours, except eating feed and wood
gnawing (Table 3). Rabbits with Norway spruce sticks ate feed significantly less time than rabbits in
Common oak group. Rabbits spent significantly greater percentage of time gnawing Little-leaf linden
and Norway spruce sticks in comparison with Common oak sticks. Difference in duration of wood
gnawing between Norway spruce and Little-leaf linden group was not significant, although mean
Frequency (%)
Figure 2: Distribution of the grade
of gnawed wood (Experiment 3)
0
10
20
30
40
50
60
70
80
90
100
1 1.5 2 2.5 3 3.5 4 4.5 5
Grade
Common oak
Little - leaf linden
N
o
Table 3: Grade of gnawed wood and the influence of environmental enrichment on mean duration
(percentage per hour) of rabbits' behaviours (Experiment 3)
Group P-value
Control Common oak Little-leaf linden Norway spruce
Grade of gnawed wood1- 1.0a2.95b2.77b0.0021
Behaviour, %
Inactivity 60.15 56.37 55.69 59.79 0.0580
Eating feed 7.99ab 8.49a7.86ab 6.91b0.0342
Biting wire and feeder 1.62 2.16 1.15 1.21 0.8759
Wood gnawing - 0.00a0.01b0.21b0.0005
Means in a row with different superscripts indicate significant differences (P<0.05). 1Five grades of visual evaluation from
1=visible marks of teeth or completely intact to 5=extremely gnawed.
3 4
PRINCZ et al.
values differed substantially. In the enriched cages a trend of decrement of inactivity (P=0.058) was
noticed, but in wire and feeder biting no significant decrement was observed.
In experiment 4, the effects of presence of a wood stick inside the cage and of the housing systems
(2, 3, 4 animal per cage) were not statistically significant on the rabbit performance. Weight gain
between 35 and 75 days and body weight at 75 days of age were not affected by treatment. The
means of these traits were between 38.0 and 39.5 g/day, and 2540 and 2626 g, respectively. As far as
the behaviour is concerned, the enriched caged rabbits performed significantly more allo-grooming
and sniffing the other rabbits, while the control animals performed significantly more gnawing the
bars of the cage. A trend was also found in these latter rabbits to show higher alert and aggressive
behaviours (Figure 3).
DISCUSSION
The highest level of gnawing stick consumption was observed for Little-leaf linden. Considerable
amount of consumption was found for White buckeye and White willow. All these species are soft
(hardness) (Kovács, 1979). The mechanical and chemical characteristics of the tree species (hardness,
smell and taste) may determine which of the investigated species is suitable for gnawing stick.
Consumption of White locust and Black poplar was small. The White locust is a tough tree and has
indelicate fibres that may explain its consumption level. Although Black poplar is a soft tree its
consumption was also small. According to rabbitsʼpreference for wood species, the results of the
experiment 3 were quite similar to results of experiment 2. Rabbits preferred sticks made of Little-leaf
linden and Norway spruce wood compared to Common oak. The possible reason of this finding
could be, as in experiment 2, mechanical and chemical characteristics of used three species. Common
oak is very dense and hard in comparison with Norway spruce and Little-leaf linden (Čermak, 1998;
Pipa, 1990) and it also contains a large amount of tannin, about 10% (Pipa, 1990). Occupation of
rabbits with environmental enrichment did not significantly reduced animalsʼinactivity, as it was
reported in several studies investigating environmental enrichment (Metz, 1987; Huls et al., 1991). In
neither group was observed any significant decrement of biting wire and feeder, which is one of the
0%
1%
2%
3%
4%
5%
6%
7%
8%
Sniffing other
rabbits
Allo-
Grooming
Agressiveness Alert Gnawing bars
of the the cage
Environmental
Enrichment
Control
**
**
n.s
*
n.s
Figure 3: Behaviour of rabbits with and without environmental enrichment. (Average values - % of total
scans) (Experiment 4).
35
GNAWING STIC K FOR RABB ITS
most common behavioural abnormalities in cage systems (Gunn and Morton, 1995; Laboratory Animals,
1993; Love, 1994). This last result is surprising as studies using different kind of environmental
enrichment reported significant decrement of these kinds of behaviours (Lidfors, 1997; Jordan et al.,
2003).
Contrary to experiment 3, in experiment 4 the environmental enrichment affected the behaviour (but
not the rabbitsʼ performance). It significantly increased social activities, such as sniffing the other
rabbit and allo-grooming. On the contrary, it decreased the behaviour of gnawing the bars of the
cage, which may be an oral stereotypy, as well a trend was found to decreased alert and aggressive
behaviours. The growth and carcass traits were not statistically significantly affected by environmental
enrichment in agreement with other previous results (Luzi et al., 2002). These results support that
environmental enrichment and housing have no effect on the production of the rabbits.
CONCLUSIONS
Based on our results the following suggestions can be made:
a) Unsuitable for gnawing stick: Black elder, European larch, European white birch tree, White mulberry
and Common oak.
b) Suitable for environment enrichment: Black poplar and White locust tree.
c) Suitable for gnawing stick: White willow, White buckeye, Little-leaf linden and Norway spruce.
d) Our results can be utilised in further experiments connected with the gnawing stick application
and determining the suitable tree species.
Housing and environmental enrichment did not affect significantly the growth rate contrary to some
rabbit behaviours. However in this case the results are not always consistent. In fact in experiment 3
the addition of wooden stick as environmental enrichment did not decrease wire and feeder biting,
which is one of the most common behavioural abnormalities in cage systems. The type of wood
significantly influenced only the duration of feed eating. On the contrary, in experiment 4 environmental
enrichment significantly decreased gnawing the bars of the cage and increased some social behaviours,
such as sniffing the other rabbit and allo-grooming. A trend was shown also to reduced, alert and
aggressive behaviours. Thus further research is needed in order to understand how environmental
enrichement may affect rabbitsʼbehaviour, possibly reducing oral stereotypies and increasing the
behavioural repertoire.
REFERENCES
Čermak M. 1998. Tehnologija lesa 1. Železniki, Pami. 205.
Gunn D., Morton D.B. 1995. Inventory of the behaviour of New
Zealand White rabbits in laboratory cages. Appl. Animal
Behaviour Science, 45, 277-292.
Hansen L.H., Berthelsen H. 2000. The effect of environmental
enrichment on the behaviour of caged rabbits (Oryctolagus
Cuni culus). Appl. Animal Behaviour Science, 68, 163-178.
Huls W.L., Brooks D.L., Bean-Knudsen D. 1991. Response of adult
New Zealand White rabbits to enrichment objects and paired
housing. Lab. Anim. Sci., 41, 609-612.
Jordan D., Štuhec I., Pečlin G., Gorjanc G. 2003. The influence of
environmental enrichment on the behaviour of fattening rabbits
housed in individual wire cages. 13. Arbeitstagung über
Haltung und Krankheiten der Kaninchen, Peltztiere und
Heim tiere , Celle , 14.-15. Mai, 119-126.
Kovács I. 1979. Wood properties, Mezőgazdasági Kiadó, Budapest
Laborat ory An imals. Refinements in rabbit husbandry. Second
repo rt of the BVAAWF/RSPCA/UFAW Joint working gr oup
on refinement. Lab. Anim., 27(1993), 301-329.
Lidfors L. 1997. Behavioural effects of environmental enrichment
for individually caged rabbits. Appl. Animal Behaviour
Science, 52, 157-169.
Love J.A. 1994. Group housing: Meeting the physical and social
needs of the laboratory rabbit. Lab. Anim. Sci., 44, 5-11.
Luzi F., Ferrante V., Heinzl E., Verga M., 2003. Effect of
environmental enrichment on productive performance and
welfare aspects in fatteni ng rabbits. It alian J . Animal S cienc e,
2: Suppl. 1, 438-440.
Martin P., Bateson P. 1993. Measuring behavior: an introductory
guide. 2° Ed. , Cambr idge.
3 4
PRINCZ et al.
values differed substantially. In the enriched cages a trend of decrement of inactivity (P=0.058) was
noticed, but in wire and feeder biting no significant decrement was observed.
In experiment 4, the effects of presence of a wood stick inside the cage and of the housing systems
(2, 3, 4 animal per cage) were not statistically significant on the rabbit performance. Weight gain
between 35 and 75 days and body weight at 75 days of age were not affected by treatment. The
means of these traits were between 38.0 and 39.5 g/day, and 2540 and 2626 g, respectively. As far as
the behaviour is concerned, the enriched caged rabbits performed significantly more allo-grooming
and sniffing the other rabbits, while the control animals performed significantly more gnawing the
bars of the cage. A trend was also found in these latter rabbits to show higher alert and aggressive
behaviours (Figure 3).
DISCUSSION
The highest level of gnawing stick consumption was observed for Little-leaf linden. Considerable
amount of consumption was found for White buckeye and White willow. All these species are soft
(hardness) (Kovács, 1979). The mechanical and chemical characteristics of the tree species (hardness,
smell and taste) may determine which of the investigated species is suitable for gnawing stick.
Consumption of White locust and Black poplar was small. The White locust is a tough tree and has
indelicate fibres that may explain its consumption level. Although Black poplar is a soft tree its
consumption was also small. According to rabbitsʼpreference for wood species, the results of the
experiment 3 were quite similar to results of experiment 2. Rabbits preferred sticks made of Little-leaf
linden and Norway spruce wood compared to Common oak. The possible reason of this finding
could be, as in experiment 2, mechanical and chemical characteristics of used three species. Common
oak is very dense and hard in comparison with Norway spruce and Little-leaf linden (Čermak, 1998;
Pipa, 1990) and it also contains a large amount of tannin, about 10% (Pipa, 1990). Occupation of
rabbits with environmental enrichment did not significantly reduced animalsʼinactivity, as it was
reported in several studies investigating environmental enrichment (Metz, 1987; Huls et al., 1991). In
neither group was observed any significant decrement of biting wire and feeder, which is one of the
0%
1%
2%
3%
4%
5%
6%
7%
8%
Sniffing other
rabbits
Allo-
Grooming
Agressiveness Alert Gnawing bars
of the the cage
Environmental
Enrichment
Control
**
**
n.s
*
n.s
Figure 3: Behaviour of rabbits with and without environmental enrichment. (Average values - % of total
scans) (Experiment 4).
35
GNAWING STIC K FOR RABB ITS
most common behavioural abnormalities in cage systems (Gunn and Morton, 1995; Laboratory Animals,
1993; Love, 1994). This last result is surprising as studies using different kind of environmental
enrichment reported significant decrement of these kinds of behaviours (Lidfors, 1997; Jordan et al.,
2003).
Contrary to experiment 3, in experiment 4 the environmental enrichment affected the behaviour (but
not the rabbitsʼ performance). It significantly increased social activities, such as sniffing the other
rabbit and allo-grooming. On the contrary, it decreased the behaviour of gnawing the bars of the
cage, which may be an oral stereotypy, as well a trend was found to decreased alert and aggressive
behaviours. The growth and carcass traits were not statistically significantly affected by environmental
enrichment in agreement with other previous results (Luzi et al., 2002). These results support that
environmental enrichment and housing have no effect on the production of the rabbits.
CONCLUSIONS
Based on our results the following suggestions can be made:
a) Unsuitable for gnawing stick: Black elder, European larch, European white birch tree, White mulberry
and Common oak.
b) Suitable for environment enrichment: Black poplar and White locust tree.
c) Suitable for gnawing stick: White willow, White buckeye, Little-leaf linden and Norway spruce.
d) Our results can be utilised in further experiments connected with the gnawing stick application
and determining the suitable tree species.
Housing and environmental enrichment did not affect significantly the growth rate contrary to some
rabbit behaviours. However in this case the results are not always consistent. In fact in experiment 3
the addition of wooden stick as environmental enrichment did not decrease wire and feeder biting,
which is one of the most common behavioural abnormalities in cage systems. The type of wood
significantly influenced only the duration of feed eating. On the contrary, in experiment 4 environmental
enrichment significantly decreased gnawing the bars of the cage and increased some social behaviours,
such as sniffing the other rabbit and allo-grooming. A trend was shown also to reduced, alert and
aggressive behaviours. Thus further research is needed in order to understand how environmental
enrichement may affect rabbitsʼbehaviour, possibly reducing oral stereotypies and increasing the
behavioural repertoire.
REFERENCES
Čermak M. 1998. Tehnologija lesa 1. Železniki, Pami. 205.
Gunn D., Morton D.B. 1995. Inventory of the behaviour of New
Zealand White rabbits in laboratory cages. Appl. Animal
Behaviour Science, 45, 277-292.
Hansen L.H., Berthelsen H. 2000. The effect of environmental
enrichment on the behaviour of caged rabbits (Oryctolagus
Cuni culus). Appl. Animal Behaviour Science, 68, 163-178.
Huls W.L., Brooks D.L., Bean-Knudsen D. 1991. Response of adult
New Zealand White rabbits to enrichment objects and paired
housing. Lab. Anim. Sci., 41, 609-612.
Jordan D., Štuhec I., Pečlin G., Gorjanc G. 2003. The influence of
environmental enrichment on the behaviour of fattening rabbits
housed in individual wire cages. 13. Arbeitstagung über
Haltung und Krankheiten der Kaninchen, Peltztiere und
Heim tiere , Celle , 14.-15. Mai, 119-126.
Kovács I. 1979. Wood properties, Mezőgazdasági Kiadó, Budapest
Laborat ory An imals. Refinements in rabbit husbandry. Second
repo rt of the BVAAWF/RSPCA/UFAW Joint working group
on refinement. Lab. Anim., 27(1993), 301-329.
Lidfors L. 1997. Behavioural effects of environmental enrichment
for individually caged rabbits. Appl. Animal Behaviour
Science, 52, 157-169.
Love J.A. 1994. Group housing: Meeting the physical and social
needs of the laboratory rabbit. Lab. Anim. Sci., 44, 5-11.
Luzi F., Ferrante V., Heinzl E., Verga M., 2003. Effect of
environmental enrichment on productive performance and
welfare aspects in fatteni ng rabbits. It alian J . Animal S cienc e,
2: Suppl. 1, 438-440.
Martin P., Bateson P. 1993. Measuring behavior: an introductory
guide. 2° Ed. , Cambr idge.
3 6
PRINCZ et al.
Metz J.H.M. 1987. Behavioural problems of rabbits in cages. In:
Agriculture: Rabbit production systems including welfare
(Ed. : Auxil ia, T.), Lu xembu rg, Comm issio n of the Eu ropea n
Communities, 221-230.
Pipa R. 1990. Anatomija in tehnologija lesa. Tehnologija tvoriv.
Ljubljana, Zveza inženirjev in tehnikov gozdarstva in
lesarstva, Lesarska Založba, 136 p.
Princz Z., SzendrőZs., Dalle Zotte A., Radnai I., Biró-Németh E.,
Metz ger Sz. , Gyovai M., Orov a Z. 200 5. Effec t of diff erent
housing on productive traits and on some behaviour patterns
of growing rabbits; In Proc.: 17th Hungarian Conference on
Rabbit Production, Kaposvár, 95-102.
SAS. 2 001. SAS /STAT. User ʼs gui de. (Rel ease 8.02). SAS I nstitu te
Inc., Cary, NC, USA.
SPSS for Windows 1999. Version 10.0, Copyright SPSS Inc.
Todes chin i R., 19 98. Int rodu zion e alla C hemiometr ia. Ed iSES ,
Napoli, Italia.
Verga M., Zingarelli I., Heinzl E., Ferrante V., Martino P.A., Luzi F.
2004. Effect of housing and environmental enrichment on
perf orman ce and behaviou r in fatt ening r abbits. In Proc .: 8th
World Rab bit Con gress, Puebl a City, 1283-1288.
37
World Rabbit Sci. 2007, 15: 37 - 41
© WRSA, UPV, 2007
Correspondence: A. Finzi, finzi@unitus.it
Received February 2006 - Accepted October 2006.
ABSTRACT:Visual Image Analysis (VIA) has been evaluated to estimate morphological traits and weights of live
rabbits and carcasses to improve the body conformation of the new breed Leprino di Viterbo. The reliability of
VIA was firstly tested on a sample of 30 does. Then, a total of 365 animal (130 additional does and 205 rabbits
at slaughtering weight of kg 2.5) was utilised to calculate some surface traits and correlations between live
and carcass weights that were later validated over a new sample of 112 rabbits (37 does and 75 fattened).
VIA gave very good results to evaluate morphological and weight measurements. Maximum observed individual
difference between data measured by metre and by VIA was only 3.6%. Since standard error (SE) of VIA was
lower than SE of metre (0.06 and 0.33 respectively), VIA was considered more reliable than the instrumental
measurement. A new parameter, Body Side Surface, was made available by the Image Analysis to estimate
Live Weight and Carcass Weight efficiently. Correlations were high (P<0.01) both in does (R2=0.87 for live
weight equation) and at slaughter time (R2=0.82 and 0.76 for live and carcass weight equations, respectively).
It was concluded that VIA is a viable, quick and practical mean to measure and select for weight and
morphological traits as head length, ear length, body length and body side surface.
Key words: Visual image analysis, morphology, body weight, carcass, rabbit.
WW
WW
WORLDORLD
ORLDORLD
ORLD
RR
RR
RABBITABBIT
ABBITABBIT
ABBIT
SS
SS
SCIENCECIENCE
CIENCECIENCE
CIENCE
VISUAL IMAGE ANALYSIS TO ESTIMATE MORPHOLOGICAL
AND WEIGHT MEASUREMENTS IN RABBITS
Negretti P., Bianconi G., Finzi A.
Rabbit Unconventional Rearing Experimental Centre. Dpt. of Animal Production, Univ. of Tuscia. VITERBO, Italy
INTRODUCTION
Visual Image Analysis (VIA) has been demonstrated as a very practical and easy mean to estimate
morphological measurements in different domestic species (Filippi Balestra et al., 1994; Negretti et
al., 1995; Borggard et al., 1996; Kuchida et al., 1996; Sakowski et al., 1996; Tözsér et al., 2000; White
et al., 2004; Negretti and Bianconi, 2005). The system is quicker and more reliable than both, subjective
linearized descriptive type traits and even instrumental measurements, showing a lower standard
error. Moreover it allows easy recording of an electronic permanent archive.
New measurements as angles and surfaces are made possible too, thus increasing the number of
parameters to be utilised with selective purposes. Reliable weight estimations (Negretti and Bianconi,
2001; 2002; 2004) are also possible, both on live and carcass weight of different species.
A trial was planned to test the possibility of introducing VIA body measurements in rabbits,
considering that biased data could be produced by measurement errors due to the small dimensions
of the animals and by the peculiar problem that could rise depending on the presence of the fur.
The purpose of this work was to obtain reliable data to improve the morphological selection of a new
Italian breed named Leprino di Viterbo, that is selected to be raised in the open air without any
pharmacological treatment, any suspected animal being stamped out (Finzi, 2004).
