The effects of feeding and housing on the behaviour of the laboratory rabbit

Transcription

1 he effects of feeding and housing on the behaviour of the laboratory rabbit. C. Krohn, J. Ritskes-Hoitinga & P. Svendsen Biomedical Laboratory, Odense University, Winsloewparken 21, DK-5000 Odense C, Denmark Summary he effects of housing, feeding time and diet composition on the behaviour of the laboratory rabbit were examined. he animals were caged individually in single or double metal cages with perforated metal floors, metal walls, and bars in the front, or kept as a group in floor pens. he light/dark cycle was 12/12 h with light from 04:00 to 16:00 hand 30 min twilight. One experiment compared feeding equal energy levels of a high energy diet (10.1 MJ/kg) and with a low energy diet (7.0 MJ/kg) at. he second experiment compared feeding the high energy diet at and at 14:00 h. n both studies the behaviour of the rabbits was recorded between 08:00 and 14:00 h and between 16:00 and 22:00 h. Feeding the animals at 14:00 h reduced abnormal behaviour during the dark period compared to feeding at, whereas no difference in behaviour could be detected between feeding a high-energy and a low-energy diet at. Animals in floor pens generally showed less abnormal behaviour than caged animals. he results indicate that the welfare for caged rabbits can be improved by feeding the animals in the afternoon rather than in the morning. Keywords welfare Laboratory rabbits; behaviour; housing; feeding time; abnormal behaviour; Attempts to improve the welfare of laboratory rabbits have mainly focused on the improvements of cage design and the increase of cage size to allow the animals to carry out basic behavioural patterns (Baumans 1994). By improving the welfare of the animals they are expected to be healthier and better able to cope with experimental procedures, and experimental results are likely to be more reliable (Morton et al. 1993). Other environmental factors like diet composition, amount of feed and availability of feed may also influence the behaviour and welfare of laboratory rabbits. n the wild, rabbits spend most of their time foraging lgibb 1993). his activity is Correspondence to: J. Ritskes-Hoitinga, Biomedical Laboratory, Odense University. Winsloewparken 21. DK 5000 Odense C, Denmark. el: Fax: E mail: M.RSKES@WNSLOEW.OU.DK mainly carried out late in the afternoon and during the night, and a large volume of roughage with a low-energy content is ingested (Mykytowycz & Rowley 1958, Fraser 1992, Krohn 1997). n many laboratories, rabbits are fed a restricted amount of a pelleted diet with a high-energy content, and for practical reasons the diet is offered to the animals in the morning. here are thus two major differences in the feeding habits of the wild and the laboratory rabbits: (i) the volume and energy content of the feed, and (iil the period of the day when the animals have access to the feed. n the following study the effects on normal and abnormal behaviour of feeding diets with different energy contents and of offering the feed at different hours of the day are examined. Furthermore the effects of cage size and pen housing on behaviour are studied. Accepted 8 July 1998 Laboratory Animals Ltd.,

2 102 Krohn, Ritskes-Hoitinga & Svendsen Materials and methods he experiments were carried out with 18 female rabbits (Ssc: CPH) (Statens Seruminstitut, Copenhagen!, 3 months of age and weighing between 2400 and 2900 g. Six animals were housed in single cages with a floor surface of 2800 cm 2, a perforated metal floor, metal walls, metal bars in front, and a cage height of 45 cm. Six animals were housed individually in double cages consisting of two connected single cages. he passage measured 16 x 20 cm. he trays under the cages were changed twice a week and the cages once a week. Six animals were kept in a floor pen with a surface area of 3.5 m 2. Wood shavings were offered as bedding and changed once a day. he floors of the animal room were washed once a day and the rooms were emptied and cleaned every second week. Light was switched on at 04:00 hand switched off at 16:00 h with 30-min twilight periods. During the dark period the room was illuminated with a red light (150 W) to allow observation. Room temperature was 21 C ± 2 C, and relative humidity 55 % ± 5%. All rabbits had access to tap water ad libitum. For behaviour observation the following ethogram was used (modified from Morton et a ): nactive behaviour: Sitting Lying still Feeding behaviour: Eating Drinking still Coprophagy Grooming Self-grooming behaviour: he rabbit is sitting or standing without performing any other activity. he rabbit is lying with its chest on the floor, and with the hindlimbs underneath the body, or with all four limbs outstretched. he rabbit is eating pellets from the hopper. he rabbit is lapping water with its tongue from the nipple of the bottle.. he rabbit is eating faecal pellets directly from the anus. he rabbit is licking or biting its fur or washing its ears with its forepaws. Exploration behaviour: Exploration he rabbit is sniffing the Abnormal Biting the bars Paw-scraping behaviour: Other behaviour: Other activity inventory of the cage. wo different diets were used in this experiment. Diet No.1: Altromin 2020 (Chr. Petersen A/S, Ringsted, Denmarkl with a metabolizable energy content of 10.1 MJ/kg (macronutrient values given in the catalogue: crude protein 17.5 g/100 g, crude fat 4.0 g/100 g, crude fibre 14.5 g/100 g), and Diet NO.2: SDS RABMA(P) (SDS, Witham, UKl with a metabolizable energy content of 7.0 MJ/kg (catalogue macronutrient values: crude protein 13.1 g/100 g, crude oil 2.2 g/100 g, crude fibre 19.8 g/100 g). he amount of feed given was restricted to about 60% of the ad libitum energy intake to avoid obesity. he energy intake was constant in all experimental groups. he following feeding schedules were tested [able 11:Diet No. 1 (140 g) given at, Diet No.1 (140 g) given at 14:00 h, and Diet No 2 (200 gl given at. For each feeding schedule tested the rabbits were observed for 2 x 6 periods lasting 25 min each during the light period (08:00-14:00 h) and 2 x 6 periods lasting 25 min each during the dark period [16:00-22:00 h). During a 25 min period, each rabbit was observed and its behaviour recorded every 30 s. n total each rabbit was observed for 300 min during each feeding schedule tested. When shifting the feeding schedule the rabbits were allowed at least one week to adjust to the new treatment. he following comparisons made. he rabbit is biting at or licking the inventory of the cage. he rabbit is scraping with its forelimbs on the ground. typically in the corner of the cage. he rabbit is performing a behaviour not mentioned above, including movement. have been he effect on behaviour of different housing conditions in animals fed a highenergy diet at.

3 Feeding schedule and behaviour in the rabbit 103 able 1 Experimental design Experimental treatment Single cage (SC) Double cage (DC) Floor pen (FP) Diet NO.1 (10.1 MJjkg) 140 g Diet NO.1 (10.1 MJjkg) 140 g Diet NO.2 (7.0 MJjkg) 200 g 14:00 h 14:00 h 14:00 h he effect on behaviour of different housing conditions in animals fed a high-energy diet at 14:00 h. he effect on behaviour of different housing conditions in animals fed a low-energy diet at 08:00.h. he effect on behaviour of feeding a high-energy,diet at or at 14:00 h. he effect on behaviour of feeding a high-energy or a low-energy diet at. Statistical procedures All data were tested statistically by using SAS version 6.08 (SASnstitute nc. 1989). he univariate testing tested all data for normal distribution. f the data were normally distributed (P> 0.8), the data were tested by the General Linear Model (GLM) procedure using the following model: Y = Housing + Diet + Housing * Diet + Observation ime + Housing * Observation ime + Diet * Observation + ndividual (Housing * Diet) he significance level was set at P < Results Figure 1 shows the frequency of inactivity behaviour in rabbits housed in single cages (SC), double cages (DC) or floor pens (FP).t appeared that the rabbits spent between 60 and 80% of the time either sitting or lying still. here was a minor but significantly higher inactivity during the light period compared to the dark period, but no difference in frequency of inactivity could be detected between animals kept in a single cage, a double cage or in a floor pen. Comparing the frequency of inactivity behaviour of animals fed Diet No.1 at 08:00 h with animals fed Diet No.1 at 14:00 h, all housed in similar cages, gave no significant differences. Similarly, no significant difference was detected between animals fed Diet No.1 at and animals fed Diet No.2 at. Figure 2 shows the frequency of feeding behaviour under the three different housing conditions. t appeared that the animals spent 12 to 20% of the time eating, drinking or performing coprophagy. No significant differences in feeding behaviour could be detected among animals undergoing the same feeding schedule in the three different types of housing. Comparing the frequency of feeding behaviour in animals fed Diet No.1 at 08:00 h and animals fed Diet NO.1 at 14:00 h all housed in similar cages, it appeared that ~ ~60!;. " '" o sc DC FP [le!{no.1 alcbjohr. c::::j Ul#ll PoMd _ hkp<nod Fig 1 nactivity behaviour as a percentage of total (sq, double cages (DC) or in a floor pen (FP) during 1 at, Diet NO.1 at 14:00 h or Diet NO.2 at. Significant differences between light and SC OC FP [le!{no.1 at 1400hr. sc ex: FP [le!{no.2 atc8johr.

4 104 Krohn. Ritskes-Hoitinga & Svendsen 25 r 20 '0' 20 ;r. i15 ;. lz 10 fi :::E t o. SC DC FP DielNo.1 at 0800 hr. sc OC FP Diet No. 1 at 1400 hr. sc oc FP Diet No. 2 at 0800 hr. SCOCFP DielNo.1 at ooסס hr. SC OC FP DielNo.1 al1400hr. n Fig 2 Feeding behaviour as a percentage of total (SCl, double cages (DC) or in a floor pen (FPl during 1 at, Diet NO.1 at 14:00 h or Diet NO.2 at. Significant differences between light and means for each group +SEM Fig 3 Grooming behaviour as a percentage of total (SC), double cages (DCl or in a floor pen (FP) during 1 at, Diet NO.1 at 14:00 h or Diet No.2 at. Significant difference5 between light and animals fed at 14:00 h had a considerably higher frequency of feeding behaviour during the dark period than during the light period. he same tendency, but less pronounced, was seen in animals fed the low-energy Diet No.2 at. Figure 3 shows the frequency of grooming behaviour in rabbits housed in single cages, double cages or floor pens. Animals fed the high-energy diet at had a significantly higher frequency of grooming behaviour during the dark period when housed in cages compared to animals housed in a floor pen. his difference was not seen in animals fed at 14:00 h or fed a low-energy diet at. Comparing animals housed in similar ways, the feeding schedule appeared to affect the grooming behaviour, since animals fed Diet No.1 at 14:00 h showed a lower frequency of grooming behaviour during the dark period than during the light period, whereas the opposite was seen in animals fed Diet No.1 at. n animals fed Diet No. 2 at, no differences between light and dark periods could be detected. Figure 4 shows the frequency of exploratory behaviour in rabbits housed in single cages, double cages or floor pens. Under all three feeding schedules the animals kept in floor pens showed a significantly higher frequency of exploratory behaviour during the dark period than animals kept in cages. Comparing the different feeding schedules, it was striking that animals fed the high-energy Diet No. 1 at showed a much higher frequency of exploratory behaviour during the dark period than animals fed the same diet at 14:00 h or the low-energy Diet No.2 at. Figure 5 shows the frequency of abnormal behaviour in rabbits under the three housing conditions. t appeared that animals kept in floor pens showed significantly less abnormal behaviour than animals kept in cages, and that animals in single cages showed significantly less abnormal behaviour than animals in double cages. t was striking that abnormal behaviour in caged rabbits mainly occurred during the dark period. Comparing the different feeding schedules, it is interesting to note the highly significant reduction in the frequency of abnormal behaviour during the dark period as a result of changing the feeding time from 08:00 to 14:00 h in caged animals. he energy content of the feed had some influence on the frequency of

5 Feeding schedule and behaviour in the rabbit J D '!Pl P<nod _ lhkpcnod.... r n o SC DC FP aetno.1 at OBOO hr. SC DC FP DietNo 1 a1400hr. SC DC FP DiatNo.2 at OBOOhr. 7 6 ::;-s Eel: t;.; ~2 0 o j!t>t Pa1<ld _ HkPcnod Fig 4 Exploratory behaviour as a percentage of total (SC), double cages (DC) or in a floor pen (FP) during 1 at. Diet No.1 at 14:00 h or Diet No.2 at. Significant differences between light and Fig 5 Abnormal behaviour as a percentage of total (SC), double cages (DC) or in a floor pen (FP) during 1 at, Diet NO.1 at 14:00 h or Diet No.2 at. Significant differences between light and abnormal behaviour since the use of lowenergy Diet No.2 instead of Diet No. at caused a minor, but non-significant, reduction in the frequency of abnormal behaviour in caged animals. Figure 6 shows the frequency of other behaviour as a percentage of total observation time for rabbits housed in single cages, double cages, or floor pens. t appeared that animals kept in floor pens showed significantly more other behaviour than animals kept in cages except in the animals fed a low-energy diet, where no significant difference in the frequency of other behaviour was recorded. rabbits. t is characteristic that while the rabbits in cages spent 2-5% of the time performing abnormal behaviour like biting in the bars or scratching the bottom of the cage, these activities were virtually absent in group-housed rabbits in floor pens. hese o '!ft?'j1hd _ l)r-kl'mod Discussion he most frequently occurring behavioural patterns exhibited by the rabbits were inactivity, feeding and grooming, accounting for more than 90% of all activities carried out during both light and dark periods. t is remarkable that the frequencies of these activities were not influenced by the size of the cage or by group housing rabbits in pens. n the remaining 10% of the observation period exploratory behaviour, abnormal behaviour and other behaviour occupied the Fig 6 Other behaviour as a percentage of total (SC), double cages (DC) or in a floor pen (FP) during 1 at. Diet No.1 at 14:00 h or Diet No.2 at. Significant differences between light and means for each group+sem

6 106 Krohn. Ritskes-Hoitinga & Svendsen animals on the other hand spent more time performing other behaviour-like moving around-as compared to animals in cages. Other experiments show the same results (Podberscek et a , Gunn & Morton 1994).he rabbits housed in double cages did not move around more than rabbits in single cages, and the increased cage area did not appear to reduce abnormal behaviour, rather the opposite. he rationale for introducing a low-energy diet (Diet No.2) was that the animals would spend more time eating, consuming a larger volume, and would consequently use less time performing abnormal behaviour. his, however, could not be confirmed. he reported energy content of diets eaten by wild rabbits was found to be 6.85 MJ/kg (Monk 1989),which is similar to the low-energy diet used in our study. Changing the feeding time from 08:00 to 14:00 h dramatically reduced the frequency of abnormal behaviour in caged rabbits to almost the same level as seen in rabbits housed in floor pens. Feeding at 14:00 h also changed the feeding habits of the rabbits, so that almost all the feed was eaten during the dark period, which mimics the habits seen in the wild rabbit. he fact that rabbits in cages may spend more than one hour out of 24 performing abnormal activities like biting the bars and scratching the bottom of the cage may indicate frustration (Morton et a ). he presence of abnormal behaviour is not acceptable and indicates that the housing conditions are unsatisfactory for the rabbit (Mason 1991). his abnormal behaviour mostly takes place during the dark period, and is therefore rarely noted by animal caretakers. Group housing of rabbits has certain limitations-only females accept this type of housing, and even with females problems may arise when new animals are introduced into the group (Love 1994). Our results indicate that feeding shortly before the onset of the dark period prevents the occurrence of abnormal behaviour in caged rabbits. A possible methodological error cannot be excluded on the basis of our results. t may be possible that abnormal behaviours peak at a relatively fixed time after feeding. f this period would be around 8-10 h, abnormal behaviours would not have been detected in the afternoon-fed animals because animals were not observed during the later part of the dark phase. More work needs to be done to reveal the possible causal relationship between feeding schedule (diet volume and time of feeding) and welfare in caged laboratory rabbits. Rabbits are nocturnal animals, which in the wild leave their burrows shortly before dark to forage during the early hours of the night. his trait may still persist in domestic rabbits, as reported by Hornicke et a1.(19841.when domestic rabbits were fed ad libitum, feeding activity increased from the hours before dark until 6 hours after the beginning of the dark period (Hornicke et a When rabbits were fed restrictedly, the locomotor activity became related to the time of feeding (Jilge et a ). Locomotor activity increased from about 2 h before until 3 h after foodaccess, and the period in between feeding was mainly used to rest (Jilgeet a ).hese findings do not support a possible methodological error in our study. Our results indicate that feeding a restricted amount of diet to laboratory rabbits is preferably done in the afternoon instead ofin the morning, as this time of day coincides with their natural foraging time. Moreover, abnormal behaviours were no longer recorded during the observation periods. Acknowledgments he authors thank the animal technicians at the Biomedical Laboratory, Odense University, for taking care of the animals, and he Society for Protection of Animals in Denmark for financial support. References Baumans V (1994) Husbandry and welfare of laboratory rodents and rabbits: the relevance of behavioural studies. n: Welfare and Science: Proceedings of the Fifth FELASA Symposium, Brighton 1993 (Bunyan J, ed.) London: Royal Society of Medicine Press, pp 65-7 Fraser KW (1992) Emergence behaviour of rabbits, Oryctolagus cuniculus, in Central Otago, New Zealand. Journal of Zoology 228, Cibb JA (1993) Sociality, time and space in sparse population of rabbits (Oryctolagus cuniculus). Journal of Zoology 229, Cunn D, Morton DB (1994) he behaviour of singlecaged and group-housed laboratory rabbits. n:

7 Feeding schedule and behaviour in the rabbit 107 Welfare and Science: Proceedings of the Fifth FELASA Symposium, Brighton 1993 Bunyan - edl. London: Royal Society of Medicine Press, pp 80-4 Hornicke H, Ruoff G, Vogt B, Clauss W, Ehrlein H-J (1984) Phase relationship of the circadian rhythms of feed intake, caecal motility and production of soft and hard faeces in domestic rabbits. Laboratory Animals 18, Jilge B, Hornicke H, Stahle H (1987) Circadian rhythms of rabbits during restrictive feeding. American ournal of Physiology 253, R46-R54 Krohn C Behavioural studies on different housing and food enrichment conditions for the laboratory rabbit (MSc hesis). Denmark: Odense University Love JA (1994) Group housing: meeting the physical and social needs of the laboratory rabbit. Laboratory Animal Science 44, 5-11 Mason GJ (1991) Stereotypes and suffering. Behavioural Processes 25, Monk KA (1989) Effects of diet composition on intake by adult wild European rabbits. Appetite 13, Morton DB, Jennings M, Batchelor GR, et a1. (1993) Refinements in rabbit husbandry: second report of the BVAAWF/FRAME/RSPCA/UFAW Joint Working Group On Refinement. Laboratory Animals 27, Mykytowycz R, Rowley (1958) Continuous observations of the activity of the wild rabbit, Oryctolagus cuniculus (1.1 during 24-hour periods. CSRO Wildlife Research 3, Podberscek AL, Blackshaw JK, Beattie AW 11991) he effects of repeated handling by familiar and unfamiliar people on rabbits in individual cages and group pens. Applied Animal Behaviour Science 28,