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Comp. B iochem. Physiol. Vol. 114A, No. 3, pp. 205-209, 1996Copyright 0 1996 Elsevier Science I nc.

ELSEVIER

ISSN 0300s9629/96/$15.00SSDI 0300-9629(95)02133-7

REVIEW

Food Selection by the Domestic Cat,an Obligate Carnivore

John W. S . Bradshaw * Deborah Goodwin, * Vhonique Legrand-Defretin, 7and Helen M. R. Nott?_

*ANTHROZOOLOGY NSTITUTE , UNIVERSITY OF SOUTHAMPTON, BASSETT RESCE NT AST, SOUTHAMPTON, U.K., SO16 7PXAND -(WALTHAM CENTRE FOR PET NUTRITION, WALTHAM-ON-THE-WOLDS, MEL TON MOWBRAY, LEICS, U.K., LE14 4RT

ABSTRACT. The domestic cat Felis siloesnis cams is the most accessible member of the family Felidae for thestudy of the relationship between food selection and nutrition. In contrast to pack-living animals such as thedog, and opportunistic omnivores such as the rat, the cat is generally able to maintain its normal body weight

even when allowed ad libitum access to palatable food by taking small meals and adjusting intake according tothe energy density of the food(s) available. The most extreme adaptations to carnivory discovered to date liein the taste buds of the facial nerve, which are highly responsive to amino acids and unresponsive to manymono- and disaccharides. Preferences for particular foods can be modified by their relative abundance, theirnovelty, and by aversive consequences such as emesis: the mechanisms whereby these are brought about appearto be similar to those used by omnivorous mammals. COMP BIOCHEM PHYSIOL 114A;3:205-209, 1996.

KEY WORDS. Felidae, cat, feeding behaviour, palatability, olfaction, taste, facial nerve, meal patterns, aversion,neophobia

INTRODUCTION

The domestic cat, now classified as Felis silvestris catus (44),

is a member of the order Carnivora. Despite their name,most of the Carnivora are not totally carnivorous and some,such as the red panda (Ailurus @gem), are totally herbivo-rous. In fact the Felidae is the only family within the Carniv-ora in which all members can be considered as truly camiv-orous, i.e. have a requirement for nutrients present only inanimal tissue within their diet.

It is thought that the domestic cat first became domesti-cated about 4000 BC and, via geographical expansion, isnow the most numerous species of felid worldwide. Theadoption of the domestic cat as a pet in millions of homeshas been accompanied by the growth of an increasingly so-

phisticated pet food industry, the research efforts of whichhave been geared to meeting the nutritional requirementsof the cat. The seemingly fickle nature of the pet cats eatinghabits has also prompted much interest in its food selectionand preferences. Research has confirmed that the cat is anobligate carnivore both in its requirements for individualnutrients and in its methods of ingestion, digestion and me-tabolism of those nutrients. In this review we summarise

Address r+riint requests to: J. Bradshaw at: Department of Biology, Univer-sity of Southampton, Bassett Crescent East, Southampton, SO16 7PX, U.KTel. 44 1703 594254; Fax 44 1703 594269.

Received 21 J anuary 1995; revised 20 J uly 1995; accepted 27 November1995.

the data available, which relate the specialised nutritionalrequirements of the cat to its mechanisms of food selectionand feeding behaviour. This has implications for the nutri-tional management of all members of the Felidae, none ofwhich has been investigated as extensively as F.s.catus. Thekey nutritional differences between the cat and other non-obligate carnivores, such as the dog, have been reviewedelsewhere (2,36,37).

Feeding Behaviour and Food Selection

For those interested in food selection, the domestic cat isone of very few species in the Order Camivora which arereadily studied. The members of the cat family are all obli-gate carnivores, and prefer to consume freshly killed car-cases, rather than carrion (47). The cat is relatively easy tohouse, feed and handle, but despite the process of domesti-cation it has retained a behavioural repertoire which makesit very successful in the feral state, that is, living wild with-out deliberate provisioning by man. Studies of diet selectionhave focused both on the way that these animals obtainfood in the wild (51), and on the way that they select foodthat is provided in the domestic environment.

Meal Patterns

Surveys of the gut contents of feral cats have shown that

although some variation exists between both individualsand local populations, the bulk of their diet is made up of

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206 J. W. S. Bradshaw et al.

small mammals, e.g. mice, rats and rabbits, while birds,frogs, reptiles and insects are found less frequently(l&19,27,32,43). The small size of the prey indicates thatthe cat wil l need to take many small meals each day in orderto meet its nutritional requirements (30).

A number of laboratory studies have also shown thatgiven al libitum access to a food supply cats will take manysmall meals during the day and night, although the amounteaten at a meal, and the frequency of meals both vary amongindividuals (41,42). Recent research on the effect of foodintake on urine pH has shown that ad libittlm feeding (nibbleeating) reduces the post prandial alkaline tide, and there-fore, the potential for struvite crystal formation in the urine(18). This may suggest that cats do not possess an effectivemechanism to avoid struvite crystal formation because theproblem would be unlikely to develop under natural feedingpatterns.

Pet cats often have a more varied diet than laboratorycats, but are liable to be fed at the owners convenience,often just once or twice a day. Food provided at these inter-vals is usually more than the cat can eat in a single meal ,and the cat will usually return later for further small meals

(33).

Energy Regulation

Cats are solitary hunters and need to be fit and active inorder to be effective predators. Obesity in the cat used tobe considered relatively unusual; for example, in I972 only

6-12% of cats in the U.K. were thought to be obese (1).More recently, a survey of cats presented at a veterinaryclinic in Denmark revealed 40% considered overweight orobese (45). In this survey 50% of cats confined indoors wereconsidered obese, compared with 30% of those with accessto the outdoors. A recent study in the United States byScarlett et al. (46) reported 25% were considered over-weight by vets in a survey of 2000 cats brought to veterinaryclinics. Factors associated with being overweight in thisstudy included apartment dwelling, inactivity and beingneutered.

In order to determine whether mechanisms exist to en-

able cats to control their energy intake, a number of labora-tory trials studied the effects of altering the caloric contentof food available. Early attempts were limited by the effectsof palatabil ity and food bulk (23,28). However, Castonguay(13) and Kane et al. (3 1) were able to show that cats offeredpurified and commercial diets of good palatability, but dif-ferent caloric contents, quickly adjusted the amount of foodingested to maintain an almost constant caloric intake.Thorne (50) also used commercial cat food with differentwater contents, and found good evidence of energy intakeregulation. Although this ability appears to exist over a rela-tively narrow range it is consistent with far fewer cases of

obesity in cats than in dogs, when highly palatable dietsare fed ( 1,24,41). Managing obesity in the cat by using aprogramme of calorie controlled reduction, based on a low

calorie diet, is recommended. This ensures that the cat con-tinues to receive adequate levels of essential nutrients,which may not be achieved by reducing the quantity of thenormal diet offered (11).

Palatability

The palatabili ty of food is a composite function of a varietyof factors including aroma, taste, texture and consistency.In the ancestral African wildcat, palatabil ity may play a rolein its preference for prey, but only if that prey can be associ-ated with its taste when caught; however, very little isknown about how they regulate their diet. In pet cats thelink appears weak, or may have been broken by domestica-tion, as they will hunt and kill shrews, which are so distaste-ful that they are rarely eaten (5).

Physical characteristics of food such as texture and tem-perature also play a role in the acceptance of food. Catsprefer their food at blood, or at least room temperature, andmany will refuse otherwise palatable food if served chilled(10).

Palatability plays an important role in food preferencewhen domestic cats are presented with a choice of commer-cial pet foods. However, there is little published informationon the relative palatabil ities of different types of food, asthe palatability of meat may be affected by its freshness, thenutritional status of the animal at slaughter, and subsequentprocessing (10).

Many cats are extremely sensitive to minute differences

in the composition of foods offered (29). It has also beenshown that the variety of foods accepted by adult cats isrelated to foods that were presented in their early life, espe-cially those foods offered after weaning (2 1). Perceived pal-atability of the same foodstuff will also vary among individ-ual cats, even if they have been raised on identical diets,implying a genetic component to individual differences inpreference.

Olfaction

Relatively little is known about the importance of odour in

food selection by cats, although anosmic dogs are unable todistinguish between the flesh of different species (25).Odour may be used as a secondary cue in detecting prey,and the sense of smell as well as taste must be involved inselecting food, but the temperature and texture of food arealso important. Bradshaw (9) was able to show that expo-sure to odour alone is not sufficient to overcome neophobia,when cats were presented with a choice between a familiarcommercial food, and that food flavoured with an artificiallamb flavnur.

Taste

Of the four cranial nerves that convey information on taste,only the facial nerve has been investigated in detail in the

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Food Selection by Domestic Cat 207

cat. These studies indicate that, when the taste abilities ofthe cat are compared with those of other species includingthe dog, adaptations to obligate carnivory have taken place.

The amino acid system is quantitatively predominant inthe facial nerve, and is most sensitive to amino acids de-scribed as sweet in man. This group trigger rapid rates ofdischarge in the amino acid units, and includes L-proline,L-cysteine, L-ornithine, t-lysine, L-histidine, and L-alanine.The amino acid units in the cat are inhibited by a group ofbitter amino acids that include L-tryptophan, L-isoleu-tine, L-arginine, and L-phenylalanine, all of which have hy-drophobic side chains. Some alkaloids also inhibit theamino acid units (8). Cats have been shown to prefer solu-tions of sweet amino acids to the bitter (452). It isthought that the preponderance of amino acid units in thecat may be related to meat-eating, giving them the abilityto distinguish meats of varying qualities. Monophosphatenucleotides, which accumulate in prey tissues after death,are inhibitors of the amino acid units in cats, and may in-hibit their feeding on carrion.

The amino acid units are also sensitive to sodium chlo-ride (NaCl) and potassium chloride, which has lead to theirbeing categorised as salt units by some workers (3,26), buttheir threshold to salt is much higher (>0.05 M) than inother species. The cats low sensitivity to NaCl has beenrelated to the high sodium content of much of their food,which makes it less important for them to be aware of thesodium content of their food than herbivores, as many plantmaterials contain low levels of salt.

The sour taste experienced by man corresponds to theresponse of the acid units in the cat. These units react tocarboxylic, phosphoric, and other Bronsted acids such asnucleotide triphosphates, histidine, histidine dipeptides andprotonated imidazoles. These units are also triggered by thesulphur-containing L-cysteine and L-taurine, but are inhib-ited by inosine monophosphate (7). Cats reject mediumchain fatty acids (8:0), but not those with short chains,which may indicate an interaction between the acid unitsand other neural groups (38). The main stimulation of theacid units may come from histidine dipeptides present inanimal tissues, as at the pH of raw meat (5.5-7.0) manyacids are not sufficiently ionized to produce maximum stim-ulation of these units. The response of the acid units totaurine may possibly be associated with the cats require-ment for this amino acid, as taurine deficiency in the catleads to feline central retinal degeneration (FCRD) (22).However, taurine is abundant in the cats natural diet, andno behavioural response to a diet with inadequate taurinelevels has yet been demonstrated.

Cats also possess the ability to taste water, which appearsto be based on fibres, including acid-sensitive units, whichdischarge to pure water after becoming adapted to NaCl inthe saliva (3). It is possible, therefore, that testing potential

tastants in pure water may be confounded by masking, dueto the taste of the water.

The facial nerve of the cat also contains X-units, which

are less well characterised, but display long latencies to elec-trical discharge, and discharge spontaneously in irregularbursts, rather than discrete peaks (7). All of these units re-spond to nucleotide di- and triphosphates, but subgroupsalso respond to other compounds, including quinine, tan-nit, malic, and phytic acids, and alkaloids. The behaviouralsignificance of these units is unclear, but cats are known tobe very sensitive to quinine, and will reject it in solutionsa thousand times more dilute than those rejected by rabbitsand hamsters (12).

No system has been found in the cat that responds tosugars at any behaviourally meaningful concentration (6).Cats have been shown to be unable to distinguish betweenwater and sucrose dissolved in water (3,4,12), but, paradoxi-cally, prefer milk if sucrose or lactose is added (4,20). It hasbeen suggested that in the latter instances cats were reactingto sensory cues other than sweetness, as solutions of sucroseand lactose in dilute milk were equally acceptable to cats,but are perceived by humans as having different sweetness(4). Kienzle (34) demonstrated that cats would accept a dietcontaining glucose, but similar diets containing galactose,sucrose and lactose led to a reduction in intake, possiblydue to a learned aversion (see below).

Modification of Palatability by Experience

A single experience of some flavours can affect subsequentpreference markedly, even if nutritional factors are con-stant. Novel flavours may either be rejected (neophobia),or preferred (novelty), depending on the degree of noveltyof the flavour and other less well understood factors. Catsand kittens that have been fed on the same diet for a periodof weeks show a persistent novelty effect (41,50) when of-fered commercial diets of equivalent palatability. Attenua-tion of neophobia by exposure to an artificial flavour hasbeen demonstrated in adult cats (9). When two foods areboth famil iar and abundant, cats tend to prefer the lessabundant of the two, possibly a mechanism to maximise thelong-term nutritional benefits of a mixed diet when energyper se is not a limiting factor (14).

In common with rats and many other species, cats rapidlylearn to avoid foods that are toxic or nutritionally unbal-anced (45). Cats given a single meal containing LiCl re-fused to eat that food 3 days later, and continued to showan aversion to the same food unadulterated for up to 40days. Even the odour of the food could be paired with theeffects of LiCl (41). Cats are unable to digest high concen-trations of sucrose, and show an aversion to sucrose solutionafter only 6 hours exposure to a concentrated sucrose solu-tion that induced diarrhoea (3). As the ability of the catto taste sugars directly is undoubtedly limited, it is thoughtthat they were responding to taste cues from impurities inthe sucrose used. A similar aversion may also develop to

other sugars, including lactose; limited disaccharidase activ-ity in the small intestine allows these substrates to pass intothe large intestine relatively unchanged, where microbial

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208 J. W. S. Bradshaw et al.

dysfermentation occurs (35). The diahorroea and attendantdiscomfort that can result are presumably the triggers for theaversion to develop. The first sytnptom of a learned dietaryaversion to the flavour of a nutritionally inadequate food isusually anorexia, as shown in two cases of foods deficientin thiamin (15,17).

6.

7.

Arginine-free diets induce aphagia within 24 hours in ad-dition to emesis and ammonia intoxication (39), and catsmay then refuse to eat a nutritionally balanced diet if itstexture and flavour are similar to that of the arginine-freediet, showing that the aversion has been learned. Feedingcan be re-initiated by adding a distinctive flavour to thecomplete diet, for example onion and garlic powder (40).

8.

9.

10.

Cats may be less able to learn to avoid foods with defi-ciencies in nutrients that produce chronic rather than acutesymptoms. For example, females fed taurine-free diets for upto 3 years, although they developed severe retinal degenera-tion, consumed similar amounts of food to taurine-supple-mented controls, and maintained their body weights (49).

11.

12.

13.

14.CONCLUSION

The most extreme adaptations to obligate camivory in thecat occur in the taste buds of the facial nerve. This is unre-sponsive to sugars, possibly to permit more sensitive percep-tion of tastants in raw meat, such as monophosphate nucle-otides, which may indicate time since the death of the prey.However, little is known about the olfactory system, whichmay also be specialised for meat eating.

zen (Felis sylvestris f. cat~s Linni, 1758) aus dem StadtbereichKiel. Zeitschrift fur Saugetierkunde 44:375-83;1979.Boudreau, J.C. Neurophysiology and human taste sensations.J. Sens. Stud 1:185-202;1989.Bourdreau, J.C.; Sivakumar, L.; Do, L.T.; White, T.D.;Ovarek, J.; Hoang, N.K. Neurophysiology of the geniculateganglion (facial nerve) taste systems: species comparisons.Chem. Sens. 10:89-127;1985.Boudreau, J.C.; White, T.D. Flavor chemistry of carnivoretaste systems. In: Flavor Chemistry of Animal Foods. Amer.Chem. Sot. Symp. Ser. Washington, DC: American Chemi-cal Society. 67:102-128;1978.Bradshaw, J.W.S. Mere exposure reduces cats neophobia tounfamiliar food. Anim. Behav. 34:613-614;1986.Bradshaw, J.W.S.; Thorne, C. Feeding behaviour. In: Thorne,C., (ed). The Waltham Book of Dog and Cat Behaviour. Ox-ford: Pergamon Press, 1992: 118-129.Butterwick, R.F.; Wills, J.M.; Sloth, C.; Markwell, P.J. A studyof obese cats on a calorie-controlled weight reduction pro-gramme. Vet. Rec. 134:372-377;1994.

Carpenter, J.A. Species differences in taste preferences. J.Comp. Physiol. Psychol. 49:139-144;1956.Castonguay, T.E. Dietary dilution and intake in the cat. Phys-iol. Behav. 27:547-549;1981.Church, S.C.; Allen, J.A.; Bradshaw, J.W.S. Anti-apostaticfood selection by the domestic cat. Anim. Behav. 48:747-749;1994.

15.

16.

17.

Cats are able to regulate their energy intake accurately,presumably as an adaptation to maintaining an optimumbody weight for hunting. Less is known of their abilities toselect foods based on the proportion of nutrients they ob-tain; Rozin (45) has expressed doubt that such mechanismswill be found in the Felidae, given that they prey on nutri-tionally exchangeable foods. The tendency of cats to seekout the rarer of two abundant food types may indicate aprobabilistic strategy aimed at obtaining a mixed diet, with-out direct detection of the nutritional composition of anyof the types of food available.

18.

19.

Davidson, M.G. Thiamin deficiency in a colony of cats. Vet.Rec. 130:94-97;1992.Dilks, P.J. Observations on the food of feral cats on CampbellIsland. N. 2. J. Ecol. 2:64-66;1979.Everett, G.M. Observations on the behaviour and neurophysi-ology of acute thiamin deticient cats. Am. J. Physiol. 141:439-448; 1994.Finke, M.D.; Litzenberger, B.A. Effect of food intake on urinepH in cats. J. Small Anim. Pratt. 33:261-265;1992.Fitzgerald, B.M.; Karl, B.J.; Veitch, C.R. The diet of feral catson Raoul Island, Kermadec group. N. 2. J. Ecol. 15:123-129;1991.

20.

21.

22.

The ability of cats to associate theff avour of a food withacute adverse nutritional consequences, is similar to thatof the rat and therefore appears to have undergone littleevolutionary change from the normal mammalian pattern.

23.

24.

25.

Frings, H. Sweet taste in the cat and the taste spectrum. Expe-rientia 7:424-426;195 1.Hart, B.L. Feline behaviour: Feeding behaviour. Feline Pratt.4:8;1974.Hayes, K.C.; Carey, R.E.; Schmidt, S.Y. Retinal degenerationassociated with taurine deficiency in the cat. Science 188:949-951;1975.Hirsch, E.; Dubose, C.; Jacobs, H.L. Dietary control of foodintake in cats. Physiol. Behav. 20:287-295;1978.Holme, D.W. Practical use of prepared foods for dogs and cats.

In: Edney, A.T.B., (ed)., Dog and Cat Nutrition. Oxford: Per-gamon Press. 1982: 47-59.Houpt, K.A.; Hintz, H.F.; Shepherd, I. The role of olfactionin canine food preferences. Chem. Senses Flav. 3:281-290;1978.

26.References

Ishiko, N.; Sato, Y. Gustatory coding in the cat chordatympani fibres sensitive, and insensitive to water. Jpn. J. Phys-iol. 23:275-290;1973.Jones, E.; Coman, B.J. Ecology of the feral cat, Felis catus (L),in southeastern Australia, I: Diet. Aust. Wildl. Res. 8:537-547;1981.Kanarek, R.B. Availability and caloric density of the diet asdeterminants of meal patterns in cats. Physiol. Behav. 15:61 l-618;1975.Kane, E. Feeding behaviour of the cat. In: Burger, I.H.; Rivers,J.P.W., (eds)., Nutrition of the Dog and Cat. Cambridge:Cambridge University Press, 1989: 1477158.Kane, E.; Rogers, Q.R.; Morris, J.G.; Leung, P.M.B. Feeding

1.

2.

3.

4.

5.

Anderson, R.S. Obesity in the dog and cat. Vet. Annu. 14:182-186;1973.Baker, D.H.; Czarneki-Maulden, G.I. Comparative nutritionof dogs and cats. Annu. Rev. Nutr. 11:239-263;1991.Bartoshuk, L.M.; Harned, M.A.; Parks, L.H. Taste of water inthe cat: effects on sucrose preference. Science 171:699-701;1971.Beauchamp, G.K.; Maller, 0.; Rogers, J.G. Flavor preferencesin cats (Felis cams and Panthera sp.). J. Comp. Physiol. Psy-chol. 91:1118-1127;1977.Borkenhagen, P. Zur Nahrungsokologie streuneder Hauskat-

27.

28.

29.

30.

7/28/2019 Food Selection by He Cat

5/5

Food Selection by Domestic Cat 209

behaviour of the cat fed laboratory and commercial diets.Nutr. Res. 1:499-507;1981.

31. Kane, E.; Morris, J.G.; Rogers, Q.R. Acceptability and digest-ibility by adult cats of diets made with various sources andlevels of fats. J. Anim. Sci. 53:1516-1523;1981.

32. Karl, B.J.; Best, H.A. Feral cats on Stewart Island; their foodand effects of kakapo. N. Z. J. Zool. 9:287-294;1982.

33. Kaufman, L.W.; Collier, G.; Hill, W.L.; Collins, K. Meal costand meal patterns in an uncaged domestic cat. Physiol. Behav.25:139-141;1980.

34. Kienzle, E. Carbohydrate metabolism of the cat. 3. Digestionof sugars. J. Appl. Physiol. Anim. Nutr. 69:203-210;1993.

35. Kienzle, E. Carbohydrate metabolism of the cat. 4. Activity ofmaltase, isomaltase, sucrase and lactase in the gastrointestinaltract in relation to age and diet. J. Appl. Physiol. Anim. Nutr.70:89-96;1993.

36. Legrand-Defretin, V. Differences between cats and dogs: a nu-tritional view. Proc. Nutr. Sot. 53:15-24;1994.

37. MacDonald, M.L.; Rogers, Q.R.; Morris, J.G. Nutrition of thedomestic cat, a mammalian carnivore. Annu. Rev. Nutr. 4:

521-562;1984.38. MacDonald, M.L.; Rogers, Q.R.; Morris, J.G. Aversion of the

cat to dietary medium chain triglycerides and caprylic acid.Physiol. Behav. 35:371-375;1985.

39. Morris, J.G.; Rogers, Q.R. Ammonia intoxication in the near-adult cat as a result of a dietary deficiency of arginine. Science.199:431-432;1978.

40. Morris, J.G.; Rogers, Q.R. Arginine: an essential amino acidfor the cat. J. Nutr. 108:1944-1953;1978.

41. Mugford, R.A. External influences on the feeding of cami-vores. In: Kare, M.; Maller, O., eds., The Chemical Sensesand Nutrition. New York: Academic Press, 1977: 25-50.

42. Mugford, R.A.; Thome, C.J. Comparative studies of meal pat-

terns in pet and laboratory housed dogs and cats. In: Ander-son, R.S., (ed)., Nutrition of the Dog and Cat. Oxford: Perga-mon Press, 1980: 3-14.

43. Nogales, M.; Rodriguez, J.L.: Delgado, G.; Quils, V.; Trujillo,0. The diet of feral cats (Felis catus) on Alegranza Island(north of Lanzarote, Canary Islands). Folia Zool. 41:209-2 12;1992.

44. Randi, E.; Ragni, B. Genetic variability and biochemical sys-tematics of domestic and wildcat populations (Felis s&e&s:Felidae). J. Mammal. 72:79-88;1991.

45. Rozin, P. The selection of food by rats, humans and otheranimals. Adv. Stud. Behav. 6:21-76;1976.

46. Scarlett, J.M.; Donohue, S.; Saidla, J.; Willis, J. Overweightcats: prevalence and risk factors. Int. J. Obesity 18:(suppl. 1)S22-S28;1994.

47. Scott, P.P. The special features of nutrition of cats, with obser-vations on wild Felidae nutrition in London Zoo. Symp. Zool.Sot. London 21:21-36;1968.

48. Sloth, C. Practical management of obesity in dogs and cats.J. Small Anim. Pratt. 33:178-182;1992.

49. Sturman, J.A.; Garano, A.D.; Messing, J.M.; Imaki, H. Felinematernal taurine deficiency: effect on mother and offspring.J. Nutr. 116:655-667;1986.

50. Thorne, C.J. Feeding behaviour in the cat-recent advances.J. Small Anim. Pratt. 23:555-562;1982.

51. Turner, D.C.; Meister, 0. Hunting behaviour of the domesticcat. In: Turner, D.C.; Bateson, P., (eds)., The Domestic Cat:The Biology of its Behaviour. Cambridge: Cambridge Univer-sity Press, 1988: 111-121.

52. White, T.D.; Boudreau, J.C. Taste preferences in the cat forneurophysiologically-active compounds. Physiol. Psychol. 3:405-410;1975.