Aspects of comparative rabbit meat hygiene : a thesis presented in partial fulfillment (60%) of the requirements for the degree of Master of Philosophy in Veterinary Pathology and Public Health at Massey University

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(2) ASP ECTS OF COMPARATIVE RABBIT MEAT HYGIENE. A thesis presented in partial fulfilment (60%) of the requirements for the Degree of Master of Philosophy in Veterinary Pathology and Public Health at MASSEY UNIVERSITY. Evangelos Christofi Evangeli 1992.

(3) 1. ABSTRACT. Th i s. s tudy. Ma s t e r t on and. i nvolve s i n the. work. carried. out. at. the. aba t to i r. in. l abora tory o f the V e t erinary Facu l t y o f. Mas s e y Un i ver s i ty , on a s p e c t s o f rabb i t m e a t hyg i ene and f a c t o r s wh i ch may a f f e c t t h e qua l i t y of rabb i t mea t . The European rabb i t ( Oryc tolagus cun i c u l u s ) , i s the anc e s tor o f a l l breeds o f dome s t i c rabb i t s ,. among wh i ch the New Z e a l and. Wh i t e i s one o f the be s t meat producers , the Angora the be s t fur prod u c e r and the Rex i s. a breed common l y u s ed for exh i bi t i on. purpo s e s on l y . The feed convers i on r a t i o , wh i ch for an e f f i c i ent commerc i a l un i t s hould b e l e s s than abi l i t y of human. the. rabb i t. con sump t i on. con t r ibute. to. the. a nd. 3.5:1. ( Anon ,. t o con s ume the. rabb i t. f i brous. h i gh. b e ing. 1987),. an. comb i n ed w i th th e. f ood uns u i table. reprod u c t i ve exc e l l ent. f or. per forman c e ,. meat. produc i ng. a n i m a l . The product ion o f rabb i t mea t , i s s t i l l i n su f f i c i en t for the demands o f the world markets and e f for t s should be made to i n c r e a s e rabb i t meat produc t i on . D i s locat ion of the neck during s l aug h t e r of rabb i t s re s u l t s i n i mmobi l i z a t i on , but n o evidence was obt a i n e d t o s how that t h i s t e c hn i que. i nduced. i mmed i a t e. i ns e n s i b i l i t y .. nonpene t r a t i v e percus s i v e s tunn i n g ,. Penetra t i ve. and. proba b l y induced i mmed i a t e. i n s e n s i b i l i t y b u t caused v i gorous body movement s .. I t w a s found. i n t h i s s t udy that pup i l lary d i l at a t i on in rabb i t s ,. genera l l y. does n o t occur unt i l 8-1 0 minutes a f ter s l aughte r , s o pup i l l ar y d i l a t a t i on i s o f n o v a l u e as a c r i ter i on f o r the a s s e s sment o f the a c tual t ime o f ons e t of insens i b i l i ty ..

(4) 2. I n v e s t i gat i on. of. carc a s s. y i elds. of. rabb i t s. s howed. that. s l augh t e r i ng rabb i t s at a g e s gre a t e r than e i gh t week s , re s u l ted in on l y marg inal incre a s e s i n carc a s s y i e l d s . I mmers ion o f carcas s e s i n water for p e r i ods longer than m i nu t e s can r e s u l t in a comme r c i a l. technique. 10.70%. 30. incre a s e i n the i r we i gh t , but the. i nve s t i g a t ed ,. resu l t ed. in. approx .. 7%. incre a s e . Wash i ng carca s s e s d i d not reduce bac t e r i a l l eve l s , but i n s t e a d tended to incre a s e carc a s s surface counts from 3 1 0 2 / cm 2 t o 1. 3 3 X 1 0 / cm2 • The mean u l t imate pH o f rabb i t meat w a s. 4.20. x. i n the reg ion o f. F a c tors a f f e c t i ng t h e u l t i mate pH i nc luded concurrent. 5. 40-6.25.. d i s e a s e s and i n t e n s i ve mus cul ar ac t i v i t y . The rate of pH d e c l i n e was. a f f e c ted. by. the. degree. of. s truggl i ng. at. the. t i me. of. s l augh t e r . The ma j or gros s l e s io ns obs erved i n the c arc as s and v i s c era of the rabb i t s s tudi ed , were those o f hepa t i c cocc i d i o s i s and to a. l es s er. degre e ,. absc e s s e s .. The. s tudy. of. the. accuracy. of. det e c t i on o f hepa t i c coc c i d i o s i s i n t h e aba t t o i r w a s de s i gned a s a mod e l for t h e s tudy of s i m i lar me a t i n s p e c t i on procedures i n other. animal s .. It. exam i n a t ion. of. spe c i f i c i ty. 100%.. coc c i d i o s i s cond i t i ons , w i th. in. the. was. found. l i ver , A. the. s tudy. rabb i t s ,. that ,. based. sens i t iv i ty. of. the. revealed. on was. h i s tolog i c a l 41%. epidemi olog y that. under. and. the. of. hepa t i c. New. Z e a l and. i t i s unl i ke l y that any farm i s free o f i n f e c t ion. E imer i a. s t i edae .. However ,. if. i n f e c t ions. are. of. low. in tens i t y , rabb i t s may not d evelop macroscop i c hepa t i c l e s i ons . I t a l s o appears that h i s tolog i c a l l e s i ons of the l i ve r ( bi l i ary prol i f e r a t i on , f i bros i s , c e l lular i n f i l tr a t i on o f th e b i l e duc t s w i t h i n f l amma tory cel l s , i n c lud i ng eos i noph i l s and l ymphoc y t e s ) are p a t h ognomon i c for d e t e c t ing p a s t or pre s e n t i n f e c t i on by � s t i eda e ..

(5) 3. ACKNOWLEDG EMENTS. My. part i cular. and. s i ncere. thanks. are. d i re c t ed. toward. my. superv i sors Pro f e s s or D . K . B l ac kmore and Mr . P . M ad i e , for the i r a s s i s t ance and guidance , not on l y i n t h i s i nve s t i g a t i on , but throughout my s tudy a t Ma s s ey . I wou l d also l i ke to thank Dr . W . A . G . Charl e s t on , Mr . W . E . Pomroy and M i s s A . k . Soe , for g u i d i ng me w i th the proce s s i ng of the mate r i al r e l a t ed to the epi dem i o l og i c a l part o f my i nv e s t i g a t i on , and a s s i s tance in the wr i t i ng of th e r e l ev a n t part o f my t h e s i s . I am grate ful to Dr . R . Marsh a l l and Mr . Fenw i ck , for the i r adv ice on the m i c rob i ol og i c a l part of. S. my. i nv e s t i ga t i ons , Mr . W . Chen and Mr . L . M . Badcoe , for a s s i s t i ng me w i th the exam i na t i on o f the s amp l e s f rom rabb i t l i ve r s , Mrs . P. Davey and Mrs . P S l ack for prepar i ng h i s tolog i c al m a t er i a l , J. S chrama for prepar i ng the med i a u s ed for the Mrs . m i c ro b i o l og i cal i nv e s t igat i ons , Mr . Tom Law for photographs and Mrs . O . Harr i s , Mr . z . F . Fu , M i s s T . L i ndholm , and Mrs S . Spanou for t y p i n g my the s i s . I am a l s o gra te ful to Mrs G . Abs o l on for her g r e a t h e l p k i nd l y offered to me dur i ng my exp e r i men t a l work e i th e r at t h e aba t to i r or in her rabbi try . Dr Ch . Kakoy i ann i s and Mr A . Orpha n ides are also among the peop l e of Mea t H y g i e n e of my coun try C yprus , who ki ndly o f f ered me g u i dance and a s s i s t ance dur i ng the wr i t i ng o f my The s i s . Spec i al thanks go to Mr . A . Orphan i d e s who a l s o d i d the s t a t i s t i cs . The f r i endsh i p and a s s i s t ance k i nd l y of fered to me by the o f f i c e r s of the reg i s try and U . G . C . , as we l l a s by the l i brary personne l , i s well known and ex treme l y appre c i a t ed . I wou l d also w i sh to expre s s my gra t i tude t o t h e Gov ernment o f New Z ea l and , for prov i d i ng the s ch ol ar s h i p to enabl e me to und e r t ake t h i s course of s tudy and to th e government of my coun t r y ,. C yprus ,. for the f inan c i al s uppor t ,. g i ve n t o my f ami l y. dur i ng t h e cour se . F i nal l y , I wou ld l i ke to t h ank my GOD for pro t e c t i ng me and my fami l y dur ing t h i s s tudy ..

(6) 4. TABLE OF CONTENTS. PAGE NO .. ABSTRACT. 1. AKNOWLEDGEMENTS. 3. TABLE OF CONTENTS. 4. L IST OF TABLE S. 5. L IST OF F I GURES. 9. CHAPTER ONE :. GENERAL INTRODUCT I ON. 11. CHAPTER TWO :. THE PROCESS ING ABATTOIR. 23. CHAPTER THREE :. SLAUGHTER OF RABB ITS AND RATES OF BLEE DI NG. CHAPTER FOUR :. CARCAS S YI ELDS AND RELATIVE ORGAN WE I GHTS. CHAPTER F I VE :. 32. 54. EFFECTS OF CARCASS WASHING ON RABB I T MEAT QUAL I TY. 71. CHAPTER S IX :. THE PH OF RABB IT MEAT. 92. CHAPTER SEVEN :. PATHOLOGI CAL L E S I ONS OF THE CARCASSES AND V I SCERA OF RABBITS. CHAPTER E I GHT :. 116. ACCURACY OF INSPECT ION PROCEDURES IN RELAT ION TO HEPAT I C COCC I D I O S I S. CHAPTER N I NE : CHAPTER TEN : REFERENCES. 12 4. EPIDEMI OLOGY OF HEPATIC COCC I D I OS I S OF RABB ITS. 1 42. GENERAL DI SCU S S ION. 163. 167.

(7) 5. LIST OF TABLES. 3.1. T h e e f f e c t s o f b l e ed i ng o n the dur a t i on o f s pontaneous body movemen t s of rabb i t s , s tunned by the pene tra t i ve percu s s ive method .. 3.2. 42. Compara t i ve blood loss and rates o f bleeding of rabb i t s subsequent to a transve r s e i nc i s ion o f t h e neck .. 3.3. Sub j e c t ive de t e c t ion o f whether or not rabb i t c a r c a s s e s have been bled .. 4.1. 47. 48. L i ve weights ( g ) , carc a s s y i e lds ( g ) and blood l o s s ( ml ) of 2 4 rabb i t s s l aughtered at the a b a t to i r .. 4.2. 58. L i ve w i ghts ( g ) and carc a s s y i e lds ( g ) , blood l o s s ( ml ) , w e i g h t s ( g ) and relat ive we i g h t s of organs of 2 0 New Z e al and Wh i te rabb i t s s l aught ered in the l abora tory .. 4.3. 59. L i v e w e i gh ts , c a r c a s s y i elds , blood los s , we i ghts and r e l a t ive w e i gh ts o f organs o f tw o young adu l t New Z ea l and Wh i t e rabb i t s k i lled i n the laboratory .. 4.4. Me a n l ive we i gh t s and carc a s s y i e l d s o f d i f ferent groups o f rabb i ts .. 4.5. 60. 62. Mean values o f c arca s s y i elds , blood l o s s and r e l a t i v e organ w e i gh t s of 22 rabb i t s w i th a mean l i vewe ight o f 2 4 2 3 grams , s l aughtered i n t h e l aboratory .. 63.

(8) 6 P age No 4.6. L i v e we i gh t ( g ) , c arca s s y i eld ( g ) , b lood loss ( ml ) and r e l a t ive organ we i g h t s o f 1 5 bled rabb i ts .. 4.7. 64. L i v e we i ght , carc a s s y i eld and re l a t i ve organ we i ghts i n gr ams o f s even unbled rabbi ts .. 4.8. 65. Compar i s on o f the mean values o f l i v e we igh t s , carcas s y i e lds , bl ood lo s s and r e l a t i v e organ w e i g h t s o f n i ne rabb i t s > 2 0 0 0 g l i ve w e i ght , w i th the mean v a l u e s of s i x rabb i t s < 2 0 0 0 g l i ve we i ght .. 5.1. 65. Water uptake o f r a bb it c arc a s s e s a f t e r d i f f erent periods o f immer s ion . ( Expe r i ment " a " ). 5.2. 80. Water uptake by t h e carc a s s of a w i ld rabbi t . ( Exper iment " b " ). 5.3. 81. Water uptake by f our h i nd legs f rom t wo dome s t i c rabb i t s ( 4 - 5 hrs a f ter k i l l i ng ) . ( Expe r i ment " c " ). 5.4. Water up t ake by 1 5 N . Z Wh i te carc a s s e s w ith l ow pH ( 6 . 0 0 ) .. 5.5. ( Experiment " d " ). 83. Water upt ake by f i ve N . Z . Whi te carca s s es wi th h i gh pH ( 6 . 7 0 ) .. 5.6. 82. ( Expe r i ment " e " ). 83. Bac t e r i o l og i cal r e sults from swabbing ten c arc a s s e s be fore ( right h ind leg) and a f ter ( l e f t h i nd leg) wash ing .. ( In cubat ion a t 3 7 °C ) .. 84.

(9) 7. P age No 5.7. B a c t e r i o l o g i cal r esu l t s from four wat e r s amp l e s t aken before and a f te r carc a s s was h i ng .. 6. 1. 85. pH values o f the mus c l e s o f 1 2 dome s t i c r a bb i t s three hours a ft e r s tunn i ng by the neck d i s locat i on m e thod at the aba t to i r .. 6.2. pH values o f the mu s c l e s o f 2 5 dome s t i c aba t t o i r r a bb i t s s tunned b y the neck d i s locat i on me thod .. 6. 3. 99. 1 00. pH values o f the mus c l e s o f three rabb i t s condemned a t the aba t to i r ( No . 1 and 2 w i th y e l low f a t , No . 3 ema c i a t ed ) .. 6. 4. 1 01. pH values o f the mus c l e s of f i ve dome s t i c r a bb i t s a f te r s tunn ing b y the neck d i s loc a t i on me thod .. 6. 5. 1 03. pH v a l u e s o f the mus c l e s o f f i ve dome s t i c r a bb i t s a f t e r s tunn ing b y the non-penetrat i ve pe r c u s s ive me thod .. 6.6. 1 04. pH v a l u e s o f the mu s c l e s o f two dome s t i c rabb i t s a f t e r s tunn i ng b y the non-pene t r a t i ve p e r cu s s ive me thod .. 6.7. 1 05. pH values o f the mus c l e s of f iv e dome s t i c rabb i t s s t o raged a t - 1 ° C a f t e r the f i r s t measurement a f t e r s tunn i ng by the pene trat i ve percus s i v e me t h od . Mean carc a s s temperature a t 4 h r s =+ 1 2 ° C and a t 2 4 h r s =+4° C .. 6.8. 1 06. pH v a l u e s o f the mus c l e s o f f i ve dome s t i c rab b i t s one t o three hours a f t e r s tunn i ng b y t h e pene t r a t i ve percus s ive method .. 1 07.

(10) 8. 6.9. pH v a lues o f the mus c l e s o f four w i ld rabb i t s 2 4 h r s post -mortem .. 6. 1 0 Mus c l e pH of two w i l d rabbi ts . 8.1. 1 08 1 09. Comp a r i son o f speci f i c h i s tolog i c al change s a s s o c i ated wi th E . s t i ed a e i n f e c t i on a t d i f f erent s i te s w i t h i n t h e l i ver ( n ine s i t e s from e ach o f e i ght l i v e r s w i th macroscopic les ions ) .. 8.2. 1 32. Comp a r i son o f preva l ence o f macroscop i c and m i c ro s cop i c l e s i ons i n rabb i t s subm i t ted for s l aughter .. 8.3. 1 33. Spe c i f i c h i s tolog i c a l changes i n rabb i t l i ve rs from groups w i th and w i thout macros cop i c l e s i ons .. 1 37. 9.1. D e t e c t ion of oocy s t s i n f aeces .. 1 58. 9.2. Re s u l t s o f m i c roscop i c a l exam in at i on o f two l i v e r s from rabb i t s f rom a hepa t i c cocc i d i o s i s f r e e f arm .. 1 59.

(11) 9. LIST OF FIGURES. 2.1. The aba t t o i r at Mas terton . L oad out area .. 2.2. P l a n o f the rabb i t proce s s i ng p l an t a t Mas t e r ton .. 2.3. 26. Pel t removal showing po i n t s o f de t achment on l egs .. 3.1. 29. Sma l l hammer and s t eel rod and tube u s ed for penetra t ive percu s s i v e s tunn i ng .. 3.2. 25. 38. Schema t i c drawing o f rabb i t head s howi ng the t a rg e t of penetrat ive percu s s i v e s tu n n i ng .. 39. 3.3. Pup i l l ary cons t r i c t ion .. 43. 3.4. Pup i l l ar y d i l a t a t i on .. 43. 3.5. Typ i c a l sku l l l e s i on wi t h b i lateral prolap s e o f t h e eyeba l l s caused by the pene trat ive percu s s i v e s tunn i ng .. 3.6. 45. The r e l a t i on s h i p between l i ve we i g h t and volume o f blood collected during bl eeding . Y. =. -. 8. +. 20 . 9 1 X. ( Change o f blood loss per Kg change i n l i ve we igh t ) 4.1. 49. Carc a s s y i eld and blood l o s s of 2 4 rabb i ts s l augh t ered a t the aba t to i r .. 66.

(12) 10 P age No 4.2. Carc a s s y i e l d and r ela tiv e organ w e i g h t s o f 1 5 b l e d and seven unbled rabb i t s.. 5.1. 67. I l l u s t r a t i on o f the water upt ake by th e carc a s s o f a w i ld rabb i t ( Expe r i ment " b " ) and four r abb i t h i nd legs ( Experiment " c " ) .. 86. 5.2. W a t e r u p t ake by t ame rabb i t s .. 87. 6. 1. De c l i ne i n pH o f S emi tend i nosus mus c l e s of groups of rabb i t s ,. f i ve per g roup ,. s tunned. by three d i f ferent methods . 6.2. 110. D e c l i ne i n pH of P soas mus c l e s o f three di f fere nt groups o f rabb i t s ,. f i ve per. group , s tunned by d i f ferent me thods . 7.1. Ab s c e s s i nvolving the mand i b l e o f an Angora rabb i t .. 8.1. 111. - S i de numbers i nd i c ate cen t ime ters .. 1 21. Rabb i t l i ver show i ng the n i n e s i te s f rom where the s ec t i ons were t aken for the pre l i m i nary h i s tolog i c al inve s t i ga t i on .. 8.2. 1 28. S e c t ion f rom a l i ver show i ng prol i fe r a t ion o f t h e bi l e duct epi the l i um and f i bros i s around t h e bi l e duc ts ( x 7 5 ) .. 8. 3. 1 30. L i ver s e c t i on wi thout any h i s topatholog ical c h anges ( x7 5 ) .. 8.4. Ooc y s t s o f E . s t i edae i n the b i l e duc t of a rabb i t l iver . The b i l e duct shows f i bros i s. 8.5. 1 34. ( x7 5 ) .. 1 35. Ooc y s t s o f E . s t i edae i n th e b i l e d u c t lumen of rabb i t l iver (X3 0 0 ) .. 1 36.

(13) 11. CHAPTER O N E GENERAL INTRO DUCTION. A l l present da y s tr a i n s of dome s t i c ated rabb i t s h a v e been deri ved. by. s e l e c t ive. breeding. ( T i tt ensor. cun i culus }. ( Oryc t o l agu s. from. European. and. L l oyd ,. w i ld. rabb i t s. 1 983 } .. The. European rabb i t i s a member of the order Lagomorpha , wh i c h a l s o con t a i n s p i kas ( Ochotona s p . } , hares ( Lepu s s p . } and c o t ton t a i l rabb i t s. ( Su l s i l epus sp . } ( T i ttensor and Lloyd , 1 9 8 3 } .. The order. cons i s t s of nine genera and approx . 5 0 spec i e s , repre s e n t a t i v e s o f wh i c h occur on mos t o f t h e ma j or l and ma s s es o f the world a s wel l as o n many i s lands ( Walker e t a l , P a l e ontolog i c a l evidence , or i g i n a t ed i n North Amer i c a ,. 1 964 } .. i nd i c a t e s. t h a t rabb i t s m a y h ave. from where th e y cou ld have s pread. wes twards v i a the Aleut i an l and bridge into Central As i a ( Thomson and Worden ,. 1 95 6 } .. It ha s also been s ugg e s ted that rabb i t s are. nat i v e t o , and o r i g i nated i n , s em i - ar i d areas of S outhern F rance , Ibe r i a. and. in troduc ed. Nor th-We s t by. cont i n e n t s. man. whe r e. to. many. they. ( Ti t t en s o r and L l oyd , Al t hough. A f r i ca .. From. other. the s e. parts. e s tabl i shed. they. Europe. them s elves. and. were other. s u c c e s s fu l l y. 1 983 } .. s om e bel i eve the rabb i t was. f i r s t c e n tury B . C . ,. of. areas. dome s t i c a t ed by. the. others sugge s t that th e f i r s t a t t empt s t o. dome s t i ca t e rabb i t s were made in French mona s t er i e s b e tween the s i xth. and. t e n t h centu r i e s A . D .. ( Adams ,. 1 972 } .. Thom s on. and. Worden ( 1 9 5 6 } s t ate that the pre s en c e o f rabbi t s i n Br i ta i n was de s c r i bed i n the 1 3 th c entury ,. and T i t te n s or and L lo y d. ( 1 983 }. c l a i m t h a t rabb i t s were introduced t o Br i tai n by th e Normans i n 1 1 76 . The n a tural d i s t r i bu t i on o f the European rabb i t s i s genera l l y in. l owl and. Carp a th i an s .. Europe ,. from. I ta l y. to. Portugal. and. up. to. the. Their numbers are more r e s t r i c ted in De nm ark , the.

(14) 12 B a l kans and I taly . Th e y have a l s o been i n troduced to the Chann e l I s l ands ,. Norweg i an. I s l ands ,. and. many. e a s tern. A t l an t i c. and. Medi terranean I s l ands . In other parts of th e world rabb i t s have been i n t roduced to northern A f r i c a , the Hawa i i an I s l ands , Ch i l e and Argen t i n a , i n South Amer i c a . I t was common for rabb i t s to be carr i ed i n the old s a i l i ng sh ips and to be rel e a s ed i n new lands i n th e hope that they m i g h t breed a n d b e a source o f food for s a i lors at a l a t e r v i s i t or when s h i pwrecked .. I n th i s way remote s ubantarct i c i s lands l i ke. the Auckl ands and MacQuarr i e were colon i s ed by rabb i t s . Au s t r a l i a. ( i n c l uding. un fortun a t e l y ,. Tasmani a ). and. been very succ e s s fu l l y. European rabb i t s ( T i t t ensor and Lloyd ,. New. Z e a l and. colon i sed by 1 9 83 ) .. have ,. i n t roduced. The i n t rodu c t i on. o f rabb i t s to Au s tr a l i a and New Z ea l and for the sport o f hun t i ng , was part i cularly i l l advi sed because o f the abs ence o f natural preda tors and the presence o f abundant food wh i ch al lowed them to mul t i p l y rap i d l y and cause exten s ive d e s truc t i on of vege t a t i on ( Walker e t al ,. 1 964 ) .. As a r e s u l t o f the detr imental e f f e c t s of the w i l d rabb i t s o n New Z ealand vege t a t i on ,. rabbi t s were c l a s s i f i ed a s nox i ou s. animals and the i r f arm ing a nd ke e pin g a s pe ts w e re banned ( Anon 1 987 ) .. Control programme s f a i led to eradicate them c ompl e t e l y ,. but s u c c e eded i n reduc i ng the i r numbe r s to a l ow l ev e l i n mos t areas .. Under the s e c i rcums tanc e s , the farm i ng o f rabb i t s i n New. Z e a l and. was. perm i t ted. by. an. order. in. Counc i l. of. May. 1 985 ,. prov i d e d loca l author i ty requi reme n t s were met . A c l o s e re l a t i ve to the rabb i t i s the hare , are 26 s pec i e s . Asia parts. The hare i s pre s en t i n mos t areas o f Europe and. i n c luding Sumatra , of. Zeal and ,. Africa. of w h i c h there. and. Aus tral i a. Java ,. Nor th. and. in. Formo s a �nd Japan ,. Ame r i c a . some. oth e r. In. South. and. Amer i c a ,. count r i e s ,. introduced by man and have become w i despread . Th e spec i e s are Lepus ameri canus and L . europaeus .. in mos t. hares. New were. mos t c ommon.

(15) 13 L agomorpha are d i f f e r e n t i ated from rod e n t s by the i r l ong e a r s a n d h i nd l e g s. ( Ti t tensor and Lloyd ,. 1 983 ) .. Rabb i t s a n d h a r e s. have an add i t i onal pa i r o f smal l , peg- l ike t e e t h l y i ng d i re c t l y beh i n d t h e uppe r pair o f i n c i sors , a fea ture wh i ch d i s t i ngui s h e s a l l Lagomorpha from rodents .. The den tal f ormula i s. 0/0,. ( Ti t tensor and L loyd ,. pm 3 / 2 , m 3 / 3 x 2 Apart. from. the. 28 .. =. colour. d i f f erences. b e t ween. :. i 2/1 ,. C. 1 983 ) .. th e. hare s. and. rabb i t s , h a r e s have longer ears , longer h i nd l egs and l i f t the i r rumps. h i gh e r. than the. r est. t e rms o f s ku l l format i on ,. of. the i r. body. when. mov i ng . I n. rabb i t s are d i s t i ngui shed from h are s. by a much narrower na sa l pas s age and i n t h e former , i n c i sors. are. more. ( Ti t tensor. developed .. and. the fron t. Lloyd ,. 1 983 ) .. Con fus i on c a n a r i s e f rom use o f the word s rabb i t and hare .. The. n am e s " j ack rabb i t " and " snow shoe rabb i t " are us ed c o l l oqu i a l l y f o r Nor t h Ame r i can hare s and the name " Be l g i an hare " i s appl i ed to a s t r a i n o f dome s t i c a ted European rabb i t ( Walker e t a l , 1 9 6 4 ) . I n some area s of Cyprus , peop l e c a l l rabb i t s hare s . The. European. rabb i t. has. gray i sh - w h i te underparts . A lb ino ,. short. den s e. A s many as. gre y- brown. fur. and. 2 0 % may be me l a n i s t i c .. long haired and s i lver p i ebald forms occur natura l l y a s. rare v a r i a n t s .. The s exes a r e qu i t e. s im i l ar but t h e head. is. n arrower and l e s s rounded i n prof i l e i n f emal e s than i n ma l e s ( T i t t ensor and Lloyd ,. 1 983 ) .. Rabb i t s and hare s are usua l l y more a c t i ve dur i ng the even i n g s and. n i gh t s. than. dur i ng. the. rabb i t s move s lowl y a round ,. day. t i me .. If. left. und i s turbe d ,. but i f t h r e a tened or cha s ed by a. predator they can move swi f t l y a c h i e v i ng s peeds o f up to 8 0 km / h . I n add i t i on to s peed , rabb i t s have other d e fence mechan i sms such a s a keen s ense o f hearing and smel l , noc turnal a c t i v i ty , burrow ut i l i z a t i on ,. and the us e of danger s i gnal s - rabb i t s drum w i th. the i r h i nd feet ( Walker e t al, 1 96 4 ) . a l s o be a d e fence mechan i sm ,. The s cream o f a rabb i t may. in that it may s t ar t l e a predator ..

(16) 14 The w e i gh t o f the adul t w i ld rabbi t i s be tween 1 0 5 0 - 2 2 0 0 g The bre e di ng p a t tern. and the f emale i s heav i e r t han the male . i n rabb i t s. is. d i f ferent. f r om that o f many o t her mammal s .. A. sexua l l y mature doe , under f avourable cond i t i on s ( adequ ate planes o f nut r i t i on , temperature and l i ght dura t i on ) , i s i n oe s trous for long p e r i ods ,. dur ing wh i c h Graa f i an fo l l i c l e s are con t i nuou s l y. develop i ng and regres s i ng i n such a way , t h a t a f a i r l y con s t a n t numbe r i s ava i l able for ovula t i on. ( Anon ,. 1 980 ) .. On the firs t ,. t h i rd , f i f th , tenth and f i f t eenth day o f l ac t a t i on , the does are ready to mate with the m al e .. I n terms o f d e t e c t i on of o e s t ru s ,. the e n l a rged and redd i s h - purple colored v u l v a and vagina i s a good i n d i c a t i on , al though s ome does w i l l m a t e e ven when the vulva is r e l a t i v e l y small and p a l e .. ( C i t ed in Anon ,. 1 986 ) .. Ovu l a t ion i n does i s usual l y s t imu l a t e d by coi tu s ,. but c an. o ccur under condi t i ons w h i ch cause inten s i ve s exual exci temen t . Th e. number. of. copu l a t i on s. doe s. not. i nc r e a se. the. number. of. ovu l a t i on s but the l a t t e r i s s t rongly r e l a t e d to the bodywe i gh t o f t h e doe . Approx . 2 5 % o f mated does f a i l t o ovu l a t e .. Th i s i s. probably due to a de f i c i ency o f l u t e i n i z ing hormone , i n s u f f i c i en t hour s o f l i ght o r incre a s i ng leve l s o f dura t i on o f l i ght . nor t hern hem i s phere ,. I n th e. s u c c e s s ful ma t i ng i s more frequent du ri n g. s p r i n g than i n the la te summer an d autumn. ( Adams ,. 1 972 ) .. The. pe r i od of ge s t a t i on is u s u a l l y 3 1 -3 2 days and the s i z e of t h e l i t t er i s normally 8 - 1 0 young ( Anon , Rabb i t s. are born b l i nd ,. 1 980 ) .. h e lple s s and naked. i n a fur l i ned. ne s t , e s pec i a l l y prepared for them , whe r e a s hares are born in an open ne s t ,. fully. furre d ,. w i th open e y e s. and are able. around wi t h i n a few m i nu t e s o f b i r th ( Wa l k e r et al , A po i n t o f spe c i a l intere s t about t h e rabb i t ,. to. run. 1 964 ) . i s i t s h ab i t. o f c oprophag i a , s omet im es re ferred t o a s p s eudorum i n a t ion .. Th i s. hab i t involves the r e i n ge s t ion o f s o f t f a e c al ma t e r i a l d i r e c t l y f rom the anus . hours. of. the. Th i s f o rm o f faeces i s produced dur i ng t h e e a r l y morn ing. and. is. a. r i ch. s ource. s y n th e s i z ed by the b a c t e r i a i n the caec um .. of. vi tamin. When rabb i t s. B, are.

(17) 15 prevented. f rom prac t i c i ng. weeks ( Adams , 19 7 2 ) .. coprophag i a ,. they. die wi thin. three. The s i gn i f i cance of coprophag i a i n r e l a t i on. to d i f fe r e n t di s e a s e s , espec i a l l y cocc i d i os i s , w i l l be d i scus sed further i n Chapter Nine . The f ecund i t y and short g e s t a t i on p e r i od o f rabb i t s , together w i th other charac t e r i s t i c s s u ch as compara t i ve smal l s i z e and e a s e of h andl ing , make the rabb i t an i deal laboratory animal for many purpo s e s .. BREEDS OF. RAB B ITS. Rabb i t s and hare s , caught in snare s ,. were of impor tance to. e a r l y man as a s ource of food and c l o t h i ng. den s e. soft. fur ,. were we l l. adapted. d i f f erent periods of h i s tory ,. The i r t h i n s k i n and. to many. uses .. as dur ing the. Later ,. at. f i r s t and s e cond. wor l d war s ,. rabb i t s became a more i mportant source of me at and. many people. ra i s ed them i n l im i ted space , as a means o f rapidly. i ncrea s i n g the supply of locally produced meat . S i n c e the European rabb i t was f i r s t dome s t i c a ted , s e l e c t ive bre e d i n g has created many d i f f erent breeds for m e a t produ c t ion , for fur and pe l t s , and fancy breeds for exh i b i t i on ( Walker e t al , 1 964 ) . The meat breeds include the Cal i forn i a and F l e m i s h G i an t . The s e a n imal s are usua l l y k i l l ed for meat produ c t i on before they be come adul t ,. for be tter econom i c a l e f f i c i ency .. F l e m i s h Gi ant. rabb i t s are one o f the larg e s t breed s , but grow very s lowly and are n o t pre ferred econom i c a l l y. ( Anon ,. 1 9 8 5a ) .. The major fur and p e l t produc i ng breeds i nc l ude the Angora , C h i n ch i l la , New Z ealand Wh i te , Rex , S i lver and Fox . Among the fur breed s ,. the Angora is. produ c t i on , Z ea l an d .. and. is. regarded as. farmed. in. one of. many. the be s t. countr i es. for f ibre. i nc l u d i ng. New. Thes e fur bree d s tend to be o f dual purpose i n that.

(18) 16 The New Z e a l and Wh i t e ,. the i r carcas s e s are a l s o used for meat .. wh i c h was developed i n the Un i ted S tate s , a l though a du al purpo s e breed ,. is. probabl y. product ion ,. the. breed. Ne therlands. commonl y. used. for. meat. because i t i s ear l y maturing and has an exc e l l ent. food conv e r s i on rat i o ( Anon , Common. mos t. exh i b i t ion Dwarf. and. 1 985a) .. breeds. i n c lude. th e. Tan ,. Rex .. These. are. no t. the of. Dut c h. and. s i g n i f i c ant. importance i n meat produc t i on and are s e l ec t ed ma i n l y for the i r colours and body conformat i on i n rel a t i on to s omew h at ar t i f i c i a l c r i ter i a r e l ated to exhibi t ion ( Anon , 1 9 8 5 a ) .. RAB B I T. MEAT PRODUCTI ON. I n New Z e al and , rabb i t s for meat produc t i on are s l aughtered at approx . 2 kg. e i ght weeks of age , when the i r l i vewe i g h t is around. ( Anon ,. 1 987 ) .. A good average food convers i o n rat i o of a. 2 Kg rabb i t i s around 3 . 5 : 1. ( Anon , 1 9 8 7 ) , wh i ch c ompared to mos t. other me a t an imal s , i s cons idered favourab l e , wi t h t h e except i on o f pou l t r y ( broi l ers ) for wh i c h a good food conv e r s ion r a t i o i s 1 .8:1. ( Anon , 1 9 8 4 a ) a t s i x weeks o f age .. c o s t o f p e l leted food for rabb i t s ,. Howeve r , w i th the h i gh. the rat i o n e e d s to be 3 . 2 : 1. t o be econom i c i n mos t c i rcum s tances ( Anon , 1 9 8 7 ) .. I t was found. that rabb i t s s l aught ered up to the age of 5 6 day s , have th e be s t f ood con v e r s i on .. When s l augh ter i s de layed for e v en one week ,. the prof i t become s l e s s as a r e s u l t of the extra l abour i nvolved and the d e c l ine of the food convers i on r a t i o ( A i tken and K i ng , 1 962 ) . Rabb i t Firstly ,. farm i ng. i ntens i v e. can. be. farming. d i v ided. into. s y s tems ,. two. where. main l arge. c a t eg or i e s . number s. of. rabb i t s o f improved breeds a n d s tr a i n s , a r e k e p t u n d e r s tr i c t l y contro l l e d envi ronmental cond i t i on s and fed a b a l anced p e l l e t ed rat i on .. S econdl y ,. sma l l. sc al e. or. backyard. l ev e l. rabbi t. produc t i on s y s tems , whi ch are s t i l l i mportant i n many coun t r i e s l i ke Ma l t a , and S p a i n .. Such s y s tems a r e s u i tabl e f o r deve loping.

(19) 17 coun t r i e s becau s e o f the i r low cap i t a l. inpu t ,. rap i d f i nanc i a l. turnover and use o f local l y avai lable c o n s t ru c t i on mat e r i al s and feed ( Owen et a l ,. 1 977 ) .. H i gh t emperature i s probably the mos t s e r i ous env i ro nm e n t a l prob l em for rabb i t s .. The normal body t emperature o f th e an imal. i s 3 8°- 3 9 °C and the thermoneu tral i t y z one be tween - 5° t o 3 0° C . When. amb i en t. t emperatures. reach. 30. degree s. or. abov e ,. the. fer t i l i t y of the ma l e rabb i t decreas e s drama t i c a l l y ( Ch e n e t a l , 1 978 ) .. The fem a le ' s fer t i l i t y i s a l s o decreased. ( Owen e t a l ,. 1 977 ) . Among. the. many. coun t r i e s. farm i n g. rabb i t s ,. Ch in a. is. the. l arge s t exporter of rabbi t meat and Angora f i bre ( wool ) , and i t s farming. s y s tems. coun t r i e s. wh i c h. are. eff i c i ent .. i mport. New. rabb i t m e at. Z ea l and. is. from C h i na .. one Th e. of. th e. pric e. of. Angora f i bre i s contro l l e d b y t h e i n t erna t i onal mark e t but. is. very m u c h i n f luenced by C h i na as t h e m a j o r world produ c e r . The magn i tude of the r abb i t indus try i n China i s i l l u s trated by i nformat i on s u pp l i ed by the Ch i n e s e Embas s y i n We l l i ng ton in re s pons e to a requ e s t by the author .. C h i na expor t s 3 0 , 0 0 0 - 4 0 , 0 0 0. tons o f frozen r abb i t meat per year , mi l l i on . marke t s .. We s t ern. Europe. and. Japan. w i th a value o f U S $ 4 0 - 5 0 are. the. ma j or. overseas. A quan t i ty o f 5 , 0 0 0 - 7 , 0 0 0 t o n s o f raw h a i r i s e xported. annua l l y w i th a value o f US$1 . 5 - 1 . 7 hundred mi l l i on .. The m a j or. mark e t s are We s t Europe , Japan and Aus t ral i a ( L i u B e i L e i , pers . comm . ). Presumab l y , a l arge quan t i t y o f rabb i t meat i s s upp l i ed. to the local market .. I t would be i n tere s t i ng to know t h e t o t a l. quan t i ty o f rabb i t m e a t consumed b y a popu l a t i on o f about 1 . 2 b i l l i on peopl e i n the Republ i c o f Ch ina , e s pec i al l y con s i de r i n g t h e l o w pr i ce o f th i s product ( Ch e n , pers . cornrn . ) . Other cou n t r i e s w i th developed r abb i t i ndu s t r i e s a r e ma i n l y i n Europe , and i n c lude I ta l y , Pol and , Bri t a i n , Hol l and , Denmark , Spa i n , German y , Mal ta , Sweden , and F rance .. France i s t h e l arge s t. producer o f rabb i t meat i n the wes t e rn world and Ma l t a h a s the.

(20) 18 world ' s h i ghe s t per c a p i t a consump t i on o f rabb i t me at o f 8 kg per person annu a l l y ( Anon ,. 1 987 ) .. The U n i ted S t a t e s and Canada produce r abb i t s for mea t , f i bre , s k i n s and fur for bot h the home marke t a s w e l l as for export . I n South Ame r i c a ,. Ch i l e and Argen t i na a r e t h e ma i n produ c e r s w i th. export marke ts for both mea t and f i bre .. Coun t r i e s i n the M i ddl e. Eas t and Th i rd Worl d countr i e s have s ta r t ed to deve lop c omm er c i al rabb i t f arms and " backyard" u n i t s s u i t e d for local cond i t i ons . Pre s e n t world rabbi t meat produc t i on world demand ,. is. insuffic ient. t o meet. and in many A s i an and P ac i f i c coun t r i e s th e re i s. a demand for larger quant i t i e s that c an b e s uppl i ed ( Anon , 1 9 8 7 ) .. D I SEASES OF RABB I TS AFFECTING THE QUAL I TY OF MEAT From a meat h y g i ene v i ewpo i n t , d i s e a s e s o f rabb i t s cons ide red in. Firstly ,. two broad c ategor i e s .. c an be. zoono s e s. wh i c h. cou ld a f f ect t h e h e a l th of t h e cons umer from endogenous i n f e c t i on of the rabb i t s or from exogenous age n t s due to contam i n a t i on o f t h e c a r c a s s dur i n g proce s s ing.. S econd l y , non - z oono t i c d i s e a s e s. wh i ch m i gh t c r e a t e unac ceptable aes t h e t i c d e fe c t s . Compared. wi th. other. food. anima l s. there. are. few. a s s oc i ated wi th t h e con sump t i on o f r abb i t meat . probably. the. rabb i t s ,. is. rabbi t s ,. mos t. important. c au s ed b y. of. the. Franc i s e l l a. endogenou s. tularen s i s. and. z oono s e s. Tu l araem i a , z oono s e s apar t. of. from. a w ide v ar i e t y o f other an im al s contract th e d i s e a s e .. I n rabb i t s , the d i sease i s man i f e s t ed by mi l i ary abs c e s s e s i n the parenchyma tous. organs. i n c lud i ng. l y mphnode s .. The. disease. is. transmi t t ed t o h umans ma i n l y by the consump t i on o f i n s u f f i c i en t l y cooked rabb i t m e a t o r by handl ing m e a t f rom i n fe c ted r abbi t s . A f f e c ted. humans. show. cutaneous. l e s i on s ,. men i ng i t i s. and. sept i c aemi a re s u l t ing in a mor tal i ty rate o f 5 - 7 % of u ntreated cases ( c i ted in Anon , 1 9 8 6 ) . A numb e r of c ountr i es i nc l u d ing New Z e a l and ( Bl ackmore , pers . comm . ) and Cyprus ( Anon , 1 9 8 5b ) are free.

(21) 19 from t u l araemi a , whereas the d i s e a s e i s endemi c in par t s o f the U . S . A . and Rus s i a . P s eudo tuberculos i s and toxopl asmos i s are regarded a s common forms of endogenous zoono s e s of rabb i t s i n New Z e aland ( Blackmore and. H umbl e ,. 1 98 7 ) .. and. pseudo tubercu l os i s ab s c e s s e s. in. P s eudotuberculos i s. the. in. l iver ,. rabb i t s lungs ,. is. is. c aused. by. man i fested. spleen. and. Yers i n i a. by. m i l i ary. i n t e s t i nal. wal l. ( Harkne s s and Walker , 1 9 8 3 ) . In human bei ngs Y . ps eudot ubercu los i s i s a meat o r water transm i t ted d i s e ase , c au s i ng acu t e m e s e n te r i c l ymphaden i t i s Humb l e ,. and. rar e l y. s ept i caem i c. i l ln e s s. ( B l a ckmore. and. 1 987 ) .. Toxopl a smos i s can a f f e c t rabb i t s and more than 2 0 0 d i f fe re n t spec i es. of. other. an i mal s. includ ing. b i rd s ,. rept i l e s. and. man .. P r e s umably t i s sue cys t s in rabb i t meat are a poten t i a l publ i c h e a l th probl em .. In humans ,. the d i s e as e c an res u l t i n c e rv i c a l. l ymphadenopathy , necro t i z i ng enc epha l i t i s , meningoencephal i t i s , and ocular l e s ions . ( Blackmore and Humble , Enceph a l i tozoonos i s. is. rabb i t s ,. caused. by. the. cun i cul i. ( wh i ch. belongs. a. common. protoz oan to. the. 1 987 ) .. z oo no s i s. of. l aboratory. Enc epha l i t o z oon. Mi crosporid i a ) .. (Nos ema) Laboratory. rabb i t s , a s we l l as dome s t i c rabb i t s , are a f fe c ted and i n Sweden the preva l ence o f the d i s ease in the l a t t e r group was found to be. up. to. rabbi t , rats. 1 4% .. Al though. the main hos t. of. the. di sease. other animal species i ncluding m an , m i c e ,. and dogs were. d i sease. is. f ound. b e l i eved. to. to. be be. infected. the. guinea p i g s ,. ( Wa l l e r ,. trans mi t t ed. is. by. 1 979 ) .. The. urine. or. t ransplac e n tal l y , and is m i l d l y contag i ou s in a rabbi try ( c i t ed i n Anon , 1 9 8 6 ) . Wal l e r ( 1 9 7 9 ) s tate s th at a l though the oral route of i n f ec t i on i s probabl y the mos t common route o f i n f e c t i on , the d i s e a s e ma y be a l s o t ransm i t ted through s k i n wounds o r by s exual i n tercour s e .. Al though. the. d i sease. is. usua l l y. i nappar e n t ,. o ccas i ona l l y rabb i t s s how var i ou s s l ig h t n eurol og i c al i n c lu d i ng. par t i al. paraly s i s. of. the . face. inc l u d i ng. d i s orders ears. and.

(22) 20 eyel ids ,. o r i n c l ined head ,. and pol yd i p s i a ( Wa l l e r ,. b l i ndne s s ,. aggre s s iven e s s ,. anore x i a. 1 979 ) .. The a g e n t i s mos t commonl y local i z ed i n the k i dn e y s and the cen tral ne rvous s y s tem in wh i c h in trace l lu l ar c o l on i e s of the paras i t e. o c cur. u s ua l l y. w i thou t. evidence. of. any. i n f l ammatory. reac t i on . When i n f l ammator y react ion s do occur t h e y con s i s t of chron i c ,. non - pur ulent ,. pathognomon i c .. No. granulomatous. succe s s fu l. chang e s. treatme n t. is. which. known. in. are. rabb i t s .. Pre sumab l y the transmi s s i on o f the d i s e a s e from rabb i t s to humans is. via. u r i ne ,. e s pe c i al l y. through. skin. abra s ions. and. is. thus. un l i k e l y to be a m e a t transm i t ted d i s e a s e ( Wa l l e r 1 9 7 9 ) . The t heore t i c a l range o f the exogenous agen t s , contam i n a t e. rabb i t. meat ,. i n c lude. enter i c. wh i ch could. p a thogen s ,. l i ke. Campyl ob a c t e r jejun i , Y . ps eudotubercu los i s, Y . e n t e roco l i t i ca , S a lmone l l a spp , C l o s t r i d i um pe r fringen s and pa thoge n s o r i g i nat ing from e x t e rnal abs c e s s e s cau s e d by S t aphy l ococc i .. [The au thor i s. aware o f a s tudy i n wh i ch C . jejuni was i so l a ted in New Z ea l and f rom a r abb i t o r i g inat i ng from the sma l l an imal u n i t ( Marsha l l , pers . c omm . ) ] . Dre s s ing faul t s , wh i ch lead to con tam i n a t ion o f rabb i t. c arcas s e s. w i th. i n t e s t inal con t ent ,. cou l d. l e ad. to. such. exogenous contam i na t i on . I n s u f f i c i en t cool ing of the carcas s e s , g i ves t h e oppor tun i t y for thes e bac t e r i a to mu l t i p l y. ( Ye r s i n i a. spp c an g row and produce tox i n even at low tempera tu re s ) and l e ad to food p o i s on i ng . S t aphylococ c u s absce s s e s. in. aureus. rabb i t s. is. a common aet i o l og i ca l. ( Fa r inha. et. al ,. 1 982 ) .. factor of. Add i t i on a l l y. Bl ackmor e a n d F r an c i s ( 1 9 7 0 ) s tate that pathogen i c s t aphy lococci were i s o l a ted f rom l aboratory rabb i t s . Ae s th e t i c d e f e c t s o f rabb i t carcas s e s c an b e a s s o c i a t ed w i th bru i s i n g. and. f racture s ,. as. in. other. in t erme d i at e s t ages o f c e r t a i n c e s todes , Tae n i a p i s i form i s ,. T.. mul t i ceps ,. T.. an i m al s .. Also. the. s uch a s th e l arvae o f. ser i al i s ,. the P e n t a s tomid. larvae of L i ngua tula s erra t a , as wel l as th e l e s i o n s c au s ed by.

(23) 21 E i mer i a. s t i edae. in. rabb i t. l iv e r ,. could. be. the. cause. of. unde s i rable l e s i ons .. RAB B I T MEAT HYG I ENE Theore t i c a l l y , the qua l i t y cont rol o f rabb i t m e a t produc t i on shoul d be based on the s ame pr i nc i pl e s as thos e appl i ed to meat from o ther an imal s . B a s ed on convent i o n a l regu l atory me at h y g iene ,. t h i s should. i nc lude both ante and pos t mor tem inspec t i on , a general con t ro l of t h e hygi ene o f the abat to i r and food hyg i en e in s pe c t ion a t the re t a i l lev e l . The M i n i s t r y o f Agr i cul ture and F i s her i e s in New Z e a l and , has produced a s e t o f draft regu l a t ions wr i t ten along the s e l i nes , wh i ch however have not y e t been promu l gated . W i th r e s p e c t to the i nspec t i on o f pou l t r y meat , publ i c h e al t h con c e rns w i l l b e b e s t me t b y a f l ock h e al th appra i s al , u t i l i z i ng f l ock records and labora tory data col l e c ted over the l i fe o f the f l ock .. Th i s. approach. i nvolves. a move. away. from. 1 00%. carc a s s. i n s p e c t ion , towards a " he a l t h y l i fe " cert i f i c at i on , w h ic h should cer t i f y that b i rds have been free of d i s e a s e be fore s l augh t e r , have. rece i ved. w i th drawal. med i c a t i on. only. t i mes adhered to.. s l aughtered. and. the i r. mea t. at. approved. In add i t ion produced. m i c rob i o l og i ca l l y s a f e c ond i t i on s .. rates. and. drug. the an ima l s mus t be under. sani tary. and. ( Ch r i s t ensen 1 9 8 7 ) .. D i s cu s s ing the prob l em o f m e a t in s pe c t i on o f dome s t i c s toc k , Bl ackmore ( 1 9 8 3 ) sugge s ted rad i c a l chang e s to the conve n t i on a l s y s tem , wh i ch h a s bas i ca l l y remai ned u na l t ered f o r more t h a n a hundred years . He a l so refer s to the i ne f fe c t i v en e s s o f the m e a t i n s pect i on me thods i n d e t e c t i ng agen t s t h a t a r e mos t frequ e n t l y a s s oc i a t ed concludes. w i th that. foodborne there. i n fe c t ions. shou l d. be. less. and. i ntox i cat i on s .. emphas i s. on. He. v e t e r i nary. i n spec t i on o f indiv idual c arc a s s e s and g r e a ter a t t en t i on paid to.

(24) 22 ensuring t h a t anima l s subm i t ted for s l aughter are from herds free from i n f e c t i ons w i th poten t i a l h uman pathogens and tox i c agen t s . Man y s tu d i e s have been carr i ed out i n r e l a t i on to hyg i en i c proce s s ing o f meat f rom the c ommon meat an ima l s , b u t pub l i shed work on rabb i t meat hygiene has not been found .. Th i s apparent. l ack o f i n f o rmat ion was a ma j or s t imul a t i on for the r e s earch work wh i ch forms the bas i s for t h i s the s i s . The work i n thi s thes i s i s an at tempt toward s : 1 .. I nve s t i ga t i on o f. the human e aspe c t s o f d i f f e rent s tunn i ng. methods used i n rabbi t s l augh tering . 2.. Measurement of the carc a s s y i e l d of s l augh tered rabb i t s and f a c t o r s that may a f f e c t i t .. 3.. S tudy o f the e f fect o f d i f ferent was h in g s i t u a t i on s on the wa t e r. uptake. and. bac t e r i olog i c a l. condi t i o n. of. rabb i t. carc a s s e s . 4.. S tudy o f the fa c tors wh i ch might a f f e c t the pH de c l i n e rate , as we l l as the u l t i mate pH o f rabb i t me at .. 5.. S tudy. of. the. prevalence. and. d e s c r i p t i on. of. pathologi c al. l e s i on s found during commerc i a l rabb i t s l aug h t e r i ng . 6.. As s e s s sment. of. the. acc uracy. of. rabb i t. meat. i ns p e c t i on. procedure s , w i th re s p e c t to l i ver coc c i d ios i s . 7.. F i na l l y , the ep idem i o l og i cal as pe c t s of l i ver cocc i d i os i s i n rabb i t s were s tudied ..

(25) 23. C HAPTER TWO THE P R OCESSING ABATIOIR. I NTRODUCTI ON The aba t t o i r a t wh i ch the f i e l d obs e rv ation s were carr i ed o u t , i s a smal l , owne r ope rated pl an t , s i tuated a t Mas t e r t on i n t h e Wai rarapa ( s ee F i gure 2. 1 . , page 2 5 ) . Norma l l y the prem i s e s a r e used f o r the proc e s s i ng o f poul t ry f o r the local marke t , but approx .. every four to s i x weeks ,. rabb i t s are s l augh tered and. processed on the pou l tr y cha i n . Th e s t a f f compr i s e s four workers . The owner and one o f the workers are members of the s ame fam i l y and they usual l y employ two other part t i me workers l i ne .. to ass i s t t hem on the proc e s s i ng. The buyer and eventual owner o f t h e rabbi t carcas s e s a c t s. as both an ' inspe c t or ' and worker when r abb i t s a r e proc e s s ed . Inspectors from the Health Departme n t , occas i on a l l y c h e c k the g eneral p l an t h y g i e n e but are usual l y n ot pre s en t dur i n g s l augh t e r. and. proc e s s ing. of. b i rds. or. rabb i t s .. The. the. " meat. i nspector" i s pay i ng spec i a l a t t en t i on t o the presence o f h e pa t i c cocc i d i o s i s ,. gros s p atholog i cal l e s i on s such as absce s s e s and. d e f e c t s that m ight a f fe c t the f i nal qual i ty of the carcas s e s and v i scera . les i ons ,. Owners. of. rabb i ts ,. wh i c h. have. evidence. of. h e pa t i c. s u f fer a $ 1 pen a l t y per c arc a s s a f fe c t ed . Th i s p e n a l t y. i s de s i gned t o s t i mulate h i gher s t andards of husbandry b y the breeders . All rabb i ts a r e purchased by the " m e a t inspector " , und e r the trad ing name " Doe Bank " . The breede rs are paid accord i ng t o the f i nal carcass we i gh t and whe ther or not they are a f f e c t e d w i th.

(26) 24 hepa t i c. coc c i d i o s i s .. Rabb i t s. are. obt a i ned. f rom. a. wide. area ,. rang i n g f rom Palmers ton North to Wanganu i and Taihape . The y are col l e c t e d. by. the. Palmer s t on North ,. " meat. i nspec tor". from. a. central. po i n t. in. or from i nd i v idual breeders located be tween. Palme r s t on North and Mas te r ton ,. on the day of. s l aught e r .. The. an imal s are transported i n w i re c ag e s in the back of a smal l , open " p i c k up" truck .. Dur i ng rainy days the cages are c overed. w i th a waterproo f cover . The. mos t. common. Z e al and Wh i te ,. breeds. proc e s se d. in. the. plant ,. are. New. c ros ses of New Z ea l and Wh i te w i th other breeds ,. and Angora rabb i t s . Rabb i t s coming from f arms s i tuated f ar away f rom the aba tto i r , commen c e the i r j ourney to the aba t t o i r at 6 - 7 a . m . o n the day o f slaugh t e r and arrive a t the plant a t approx . m i dd a y . S l augh t e r commen c e s soon a f t erwards .. THE P ROCE S S I NG PLANT The. plant. proc e s s i ng o f. ( s ee F i gu r e poul try ,. but. 2. 1 ,. page. 25 ). occa s i onal l y. is. d e s i gned. ducks ,. for. the. pheasants. and. rabb i t s are also sl aughtered . The general layout o f the plant i s s hown i n F i gure 2 . 2 ,. ( pa g e 2 6) , together w i th apparat u s , denot e d. by d i f fe rent f i gure s , r e f erred to i n the fol l owing text . Proce s s i ng Room Th i s i s the larg e s t r oom o f the plant ( Room A ) . Large doors a t one end open to an outs ide concret e pad , load - i n area. (1 ). ( s e e F i gure. 2.2,. page. 26) .. wh i ch s e rve s a s a The convent i on a l. poul try cha i n ( 2 ) extends t h e l ength o f the room . H igh pres s u r e hos e s a r e ava i l able. (3) .. Below the f i r s t p a r t o f the cha i n a. s t a i nl e s s s teel trough ( 4) prevents blood from s p i l l i n g onto t h e f l oo r . Receptac les for the rubbi sh ( 5 ) a l s o exi s t a n d a t the end of. the cha i n there. is. a scalde- r. ( 7) by. the s id e. of wh i c h a. d e f e athe r i ng machine i s s i tuated ( 8 ) . Up to 9 6 rabb i t s or b i rd s can b e pro c e ssed on t h i s cha in a t any one t ime ..

(27) 25. F igur e 2. 1 - The aba t to i r a t Mas t e rton . Load o u t area. Carca s s Wash i ng Room Th i s room ( B ) is s i t u a t e d next to the proc e s s i ng room and has three s t a i n l e s s s t eel t anks ( 9 ) , wh i ch are u s e d as dunk baths for the wash i ng o f rabb i t carcas s e s . Next to th e t anks is a ra i l ( 1 0 ) for h ang i ng the carca s s e s when they are b e i ng spray washed .. A. hand operated wash bas i n , w i th hot and cold w a t er i s c l o s e to one of. the dunk baths. pro t e c t i v e. (11 ) .. c l oth ing .. On the w a l l. Carcas s e s. are. i s a r ack su b j e c ted. (12) to. u s ed a. for. f i nal. i n s pe c t i on on a m eta l t ab l e ( 1 3 ) ne x t to the wa s h i ng troughs . P a c k i ng Room The r a i l from the was h i n g room leads through an opening i n the w a l l to the pack ing room ( C ) , where the carca s s e s are we i ghed and packed .. A scale balance. (14). is s i tu a t e d on a l arge m e t a l. t a b l e ( 1 5 ) i n t h e m idd l e o f the room tog e t h e r w i th a smal l ,.

(28) figure 2. 2. Plan of lbe rabbit processing plant at "..asterloo. e.oo. ). .. s;. gS_ -I. I. ...,. I <>•. ,. 26. --;:;::! "'I. !. J. �I. �l. =:::t.. �,. E. .,. c ::11. o' ..... :. �!. 15. ?i !. o ""•. "'I. I. � 16. �. !I. 2�-:::.. ''. �. �iM. H. F. !. li. I. o=%"-=. �.. I. i. !I oo. "'' "'i. F'. 'r ,, i'. G. -20. 2. K so. .,. .20. .so, 1 2:1. · ,. .SJ. .2 :>. 2.SO. I .20. I. B. �a.sbingRoom. D. Olber RooJr.S. 9. Dun>; baths. D, D':. freezers. 10. Rail. E. Stor eroom. ll. Ha.Dd o;>erated ba.S in. r, r': Offices. 4. Bleeding trough. 12. ·Rack for aprons. G. IUtcben. 5. Receptacles for. 13. Table. R. Locker roo11. lbe beads aDd. C. Packing Room. I,. intestines of the. 14. Scal-e Balance. rabbits. 15. Packing table. }-... Processing. Roo11. l. Covered load - in area. 2. Cbai.n 3. Rater bose. 6. Lights. 16. Packing apparatus. 7. Scalder. 17. Cooling systeJa. 8. Def ealber1.ng machine. I': Toilets. J. Boiler. IC. Covered 1�d- o u t area.

(29) 27 s i mp le and e f f ect ive manual l y operated pack ing apparatus norm a l l y. used. apparatus. for. bagg ing. pou l t ry. producing cold air. (17) ,. carcasses . is. A. (16). cool er ,. an. s i tuat ed on one of. the. wal l s abo u t 1 . 7 m above f loor l e v e l . B l a s t Free z e r s Two b l a s t freez er s ( D , D ' ) oppo s i t e. the. packing. room .. ( approx . The s e. 20 m. 3. free z e r s. each ) a r e s i t u a t ed are. placed. in. the. center of the bu i ld i ng . Other Rooms The. loc a t i on. of. anc i l lary. rooms ,. s u ch. as. s toreroom ( E ) ,. o f f i c es ( F , F ' ) , a k i tchen ( G ) , a locker room ( H ) , to i l e t s ( I , I ' ) and a bo i l er room ( J ) is shown in F i gure 2 . 2 . , ( page 2 6 ) . The f l oors and wa l l s of the bu i l d i ng are cons truc ted o f conc r e t e and the roo f of corrugated i ron . E l e c tr i c i t y and hot and c o l d w a t e r i s supp l i e d t o t h e ma j or i t y o f rooms . A covered load o u t area ( K ) a l s o ex i s t s .. THE PROCEDURE STUNNING The rabb i t s are s l aughtered b y manual d i s loca t i on o f the neck fol lowed by d ecapi t a t i on . They are pi cked up from the c ag e s by one per s on and handed to the operator c ar r y i ng o u t d i s l o c a t i on of the n e ck . Th i s i s an expe r i e n c ed person who holds the animal by the h i nd l e g s with his l e f t h an d and i t s head d i re c t l y beh ind the ears w i th h i s r i g h t hand . Then by pu l l i ng s harp l y on the head w i t h a d ownwa rd and backward twi s t o f the hand h e e f f e c t i ve l y breaks t h e n e c k . Immed i a t e l y a f t e r neck d i s locat i on the rabb i t s are hung o n t h e chain b y the h i nd legs ..

(30) 28 Exs a ngu inat i on Exsangu i na t i on i s c arried ou t by a per son s t and i n g a t the beg i nn i ng o f the cha i n where the rabb i t s are decap i t a t e d w i th a sharp kni fe . The " s tun- to- s t i ck " i n t e rval ranges from t e n s e conds to f i ve minutes . The ma j or i ty o f a n i m a l s s how no movem e nt s at any t i m e a f ter d i s l oc a t i on of the neck and the proc edure i s general l y smo o th and e a s y . The h e ads are d i s c arded i n t o a b i n .. The c h a i n. automa t i c a l l y c arries the decap i t a t ed carca s s es to th e p o i n t o f pe l t ing . P e l t ing-E v i s c e r a t i on Removal o f the pe l t i s carr i ed out by the s ame p e rson who d i sloc ates. the. neck .. A f ter. having. s tunned. changes pos i t i on to t h e pel t i n g area .. 20-30. rabb i t s ,. He removes. he. th e pe l t by. cut t i ng around the t i b i o - tars al j o i n t s and making a l ong i tu d i n a l i n c i s i on o n t h e med i a l aspect s o f e a c h h i nd leg .. The p e l t. is. pulled downward and i n s i de ou t , thus be i ng freed from t h e f a s c i a and mu s c l e s .. The pe l t. i s cut f rom the carcass. just. above the. carpal j o i n t s of both f ront legs ( s ee F i qure 2 . 3 , page 2 9 ) . The pro c e s s. of. p e l t ing. is. comp l e t e d. within. 50. s e conds .. The. une v i scerated c arcas s e s are handed to ano ther ope rator on the oth e r. s i de. of. the. cha in ,. one. m e tre. awa y .. He. s h a ck l e s. the. c a r c a s s e s by the h i nd l egs and e v i scerates them by an i nc i s i on from the pub i s to the x i ph i s te rnum . The g as troin t e s t i na l tract ( GI T ). is. removed. f i rs t ,. fol lowed. by. the. l i ver .. The n. by. an. i n c i s ion to one s i de of the s t ernum the thorac i c cav i t y i s opened and the lungs and hear t are removed and d i s carded in the s ame r e c e p t a c l e as t h e GIT . At th i s po i n t , u s ing a pa i r of s ec a t eurs , the rema i n i ng part of the neck i s c u t o f f and the f ron t and h i nd l e g s are removed a t the carpal and tarsal j o ints r e s p e c t i ve l y . The whol e pro c e s s o f e v i scera t i on s e c onds .. is. compl e ted i n approx .. 40.

(31) 29 I n spec t i on L i vers are inspe c t e d for gros s le s i ons o f hepat i c cocc i d i o s i s by. the. purcha ser. of. t he. rabb i t s. and. the. carcas s e s. are. then. t rans ferred by her t o the table in the washing room .. F igure 2.3 .. -. Pelt removal showing points of deta chmen t on legs ..

(32) 30 Was h i ng C a r c a s s e s A f t e r i n spe c t ion ,. the carc a s s e s a r e hung o n hook s f rom the. pe l v i c bone unt i l washed by imm e r s i on i n a tank . Wa t e r is runn i ng i n t o the tank from a tap , and i s d i s charged from an o u t l e t on the s i d e . The r a t e o f rep lacement is approx . ten l i t r e s per m i nu te . The car c a s s e s are l e f t in the water for two to t e n m i n u t e s and then t r an s f erred manual ly to hooks on a r a i l for w a s h i n g by a hand h e l d sprayer and f i nal minor t r i mm i ng . T r i mm i n g and s pray ing takes be tween 3 0 and 6 0 seconds to compl e t e . The c a r c a s s e s are then usua l l y l e f t on the r a i l for one to two hours d u r i n g wh i ch t ime. surface. water. is. lost. f rom. the. carca s s e s. by. drip. and. ev apora t i on . Packing Carcas s e s The c ar c a s s e s a r e then trans ferred manua l l y , o r on the ra i l , from the w a s h i ng room to the packing room where t h e y are we i ghed and the. we i ght. recorded on a. label w h i c h. is. a t t ached. to. the. d e s i gned. for. level. the. ou t s i d e of the plas t i c bag con t a i n ing the carcas s . In. order. poul try ,. to. pack rabb i t s. into pla s t i c. the back of the carcass. is. cut. at. bags the. of. lumbar s a c r a l j unct i on , the spi nal col umn broken man u al l y and the h i nd legs pushed forward into the thora c i c cav i t y . Th e r o l l e d and t e l e s coped carcass i s then push ed through a metal cone (pack ing appara t u s ) i n t o a p l a s t i c bag . E f forts are made to r emove as much a i r as pos s i ble from the bag which is t hen seale d and l ab e l led . The bagged carc a s s e s are pu t in plas t i c boxes or c a r t on s and sent d i re c t l y t o the r e t a i l marke t or put i n the blas t f r e e z e r . Add i t i on a l I n forma t i on The. abattoir. is. small. and. there. are. no. arrangements. for. further proce s s ing . No other produc ts th an the carcas s e s , l i vers and pel t s are saved ..

(33) 31 The water used i n the aba t t o i r i s o f potab l e qual i ty and come s from the mun i c i pa l supply .. I t i s c h l o r i nated and checked. regu larly by the local author i t y . The ma i n areas where inve s t i gat i ons were carr i e d out , were a t the po i n t s of s l aughter , ev i s cerat i on , w as h ing and pack i ng . Inve s t i ga t i on s included observ a t i ons on the s l aughter proc e s s , i n c l ud i ng exs anguinat i on and the ac curacy o f d e tec t i on o f hepa t i c coc c i d i o s i s.. Wa shing procedur es were inve s t i gated i n terms o f. both m i c rob i a l con tam i nat i on and water uptak e of c arc a s s e s , and mus c l e pH mea s urements were t aken a t various point s in the who l e operat i on . Four v i s i t s were p a i d to the aba t t o i r to obta i n the d a t a for t h i s the s i s . F urther s amp les , r e l a t ed spec i f i c ally to the s t udy of hepa t i c c o c c i d i os i s , i n d i v i dual spec i f i c. r abbi t r i e s .. aspects. of. were c o l l ec t ed dur i ng v i s i t s to three F i nal l y ,. rabb i t. in. order. proces s i ng ,. 20. to. col l e c t. New. data. Z e a l and. on. Wh i t e. rabb i t s of 2 - 3 Kg l i ve we i ght , were bough t f rom the Smal l An imal Un i t at Mas s e y Un ivers i ty and s l augh tered and proc e s s ed i n the unde rgradu a t e ana tomy l aboratory of the Faculty S c i ence. at. Mas sey. Uni vers i ty .. Data. ob ta i ned. of Ve t e r i nary. f rom. all. the s e. a n i m a l s w i l l b e presented and d i s cu s s ed i n re levant chapters o f thi s the s i s ..

(34) 32. CHAPTER THREE. SLAUGHTER OF RABBITS AND RATES OF BLEEDING. I NTRODUCTI ON There i s increas i n g pub l i c concern for the w e l f a r e of an i ma l s i n c lud i ng. the. s l aughter. of. s tock .. Th i s. has. l ed. to. var i ou s. s t atutory a c t s and regulat i ons, a i med a t e n s ur i ng the we l f are o f a n i mal s. dur i ng. Z e a l and ,. the. s tunn i ng. and. s l augh te r. proc e s s .. the we l f are of s tock dur i ng s l augh te r,. In. New. i s covered by. " The s l aughter of s tock, game and pou l t r y regul a t i on s 1 9 6 9 " and amendmen t. No . 1. r e gu l a t i on s p l ace,. s tate. the. s ame. that. " no. regul a t i on s person. s ha l l. s l augh ter any head of c a t t l e. horses, been. of. sheep,. rendered. l ambs,. goa ts or swi ne,. i n s e n s ible. to pain,. (.Anon, in. any. 1 977 ) .. These. s l augh t e r i ng. ( i n c l ud i ng bobby c a l v e s ) , u n l e s s and un t i l i t h as by. a. me thod. d e s cr i be d. in. s ubclau s e ( 2 ) o f th i s regula t ion and w i l l rema i n so unt i l d e a t h s uperven e s f rom t h e opera t i on o f b l e e d i ng, wh i c h s h a l l b e c ar r i ed o u t promp t l y and sk i l l fu l l y . " I n subc l a u s e ( 2 ) o f the S l aughter of S tock, Game and Poultry Regu l a t i on ( 1 9 6 9 ) ,. it is s t ate d that. t h e me thod s o f i nduc i ng insens i b i l i t y t o pa i n shal l : a). I n the c a se of c a t t l e ( except bobby c al v e s ) ,. hor s e s ,. goats. a n d swi ne, by the means o f : (i). A capt i ve bolt type o f s tunn i ng i n s trumen t , ope r a t e d by explos ive charge or c ompres sed a i r;. ( ii ). An i n s t rument wh i c h causes i n s en s i b i l i t y b y th e adm i n i s trat ion o f an e l e c t r i c shock ; or.

(35) 33 ( i i i ) The u s e o f carbon dioxide gas i n a s u i tab l y enclosed chamber . Prov ided. that. at. s l aught e r i ng. s l augh t e rhouses and aba t to i r s ) ,. p l aces. ( o ther. than. export. a s u i table s a f e f i rearm w i th a. type o f s o l i d b u l l e t or f ra g i l e bu l l e t, wh i c h renders the animal i n s t an t aneou s l y in sens i t i v e to pain, may be u s ed . b). I n the case of bobby c alves, i nduc ing. i n s ensibi l i t y. be by any o f the me thods of. or by manual. s tu nn i ng by. a. s i ngle. b l ow to the fron tal r e g i on o f the head . Rabb i t s,. be ing " an i ma l s ". accord i ng. to. t h e Meat Ac t,. 1 981. ( Anon 1 9 8 1 ) , are not covered by t h i s s e c t i on o f the regu l a t i ons, b u t b y paragraph 8 , wh i c h requ i r e s a s laugh t e r method approved by the D i rector. and by paragraph 1 3 , wh ich s t a t e s that :. ( 1 ) " The. s l augh t e r of any s tock, game, or other anima l s i n a s l aughter i ng p l ace o r of pou l try in prem i s es l i censed pe rs uant to s e c t i on 6 1 ( a ) o f the Act, shall be s o coordinated that t h e t i me be tween the s tock, game, other an ima l s or poul try be i ng rendered i n s en s i b l e ( wh e r e t h i s appl i e s ) and b e i ng sub j e c ted to b l ee d i ng i s kept t o the abs olute m i n i mum . " Apart f rom the humane aspect o f the s tunn i ng and s l augh te r procedure, ( c i t ed. in. t his operat i on can a l s o a f fe c t th e qual i ty o f me at B l ackmore. a nd. con s i de red appropriate. to. Del any,. 1 988 ) .. inves t i gate. It. some. of. was. there fore. the me thods o f. s l au g h t e r wh i c h could b e appl i ed to rabb i t s . A h umane s t unning and s l augh te r procedure, comp l y i ng w i th the above. regu l a t i on,. s u f f i c i ent. shoul d. durat ion. to. induce ensure. i mmed i a t e the. an i ma l s. i n s en s i b i l i t y do. not. of. rega i n. s e n s i b i l i t y, un t i l they have been rendered p e rmane n t l y i n s en s i b l e f rom e x s angu i n a t ion .. Methods o f i nduc ing i n s en s i b i l i t y c a n be ·. broad l y. into. c l as s i f i ed. three. g roups :. (a). c arbon. d i ox i d e. anae s th e s i a, ( b ) elec t r i c a l s tunni ng, and ( c ) percu s s i v e s tunn i ng ( c i t ed i n Bl ackmore and D e l any,. 1 988 ) ..

(36) 34 Al though. carbon. di ox ide. is. cons i d e red. e f f e c t i ve. for. ana e s the t i z i n g rabb i t s ( Adams , 1 9 7 6 ) it woul d be an i nappropr i a te me t hod. in. the. aba t t o i r becau s e. of. the. h i gh cap i t a l. cos t s. of. equ i pment and h i gh running cos t s as s oc i a te d w i th t h e l o s s of C0 2 removed f rom the C02 chamber trapped i n th e fur o f th e anima l s . The r e i s a l s o controversy conc erning the humane a s p e c t s o f the m ethod ( B l omqu i s t , 1 9 5 7 ) . El e c t r i c a l s tunn i ng can be d i vided i n to head- o n l y and head to-body. me t hods .. S t unning. by. t he. head -on l y. me t hod. norma l l y. i nduces i n s e n s i bi l i ty o f approx . 3 0 - 4 0 s ec onds dura t i on on l y . For thi s me thod. to be humane in a n i ma l s wh i ch have no connec t i on. be tween the vertebral artery and the ros t ral rete v i a the c audal rete ,. the s tun- to- s t i ck interval mu s t be l e s s than 2 0 s econds ,. s i n c e permanent i n s e n s i b i l i t y f rom exsangui na t i on m a y take up to e i ght seconds to be induced. ( T i d swe l l e t al ,. 1 987 ) .. The bl ood. supp l y to t h e brain o f rabbi ts i s very s i m i lar to t h a t of sheep . In. th i s. species ,. (O.V.A. ) ,. apart. there. ver t ebral. is. from. another. occ i p i ta- vertebr a l small. and caro t i d arter i e s ,. ( c i t ed i n B l ackmore and Delany , Head - t o - body. e l e ctrical. anas tomos i s. known a s. anas tomos i s b e tween. the condy l ar. the. artery. 1 988 ) . s tunning ,. indu c e s. permanent. i n s ens i b i l i t y due to concurrent i nduc t i on of card i a c d y s func t i on , thus s tun- t o - s t i ck i n tervals are not theor e t i cal l y i mpor tant in r el a t i on t o a nim a l wel fare ( c i t e d in B l ackmore an d D e l any , 1 9 8 8 ) . Lauberge r ( 1 9 8 4 ) described a s y s tem for e l ec t r i c a l s tunn ing o f rabb i t s and other l abora tory an ima l s , but to t h e knowledge of the. author ,. s y s tems rabb i t s ,. used. the s y s tem ha s not be e n evaluated c r i t i c a l l y . for. s l aughtering. relatively. t h e h i gh capital cos t s o f. sma l l. numbers. i n s t a l l ing s u c h. In of. apparatus. wou ld be proh i b i t ive . Percu s s i ve me thods of s tunn i ng are probab l y b e t t e r s u i ted to the commerc i al s l aughter o f rabb i t s and can be d i v i d e d i n t o non penetra t i v e. and. penetrat ive. me thods .. Non-pene t r a t i v e. methods.

(37) 35 induce. by. i ns ens i b i l i t y. phys i c a l. wav e s. d i s tor t i on. bra i n. damage. insens i b i l i ty .. transm i s s i on. to. is. of. bra i n,. su f f i c i e n t. Pene t ra t i ve. depo l ar i z a t i on. the. of. h i gh. wh i ch. the. me thods. neurons. damage to the brain t i s s u e,. due. to. wh i ch,. permanent. s tunn i ng,. t o percu s s i v e. cau s e. 1 9 7 9 ) , but. c au s e. of. v e l oc i t y. can. f o r 3 0 - 4 0 seconds ( B l a c kmore,. in s e n s i b i l i t y l a s t ing of ten. the. c au s e. effects. and. prov i de d v i t a l c e n te rs are. d e s t r o y e d, res u l t s i n permanent i n s e n s i b i l i ty . Sheep and c a l v e s s tunned by both me thods o f percu s s i ve s tunni ng,. deve l op ton i c. spasms, wh ich occur i mmed i at e l y and l a s t for a t l e a s t 1 5 s e cond s . Th e s e are f o l l owed by c l on i c spasms, four m i n u t e s .. ( Bl ackmore,. wh i ch may l a s t for up to. 1 9 79 ) .. I n rabb i t s s l augh tered i n aba ttoi rs, the mo s t common methods o f i nduc ing i n s ens ibi l i t y i s by d i s location of the neck, a bl ow to the he ad, or decapi tat i on wi th a gu i l l o t i n e . Neck d i s locat i on i s p e r f o rmed by ho lding the animal by the h i nd l eg s i n one hand, and w i th the other hand hol d i ng the rabb i t ' s h e ad d i re c t l y beh i nd the e a r s . Then by pul l i ng s harp ly on the head w i th a downward and backward twi s t of the hand,. the neck wi l l be d i s located a t the. occ i p i t o - at lantal. A mod i f i c at ion. j unct i on .. of. this. me thod. carr i ed out by a blow to the extended neck o f the rabb i t .. is The. h i n d l e g s are held in one h and wh i l e the other h and, extended and r i g i d, d e l i vers a " Karate chop " to the back of the rabb i t ' s neck . I n s t e a d of the hand, 1 976 ) .. It. has. method. of. neck. a heavy s t i ck may be u s e d ( S cot t and Ray,. been obse rved. that. d i s l ocat i on. o f t en. rabb i t s. s ub j e c ted. voca l i z e. dur i ng. to. th i s. s ubs equent. bleed i n g, wh i c h sugge s t s t h a t the animals are not always rendered i n s en s i b le. and may s u f f e r. d i s tre s s. dur i ng. b l e ed i ng. ( personal. ob s e rv a t ion ) . I t i s recommended that d i s loca t i on shou l d be fo l l owed by. s ev e r i ng. the neck w i th. a kn i fe. ( Owen. et. al ,. 1 977 ) .. Neck. d i s l o c a t ion, a s oppos ed to d i re c t s everance of the s p i n a l cord, may r e s u l t in pres sure e f fe c t s on the bra i n and s p i n a l cord, both ros t r a l l y and c auda l l y to the d i s l oc a t i on s i te,. w i t h pos s i b l y.

(38) 36 conc urrent De l an y,. e f fects. on. the. c e rebral. func t i on. ( B l a ckmore. and. 1 9 88 ) .. Decap i t a t i on by a gu i l l o t i n e , i s a l s o u s e d for the s l augh t e r of r abb i t s .. M i keska a n d Kl em. aspect. this. of. me thod. encephalograph i c. ( EEG ). on. ( 1 975 ) ,. l aboratory. techn i qu e s .. a f t e r decap i t a t ion ( low vol t age, to. ind i c a t e. d i s comfort. in ve s t i gat i ng the humane. and. The. r a t s, EEG. used. act i v i t y. e l e c tro recorded. fas t ac t i v i ty ) w a s con s i dered. pain .. T i d s we l l. et. al,. ( 1 987 ),. i nve s t i gat i ng EEG a ct i v i ty o f d e capi t a t e d h e ad s o f l ambs, found no obv ious. change of. decapi tat i on,. and. the EEG p a t tern for e i ght. subs equent. c h anges. a s so ci ated w i th exsanguina t i on o n l y . is. n o evi dence. to s ugge st. that. were. s e c onds a f ter. s i m i l ar. to. those. It is appare n t that there. decap i t a t i on cau s e s. in s ens i b i l i t y and t h a t i t i s a humane procedure f o r. immed i at e. s l augh t e r i ng. anima l s . In. the. present. e xper ime n t a l. work,. emphas i s. was. paid. to. inve s t i ga t i on s de s i gned to d e t e rm i n e the humane a s p e c t s of the d i s locat i on me thod, wh i ch is w i d e l y used a s part o f t h e s l augh t e r pro c e s s. for. per cus s i ve. rabb i t s . s tunning. Attemp t s of. were. rabb i t s ,. also. w i th. a. made. to. i nve s t ig ate. v i ew. to. the. future. deve lopment o f a pra c t i cal pen e t ra t i v e percu s s i v e s tunn e r for t h i s spec i e s . Exsangu i n a t i on was inve s t i ga ted in t e rm s o f blood los s and the rate of b l e ed i ng ..

(39) 37 MATERIALS AND METHODS Methods of S laugh ter Neck D i s l o c a t ion and Decapi t a t i on. (a). Dur ing the c ours e o f t h i s s tudy ,. approx .. 2 5 0 rabb i t s we re. ob s e rv ed , wh i c h were s tunned by d i s l oc a t i on o f th e n e c k a t th e abat toi r a t Mas t e r ton by an expe r i enced opera tor . He h e l d each animal t o be s l augh t e red , by t h e h i nd l e g s w i t h t h e o n e h and and w i t h the other hand ,. the rabbi t ' s head d i rect l y beh i nd the. ears . Then by pu l l ing on the head w i th a downward and backward twi s t o f the hand , an ima l s .. he e f f e c t i v e l y d i s located the neck o f. th e. The a n i m a l s were subsequen t l y d e c ap i tated by an oth e r. b utcher wi t h i n. ten. rabb i t s. exami ned. were. s e conds in. to. f ive. d e ta i l. m i nu t e s. of. s tunn i n g .. immed i a tely. after. Te n neck. d i s loc a t i on and during the period fol low i ng decap i t a t i on . Neck D i s l o c a t ion and Bleed ing. (b). The necks o f f i ve New Z e a l and Wh i t e rabb i t s were d i s l o c a t e d by t h e author i n t h e l aboratory a n d s ubsequ e n t l y b l ed w i th i n te n se conds by a t r an s v e r s e. inc i s ion o f the m a j or ves s e l s o f. the. neck . (c). Non-pe n e t r a t i v e P e rcus s i ve S tunn ing and Bleed i ng F i ve rabb i t s were s tunned by a blow to the head w i th a s t e e l. f o r sharpe n i ng k n i v e s . O n e person r e s t r a i ned the rabb i t s wh i l e ano ther de l i ve r ed a blow to the head j u s t c audal to the orbi t s . The. r abb i t s. w er e. subs equen t l y. e x s angu i na te d. by. a. transverse. inc i s ion o f the n e c k w i t h i n ten s e conds o f s tunn ing . (d). Penetrat i v e Percu s s ive S tunn i ng The s tunn i n g was c a r r i ed out by a s impl e ins t rume n t. con s i s t i ng of a s t a i n l e s s s t e e l rod ,. 1 . 2 cm in d i ame t e r a n d 1 9. cm in length . The i n s t rument ( s ee f i gure 3 . 1 , page 3 8 ) w a s h e l d in a ve r t i c a l pos i t ion o n the head o f t h e rabb i t behind th e e y e s and be tween the b a s e o f t h e ears ( s e e f i gure 3 . 2, page 3 9 ) by one person , wh i l e another person h i t the protrud ing bol t w i th a.

(40) 38 1 . 5 kg w e i gh t hamme r , f rom a h e i ght o f approx . 1 0 cm . One rabb i t had t o b e s tunned t w i c e a s the opera tor h o l d i n g the i n s t rument f a i l e d to place it c orrec t l y on the a n i m a l ' s head .. F i gure 3 . 1 - Sma l l hammer and s te e l rod and t ube u s e d f o r p enetrat ive percus s i ve s tunn i ng . Of t e n rabb i t s s tu nned by the pene t r a t i ve percu s s i v e me thod , four were e x s angu i na t ed by a transvers e i n c i s i on o f the n e c k 1 0 s e conds. l ater .. One. r abb i t was. inadv e r t e n t l y d e c ap i t a t e d .. The. rem a i n i n g f i ve anima l s were not bled . ( e ) Exam i n a t ion o f He ads and Spi nal Cord s The. i n v e s t i ga t ion. of. the. superf i c i al. l e s i on s. in. rabb i t s. i mmob i l i z e d b y neck d i s loca t i on wa s c a r r i e d out b y remov i n g the s k i n of. the neck area be fore compl e t e l y pe l t i ng. the a n i ma l s .. Further i n v e s t i g a t ions were carried out by remov i ng the s k i n o f the head. and. s ub s equently. the. top o f. the. sku l l. in. order. to. observe l e s ions i n the cran i a l cav i t y . The l e s i on s o f t h e h e ads and s p i n a l cords of anima l s s tunned by the percu s s i v e m e thods were a l s o examined .. S amples of bra in t i s sue were c o l l e c t e d for. h i s to l og i c a l exam i n a t ion ..

(41) F i au r e 3 . 2 - S ch emat i c d r a w i ng o f rabb i t head s h ow i na t h e t ar ae t o f pene t ra t i v e pe rcus s i ve s t u nning . ( f ) R e cord i n a R e f l ex e s T h e h e a r t a c t i v i t y w a s a s s e s s ed b y means o f a s t e t h o s c o p e and by p a l p a t i on of e x s a n gu i n a t i o n .. t h e c h e s t i mmed i a t e l y a f t e r s t u n n i n g a n d d u r i n g Re s p i r a t o r y. activ i t y. �as. de tec ted. by. vi sual. ob s e rv a t i on . T h e p a l p e b r a l and cor n e a l r e f l e x e s � e r e a s s e s s e d b y tou c h i n g. the. inner. canthus. of. the. eye. and. the. cornea. w i th. a. f i n g e r . P u p i l l a r y d i l a t a t i o n w a s e s t i m a t e d by v i s u a l o b s e r v a t i on of. the. d i am e t e r. of. the. pu p i l s. of. both. ey e s. p e r i od i c a l l y .. Th e. ped a l r e f l ex was c h e c k e d b y p i n ching t h e s k i n b e t w e e n t h e d i g i t s of. t h e h i nd and. fore. legs .. The. s po n t a n e ou s. b o d y m ov e m e n t s. were. v i s u a l l y ob s e r v e d .. At. the. aba t t o i r ,. t i m e o f o b s e rv a t i on . a. v e rba l l y. on. a. re flexes. were. r e c o rd e d. in. wr i t i n g. at. the. I n t h e l abor a t o r y t h e r e f l e x e s w e r e r e c o r d e d. t ap e. r e corder. wh i c h. was. later. replayed. and. an a l y z e d .. ( g ) Bl ood Col l e c t ion a n d R a t e s o f B l e e d i ng Th e b l ood w a s col lec ted from the neck wou nd th r ou g h a f unne l into. a. 1 00. intervals .. ml Th e. p l a s t i c meas u r i ng c y l i nder rate. of. bleed in g. was. c a l i br a t e d. obta i n e d. by. in. 1. ml. r e cord i n g. verb a l l y on a t a p e recorder the vol ume of blood recov e r e d every f i ve t o ten s e conds a f ter bleed ing had commenced . The rec ord ing wa s an a l y z ed i n d e t a i l l a ter ..

(42) 40 ( h ) Carc a s s Evalua t ion i n Terms o f Re s i dual B lood F i ve. carca sses. of. rabb i t s. s tunned. by. the. percu s s i ve method were used for thi s evalua t i on . by a transverse i nc i s ion o f t h e neck .. pen e t ra t i ve. Two were b l e d. The other t h r e e rabb i t s. were not bled but one of these lost an e s t imated 1 0 - 1 5 m l o f blood f rom the s tunn ing s i te . random order o n a cons i s t i n g m embers. of. of. t able. three. the. The carc a s s e s were p r e s e n t e d i n. f o r evalua t i on b y a pane l. v e t e r i n ar i ans ,. l aboratory. staff .. one In. s ecretary. th e. f i rs t. of. s ev e n ,. and. th r e e. trial ,. the. c arcas s e s were presen ted to the panel unwashed . The s econd t r i a l was carr i ed out us i ng the s ame carc a s s e s a f t e r each c a rc a s s had been wa shed i n runn i n g water for two m i nu t e s and then p re s e n t ed on the s ame tabl e , but in a d i f ferent order . The t h i r d t r i a l was ca r r i ed out w i t h one h i nd l e g f rom each r abb i t on the s ame t ab l e b u t in a d i f ferent order . I n a l l three c a s e s the memb e r s o f the team we re told some an ima l s had been bled and others had not , and were asked to iden t i fy the carcas s e s ,. or the legs o r i g i n a t i ng. f rom rabb i t s wh ich h ad been bled .. RES ULTS R e f lexes Assoc i at e d Wi th S la ughter Heart Ac t i v i ty and Respi ra t i on In the c a s e s i n wh i ch ca rd iac ac t i v i t y was checked , found to last for approx . two minutes ,. i t was. i rrespect i v e of s tunn ing. method . Respi rat ion was not apparent i n the m a j ori t y o f c a rc a s s e s exam ined .. In. pen e t ra t i ve s econds ,. one. rabb i t. percu s s i ve. res pi ra tory. wh i ch w a s u n s ucce s s fu l l y s t unn i ng. gasps. bu t. appeared. r e s tunned four. t ime s. s tunned. w i th i n within. a. by few. three. minutes a f te r s tunn i ng . The s ame rabb i t vocal i z ed by s c r e am i ng immed i a t e l y a f te r the unsuc c e s s ful s tun ..

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