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.

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