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Morphometric and radiographic characterization of leg disorders in broiler chickens Cruickshank, John Johnston 1985

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MORPHOMETRIC AND RADIOGRAPHIC CHARACTERIZATION DISORDERS IN BROILER CHICKENS  OF LEG  BY JOHN JOHNSTON B.Sc.(Agr.)»  The U n i v e r s i t y  CRUICKSHANK of B r i t i s h  Columbia,  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE  REQUIREMENTS MASTER  FOR THE DEGREE OF OF SCIENCE  in THE  FACULTY OF GRADUATE STUDIES  (Department  We a c c e p t t h i s to  THE  of Poultry  thesis  the r e q u i j e d  Science)  as conforming standard  UNIVERSITY OF BRITISH  COLUMBIA  A u g u s t 1985 © J o hn J o h n s t o n C r u i c k s h a n k , 1985  19  In p r e s e n t i n g  this thesis  r e q u i r e m e n t s f o r an of  British  it  freely available  in partial  advanced degree a t  Columbia,  for  Library  s h a l l make  for reference  and  study.  I  f o r extensive copying of  h i s or  be  her  copying or  f i n a n c i a l gain  g r a n t e d by  publication  s h a l l not  of  The U n i v e r s i t y o f B r i t i s h 1956 Main Mall V a n c o u v e r , Canada V6T 1Y3 Date  the  be  of  further this  this  Columbia  my  It is thesis  a l l o w e d w i t h o u t my  CAJM02  thesis  head o f  representatives.  permission.  Department  University  the  f o r s c h o l a r l y p u r p o s e s may understood that  the  the  I agree that  agree that permission d e p a r t m e n t o r by  f u l f i l m e n t of  written  ABSTRACT  The  objective  effects  of  cage  incidence  and  chickens.  In  graphic  of  this  study  density  severity  of  addition,  in  develop  pattern  a  normal  and  to  investigate  and  excess  vitamin  leg  abnormalities  Dg  of  leg  abnormal  recognition  bone  in  for  leg  i n an  the  broiler radio-  development  broilers  the  on  s e q u e n t i a l m o r p h o m e t r i c and  characteristics  described  was  were  attempt  abnormalities  to in  poultry. Twisted (varus) was  or  the  (valgus)  of  the  deviations  incidence than  density  significant  i t occurred  on  and  excess  increase  in  in  incidence  differences  in  body  broilers  the  less  body  weight,  been  involved.  severity  of  the  effect  severity.  the  not  density  feed Dg a  the  was  Lateral (92%  and  right  and  considerably  be  Dg of  resulted twisted  explained  metabolic appeared excess  to  leg.  However,  but  stress  gained may  have  increase  vitamin  in  through  consumption.  consumed more  while  tibiae  4%, r e s p e c t i v e l y ) .  incidence  or  vitamin  disorders,  vs  leg  on  dietary vitamin  suggesting  High  (21%  could  weight  excess  twisted  litter  Differences  fed  of  equally  medial  distal  were more common t h a n m e d i a l  i n cages  on  progressive  observed.  The  High  a  abnormality  leg.  higher  by  deviation  leg  r e p e c t i v e l y ) and  left  a  lateral  characterized  predominant  deviations 8%,  leg,  Dg  had  the no  iii  Morphometric from  normal  that  the  broilers  abnormality  condyle  associated functional primary  with  plasia 20%  and  the  of the  Sequential  20%,  those  of  twisted  i n the  to  the  a  high  be  be  tibiae; in  of t i b a e  suggested  namely  to  a  shallow  morphology  d i s o r d e r appeared rather  than  as the  themselves. from  i n c i d e n c e of  m e t a p h y s e s a t 3, I t was  tibiae  related  tibiae  deformation  bone d e v i a t i o n s  respectively). may  l e g may  distal  of  twisted leg  p r o g r e s s i o n of the  proximal  dyschondroplasia  with  Changes  radiography  revealed  i n the  and  grooves.  adaptations  cause  broilers  r a d i o g r a p h i c comparisons  development  structural distal  and  clinically tibial  4 and  more common t h a n  i t is  dyschondro-  5 weeks  concluded  normal  that  (60%, tibial  realized.  TABLE OF CONTENTS Page ABSTRACT  1  L I S T OF TABLES  vi  L I S T OF FIGURES L I S T OF APPENDIX  1  v i i TABLES  ix  ACKNOWLEDGEMENTS  x  I  GENERAL INTRODUCTION  1  II  LITERATURE REVIEW  3  AVIAN  SKELETON  3  S k e l e t a l Development G r o s s Anatomy o f t h e C h i c k e n L e g LEG  ABNORMALITIES  3 5  IN POULTRY  8  GENETIC ETIOLOGIES  10  T i b i a l Dyschondroplasia Chondrodystrophy Rickets Spondylolisthesis Long Bone D i s t o r t i o n NUTRITIONAL  10 12 13 15 16  ETIOLOGIES  18  T i b i a l Dyschondroplasia Chondrodystrophy Ricketts Spondylolisthesis Long Bone D i s t o r t i o n ENVIRONMENTAL/MANAGERIAL  18 18 21 23 25  ETIOLOGIES  26  S P E C I F I C PATHOGENS III  29  EFFECT OF EXCESS VITAMIN Do AND CAGE DENSITY THE INCIDENCE OF LEG ABNORMALITIES IN BROILER CHICKENS Introduction M a t e r i a l s and Methods R e s u l t s and D i s c u s s i o n  iv  ON 32 32 34 36  V  Page  IV  V VI VII  SEQUENTIAL MORPHOMETRY AND RADIOGRAPHY OF THE T I B I A E FROM NORMAL BROILER CHICKENS AND THOSE WITH TWISTED LEG  51  Introduction M a t e r i a l s and Methods  51 54  Results  59  SUMMARY AND  and D i s c u s s i o n  CONCLUSIONS  82  LITERATURE CITED  85  APPENDIX  94  LIST  OF  TABLES  Table  Page  3.1  Composition  3.2  Main E f f e c t s o f V i t a m i n D and Cage D e n s i t y on t h e S e v e r i t y o f Leg A b n o r m a l i t i e s  43  R a d i o l o g i c a l Techniques of B r o i l e r C h i c k e n s . .  57  4.1  of Experimental  Diets  35  3  used  vi  to X-ray  the T i b i a e  LIST  OF  FIGURES  Figure  Page  1.0  The  3.1  Normal and  3.2  Moderate M e d i a l ( V a r u s ) Bending of the D i s t a l T i b i o t a r s u s and P r o x i m a l T a r s o m e t a t a r s u s a t 28 Days  39  I n c i d e n c e o f Leg A b n o r m a l i t i e s ( I L A ) i n B r o i l e r s Fed C o n t r o l L e v e l s (400 ICU/kg f e e d ) o r H i g h L e v e l s (4000 ICU/kg f e e d ) o f V i t a m i n D3 i n the D i e t  40  I n c i d e n c e of Leg A b n o r m a l i t i e s ( I L A ) i n B r o i l e r s R e a r e d i n H i g h D e n s i t y (340 c m ^ / b i r d ) o r Low D e n s i t y (680 c m / b i r d ) Cages  41  Feed C o n s u m p t i o n ( F C ) o f B r o i l e r s R e a r e d i n H i g h D e n s i t y (340 c m ^ / b i r d ) or Low D e n s i t y (680 c m ^ / b i r d ) Cages  44  Body Weight (BWT) o f B r o i l e r s R e a r e d i n H i g h D e n s i t y (340 c m ^ / b i r d ) o r Low D e n s i t y (680 c m / b i r d ) Cages  45  Body Weight (BWT) o f B r o i l e r s Fed C o n t r o l L e v e l s (400 ICU/kg f e e d ) or H i g h L e v e l s (4000 ICU/kg f e e d ) o f V i t a m i n Dg i n t h e D i e t  48  Feed C o n s u m p t i o n ( F C ) o f B r o i l e r s Fed C o n t r o l L e v e l s (400 ICU/kg f e e d ) o r H i g h L e v e l s (4000 ICU/kg f e e d ) o f V i t a m i n D3 i n t h e D i e t  49  3.3  3.4  Gross  Anatomy o f t h e C h i c k e n Leg  7  C h i c k s a t 5 Days  38  Abnormal  2  3.5  3.6  2  3.7  3.8  4.1 4.2  4.3 4.4  Morphometric criteria and t o measure t h e t i b i a e T o t a l Leg Leg and Trial  methodology  used 55  Abnormalities, P r o p o r t i o n with Twisted F l o c k M o r t a l i t y o v e r the S i x Week 60  P r o g r e s s i o n of T y p i c a l Deformation  Unilateral  P r o g r e s s i o n of T y p i c a l Deformation  Bilateral  Valgus 61 Varus 62  vii  viii A.5  4.6 4.7 4.8  4.9  4.10  4.11 4.12 4.13  4.14  4.15 4.16  4.17  S e q u e n t i a l R a d i o g r a p h y of B r o i l e r C h i c k e n s Showing Normal T i b i a l Growth and Development P r o g r e s s i o n of B i l a t e r a l V a r u s D e f o r m i t y seen w i t h S e q u e n t i a l R a d i o g r a p h y  64  as 65  P r o g r e s s i o n of U n i l a t e r a l Valgus Deformity seen w i t h S e q u e n t i a l R a d i o g r a p h y  as 66  A n t e r o p o s t e r i o r R a d i o g r a p h s of t h e L e f t T i b i a e from C l i n i c a l l y Normal B r o i l e r C h i c k e n s Revealed S u b c l i n i c a l Dyschondroplasia i n the P r o x i m a l Metaphyses  68  L a t e r a l Radiograph of L e f t T i b i a e of C l i n i c a l l y Normal B r o i l e r C h i c k e n s a t 4 weeks R e v e a l i n g S u b c l i n i c a l Dyschondroplasia  69  L o n g i t u d i n a l S e c t i o n s Through P r o x i m a l Metaphyses R e v e a l i n g Abnormal Masses of C a r t i l a g e T y p i c a l of D y s c h o n d r o p l a s i a  70  Body Weight (BWT) o f Normal (N) B r o i l e r s T h o s e A f f e c t e d w i t h T w i s t e d Leg ( T L )  71  and  T i b i a l L e n g t h ( T i b . L ) o f Normal (N) B r o i l e r s and Those A f f e c t e d w i t h T w i s t e d Leg ( T L )  73  C o n d y l e Groove D e p t h (CGD) of Normal (N) B r o i l e r s and Those A f f e c t e d w i t h T w i s t e d Leg ( T L )  74  C o n d y l e G r o o v e W i d t h (CGW) o f Normal (N) B r o i l e r s and Those A f f e c t e d w i t h T w i s t e d Leg ( T L )  76  T i b i a l D i a m e t e r (TD) o f Normal (N) B r o i l e r s and T h o s e A f f e c t e d w i t h T w i s t e d Leg ( T L )  77  P e r c e n t C o r t i c a l T h i c k n e s s (PCT) o f Normal B r o i l e r s and Those A f f e c t e d w i t h T w i s t e d Leg ( T L ) Percent Those  Ash (PASH) o f Normal (N) B r o i l e r s Affected with T w i s t e d Leg  (N) 78 and 80  L I S T OF  APPENDIX TABLES  Table  I II  III IV V VI  Page  R e g r e s s i o n A n a l y s i s of P r o d u c t i o n f o r D i e t Over B i r d Age  Parameters  R e g r e s s i o n A n a l y s i s of P r o d u c t i o n f o r D e n s i t y Over B i r d Age  Parameters  A n a l y s i s of V a r i a n c e Leg A b n o r m a l i t i e s  95  96  on S e v e r i t y S c o r e s  of 97  R e g r e s s i o n A n a l y s i s o f Body Weight Morphometric Parameters Main E f f e c t Means o f V i t a m i n on P r o d u c t i o n P a r a m e t e r s  D3  and  and 98 Cage  Mean V a l u e s f o r M o r p h o m e t r i c P a r a m e t e r s , Ash, and % C o r t i c a l T h i c k n e s s  ix  Density 100 Tibial 101  ACKNOWLEDGMENTS  I wish for  to express  initiating  this  my  study  throughout.  Thanks  Fitzsimmons,  D r . K.M.  and  D r . J.W.  committee  people  also  Cheng,  have  Assistance  Department G.  and f o r h i s s u p p o r t  are  Knickerbocker  g r a t i t u d e t o D r . J . S. Sim  i n order  for their  staff  I  guidance  Dr.  R.C.  D r . D. L i  v a l u a b l e s u g g e s t i o n s as  c o n t r i b u t e d to the success  from  the s t a f f  and  H.  Song,  and  M.  of the Radiology  Newcombe  Columbia would  unyielding  also  support  Finally, parents  Acute  who  Care  like  to thank  like  always  i s  this  i n the  R. Soong,  gratefully  by C. H u t c h and  at the U n i v e r s i t y  of  U n i t i s much a p p r e c i a t e d .  and e n c o u r a g e m e n t  I would have  Department  of  students  o f P o u l t r y S c i e n c e , and i n p a r t i c u l a r  Schierman,  British  to  D r . J.H. Robinson,  acknowledged. Technical assistance provided the  and  members.  Many study.  sincere  my  wife  Pam  throughout  to dedicate encouraged  me  this  f o r her  this thesis  i n my  study. t o my  scholastic  endeavors.  and  Financial  suppport  the B r i t i s h  Columbia  was  provided  Ministry  V  by A g r i c u l t u r e  of A g r i c u l t u r e  Canada  and F o o d .  CHAPTER  ONE  GENERAL INTRODUCTION  Poultry the  world  production  i s c a r r i e d out  efficient  branch  (1983) r e v e a l s meat  has  tonnes, with dollars.  reports of  farm  citing  and  of  success,  at  problem  in  in  leg  has  of  an  of  to  major  numerous  losses and  430.2  million  the  with  millions for  the  medication  condemnation  processing. with  resolve  of  industry  mortality carcass  608.2  one  represent  poultry  exceeded  over  are  of  Canada  the  As  and  a  result,  varying  degrees  leg  abnormality  poultry.  centered  work i n the on  qualitative  terms  Despite  the  The  has  the  time  and  poultry  i n terms o f  attempt  abnormalities  factors  years  have been c o n d u c t e d ,  disorders.  disorder.  the  specialized,  Statistics  industry,  increased  the  Much r e s e a r c h ities  poultry  throughout  production  abnormalities  costing  losses  numerous s t u d i e s  i n recent  abnormalities  terms  grading  domestic  the  them as  also  industry.  receipts totalling  leg  for  Leg  in  farming  annual  cash  generally  primarily in a highly  increasing  concern  producer  down  the  However,  dollars.  costs,  of the  been  a r e a s of  i n Canada, and  area  sometimes l e d being  used  to  used  They  to  several  include  the  to  leg the  abnormalvarious  describing  describe  contributing  1  in  of  confusion,  confusion,  have been r e p o r t e d  leg abnormalities.  poultry  characterization  terminology  this  of  with  several  a particular  general the  these  causative  e t i o l o g i e s of  following:  Genetical,  2  Nutritional,  Pathological,  Therefore, vestigate and in  a  the purpose  the e f f e c t s  managerial  poultry.  In  radiographic described develop poultry.  of the present  (cage  addition,  and  density)  study  on  sequential  characteristics  pattern  Environmental/Managerial.  of a n u t r i t i o n a l f a c t o r  factor  i n normal a  and  of  abnormal  recognition  to i n -  (Vitamin  leg  development i n an  Dg)  abnormalities  morphometric  l e g bone  broilers  was  attempt  for leg abnormalities  and were to in  3  CHAPTER  TWO  LITERATURE REVIEW  AVIAN  The  avian  locomotion, divided the  mineral  into  two  appendicular  consists The  skeleton  of  girdles  Lightness most  aspects  skeleton  These  bones,  girdle  and  relatively great and  a i r sacs  high  and  pelvic  of the s k u l l ,  Skeletal The  a  skeleton  axial  ribs the  rate  and  skeleton  and  sternum.  pectoral  themes  and  exhibited  (Feduccia,  1975).  of the e x t e n s i v e  by The  a i r sac  bone marrow i n many o f t h e  v e r t e b r a l column  f u n c t i o n a l adaptation and  (Romer and  extent  and  demand  P a r s o n s , 1977). often  pelvic  to the b i r d s  consequent  by f u s i o n , and  to a great  (Koch,  arbitrarily  limbs.  skeleton  metabolic  occur  The  of  major  replace  are a t t a i n e d  limb  are  by e x t e n s i o n s  represent  ridgidity  associated  avian  amounts o f oxygen  bones, and  the  parts  consists  strength  i s lightened  system. limb  of  been  v e r t e b r a l column,  their  protection,  the a x i a l  (Koch, 1973).  skeleton  and  has  components;  skull,  with  i n support,  h o m e o s t a s i s and  major  appendicular  pelvic  functions  skeleton  the  SKELETON  for  Strength  deletion  i n t h e bones  of the  of  wing  1973).  Development avian  mesoderm. The  skeletal  system  differentiation  of  develops the  from  embryonic  p r i m i t i v e me s o d e rm-  4  derived of  cells  (mesenchymal  two r o u t e s ;  traditionally  membranous o s s i f i c a t i o n (Moore,  1973).  of  from  bone  mesenchyme to  the  into  calvarium  (ii)  cedes  mechanism  include  skeleton  of bones  chicken The  young  (Riddell, persist  1981).  until  11-14 days  are gradually  1973).  proliferating  bands  pre-  c e l l s , the or  intra-  portion  model of the  I t i s through t h i s  process  the limb  bones  develop i n  1952).  skeleton  of the long  post-hatching  replaced  i s dependent  model  at hatching  of the c a r t i l a g i n o u s  Continued l o n g i t u d i n a l  mammals  1984).  portion  h a s an immature  Remnants  the f a c i a l  from t h i s  1925; Wolbach and H e g s t e d ,  chick  this  of the appendicular  1984).  i n the metaphysis  cartilage they  (Fell,  formed  of the a x i a l  a l l t h e bones  and B e r i n g e r ,  cartilage  mesenchymal  Bones  from  and B e r i n g e r ,  endochondral  e n d o c h o n d r a l osteogenesis that  the  and  ossification.  and  (Borysenko  t o as  i s referred  of the mandible;  from  of  t e m p o r a l , and p a r t o f  hyaline  o f bone  i s referred  development  Bones f o r m e d  (Borysenko  i f an i n t e r v e n i n g  (i) intra-  differentiation  parietal, part  by one  ossification  i s a direct  ossification.  of the s k u l l ,  the m a j o r i t y  as e i t h e r  c e l l s , t h e mechanism  the f r o n t a l ,  cartilaginous  of  osteogenic  the formation  can occur  or ( i i )endochondral  and t h e c l a v i c l e s Second,  described  t h e c o n d e n s a t i o n and  include  bones  t o bone  ( i ) F i r s t , i f there  as intramembranous  model  cells)  by bone growth  bones  as cones of  ( L u f t i , 1967), (Wise  when  and J e n n i n g s ,  o f bone i n b o t h  upon t h e a c t i v i t y  of c a r t i l a g e  model  o f two  c e l l s , one s i t u a t e d  birds  actively a t each  5  end  o f t h e bone  known  as growth  cartilages  growth p l a t e s (Wise and J e n n i n g s , The occurs  entire  growth  siderable  plate  variation  growth p l a t e .  Using  The  zone o f p r o l i f e r a t i o n  the  epiphysis  thin  and  Beringer,  Gross  Anatomy There  chicken  zone  between  has been  matrix  occurs; zone  (1)  adjacent to  layer  f o r the  ( 2 ) The p r e -  by o t h e r s )  where  (1981)  four zones.  1978);  of  con-  to d e s c r i b e the  of R i d d e l l  into  the zone  formation i n the e p i -  immediately  (Brighton,  of h y p e r t r o p h y ,  represents a  proliferation initial  calcif-  ( 4 ) , The  zone o f  t h a t bone r e p l a c e s  cartilage. i s accomplished  in typical  endochondral  down on t h e p e r i o s t e a l  on t h e e n d o s t e a l  s u r f a c e o f t h e bone  surface (Borysenko  1984).  of the Chicken Leg  is little  difference  as d e s c r i b e d  information  lies  I t i s i n the f o u r t h  following  Riddell  which  as new bone i s l a i d  resorbed  the  zone  i n width  and  be d i v i d e d  (or maturation  hypertrophic  fashion  may  of the c a r t i l a g e  Growth  used  the terminology  growth c a r t i l a g e  ossification. the  plate  ( 3 ) , t h e zone  ication  There  and f u n c t i o n s as t h e g e r m i n a l  transition  and  1981).  bone  continuum  i n the terminology  avian  hypertrophic  columnar  (Reddi,  the  epiphyseal  growth  1973).  of endochondral  i n a highly organized  physeal  avian  sequence  or e p i p h y s e a l  brief  gathered  (1981),  except  i n the gross  anatomy  by v a r i o u s i n v e s t i g a t o r s . description from  Koch  i s a  (1973),  Therefore,  compilation  Feduccia  where s p e c i f i c a l l y  of the  noted.  (1975),  of and  6  The  leg  fibula,  has  the  pelvic  a prominent the  head  the  shaft  of  the with  condyles,  articulate  with  The  the  tibia  tibia  w h i c h have t h e  segment  attachment  epiphysis condyles  of  the  of b i r d s  The  fibula  fused  shorter  than  Distal embryonic III,  IV)  in the  the  and  upper much  end,  large  femoral  distinctly condyles,  Proximally  condyles  cnemial  extensor  crests The  a ridge for  Distally  with  two  called  the  is typically  the  prominent  tasometatarsus.  i s also  for  muscles.  fibula.  bones, and  with  The  l e g bones.  a trochlea  several places  slightly  contact  lateral  tarsal  in birds  femur  respectively.  by  the  acet-  in  two  diaphysis exhibits  with  The  (Trochanter  remains  prominent  reduced  1).  of the  extending  fused  These  for that  reason  tibiotarsus. greatly the  reduced;  tibia,  and  long, always  tibia.  elements  development so  two  of i m p o r t a n t  for a r t i c u l a t i o n  tibia  of the  i s c h a r a c t e r i z e d by  represent  and  fibula,  femur  of t h e  condyles  thin,  the  end  acetabular rim.  medial  largest  origins  which  tibia,  the  trochanter  the  i s c h a r a c t e r i z e d by with  t o and  at i t s d i s t a l  and  femur, (Figure  proximal  and  tibia  i s the  articulation  the  cartilage,  bent  a  proximally with  This  of t h e  of  phalanges  The  femur.  antetrochanter  is slightly  lateral  , and  girdle.  separate  the  consists  trochanter l a t e r a l  major) i s covered with  chicken  t h i g h bone, a r t i c u l a t e s  of  above  the  ta r sometatarsus  femur, or abulum  of  that  a  of  the  tarsal  with  the  elongated  single  bone,  the  bones  fuse  during  metatarsals  (II,  tarsometatarsus  or  7  FIGURE  1.0  The G r o s s Anatomy of the Chicken Leg. A, R i g h t f e m u r , t i b i o t a r s u s , f i b u l a of c h i c k e n ; c r a n i a l view. B, L e f t t a r s o m e t a t a r s u s , and p h a l a n g e s o f c h i c k e n ; c r a n i a l v i e w . I , Femur; a, t r o c h a n t e r m a j o r ; b, h e a d o f f e m u r ; c , l a t e r a l c o n d y l e ; d, m e d i a l c o n d y l e ; e, t r o c h l e a ; I I T i b i o t a r s u s ; f , i n n e r c n e m i a l c r e s t ; g, m e d i a l c o n d y l e ; h, l a t e r a l condyle; i , trochlea; I I I , Fibula; IV, Tarsometatarsus; j , dorsal m e t a t a r s a l g r o o v e ; k, m e t a t a r s a l 1; 1, t r o c h l e a f o r d i g i t s I I , I I I , IV (from l e f t to r i g h t ) with t h e i r r e s p e c t i v e p h a l anges ( f r o m F e d u c c i a , 1975).  8  "running and  bone" i s f o r m e d .  fused  the  metatarsus  has  two  articulation  tibial  protrusions This  for  condyles  f o r the  region  Distally,  is  the  at  the  the  distal  metatarsus  posteriorly  d i r e c t e d toe  Toes  II,  I I I , and  respective  IV,  rudimentary  Proximally,  and  of  the  where  posteriorly  the  tendons  to  as  carries  of  the  I which  of  the  three  which  the  two  has  two  the  toes.  hypotarsus.  large  articulates  correspond  three,  tarso-  trochleae IV.  Post-  tarsometatarsus  I, c o n s i s t i n g of  t r o c h l e a e , have  is  p h a l a n g e s I I , I I I , and  end  rudimentary  I  surfaces  referred  tarsometatarsus with  II.  insert,  insertion  often  articulation  eriorly,  metatarsus  with  metatarsus distal  The  with  three  is  the  short  phalanges.  i n l o c a t i o n to  f o u r , and  the  five  their  phalanges,  respectively.  LEG  Leg the 1% and  abnormalities  poultry of  the  b i r d s i n many  However,  not  culled  die.  of  4%  (Riddell,  or  cause  of  National  Many a r e  depressed  growth  Federation,  1971).  or  culling  broiler  Turkey  a f f e c t e d with processed.  i s not and  death  economic  chicken male  Federation,  for than  flocks turkey 1971).  leg abnormalities  However, t h e  generally  loss  of more  b i r d s i n many c o m m e r c i a l  a l l birds  crippled birds  POULTRY  commercial  the  1981;  IN  significant  industry; causing  more t h a n  flocks  ABNORMALITIES  profitable  downgrading  are  processing because  (National  of  Turkey  9  During the  the past  twenty  classification  poultry. of  Recent  leg  (1975;  include  infectious  and n o n i n f e c t i o u s  different  disorders  systems.  classified as  those  of Nairn  diseases  Etiological  Generally,  classified  into  and encompass  many  the nervous,  m u s c u l a r and  factors  been  and H e s t e r  nutritional,  types  and Watson  1981).  are broadly  affecting  by P i e r s o n  genetic,  r e v i e w s on common  1978), R i d d e l l (1978; i n poultry  has been made i n  of l e g a b n o r m a l i t i e s i n  and c o m p h r e h e n s i v e  abnormalities  skeletal  progress  of the types  leg abnormalities  ( 1 9 7 2 ) , Wise  years,  have  broadly  ( 1 9 8 2 ) and J u l i a n  p a t h o l o g i c a l , or  (1981)  environmental/  managerial. Potential tensively concern these  studied  relating  to the p o u l t r y  and  industry.  (bacteria,  also that  in eliciting  l e g a b n o r m a l i t i e s of  Therefore, include  rickets,  i n this  tibial  reviewed  dyschondro-  on t h e b a s i s  predispositions.  more t h a n  involved  separately.  one e t i o l o g i c a l  a particular  of  their  Environ-  i n f e c t i o u s pathogens  mycoplasma) discussed  review,  s p o n d y l o l i s t h e s i s and  f a c t o r s and s p e c i f i c  were  to r e a l i z e  involved  were  viruses,  abnormalities portant  which  nutritional  mental/managerial  f a c t o r s have been ex-  t o t h e major  chondrodystrophy,  bone d i s t o r t i o n ,  genetic  be  and n u t r i t i o n a l  leg abnormalities  plasia, long  genetic  with l e g I t i s imf a c t o r may  l e g abnormality.  10  GENETIC  In  response  breeders feed  workers  feel  caused type  t o t h e demands  have s o u g h t  efficiency  ETIOLOGIES  primarily  o f meat  that  this  type  sort  to improve  birds.  (Wise  and J e n n i n g s ,  The  importance  leg  abnormalities  researchers  who  incidence breeding  of  also  various  programs  Austic  e t a l . , 1977; S h e r i d a n  Tibial  Dyschondroplasia  Tibial  i n the metaphysis  and  commonly  the  growth  broiler  by L e a c h  chickens  McCapes  by  Olsson  r e s p e c t to the i n c i d e n c e of shown  strains  by  numerous  showing  high  through  e t a l . , 1974,  (1967). (1978),  beneath  selective  abnormality  the proximal  tibiotarsal  plates.  I t was  and Nesheim  I t has a l s o and  focal  o r low  1976).  i s a cartilage  distal  tarsometatarsal  by  et a l . , 1978).  by a mass o f a v a s c u l a r h y p e r t r o p h i c  situated less  meat-  1973, 1976; Khan e t a l . , 1977;  dyschondroplasia  characterized  d e f o r m i t i e s i n modern  leg disorders  (Riddell,  and  have  been  have e s t a b l i s h e d  rate  s t r a t e g y may  1972; P o u l o u s  of g e n e t i c s with has  growth  poultry  However, many r e s e a r c h  of b r e e d i n g  the increase i n s k e l e t a l  birds  of the producers,  tibiotarsal  and  first  (1965),  been termed  cartilage  proximal  described i n  and  i n turkey  osteochondrosis  osteodystrophy  by  McCapes  (1967) . Clinically,  affected  birds  tend  to squat  and a r e o f t e n  11  reluctant is  to  move.  associated  tarsus  with  1975).  The  plasia 1970)  (1965) mating  one  showing  plasia. a  and  through  selected  than  cases  and  selection. nature  to  (Riddell,  (Hemsley,  However  sub-  common  than  (Riddell  et a l . ,  Sheridan of  t h e i r s u s c e p t i b l i t y to  the  However, Edwards  incidence  of  49%  and  been  to  the  males al.  due  females  of  by  two  of  strains  tibial  (1974;  (41%)  1976)  associated et  (1983) was  31%.  showed  of  able  with This  growth  a  major  a l . (1971) and  development  tibial  males  that  the  sexes  dyschon-  show  a  sig-  showing  difference rate.  Prasad  between  to  in  indicated  with  show a d i f f e r e n c e  sex  selected  dyschondroplasia  may  to  and  dyschondro-  investigations  be  Nesheim  t h i s disease  Their  faster  (1978)  L e a c h and  incidence of  al.  Riddell  in  difference  high  tibial  chickens.  gene.  et  dyschondroplasia  develop  (16%)  incidence  to  et  tibio-  dyschondro-  more  tibial  a low  recessive  Poulous  1970).  more  of  a  a l . (1972) were u n a b l e  and  or  demonstrating  et  due  tibial  be  which  proximal bowing  to  may  26%  dams  dyschondroplasia  nificant  gait  in broiler flocks  heritable  that  droplasia.  lateral  severity  meat  linked  the  (Siller,  of  Australian  sex  1%  awkward  of  l a m e n e s s due  the  incidence  tibial  and  genetic  sires  Similarly, high  an  a l . , 1978).  established  another  for  less  incidence  broilers:  of  frequencies  changed  have  dyschondroplasia  Poulous et  be  anterior  i n severe  with  The can  from  birds  enlargement  incidence  tibial  thought  an  marked  4-40%  clinical  1971;  with  varies to  These  may  Riddell  an  have  (1975),  incidence  of  12  tibial  dyschondroplasia  diminished  when  i n growing  t h e growth  chickens  rate  was  significantly  reduced  by  dietary  manipulations. Breed to  tibial  is  well  1978)  differences  also  e x i s t i n terms o f s u s c e p t i b i l i t y  dyschondroplasia. documented  While  in broiler  tibial  and t u r k e y  White Leghorns a r e not a f f l i c t e d  (Rieland  dyschondroplasia flocks (Riddell,  with  this  abnormality  e t a l . , 1978).  Chondrodystrophy Chondrodystrophy ality It  manifested  has a l s o  However, suggested in  avian  things  and W a t s o n  that  as a g e n e r a l i z e d  bones  such  that  this  legs  gastrocnemius  cases  Several manganese,  Wise  linear  impairment  tendon  (Norris  later  perosis  meant d i f f e r e n t  growth  1981).  joint  discontinued  chondroplates  i s impaired,  growth  remain  or v a l g u s  while  thickened,  deformation  Displacement  (hock)  of  normal.  groove often  of the at the  occurs i n  1965).  deficiencies, including  biotin,  (1975)  be  of the growth  varus  and S c o t t ,  choline,  Wise  perosis  o f f i t si n t e r condyloid  nutritional  pathologists.  r e s u l t s i n shortened,  secondary  (Riddell,  development.  (1975) defined  disorder  tibiotarsal-tarsometatarsal severe  that  and a p p o s i t i o n a l  bones and o f t e n the  by many  (1972) and  to d i f f e r e n t people.  Clinically,  of  perosis  argued  i s a l e g abnorm-  cartilage  t h e use o f the term  mineralization  long  abnormal  termed  p a t h o l o g y . They  dystrophy long  through  been  Nairn  as i t s name s u g g e s t s  nicotinic  acid  t h o s e of  and  zinc  13  interfere impair  with  linear  normal growth o f  (1973a) c o r r o b o r a t e d that  slowing  chondrocytes these  in  this  of  the  the  increased little  linear  no  impairment  surmised  that  growth and  Although  not  abnormal. amount of  and  i t s production. Lamoreux  clearly recently,  a  heritable  and  lethal  abnormal  and  to with  progeny  be  were  Scott of  in  cartilage  was  (1965) the  (growth  in  width).  accepted  by  that  in  for  a  genetic  Asmundson  as  a  broiler  chickens.  turkey  embryos,  of  phenotypically  3:1  evidence  of  i n h e r i t e d chondrodystrophy  strains  of  turkeys  recently  1944)  chondrodystrophy  incidence a  basis  (1942,  a  has  bones  affected  as  fitting  found  long  inherited  the  a  reduced  primarily  evidence  studies  trait  to  nutritional deficiencies,  (1975) w o r k i n g w i t h  chondrodystrophy recessive  Early  stated  proliferating  generally  by  (1942) d e m o n s t r a t e d  Gaffney  They  growth  is  Wise e t a l .  Histopatho1ogically ,  chondrodystrophy appositional  and  related  of  of m i n e r a l i z a t i o n  precipitated  plates  .further  intervening  Norris  many i n v e s t i g a t o r s have c i t e d in  rate  plates.  chondrodystrophy  abnormality  and  specifically  mitotic  ( R i d d e l l , 1978).  or  thus  the  growth  ( R i d d e l l , 1978).  was  growth  and  of  description  chondrocytes appear  number, s w o l l e n ,  leg  bones  chondrodystrophy  selective  and  development  single,  ratio. in  been  provided  More found  autosomal,  Still  large  was  normal further  and  medium  by  Nestor  (1978).  Rickets Rickets  is a  disease  of  growing  birds  characterized  by  14  poor m i n e r a l i z a t i o n whereas  in adults  Kennedy,  1970).  between  two  appearance  snap,  and  widened  (Riddell,  proximal  ends  The  1981).  bowed  of  a  Dg  or  to  a  stunted  break enlarged  and  facilitates'  the  noticeable  generally  been  levels the  of  The  a  than  control  phosphorus,  had  dwarfs.  significantly  However,  nutrients  but  not  the  greater  due  t o an a l t e r a t i o n i n t h e r a t e  controls.  suscepibi1ity  bone m i n e r a l ,  with  the  decreased  the  role  Their  studies  chickens,  highly  strain  and  low  reared  that  under  even  vitamin  significantly  the  i n the  of  calcium,  (Riddell,  demonstrated  results indicated  calcium,  controls  strain  at the  a t t r i b u t e d to  thereof  in i t s production. dwarf  with  1975).  combinations  r i c k e t s and  mineralization  of  than  are o f t e n  most  e t a l . (1977)  sex-linked  conditions.  provided,  include  M i n e r a l i z a t i o n of the  often  appearance  and  and  often  rather  plates  r i c k e t s has  selection  susceptible  optimal  bend  (Jubb  encountered  1978)  and  1972).  This  often  (Wise,  of the t i b i o t a r s u s (Wise,  vitamin  genetic  identical  most  feathering  growth  However, A u s t i c  involved  osteomalacia  are  t h u s bones  cartilage;  d e f i c i e n c i e s e s p e c i a l l y d e f i c i e n c i e s of  phosphorus,  of  a  cause  nutritional  poor  and Watson,  and  of  signs  epiphyseal  as  weeks o f age  epiphyseal  development  1978).  three  (Nairn  and  i t i s known  t o walk,  bone i s i m p a i r e d a  osteoid  Clinical  and  a reluctance  of  when  Dg  greater  were bone  l e v e l s o f two  bone  ash  in  dwarfs  Consequently they suggested of  the  dwarfs  to  dwarfs  being  that  r i c k e t s may  of d e p o s i t i o n more  or  of  be  resorption  sensitive  to  15  marginal  deficiencies.  genetic  abnormality  strain.  This p o s s i b i l i t y  be  given  of  rickets  1977)  further  and  have  No  r e f e r e n c e was  in nutrient  made t o  absorption  i s strengthened  and  consideration in poultry been  identified  as  i n man  a  i n the  dwarf  perhaps  should  over  causes  (Dent  some i n c l u d e many m a l a b s o r p t i o n  potential  30  and  Stamp,  syndromes.  Spondylolisthesis Spondylolisthesis from  a n e u r a l impairment  Howell and/or  (1972)  This  compression  paralysis aid or  failure  deformed (Wise,  spinal 1973;  disease  as  sixth  and  causes  posterior  a  seventh  thoracic  paralysis  with  spondylolisthesis  commonly No  unable  due  of  However  spinal  to  the  degenerative  denervation  were  assume a  posterior  t o move, e x c e p t  cord  in  due  1970).  abnormalities i n epaxial  the  and  distortion  most b i r d s  However,  resulting  Riddell  (Wise,  Subclinical cord  the  limbs.  interspinuous ligaments  1970).  (1977).  lower  cord  are  of  disturbance  spinal  wings.  to  the  posture.  region  attributed  of  o f the  they  of t h e i r  the  deformation  Clinically, hock-sitting  to  characterized  displacement  vertebra. to  i s a locomotory  were  with  the  musculature  found  in  the  spondylolisthesis  changes i n l e g muscles  reported  spondylolisthesis  by  without  i s a p p a r e n t l y common i n b r o i l e r  Khan  et  damage t o  chickens  a l . the  (Wise,  Khan e t a l . , 1977) . There  thesis.  is a  Riddell  hereditary predisposition (1973)  bred  broilers  to  that  spondylolishad  recovered  16  from  clinical  clinical  s p o n d y l o l i s t h e s i s t o 9%  Similarily, incidence cessive Wise  Khan  resulted  may from  genetically  growth  Long Bone  tion  may to  felt  This  concept  (Wise,  early  i n the  p'revent  four  suc-  selected imposed  i s supported  by  life,  major,  i n part  Wise  i t s development  f o r or  (redistri-  By a r t i f i c i a l l y  birds  and  i n the t h o r a c i c  conformation  1973).  high  spondylolisthesisin  specifically stress  a  Osbaldiston  t h a t weaknesses  c h a n g e s i n body  by  slowing  (1973)  was  r e g a r d l e s s of  growth r a t e s .  distortion  Oteodystrophy i s used  is a  general  by d e f i n i t i o n  in this  review  form  result  from  as i t was  defective cortical  abnormal c a r t i l a g e have  been  coined  include "twisted  deformation",  formation  to  bone  to d e s c r i b e  a  few.  osteodys-  as opposed Several  osteodystrophies  l e g " , and Wise  (1981)  bones i n p o u l t r y  formation  these  forma-  by R i d d e l l  (chondrodystrophy).  l e g " , "bowed name  of  i s d e f e c t i v e bone  emphasize t h a t a b n o r m a l i t i e s of the long  although  generations.  to m a i n t a i n  progeny.  mechanical  research  bone  and  terms and  able  of  Distortion  Long trophy.  i n three  to d e s c r i b e  been  induced  to completely  subsequent  to  They  undue  rate  broiler  the f i r s t  have  the i n c i d e n c e  s p o n d y l o l i s t h e s i s through  of  o f body m a s s ) .  recent  able  were  chickens.  vertebrae  the  of  generations  broiler  more  e t a l . (1977) were  (58-66%)  (1967)  bution  s p o n d y l o l i s t h e s i s and r a i s e d  "varus-valgus  (1978)  t h e above a b n o r m a l i t i e s a r e a s s o c i a t e d  warned  that  with  gross  17  deformities for  o f the l e g s k e l e t o n ,  separating  when more sidered drome  them  into  and  they  were  i n that  may  be  Ferguson  et  will  be  i n the  future  a l . (1974)  a l l manifestations  light  justification  i n d i v i d u a l diseases  i s known. H o w e v e r ,  that  there  con-  o f t h e same s y n -  treated  as  such  in  this  review. Initially, and  Watson  ( 1 9 7 2 ) , Wise  used  the  with  which  term  b r o i l e r  no  distal  was  not always  leg". leg"  of  a lateral  displaced More  was  Haye  an  incidence and  and  the  with  been  and The  term axis  outward  gastrocnemius growth  Mills  t h e term  "varus-va1gus  descriptions,  that  twist,  incidence  plates  defor-  f o r the  that  most  "twisted "twisted  i n the sense  of a  involved.  influenced differences that  tendon  description  l e g i n b r o i l e r s has  l e g and  of  ( 1 9 8 1 ) and  t h e terra  (1981) a r g u e d  strain  to t w i s t e d  under  and  bending  and  be  in  unilateral  o f a bone, was  to  (1978)  associated  epiphyseal  as no  Nairn  abnormlality  Randall  Mills  (1978)  the  Simons  a leg  was  t h o s e used  and  r e s u l t s showed  exist,  to  of t w i s t e d  Simons  susceptibility  also  twisting  However t h e i r  the long  and  later  t o a t t a i n a more p r e c i s e  inaccurate  about  had  lesion  recently  identical  (1967) and  Haye  of the t i b i o t a r s u s .  Howver, R a n d a l l  The  Their  The  i n an a t t e m p t  were  rotation  by  chondrodystrophy  the d i s o r d e r .  part,  Wise  l e g " to d e s c r i b e  ( 1 9 8 4 ) have i n t r o d u c e d  mations" of  end  normal.  Julian  "twisted  by  the  and  ( 1 9 7 5 ) , and  chickens.  characterized  were  Osbaldiston  by  been  genetics.  exist in  sex  f o r males being  shown  terms  differences twice  that  18  for  females. Buffington  described rotated  the  ( 1969)  strain  of  tarsal  were  of  more  bowed  identified  and  bent  an  or  both  found  and  in  less  males  responsible  frequently females.  gene i n  for twisted  bones.  affected  turkeys,  than  autosomal r e c e s s i v e  tarsometatarsal  b i r d s were  one  leg  frequent  c h i c k e n s w h i c h was  recessive either  a l . (1975), working with  incidence  tibias  Somes  et  to  All  one  tibio-  homozygote  varying  degrees  classes  of  in  legs.  NUTRITIONAL ETIOLOGIES  The are  nutrient  well  Research  documented has  shown  important  in  Consequently, nutrition  during  Tibial  and  wide  range  has  the  been  Hester  most  Research of  past  a  and/or  topic  reviews (1982),  of  include and  and  several  Wise  growth  production intense  1981).  factors  years,  those  poultry  Council,  dietary  development  prevention  comphrehensive  Pierson  a  for  (National  normal  i n the  abnormalities and  requirements  of  the  of  be  bone.  role  poultry  study.  of  to  of leg  Current  Sauveur  (1984),  (1978).  Dyschondroplasia  Although strongly  linked  also  been  that  rapid  the to  cause  dyschondroplasia  tibial  genetics,  implicated growth  of  may  dyschondroplasia  many n u t r i t i o n a l  i n i t s e t i o l o g y . I t has be  an  (Siller,  etiological 1970;  has  been  factors  have  been  factor  Poulous  et  suggested in  tibial  a l . , 1978).  19  Poulous  et  a l . (1978)  treatments of  tibial  that  which  observed  decreased  growth  chondroplasia, between  the  but  Riddell  decreased no  the  significant  rate  of  bone  dyschondroplasia  in  individual  suggested uting  factor  looking and  at  of  the  growth  the  rate  (1964)  end  of the  proximal  T h i s may  Riddell weight the  bowing the  of  Riddell  demonstrated  could  development  no  He  In  fastest  rate  p l a t e s i n the  same  second  ends  occurrence  of  Church  rate  the  proximal  when  growth  had  the  contrib-  the  tarsometatarsus  more common  a  that  fastest  at  therefore  found  the  growth  tibial  bones,  had  other  seen  addition,  individual (1975a)  dys-  be of  more t h a n  tibiotarsus  with  incidence  the  of  dys-  tibiotarsus  and  tarsometatarsus. In  in  be  growth  e x p l a i n the  chondroplasia the  and  growth when compared  bird.  and  dyschondroplasia. of  dietary  i n c i d e n c e of t i b i a l  chickens.  may  the  (1975a)  correlation  growth  rate  in tibial  Johnson  proximal and  that  that  growth r a t e r e d u c e d  dyschondroplasia.  slowed  consistently  terms (1975b) on  the  to  of  the  cortex  of  in the  support  of  tibial  (Riddell,  evidence  hypothesis t o be  was  that  the  found  excessive  primary  dyschondroplasia.  and  a compensatory to  be  a  direct  by  factor However  t h i c k e n i n g of response  to  1975b).  capillary  growth  the  appeared  normal  no  tibiotarsus  tibiotarsus  bearing  important  weight,  proximal  Metaphyseal  region  body  pathogenesis  concave  weight  of  t u n n e l i n g has  endochondral  bone  plates (Brighton,  been  shown  formation  1978).  It  to in  has  be the  been  20  suggested  (Riddell,  cartilage  in  1981)  tibial  the  cartilage elicited  in  from  Jennings  tunneling.  primary  or  lesion  the  the  may  fail  plates  in rapidly  tibial  to  This  indicate  that  Several factors  in  that  (Leach  choride  relative 1974)  and  in  Nesheim, to  as  to  evidence  the  supply  could  be  (1970) and  Wise  and  metaphyseal on  thus  the  blood growth  cause  tibial  i s f u r t h e r supported that  was  grossly  in natural  chickens.  excessive  cases with  These  development  been  i m p l i c a t e d as  by and of the  studies  weight  the  increased  acidosis  did  the a l .  in rachitic 1-25(0H)  acidosis 1972)  sodium  metabolic  into  and  defect  and  metabolic  et  3  an  linked  of  dyschondroplasia.  Sauveur  Dg  to  pressure  in broiler  have  plasia.  vitamin  be  s u r g i c a 1, i n t e r f e r e n c e  growth  minerals  chloride  Mongin,  of  development  the  defect  the  degradation  may  of  be  tibial  in poultry.  tibial  established  by  factors  dyschondroplasia  25(0H)D  to  supply  rapid  contributing  Siller  hypothesis  similar  blood  the  that  a  no  blood  birds  produced  dyschondroplasia  metaphyseal  in  excessive  growing  (1975) who  histologically  was  suggested  due  might  However  literature .  dyschondroplasia. Riddell  delayed  metaphyseal  (1972) have  supply  the  dyschondroplasia  absence of c a p i l l a r y whether  that  2  potassium  (1978)  c h i c k s by  However,  the  there  ammonium excess  of and  dyschondrothat  renal  reducing  well  (Sauveur  revealed  alter  now  by  a simple  i n c i d e n c e of t i b i a l  in fact  Dg.  is  induced  or by  and  It  etiological  chronic  metabolism  of  conversion  of  i s no  evidence  21  of  rickets  (Riddell, effect  i n birds affected  with  1981).  i tis difficult  of a high  chloride diet  dyschondroplasia It nor  Therefore,  claimed  phosphorus  1965).  that  of t i b i a l  Recent  Lilburn  calcium  factors  phosphorus  producing broilers. a  They  clearly  i n causing  results  ratio  increased,  was  reducing  available  Veltmann  accentuate  showing  indicated  tibial  found  that  the high  high  chloride level  tibial  of calcium  dyschondroplasia that  t h e Ca:P  incidence  high  when  ratio  They  the acid-base  o r by Edwards  levels  to  suggested  may be a c t i n g s i m i l a r  dyschondroplasia  with  calcium  phosphorus  in  t h e Ca:P  In f a c t ,  of the l e s i o n .  upsetting  the t i b i a l  of  importance i n  by a d d i t i o n a l  phosphorus l e v e l  a r e major  the l e v e l s  phosphorus i n the d i e t .  (1983)  indicating  dyschondroplasia,  a lower  either  the development  precipitating  tibial  Nesheim,  ( 1 9 8 3 ) and  i n the diet  that  to the  and  new e v i d e n c e  are of great  preventing  The r e s u l t s  (Leach  the expression  concluded  tibial  calcium  related  and V e l t m a n  levels  i n the r a t i o n  and/or  factor  provided  influencing  consistent  and  by E d w a r d s  of  that neither was  dyschondroplasia  and p h o s p h o r u s  dyschondroplasia.  was  i n the diet  studies  to e x p l a i n the  v i t a m i n Dg m e t a b o l i s m .  f o r many y e a r s  e t a l . (1983) have  nutrient  and  level  dyschondroplasia  on t h e i n c i d e n c e  by i n t e r f e r e n c e w i t h  has been  incidence  tibial  to the  balance  and  condition.  Chondrodystrophy As  previously  mentioned,  many  primary  nutritional  22  deficiencies  have  development  of  growth  symptoms  in  manganese  (Wilgus  zinc  acid  and  shown  and  et  cause  a l . , 1946)  and  Hegsted,  a l . , 1958),  1942), n i a c i n ( B r i g g s  normal  deficiencies  Wolbach and Young e t  with  chondrodystrophic  include  a l . , 1936; 1957;  interfere  and  These  Savage,  Bird,  (Daniel  et  to  plates  poultry.  (O'Dell  (Jukes  been  1953), choline  e t a l . , 1943),  pyridoxine  (Gries  and  attempt  provide  a  of  folic Scott,  1972). Wise e t  a l . (1973a),in  hypothesis  to  result  chondrodystrophy,  in  interfere  with  conclusion lesion the  explain  turkey  mitosis  normal  was  i n the  a l l the  zone of  on  his  the  epiphyseal  (i)  a lack  of  The  c a r t i l a g e for columnar  matrix  of  smaller  than  normal  zone o f  (Leach,  1967;  1971)  i t was  i n the  in  in  the  also  and  that  the  o f manganese a c t i o n  involved  in  chondroitin working  with  i n the  was  namely  the  enzyme s y s t e m s i n v o l v e d  sulphate.  The  d e f i c i e n c i e s of  results choline  plates to  of and  of with  ( i i ) an  proliferation In  other  that  in  a reduction  in  chondroitin  sulphate  appeared  i n the Wise  of  depress  capacity  demonstrated  e x t r a c e l l u l a r matrix, site  a similar  hypertrophy.  there  may This  associated  zone of  the  primary  a l l  chondrocytes  the  chicken  growth  hock j o i n t  growth was  arrangement  they  produce  the  reduction  and  manganese d e f i c i e n c y  to  the  in  studies  of  of  that  might  chondrocytes.  of  increase (iii)  amount  of  ability  irradiation  unifying  deficiencies  suggested  proliferation  chondrocytes.  to  above  proliferation  based  using  of  why  an  et  to  be  synthesis  of  al.  nicotinic  (1973a)  acid,  and  23  and  those  concept  of Westmoreland that  supply  is  the  of  as  proliferative  lesions zone  t o be  observed  like  associated  growth r a t e  of  broiler  although  away  from  (Summers  a l . , 1978).  et  the  potential  deficiencies modern b i r d s cause  may and  tibial  i t s blood of  chon-  areas  the  the  of  the  descending  dyschondroplasia,  rapid  that  growth  dietary  reduce  the  chickens  recommendations  have changed  that  from  pathogenesis  e t a l . , 1978).  requirements  least  the  with  usually  (Poulous  efficiency  improved  chondrocyte  support  were p r e s e n t i n t h o s e  consistently  abnormalities feed  (1969)  vessels.  been s a i d  decrease  in  furthest  Chondrodystrophy,  been  Hoekstra  d i s t a n c e of the  importance  drodystrophy  epiphyseal  and  little  which  i n c i d e n c e of  these  The has  the  from  that the  i t i s t h e s e minor  chondrodystrophy  growth r a t e  been  past  minor  rapid  drastically vitamin  twenty  growth  1981;  and  years or at  nutritional  nutritional  (Riddell,  has  treatments  f o r m i n e r a l and  over  It  T h e r e f o r e , i t seems l i k e l y ,  exists  result  rate.  has  of  todays  deficiencies  Poulous  et a l . ,  1978).  Rickets Rickets deficiency  i s generally  of  vitamin  imbalance  of  are  diagnosed  of  rarely  turkeys)  these  and  Dg,  c o n s i d e r e d t o be calcium,  nutrients. i n poultry  many c a s e s may  or  Field  phosphorus outbreaks  ( w i t h perhaps be  due  the r e s u l t  the  to simple  of  of a  or  an  rickets  exception feed-mixing  24  errors  (Wise,  descriptions of  rickets  1975;  Nairn  of r i c k e t s  and  Watson,  i n the  i n experimental  field  1972).  chickens.  Groth  experimental  rickets  i n fowl  calcium,  p h o s p h o r u s and  vitamin  Dg  diets fed  changes produced  produced. a similar  aspects  deficiency  were  growth  small  zone  of  reduced  disrupted  to  low  is  a  blood  be  or  and  replaced  calcium  ciencies, plate  vitamin  by  from  the  however,  gut  hypertrophic thickening  of  usual  the  of  irregular  no  delayed  growth p l a t e  i n some  r e g i o n of  was  the  the  parathyroid  1981).  (Groth  and  with  This  vitamin  hence  calcium  Phosphorus  by  an  Frey,  may  of  the  calcification  evidenced  and  response  associated  d i s r u p t i o n of the  little  metaphysis  In  p r o t e i n and 1975).  a  longitudinal  tissue.  (Riddell,  the  only  cartilage  orderly  Dg the  in  and  There  ricketts  binding  were  vitamin  main e s t a b l i s h e d r o l e  as  deficient  proliferation  hypertrophic  of  pathol-  birds  and  present.  (Wise,  cartilage  the  calcium  h y p e r p l a s i a of  produced  a r c h i t e c t u r e but  deficiencies  i f these  zone o f  D deficiencies  calcium  (1966)  d i s o r g a n i z a t i o n of  fibrous  levels,  s i n c e the  stimulate  absorption  The  bony s p i c u l e s i n t h e  surprising  i s to  with  The  pathological feature  calcium  Dg  of  or  Calcium  of the  invasion.  Frey  a syndrome d i f f e r i n g  was  calcification  with  Dg  thickened,  hypertrophy  vascular  arrangement  was  and  described  but  resulted.  associated  cartilage  provisional  was  diet  plate architecture.  epiphyseal  not  Vitamin  a phosphorus d e f i c i e n t  pathologic  and  syndrome,  general,  agree with d e s c r i p t i o n s  produced  ogical  In  defigrowth of  the  increased 1966).  25  Spondylolisthesis Wise  (1973)  importance  of  However, factor  rate  Wise  restriction  Khan e t  genetics  growth by  and  in  i n the was  week p o s t - h a t c h i n g  to  be  a  demonstrated  rate  completely  spondylolisthesis  shown  He  growth  the  e t i o l o g y of s p o n d y l o l i s t h e s i s .  also  (1973). the  a l . ( 1 9 7 7 ) have e m p h a s i z e d  in  regardless  of  that  broilers  prevented  the  the  contributing  for  severe the  first  development  subsequent  rate  of of  growth.  Long Bone D i s t o r t i o n Little in  the  could  evidence  production be  "twisted the  and/or  discerned  (1978) found  that  as  to a p o t e n t i a l n u t r i t i o n a l prevention  from  feed  the  birds  were  as  allowed  reduced  body w e i g h t  ad  libitum  body w e i g h t  valgus  the  s e v e r i t y of  deformities)  influence and  on  of  body w e i g h t  e n v i r o nme n t a 1/ma  weight  by  harnessing  and  poults.  the  fowl  weight severity  They  i s capable as of  in  that  supporting weight  leg abnormalities.  In of  and  the  on the  lower to  loading  t h a n when diet.  independent  effect  order  the  to  the  of  body  chicks  structure  greater  Unfortunately,  make  nutritional  backs  no  (varus-  increased  skeletal  had  of  the  they  a load  Simons  occurence  genetic,  effects,  weights  concluded  artificial  Haye  was  the  poultry.  na g e r i a 1  of  distortion  leg abnormalities  independent  steel  bone  access  However, Cook e t a l . (198A) a d d r e s s e d of  long  literature.  restriction  leg" in broilers  of  etiology  than  effect no  of  normal on  the  attempt  was  26  made t o e v a l u a t e the  incidence  different, the  those  al.,  of  artificial  abnormalities.  results  are  growing  grow more  of  et  still  slowly  a l . ( 1 9 7 9 ) were  i n which  (1978) c o n c l u d e d have an  i n general  (Riddell,  be  and  "twisted  genetics,  Many  i n the  research  suggested influence (Pierson Simons,  that the and  1978).  lacked  l e g " was  simple  elimination  of  Lighting  had  agreement  with  abnormalities Hulan  leg  workers  and  environmental  occurrence Hestor,  of  1982;  together  or  has  bone b r e a k a g e regimes are  abnormalities  demonstrated  in  that  significantly  et  any  groups  occurring.  and  feed  "twisted  Wise  appear  could  ETIOLOGIES  producers  managerial  et of  the  have  factors in  a l . , 1984;  lumping  may  poultry Haye  published  a l l forms  and work  of  leg  been d i r e c t e d more t o w a r d s during  to  leg".  abnormlaities  much  the  processing.  known t o i n f l u e n c e t h e  occurrence  poultry.  a l . (1973;  turkeys  more  and  Wilson  by  to v a r i o u s  commercial  leg  Unfortunately,  demonstrate  nutrient deficiences  e t i o l o g y of  s p e c i f i c i t y  abnormalities  1976)  on  slightly  1983;  to  vitamins  environment  i n f l u e n c e ; however implicated  unable  ENVIRONMENTAL/MANAGERIAL  of  loading  Although  b i r d s have more l e g  a d d i t i o n a l minerals  broilers  has  weight  1979).  effect  not  effect leg  fast  that  Hulan  of  of  these  view t h a t  than  the  leg  Buckland  grown  in  et  continuous  abnormalities  than  light those  27  subjected tored and  to  intermittent  plasma  that  under  lighting  no  system.  causal  levels in  to  the  al.  ation  incidence  literature.  that  had  illumination  leg  those  was  et  on  leg  to  could  be  found  Wilson  1976)  et  results.  continuous i l l u m i n -  more  under  activity  partial  relate  corticosterone  a l . ' s (1973;  and  bi'rds  abnormalities  b r o i l e r s by  birds  a  made  elevated  more,  bird  as  of  grown under  those  held  was  in  more s t r e s s f u l  abnormalities  work  birds  a  stress  severe  leg  ab-  i n t e r m i t t e n t  under  intermittent  explanation  for  the  legs. reared  abnormalities  1971).  Studies  incidence  of  broilers also  in  by  to  metal than  covered  wire.  incidence  by  cages  birds  Haye  show  reared  and  on  Simons  leg"  (long  on  litter.  than  a  higher litter  (1978)  bone The  frequency (Reece e t  found  a  distortion) type  of  cage  have a s i g n i f i c a n t e f f e c t , w i t h wire  those  varied  explained  than  cages  found on  in  "twisted  problems  was  attempt incidence  Buckland  Increased  Broilers  reared  of  Similar  than  illumination.  was  the  significantly  normalities  stronger  no  moni-  i n d i c a t o r of  reflected  r e l a t i o n s h i p between  the  showed  light  l e v e l s to  an  They  corticosteroid levels  However,  (1984) c o n f i r m e d  They  leg  raised  continuous  corticosterone and  schedules.  c o r t i c o s t e r o i d l e v e l s as  concluded  raised  lighting  and  perforated  reared  on  sheets  plastic  and  Andrews  et  a l .  (1974)  with  of  cage  f l o o r i n g . This  type  differences  in  also  movement,  higher with floor  more  leg  plastic  found  with  al. ,  broilers  having  mats  of  that  difference the  birds  28  being  able  plastic  t o walk more e a s i l y  or  plastic-covered  Results suggested leg  that  fewer  floor  birds.  the  (stronger (Meyer  was  incidence  of  on  of  more  incidence  of  leg abnormalities et  ambient  strength  However,  higher  temperature  intake  causing  phosphorus. al.  This  (1967) found  the  a  processing  and  temperatures  cages.  Siegal  the  that  be  et  these  to reduce  the  cage-reared  the  related  incidence  a l . (1973)  a depression  confinement  have  marginal  may  Anderson  studies to  that  during  from  i n f l u e n c e bone  augmented  depression may  of  caged  breaking  1981;  drawn  these  about  shown  bones  necessary  none o f  temperature w i l l  with  showed  production.  a l . (1971)  associated  Merkley,  of  supported  bone  broken  processing  bones a t  during  shown e n v i r o n m e n t a l high  was  bones d u r i n g  broken  the  water  between  have  greater  fewer  exercise  (1971)  is further  reports  1974;  of  when b i r d s moved  conlusions  that  on  incidence  processing  have  Sunde,  It i s unfortunate  Rowland  as  Numerous  the  Dammrich  during  general  broken  and  and  location  increases  hypothesis  floor  and  more e x e r c i s e  and  occurred  bones)  The  that  size  Rodenhoff  exercise  get  flooring.  exercise  birds.  a l . , 1979).  studies  cage  bone b r e a k a g e  reared  processing  the  on  reared  strengths  et  on  a l a c k of  l a c k of  research  birds  wire  leg abnormalities  more. T h i s  and  studies  abnormalities.  that  by  of  and  of  been  bone due  increasing  especially levels  of  strength in  at  depressed of  bone  broilers  strength  to  deficiency  likely,  of  have  the feed  calcium  s i n c e Rowland either  to  or et  mineral  29  increased also of  bone s t r e n g t h .  shown  by  High  Reece e t a l . (1971) t o i n c r e a s e  Specific species  of  i n bone  pathogens  Mycoplasma or  or  such  as  may  lameness  agents  of  be  industries, nature.  most  following  The  produce  the  major  i n fowl  viruses  are  development  of  initial  route  Hestor,  1982).  reovirus  these of  coli  are  and  capsules,  Hestor  infectious  of  a  broiler  nutritional  currently  arthritis,  known t o  bacterial  by  bacteria, the  disorders, remains  causative  mycoplasma  primary but  in  cause  most  undetermined  agent  in viral  infecting  are S t a p h y l o c o c c u s a u r e u s  of  the  cases  the  (Pierson  arthritis  bacteria and  or  in  and is a  synovitis  Escherichia  1982).  Arthritis dense  viral  be  w h i l e t h e commonest  (Wise,  and  by  joint,  t u r k e y syndrome 196-5.  to  entry  The  osteomyelitis  produced  or  to l e g  c o n c e r n t o t h e t u r k e y and  infections  thought  a  leading  Pierson  leg abnormalities  synovitis/osteomyelitis, Septicemic  lesions  pathogenic conditions  lameness  viruses,  i n or around  in birds.  the l e g a b n o r m a l i t i e s  to  bacteria,  cause  (1982) r a n k e d  the  incidence  PATHOGENS  when l o c a l i z e d  cartilage  abnormalities  or  the  was  leg abnormalities.  SPECIFIC  or  environmental temperature  and  synovitis  connective tissue tendon  sheaths  i n poultry membranes  and  bursae  are i n f l a m m a t i o n s of lining  the  articular  of d i a r t h r i t i c  joints  30  (Olson  et  a l . , 1956).  condition long  of  bones  and  synovitis  and  swelling  epiphyseal may  (Nairn,  secondary  al.,  the  1973;  Wise,  they  1975).  In  were c o n f i n e d  in  of  the  consequence  was  The  bodies  region  with  typical  to  origin by  a  s p i n a l cord  minor  one  and  (Olson  et  outbreaks  of  (Wise,  or  damage  (TS65) i s an  associated  1971).  more v e r t e b r a l  and  paraplegia,  be  long  The  by  seen  in  the  is  of  weeks  with  which  of  turkey cases  fact  the  the  d e c l i n i n g importance oviduct  to  egg)  of  with  (Wise in  the  TS65  are  chondrodystrophy the  syndrome  However, i t has  growth  and  mycoplasma  changes  mycoplasmas  may  age,  infection  deficiency  mycoplasma  the  of  of  early  poults  that  nutritional  i s obscure.  nutrition  2-4  histological  bones o f  despite  proper  at  infectious condition  Mycoplasma m e l e a g r i d i s  (1978) t h a t  (infected  1965  to  primary  abnormalities  now  articulation  of  turkeys  those  mechanism  Wise  collapse  1974).  p l a t e s of  dietetic caused  lameness i s  t i s s u e damage  vertebrae  young  normally  a l . , 1973b;  identical  by  in  appears  infection,  The  Syndrome  develops  growth  with  of s p o n d y l o l i s t h e s i s .  usually  et  the  v e r t e b r a l column, u s u a l l y  thoracic  the  subsequent  Turkey that  5-7  the  of  together  Clinical  degrees of impair  regions  or  some f l o c k s , to  inflammatory  metaphyseal  1982).  d e v e l o p s when t h e that  i s an  separately  Wise,  osteomyelitis the  and  occur  become s u c h  1956;  Osteomyelitis  (Wise,  cause been  long  vertical  M.  meleagrides  leg  postulated to  bones.  as  not  1982).  the  cause a b l o c k  p l a t e s of  is  of  the TS65  transmission has  been  31  controlled (Wise,  by e r a d i c a t i o n  1978).  o r by a n t i b i o t i c  dipping  of  eggs  CHAPTER  THREE  EFFECT OF EXCESS VITAMIN D3  AND  INCIDENCE OF LEG ABNORMALITIES  CAGE DENSITY ON IN BROILER  THE  CHICKENS  INTRODUCTION A  comphrehensive  variety  of f a c t o r s  review  contribute  p o u l t r y . The e t i o l o g i e s ities  a r e complex  ities  can  problems  be  and o f t e n  attributed  (Pierson  to l e g a b n o r m a l i t i e s  due  poorly to  a  defined. single  Few  environment,  and H e s t o r ,  in  abnormalabnormal-  f a c t o r . Most l e g  to the i n t e r a c t i o n  involving nutrition,  pathology  has shown a  and p a t h o g e n e s e s o f t h e s e  are probably  factors  of the l i t e r a t u r e  of  several  genetics  1982; N a i r n  and  and/or  Watson,  1972). It leg  has been  claimed  abnormalities  strains  and  environment  that  or n u t r i t i o n  abnormalities  al.  (1984) w o r k i n g  1976)  working  under  continuous  High  broilers leg  with  i n commercial derived  trigger  broilers  turkeys  those  had  was  the incidence  than  those  reared 32  1985).  from the  that  of  Wilson  et  b i r d s grown  more  intermittent shown  signs  e t a l . (1973;  significantly  i n c a g e s have shown  abnormalities  either  and B u c k l a n d  b i r d s under  broiler  the c l i n i c a l  demonstrated  temperature  to increase reared  may  lighting  environmental  (1971)  factors  p r e d i s p o s i t i o n s to  ( S i m and C r u i c k s h a n k ,  with  than  hereditary  are widespread stress  leg  normalities  that  l e g ablighting.  by R e e c e  eta l .  of l e g a b n o r m a l i t i e s a higher  incidence  and of  on l i t t e r ( R e e c e e t a l . o  33  1971;  Haye and Simons,  Similarily, nutrition  1978).  during  the past  i n the p r e v e n t i o n  several  and/or  production  abnormalities  has been  Dg  as one o f t h e n u t r i e n t s  has emerged  importance Deluca, ment  a  1978),  normal  (Soares,  chick  disease  of growing  of o s t e o i d  Kennedy,  identified,  of V i t a m i n  meta-  Dg  have  result i n rickets;  characterized  by poor  mineraliz-  cartilage  ( J u b b and  epiphyseal  stress  little  research  has been  or vitamin  interest birds  since under  (especially with  Dg  Dg  abnormalities  the  poultry  in broiler  chickens.  are of  They a r e  are fed diets of  of the present density  and  on t h e  production  conditions. and  been  on t h e  two a r e a s  i n excess  of cage  incidence  published  These  intensive  much  have  overnutrition  routine  the o b j e c t i v e  the e f f e c t s  on  factors  at brooding)  nutrients  Therefore,  investigate  vitamin  and  and d e v e l o p -  and p h o s p h o r u s  potential  rearing  supplemented levels.  paramount  and g e n e r a l l y  of l e g a b n o r m a l i t i e s .  particular  crowded  Vitamin  (Sunde  bone g r o w t h  many  of d e n s i t y  incidence  involves  and  study.  1970).  Although  effects  birds  of avian l e g  t o be o f  Deficiencies  studied  the r o l e of  development  post-hatch  1984).  extensively  ation  to  i n embryonic  of i n t e n s e  ( Y u i l e e t a l . , 1967), and c a l c i u m  bolism been  a topic  years  required study  and  severity  was  excess of l e g  34  MATERIALS AND A n i m a l s and One  Experimental  hundred  broiler  cm^/bird; density) heated  chicks  and  brooders  basal  levels the ICU/  Aldergrove  d e n s i t i e s of  per  They were housed  cage.  twenty  raised  to  meal  wire  NRC  as  of v i t a m i n  (340  basal  diet  kg  feed. the  to  B.C.).  Chicks  ten  (680  cm^/bird;  high  in  electrically  Petersime  protein,  nutrient  ground  major  Dg  22%  (1977)  using  the  commercial  battery  floors.  containing  meet  Hubbard  either  or  chickens  throughout  local  density)  diet  formulated  soybean  a  thermostatically controlled  with  broiler  into  commercial  from  Hatchery,  divided  low  day-old  purchased  (Centennial  were r a n d o m l y  Design:  eighty,  c o c k e r e l s were  hatchery  A  and  METHODS  corn,  2879  ME/kg  requirements ground  f e e d s t u f f s (Table  Feed  and  either water  400 were  4 week e x p e r i m e n t a l  ICU/kg  and  3.1).  feed  provided  period.  for  wheat,  Two  (500,000 ICU/g) were i n c o r p o r a t e d  supply  was  or  ad  The  into 4000  libitum  experiment  o was bird  a 2  factorial  densities,  Production  arrangement  and  two  levels  with  three  of v i t a m i n  replications,  two  Dg.  Data:  Weekly  feed  consumption,  leg  abnormalities  was  defined  as  were r e c o r d e d  the  percentage  body w e i g h t for of  four  and  incidence  weeks.  of  Incidence  b i r d s i n e a c h cage  demon-  35  Table Composition  3.1  of Experimental  Diets  INGREDIENTS  GroundCorn Ground Wheat Soybean M e a l Meatmeal Animal Tallow Limestone Calcium multiphosphate V i t a m i n mix 1 » M i n e r a l mix 3  31.0 30.0 28.2 5.0 3.5 0.6 0.7 0.5 0.5  2  Calculated  Analysis:  Crude P r o t e i n (%) M e t a b o l i z a b l e Energy C a l c i u m (%) A v a i l a b l e Phosphorus M e t h i o n i n e (%) L y s i n e (%)  22.00 2878.90 0.97 0.71 0.44 1.17  (kcal/kg) (%)  Supplies p e r kg of c o n t r o l diet: vitamin A, 8,800 IU; v i t a m i n Do, 400 ICU; v i t a m i n E, 21.9 IU; v i t a m i n B i » 0.03 mg; riboflavin, 13.2 mg; pantothenic acid, 15.8 mg; n i a c i n , 44 mg; c h o l i n e 475 mg. 2  S u p p l i e s p e r kg o f e x c e s s v i t a m i n e x c e p t v i t a m i n D3, 4000 ICU. Supplies p e r kg o f c o p p e r , 25 mg.  diet:  D3  diet:  manganese, 30  as c o n t r o l mg;  zinc,  97  diet mg;  36  strating  at least  addition,  on days 21 and 28 o f t h e e x p e r i m e n t ,  of  each  l e g abnormality  scoring gait,  some  system:  kind  was e v a l u a t e d  Chicks  with  deformity  (moderate  t i b i o t a r s u s ) as 2 and t h o s e similar  scoring  classification  Statistical The  Dg  was used  the f o l l o w i n g  deformity  (awkward  a s 1; t h o s e  with  a  bowing, r o t a t i o n o f  severe  o f body w e i g h t ,  i n the diet analysis  data  were  and Duncan's  separations  (Duncan,  data  i n percentages  yses  (Steel  were  conducted  and  with  the s e v e r i t y  d e f o r m i t i e s a s 3.  by J u l i a n  (1984) i n h i s  Analysis  over  bird  1955). A r c s i n  1980).  System  Columbia  Computer  were  (Steel  test  1980).  of variance and  Torrie,  was used  f o r mean  transformations before  on t h e  statistical  The s t a t i s t i c a l  procedures  of  c o m p a r e d by  and T o r r i e ,  the a i d of the "General  of the  anal-  analyses  Linear  (SAS, 1982) a t t h e U n i v e r s i t y Center.  and t h e  the l e v e l  t o an a n a l y s i s  arrangements  " A n a l y s i s of V a r i a n c e "  Analysis  age ( S t e e l  m u l t i p l e range  and T o r r i e ,  consumption  density  were p e r f o r m e d  with  feed  to e i t h e r  or cage  subjected  (ANOVA) f o r 2^ f a c t o r i a l 1980)  bending,  of l e g a b n o r m a l i t i e s  regression Severity  scored  In  of l e g a b n o r m a l i t i t e s .  responses  incidence vitamin  system  using  a slight  r e l u c t a n c e t o move) w e r e  moderate  A  of l e g abnormality.  Models"  Statistical of B r i t i s h  37  RESULTS AND  Leg At  abnormalities  this  age  awkward often  the  and  stance,  at  or  14-28  valgus  Mills  bending  of  left  and  or  to  significant  the  in  therefore  regression on  figure  increase  the  3.3 i n the  with  two  levels  vitamin  shown  Randall  (varus) proximal  of  the  same  were most  often  between  the  right  of  vitamin  Dg  3.4  increased  i n t e r a c t i o n s (p>0.05) between the  main  incidence 3.4  Dg  of  effects  of  showing  age  A  leg (p<  different  i n the  when  compared  with  the  of  leg  q u a d r a t i c a l l y with  respect  to  are  significant  responses.  rise  incidence  diet  0.05), w i t h  a sharper  the  of  abnormalities  caused  shows  anal-  leg abnormalities  the  to b i r d  were  main e f f e c t s  respectively.  incidence  respect  abnormalities  Figure  and  abnormalities  a n a l y s i s . The  and  observed  leg  The  typical  medial  condition  predominance  was  excess  severe  by  3.1).  abnormalities  tibiotarsus  more  3.2).  no  cage d e n s i t y  linear  a  an  t o move,  (Figure  described  (valgus)  d i s t a l  of  s i g n s were  lateral  d e s i t y and  for  shown  deformities  age.  leg.  and  yzed  clinical  slight  T h e r e were no diet  gross  The  with  merely  hock-sitting position  (1984).  the  5 days o f  consisted  Julian  (Figure  unilateral,  at  and  tarsometatarsus deformity  observed  b i r d s showed a r e l u c t a n c e  varus  (1981) from  and  the  days the  and  progressed  were f i r s t  abnormalities  r e s o r t i n g to a  Later, of  the  DISCUSSION  cage  The  incidence  control  the  of  diet.  abnormalities density.  The  Figure  3.1  Normal and Abnormal C h i c k s a t 5 Days. The b i r d on the r i g h t i s normal. The b i r d on the l e f t shows s l i g h t m e d i a l ( v a r u s ) b e n d i n g o f the d i s t a l t i b i o t a r s u s and p r o x i m a l t a r s o m e t a t a r s u s .  39  Figure  3.2  Bending of the D i s t a l Moderate Medial (Varus) Proximal Tarsometatarsus at Tibiotarsus and 28 Days.  40  Figure  3.3  I n c i d e n c e of Leg A b n o r m a l i t i e s ( I L A ) i n Broilers Fed C o n t r o l Levels (400 ICU/kg feed) or H i g h L e v e l s (4000 I C U / k g f e e d ) o f V i t a m i n D i n the Diet. 3  The e q u a t i o n s  f o r the l i n e s a r e :  Control,  ILA=  0.71X ( ± 0.16)  High,  ILA= 0.97X ( ± 0.16)  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< 0 . 0 5 ) . Intercepts are not s i g n i f i c a n t l y d i f f e r e n t from z e r o (p> 0 . 0 5 ) . + Standard E r r o r of Estimate. r=0.72 (p<0.05).  41  gure 3.4  I n c i d e n c e of Leg A b n o r m a l i t i e s ( I L A ) i n Broilers Reared in High Density (340 c m / b i r d ) or Low D e n s i t y (680 cm / b i r d ) Cages. 2  2  The  equations  f o r the  lines  are:  High,  ILA=  2.31X ( + 0.6)  0.05X (+0.02)  Low,  ILA=  1.11X ( ± 0.6)  0.0067X (+ 0.02)  2  2  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< 0.05). I n t e r c e p t s are not s i g n i f i c a n t l y d i f f e r e n t from z e r o (p> 0 . 0 5 ) . + S t a n d a r d E r r o r of E s t i m a t e . r=0.74 (p<0.05).  42  two  cage  densities also  responses increase to  the  the  main  no  incidence  density  a  The  not  significance  initial  with  the  explained  reported  that  ities  than  birds  reared  depression  birds  i n feed  and  3.6,  leg  abnormalities.  may  plateau  density be  Haye and further  Simons  f o r feed  at  days.  However,  days  this  i n the i n c i d e n c e i n the  (1983)  Diet  the l e g  the  high  difference  of l e g  high  cages and  initially  showed a  responded  high  or  feed  a l . (1979) abnormal-  experiment,  body w e i g h t  those  significant (Figures  3.5  with  increased  rise  i n the  incidence  density  cages,  together  sharp i n i t i a l  water  et  b i r d s have more l e g  density  cages i s  weight  Hulan  b i r d s . In t h i s  later  abnormal-  density  i n body  and  21  days  suggests that i n -  detrimental  to the  chicks,  on.  (1978) f o u n d and  3.2.  28  i n the  beneficial  table  and  growing  be  in  s e v e r i t y of  observed around  may  both  on t h e s e v e r i t y  the  r e s p e c t i v e l y ) , yet s t i l l  the  creased  on  differences  The  compared  of the t r i a l  density  shown  or 28  consumption  leg abnormalities  with  are  reared  high  as  i n c r e a s i n g the s e v e r i t y of  slower growing under  end  a more r a p i d  towards  Riddell faster  caused  (p=0.08).  increase  through  consumption.  but  trend  the  and  effect  leg abnormalities,  approached  by  diet  a t e i t h e r 21  showed  density  different  of l e g a b n o r m a l i t i e s .  of  significant  significantly  of l e g a b n o r m a l i t i e s  however  effects  abnormalities  ities  high  leg abnormalities  showed  of  The  density;  a similar  The  the  0.05).  i n the i n c i d e n c e low  showed  of  (p<  produced  had  that  birds forced  lower  incidences  to  walk  of l e g  43  3.2  Table Main E f f e c t s of V i t a m i n o f Leg A b n o r m a l i t i e s .  Age (Days)  Diet Control  Dg and Cage D e n s i t y  on t h e S e v e r i t y  Interaction  Density  1  High  Low  High  Diet*Density  21  1.6  1.7  1.4  1.9  NS  28  1.6  1.9  1.4  2.1*  NS  C o n t r o l , 400 ICU v i t a m i n Dg/kg f e e d .  Dg/kg  High,  680  NS  340 c m / b i r d ;  denotes  Difference  2  Low,  feed;  High,  cm /bird. 2  a nonsignificant interaction approached  4000 ICU  significance  (p>0.05).  (p=0.08).  vitamin  44  800  DENSITY  -• LOW A HIGH  700-  0)  z o  600-  500-  &  a (A  400-  z o  u  Q  w ui  300-  200-  lOO-  -r  14 AGE (days )  Figure  3.5  T  21  T  28  Feed Consumption (FC) of B r o i l e r s Reared i n High Density (340 c m / b i r d ) o r Low D e n s i t y (680 c m / b i r d ) Cages. 2  2  The  equations  f o r the l i n e s a r e :  High,  FC= 23.6X ( ± 0.6)  Low,  FC= 25.9X (±0.6)  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< 0 . 0 5 ) . ±Standard E r r o r of E s t i m a t e . r=0.99 (p<0.05).  45  AGE (DAYS )  Figure  3.6  Body Weight (BWT) o f B r o i l e r s R e a r e d i n H i g h Density (340 c m / b i r d ) o r Low D e n s i t y (680 cm^/bird) Cages. 2  The  equations  f o r the l i n e s are:  High,  BWT= 20.81 + 12.85X +0.69X (±16.2) (±2.7) (±0.09)  Low,  BWT= 18.27 + 12.46X +0.84X (±16.2) (±2.7) (±0.09)  2  2  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< 0.05). I n t e r c e p t s a r e not significantly different (p> 0 . 0 5 ) . ±Standard Error of Estimate r=0.99 (p<0.05).  46  leg  abnormalities.  broilers  provided  abnormalities suggested compete  Similarily,  than  that  less  w h i c h may  with  more f e e d i n g  those  birds  f o r feed  Wilson  given given  space.  more  feeding  space  and t h e r e f o r e  reared  activity  and  and  fewer  sharp  rise  mats  showed than  reported  of f l o o r i n g more  increased  those  reared  density  or p l a s t i c  was  covered  more d i f f i c u l t y  walking  observations  increased  activity  especially  when  from  level  feeding.  associated  with  c o n s i s t e n t l y that  important than  wire.  accentuated  the d i f f i c u l t y  Therefore,  chicks  may  on t h e w i r e  with  floors  These  than  1978), wire  made o f  differences  with  the b i r d s  floors  (Andrews  1978). this  experiment  i n the high  Perhaps the  is  i n cages i s g r e a t e r  l e g problems  a l . , 1974; Haye and Simons,  level  from  i n that  the i n c r e a s e d  a t t r i b u t e d t o d i f f e r e n c e s i n movement,  Casual  Results  in leg abnormalities  i t has been  the type  plastic  having  exercise  (Reece e t a l . , 1971; Haye and Simons,  producing  et  i n which  of l e g a b n o r m a l i t i e s  floors  were  manner  However  that  had t o  suggestion  light  leg abnormalities  the i n i t i a l  on l i t t e r  intermittent  They  light.  precise  incidence  that  under  continuous  unclear. the  less  have r e s u l t e d i n more l e g p r o b l e m s .  birds  caused  recieved  this  found  showed more l e g  feeding  (1982) f u r t h e r s u b s t a n t i a t e s  The  space  less  Simons  under  et al.(1984)  showed  density  the i n c r e a s e d  high  i n walking  have been f o r c e d  density on  an  cages; activity  initially  the wire  cages.  t o move on t h e w i r e  47  floor  when t h e y  joint. on  Later  the wire  provided and  were l e a s t  o n , when  increased  Both  levels  level  metabolic the  t o walk  may  have  t h e l e g bones  observed  l e g i n the high  vitamin Dg  despite  toward  density  mechanical  consumption Dg . T h o s e  consistently  elevated  feed  cages aggra-  stress  may  appeared  together  Dg may s u g g e s t  t o be  b i r d s fed the high showed  consumption with  of l e g a b n o r m a l i t i e s  of vitamin  depressed (Figures  the sharper  3.7 rise  f o r the b i r d s f e d the that  a dietary  induced  be c o n t r i b u t i n g t o t h e e t i o l o g i e s o f  abnormalities. Competition  sorption  among  and t r a n s p o r t  increase of  The t r e n d  by i n c r e a s e d  3.8 r e s p e c t i v e l y ) . T h i s ,  high  able  activity  to strengthen  and f e e d  of v i t a m i n  the incidence  t h e hock  leg abnormalities.  to excess  body w e i g h t s  in  i n part,  body w e i g h t  sensitive  and  exercise  s e v e r i t y of twisted  of e x i s t i n g  were b e t t e r  the increased  leg abnormalities.  may be e x p l a i n e d , vation  and t h u s s t r e s s e d  the chicks  floors,  sufficient  reduce  able  the f a t - s o l u b l e vitamins  f o r ab-  has been d e m o n s t r a t e d , w i t h  a marked  i n the d i e t a r y  level  one o r more o f t h e o t h e r  al.,  1982).  vitamin  March  E (2200 IU/kg  both v i t a m i n  e t a l . (1973)  A suppresses  Hegsted,  1952),  reported  feed) i n c r e a s e d  D and K; w i t h  a deficiency  fat-soluble vitamins  (Scott et  that  excess  the requirement f o r  a f f e c t e d b i r d s showing  growth and bone c a l c i f i c a t i o n . osis  o f one c a u s i n g  depressed  Interestingly, hypovitamin-  endochondral  bone  and h y p o v i t a m i n o s i s  growth E  ( W o l b a c h and  causes  myopathy  A8  Figure  3.7  Body Weight (BWT) o f B r o i l e r s Fed C o n t r o l L e v e l s (A00 ICU/kg f e e d ) o r H i g h L e v e l s (A000 ICU/kg f e e d ) o f V i t a m i n D i n t h e D i e t . 3  The  equations  High,  f o r the l i n e s are:  BWT= 19.56 + 11.81X +0.80X (±20.3) (±3.A) (±0.11)  Control,  2  BWT= 19.53 + 13.50X +0.73X (±28.7) (±3.A) (±0.11) 2  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< 0.05). I n t e r c e p t s a r e not significantly different (p> 0 . 0 5 ) . ±Standard Error of Estimate. r=0.99 (p<0.05).  49  VITAMIN D  •  »  3  CONTROL  AGE (days)  Figure  3.8  Feed Consumption (FC) of B r o i l e r s Fed Control Levels (400 ICU/kg feed) or H i g h L e v e l s (4000 ICU/kg f e e d ) o f V i t a m i n D i n the D i e t . 3  The  equations  f o r the l i n e s a r e :  High,  FC=  25.4X ( ±0.6)  Control,  FC=  24.2X (±0.6)  S l o p e s a r e s i g n i f i c a n t l y d i f f e r e n t (p< ±Standard E r r o r of E s t i m a t e . r=0.99  0.05). (p<0.05).  50  (nutritional muscles this  muscular  (NRC,  experiment  ment  f o r these  toxic  effect  normalities vitamins. the  1984). may  dystrophy) I t may  have c a u s e d  other  that an  appear  secondary  metabolic  stress  breast  excess  on  growth  or  to d e f i c i e n c i e s  excess  vitamin  leg  v i t a m i n Dg  i n the  r e s e a r c h i s needed of  and  v i t a m i n s and  o f t h e e x c e s s v i t a m i n Dg may  the  increase  fat-soluble  However, f u r t h e r  development.  be  of  to Dg  in  requirethus  any  leg  ab-  of  these  delineate on  bone  CHAPTER FOUR SEQUENTIAL MORPHOMETRY AND  RADIOGRAPHY OF  NORMAL BROILER CHICKENS AND  THE  T I B I A E FROM  THOSE WITH TWISTED  LEG  INTRODUCTION A  medial  distal  or  tibiotarsal  abnormalities initially and  later  (1984)  by  bone  describe  Nairn  and  The  the  abnormality  may  be  weeks of age  distal  (Julian,  and  Mills  of  the  common  leg  1984). I t Wise  Haye  (1981)  (Riddell,  by  was  (1967)  and  Simons  and  Julian  deformation  to  observed  as  both  tendon  condyles  as  legs  may  (Riddell,  early  an  Clinically,  although  gastrocnemius  with  be  1981).  five  days  frequently noticed after  2  1981).  of  twisted  genetical  found  incidence varied (1985) f o u n d  l e g has  factors.  prevalent  strains  flocks,  1975).  unilateral,  i s more  i t more  between b r o i l e r  broiler (Wise,  tibial  been  but  incidence  Cruickshank  shaft  most  varus-valgus  unusual  reported the  term  the  has  1984;),  influenced  the  (1972)  i n most  being  and  o f f the  abnormality  The  the  the  O s b a l d i s t o n and  R a n d a l l and  is usually  involved  (Julian,  chickens  i s seen  o f 5 % not  displaced  of  of  abnormality.  syndrome  incidence  one  Watson  suggested  the  is  t w i s t e d l e g by  More r e c e n t l y have  deviation  in broiler  termed  (1978).  The  lateral  Haye  i n males  and  than  between b r o i l e r  the and  been  shown  Simons  strains.  51  within  strain  be  (1978)  i n females  i n c i d e n c e of t w i s t e d l e g also  to  Sim  and and  varied  depending  on  52  from which Somes  breeder  ( 1969)  strain  of  tibiotarsal  and  hatching  an  which  and  tarsometatarsal  bent  was  through  lighting  manipulations  regimes  1978),  of  cage  ( R e e c e e t a l . , 1971), have been leg abnormalities.  decreased the  activity  increased  Wise  growing  bones  forces  are  deformity  may  found  of  imbalances  which  that  may  and  shown t o  Haye  Simons, temper-  increase  exercise  partially  the  associated  responsible  studies.  them  to and  suggested  that  deformity  when  that  p o s s i b l y as  a  there at  may  leg be  least  the  ability  through  to  frame.  increase  environmental  a structural partially  skeletal  result  for potential genetic predisposition with  and  skeletal  evidence  twisted  be  (Haye  subject  mass  1976;  e t a l . , 1971;  a l . (1978)  to  environment.  muscle  leg, together  suggests  are  leg  between  to  of  et  of  environmental  i n many b r o i l e r s  the  incidence  a l . , 1973;  Reduced  i n these  applied  Moreover, twisted  high  been h e l d  Poulous  abnormal  be  has  incidence  (1978) and  rapidily  and  incidence  et  floor  ature  for  a l . , 1974)  one  twisted  the  (Reece  Andrews  for  of  (Buckland  1978;  of  et  type  supplied.  bones.  i n v e s t i g a t o r s have a l t e r e d the  Simons,  with  were  responsible  e t a l . , 1984), cage r e a r i n g  incidence  eggs  a u t o s o m a l r e c e s s i v e gene i n  chicken  abnormalities  Wilson  the  identified  Several  Continuous  farm  defect  factors  i n the  responsible  the  tibiae  for  the  disorder. Therefore, tibiae  of  normal  this  experiment  broiler  was  chickens  designed with  to  those  compare  the  exhibiting  53  twisted f o r  l e g i n an  t h i s  determined differences  l e g  attempt  to develop  d i s o r d e r .  using were  conventional determined  a  pattern  Q u a l i t a t i v e radiography using  recognition  d i f f e r e n c e s and  sequential  were  q u a n t i t a t i v e  morphometry.  54  MATERIALS AND  Five  hundred,  cockerels  were  day-old  housed  f o r s i x weeks.  water  a standard  minimum weighed birds of  crude on day  were  lameness for  C h i c k s had  commercial  protein). 1 and  ad  broiler  A l l birds  daily,  and  recorded.  were put i n t o  Hubbard on  starter  were  ease of i d e n t i f i c a t i o n  and  a c c e s s to  ration  (23% and  f o r s i x weeks.  The  and  birds  a s e p a r a t e pen  wood  wing-banded  mortality Those  broiler  hemlock  libitum  e a c h week t h e r e a f t e r  observed  leg abnormalities  commercial  conventionally  shavings and  METHODS  the  showing  (within  incidence signs  t h e same  of  barn)  observation.  Morphometry Weekly normal made  broiler  starting  determining showing birds  morphometric  (1-7),  sampled  c h i c k e n s and at  two  when and  signs  b i r d s were weighed Tibiae  were  measured. dyle  lateral  many b i r d s  then k i l l e d  removed,  cleaned  depth, d i s t a l  (Figure cortical  normal  4.1).  by  of  tibiae  twisted  there  leg, a variable eight  the  at a given  was age  were  no  were  way  of  would  be  abnormal randomly  comparison.  cervical  from  leg  number o f  birds  for morphometrical and  of  with  Because  Measurements i n c l u d e d  groove  midshaft  how  at l e a s t  week  those  weeks.  of t w i s t e d  and  each  comparisons  These  dislocation.  surrounding tissue  tibial  length  , distal  and con-  condyle groove width, diameter at  Medial  cortical  t h i c k n e s s were a l s o  thickness,  measured  and  to c a l c u l a t e  %  55  TIBIAL LENGTH  CONDYLE GROOVE WIDTH  % CORTICAL THICKNESS=LCT +MCT/TIBIAL DIAMETER AT MIDSHAFT  Figure  4.1  Morphometric c r i t e r i a and m e t h o d o l o g y used t o measure the t i b i a e . LCT, lateral cortical thickness; MCT, medial cortical thickness ( f i g u r e o f t i b i a a d a p t e d f r o m F e d u c c i a , 1975).  56  cortical  thickness  (Barnett  measurements were made u s i n g  and  dial  Nordin,  1959). A l l  c a l i p e r s s e n s i t i v e t o 0.01  mm.  Radiography Routine  mediolateral  were t a k e n  of a l l t i b i a e  parisons.  In a d d i t i o n ,  the of leg  beginning their  four  b i r d s were r a n d o m l y  Similarily,  Anteroposterior  of these  portable  x-ray  TL  film  x-ray  matic  live unit  for sequential  birds  University  Radiology  twisted  as t h e a b n o r m a l i t y  became  x-rays  of the  of  British  used  with  Acoma  Kodak X-Omat  i n t e n s i f y i n g screens.  of the x-rays  of l i v e  chicks  sides  ( f o r mediolateral  backs  was  generously  Columbia  Auto-  provided  Acute  used  were  obtained  (for anteroposterior view),  of p l e x i g l a s s .  so e x c e l l e n t  Bone Ash  signs  mediolateral  tungstate  on t h e i r  techniques  of  (model PX-30) was  either  taped  radiography  Care  by  Unit,  Laboratory.  X-rays  a piece  and  showing  com-  selected at  b i r d s were t a k e n once a week. An  and f a s t  processing  radiographs  f o r the morphometrical  were s e q u e n t i a l l y r a d i o g r a p h e d  tibiae  to  anteroposterior  sampled  of the experiment  tibiae.  apparent.  the  and  films  a r e shown  and t a p i n g  The c h i c k s could  be  i n table  by  v i e w ) o r on their  relaxed made.  placing  tibiae  when  The  them their down  securely  radiological  4.1.  Determination:  Subsequent  to  the  morphometry,  tibial  ash  was  57  Table  4.1  Position  R a d i o l o g i c a l T e c h n i q u e s used t o X - r a y t h e T i b i a e of Broiler Chickens. Radiographs were t a k e n w i t h an Acoma p o r t a b l e x - r a y u n i t (model PX-30), Kodak X-Omat TL Ready Pack Film, and fast tungstate i n t e n s i f y i n g screens.  B i r d Age (Weeks)  Tube c u r r e n t (milliamps)  Voltage (kilovolts)  Exposure (seconds)  Anteroposterior 2  20  60  0.63  3  20  60  0.80  4  20  50  1.00  5  20  60  1.00  6  20  60  1.00  2  20  60  0.53  3  20  60  0.63  4  20  50  0.80  5  20  60  0.80  6  20  60  1.00  Mediolateral  58  determined muffle  by  furnace  Statistical The age  by  the  h o u r s a t 600  using  transformations  The  (24  hrs.  at  90  C)  in a  over  bird  C.  Analysis  regression analysis  before  Linear  from  the U n i v e r s i t y  on  the  data  analyses  analyses Models"  Statisical  of B r i t i s h  were  compared  body w e i g h t  the  statistical  statistical  "General  procedures at  f o r 5-7  tibiae  criteria  performed  of  dried  morphometrica1  Arcsin  1980).  ashing  in  as  a covariate.  percentages  (Steel  were c o n d u c t e d and  and  Torrie,  with  the a i d  " A n a l y s i s of  A n a l y s i s System  Columbia  Computer  was  Variance" (SAS,  Center.  1982)  RESULTS  Twisted observed, The  of these  75%  l e g was  observed  were  abnormalities  0.04%  included  (hock) j o i n t s  associated  birds.  excluded  from  the r a d i o g r a p h i c  Mortality end  runted  increased  o f t h e s i x weeks  (Figure  2%  the  displaying nonspecific  sents  Therefore, a chronic  Clinical one  week.  and  (lateral) showed Mills  signs  Figures  signs  4.2).  Other  bruised t i b -  were  most  reason  often  they  were  comparisons.  week t o 5% a t t h e could  However,  of lameness  that  and  Clinical  mortality  twisted  l e g were  the d e f o r m i t y  either  of s l i g h t  was  varus  of the d i s t a l unilaterally; bilateral  deviations  (92% l a t e r a l ; and l e f t  and  a t one  appear  of t w i s t e d  deformation  The  week  be  one o f  died  at 4  leg repre-  problem.  (1981) r e p o r t e d  medial right  i t would  the abnormality  common.  swollen,  to l e g a b n o r m a l i t i e s .  Typically,  consisted  (Figure  4 . 2 ) . No  attributed  weeks.  one  and m o r p h o m e t r i c  directly runts  at  For t h i s  from  abnormality  non-specific.  iotarsal-tarsometatarsal with  leg  of a l l l e g disorders.  t o 5.4% a t s i x weeks  abnormalities  signs  to over  of t w i s t e d  steadily  DISCUSSION  by f a r t h e p r e d o m i n a n t  contributing  incidence  increased leg  l e g was  AND  were  first  slight  at t h i s  (medial) tibiae.  or  frequently  8% m e d i a l ) and o c c u r r e d  Most  were lateral  equally  age  valgus  although Randall  deformations  more  observed at  birds and most than  on t h e  legs. 4.3  and  4.4  show 59  the  progression  of  the  60  |"*"| Total Leg Abnormalities ^  Proportion with Twisted Leg  —  Mortality  1  I  1  •  11 AGE  .2  (Weeks)  T o t a l Leg A b n o r m a l i t i e s , P r o p o r t i o n with Twisted Leg and F l o c k M o r t a l i t y over t h e S i x Week T r i a l .  61  Figure  4.3  Progression of T y p i c a l Unilateral Valgus Deformation. A, deformity at 2 weeks; p o s t e r i o r view; B, a t 4 weeks; p o s t e r i o r view; C, at 6 weeks; a n t e r i o r view. The l a t e r a l d e f o r m a t i o n a t two weeks was s l i g h t , w i t h the c h i c k a s s u m i n g an awkward s t a n c e . However, as the deformity developed, progressive lateral bending of t h e d i s t a l t i b i a e made locomotion increasingly difficult. At s i x weeks, when the deformation was most severe, the b i r d s could o n l y use t h e a b n o r m a l hock f o r s u p p o r t and t h u s t h e p o s t e r i o r a s p e c t o f t h e hock was often severely bruised, s w o l l e n , and presuma b l y more s u s c e p t i b l e t o s e c o n d a r y i n f e c t i o n .  (,1  A  62  Figure  4.4  Progression of Typical Bilateral Varus Deformation. D e f o r m i t y a t 3 weeks (A) and 6 weeks (B); posterior views. The b i l a t e r a l varus c o n d i t i o n developed with a p r o g r e s s i v e medial bending of the distal tibiae a s s o c i a t e d w i t h some o u t w a r d r o t a t i o n o f t h e anterior surface. The proximal tarsometat a r s u s was r o t a t e d inwards resulting in a "bow legged" stance which made movement difficult.  A  63  unilateral typical  valgus  of  twisted  progressed, Birds  and  preferentially birds  limp.  In  cases  birds  would  severe use  s i t on  would of  (Figure  was  often  more s u s c e p t i b l e  the  end  s i x week  the  o f t w i s t e d l e g had Sequential 4.5)  bilateral 4.7)  deformations.  a slight  deviation  remodeling, and  as  twisted  side  was  a  nature  cause  of the  Sequential morphometry many o f the  with  instead the  of  by  infection.  the  birds  from from  tendons.  normal  birds  the  characteristic changes  the  distal  birds  displaying  valgus  (Figure  tibiae.  i n the and  cortex  bone  are the  deformations  bone d e v i a t i o n s  subclinical  on  from  Adaptive  the  tibiae weight  r a d i o g r a p h i c f e a t u r e of  appear  of  By  showing  p r o g r e s s i v e bowing o f t h e of  the  bruised, swollen,  unilateral  o f the  a  posterior  forms o f t w i s t e d l e g d e v e l o p e d  radiography  showed  forced  deformations,  gastrocnemius  those  or  torsion  of  of  tibiae  with  4.6)  adaptation  progressive  of  thickening  l e g . These  functional  primary  or  evidenced  compensatory  bearing  Both  75%  displaced  radiographs  (Figure  severly  hindered.  walk  valgus  to secondary  trial,  were compared  varus  deformity  When  then  Subsequently,  presumably  (Figure  the  hocks.  and  unilateral  and  signs  As  their  hesitate  4.3c).  the hock j o i n t  of  deformations  the a b n o r m a l hock f o r s u p p o r t  tarsometatarsus of  varus  movement became i n c r e a s i n g l y  t o move, a f f e c t e d  aspect  bilateral  leg, respectively.  the b i r d s  would  the  the  most  likely  result  of  the  than  the  sampled  for  rather  a  themselves. tibiae  s i g n s of d y s c h o n d r o p l a s i a i n  p r o x i m a l metaphyses of c l i n i c a l l y  normal  birds.  64  Figure  4.5  Sequential Radiography of Broiler Chickens Showing Normal T i b i a l Growth and Development. A, r i g h t and l e f t t i b i a e a t 2 weeks; B, at 4 weeks; C, r i g h t and l e f t t i b i a e a t 6 weeks; ( A n t e r o p o s t e r i o r v i e w s ) . The b r o k e n f u s e i n B was s i m p l y used f o r s c a l e .  65  Figure  4.6  P r o g r e s s i o n o f B i l a t e r a l V a r u s D e f o r m i t y as seen with Sequential Radiography. A, r i g h t and l e f t t i b i a e a t 2 weeks; B, a t 4 weeks; C, a t 6 weeks; ( A n t e r o p o s t e r i o r views ) . N o t i c e the p r o g r e s s i v e b e n d i n g ( L T ) and outward r o t a t i o n o f the d i s t a l t i b i a e ( H ) . An a p p a r e n t i n w a r d r o t a t i o n of the p r o x i m a l t a r s o m e t a t a r s a e i s a l s o shown. Regions of thickened cortex represent an attempt to s t r e n g h t e n t h e bone on t h e s i d e t h a t i s c a r r y i n g the most weight (Julian, 1984) and r e p r e s e n t s i t e s of a d a p t i v e remodeling ( C a r t e r , 1984).  66  a  Figure  4.7  P r o g r e s s i o n of U n i l a t e r a l Valgus D e f o r m i t y as seen with S e q u e n t i a l Radiography. A, two right tibiae a t 3 weeks; B, a b n o r m a l r i g h t t i b i a a t 4 weeks; C, right t i b i a at 6 weeks; (Anteroposterior views). Notice the p r o g r e s s i v e lateral d e v i a t i o n o f the distal t i b i a e and compensatory remodeling of the tibiae particularily on the weight bearing (concave) s i d e s ( — > ) . T h i s a d a p t i v e or structural r e m o d e l i n g o f bone ( C a r t e r , 1984; R u b i n , 1984) i s an attempt to strengthen bone and hence r e s i s t functional strains. An outward rotation of a f f e c t e d t i b i a e i s a l s o o b s e r v e d a t 4 and 6 weeks. A s s o c i a t e d with t h i s deformation of the t i b i a e i s a p r o g r e s s i v e inward r o t a t i o n of the t a r s o m e t a t a r s a e .  67  Sixty  percent  percent  of  of  the  radiographic Radiolucent to  regions  the  birds  birds signs  of  retained  joint  was  pronounced  lateral appear  space.  tibial  is  clinically  of  dyschondroplasia  3 weeks,  four  proximal  and  affected  (Figure  i n any  of  the  showed  (Figure  4.8).  corresponded  appearance  bowing o f  4.9).  as  the  seen  no  be  more  tibiae  the  i t would  common  radiographic  distal  of  tibiae  with  Therefore,  may  r e a l i z e d . T h e r e was  weeks  five  birds  dyschondroplasia  twenty  gave the  Anteroposterior in  and  metaphysis  c a r t i l a g e and  radiographs  that  at  at  dyschondroplasia  i n the  a widened also  sampled of  regions  sampled  than  evidence  of  affected  birds. Splitting (after  the  proximal  morphometry) c o n f i r m e d  dyschondroplasia. were r e t a i n e d 4.10)  and  morphometric detected  Birds  i n the  metaphyses  These  to  the  birds  comparison.  birds. with  especially  i n any  showing  consistently  evident  the  of  and  Pronounced birds  of  affected  the  or  not was  by  after five  of  regions  included no  (Figure on in  the the  dyschondroplasia the  tibiae  metaphyses.  signs  of  twisted  i n poorer  differences  showing  birds  splitting  distal  generally  diagnosis  uncalcified cartilage  radiolucent  There  clinical  lighter  evident  radiographic  were  r a d i o g r a p h i c a 11y  longitudinally  metaphyses l o n g i t u d i n a l l y  Abnormal masses o f  corresponded  radiographs.  normal  tibial  severe  in  condition  body  weight  disorders  weeks ( F i g u r e  leg  4.11).  and  were than were were  6 8  Figure  4 . 8  A n t e r o p o s t e r i o r Radiographs of the L e f t T i b i a e from Clinically Normal Broiler Chickens Revealed Subclinical Dyschondroplasia i n the Proximal Metaphyses (-^~). A, 3 weeks; B, 4 weeks. Radiolucent regions corresponded to r e g i o n s of retained uncalcified c a r t i l a g e and t h u s make the j o i n t s p a c e a p p e a r e n l a r g e d .  69  4T  Figure  4.9  Lateral Radiograph of L e f t T i b i a e of C l i n i c a l l y Normal Broiler Chickens a t 4 weeks R e v e a l i n g S u b c l i n i c a l Dyschondroplasia. T i b i a on t h e l e f t appears normal. T i b i a on t h e r i g h t shows a d i s tinct r a d i o l u c e n t r e g i o n i n t h e p r o x i m a l metap h y s i s , and p r o n o u n c e d a n t e r o p o s t e r i o r bowing.  Figure  A.10  L o n g i t u d i n a l S e c t i o n s Through P r o x i m a l Metap h y s e s R e v e a l i n g Abnormal M a s s e s o f C a r t i l a g e T y p i c a l of D y s c h o n d r o p l a s i a . Abnormal C a r t i l a g e a p p e a r s as opaque p l u g s i n t h e p r o x i m a l m e t a p h y s e s ( ) . A, 3 weeks; B, k weeks.  3  T  4  AGE (Weeks)  Figure  4.11  Body w e i g h t (BWT) o f n o r m a l (N) b r o i l e r s those a f f e c t e d with twisted l e g ( T L ) . The  equations  N,  BWT= -45.89 + 121.86X + 3 5 . 8 X (±121.3) (±68.3) (±8.5)  TL,  BWT= -1563.88 + 974.2X - 8 4 . 7 X ( + 389.9) (±191.2) (±21.9)  and  of the l i n e s a r e : 2  2  Slopes are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). ± Standard Error of Estimate r= 0.99 (p<0.05)  72  Sequential chickens  and  significant  morphometry  those  on  affected  differences  the  with  (p<0.05)  tibae  from  twisted  in  the  normal  leg  growth  revealed  parameters  measured. Figure over  bird  the  birds  4.12  age.  differences distal  tibial  Tibial  their were  4.13  increased  birds.  However,  consistently difference of  the  example,  of  those  leg  the  any  despite  the  progressive  real  have  defect  in  birds  been  in  normal these  bending  difference  or in  i n the when  in  of  actual  has  dogs  varus  disposed  to degenerative  valgus  or  changes.  allows time  This  the  species.  For  luxation)  has  et a l .  the the the  1981)  et  al.  structural patellar patella knee  p o s i t i o n and  Recurring  had  develop-  (Flecknell  Specifically,  a  leg  considers  been l i n k e d t o a  f l a t t e n e d and  affected  initial  one  cat  condyle  grooves.  (Pedersen  With  deformed  and  i n other  laterally.  becomes  distal  twisted  (patellar  h o r s e and  femur.  groove appears u n u s u a l l y  normal  deformities  i n the  the  condyle  important  breeds of  distal  of  a f f e c t e d with  leg abnormality  i n toy  disengage medially  both  distal  leg abnormality  the  depth  especially  analagous  frequently This  the for  shallow  a similar  1979).  age  disorder;  described less  with  more  may  etiologies  and  of  than  shows t h a t  groove  been  length  plates. I t i s possible that  result  rather  of t i b i a l  were c o n s i s t a n t l y s h o r t e r  twisted  growth  line  length.  Figure  ment  with  the  tibiae  regression  lengths  affected  appearance of  the  shows the  to  joint  is  dislocation  preof  73 90-  AGE (Weeks)  Figure  A.12  T i b i a l Length (Tib.L) of normal and t h o s e a f f e c t e d w i t h t w i s t e d  (N) b r o i l e r s leg (TL).  The  equations of the l i n e s a r e :  N,  Tib.L=  32.A + 13.AX - 0 . 7 0 X (±1.9) (±1.1) (±0.15)  TL,  Tib.L=  28.0 + 15.9X - 1 . 0 7 X (±6.8) (±3.5) (±0.38)  2  2  Slopes are s i g n i f i c a n t l y different (p<0.05). ± S t a n d a r d E r r o r o f E s t i m a t e . r = 0.99 ( p < 0 . 0 5 ) .  AO-  AGE (Weeks) Figure  4.13  C o n d y l e G r o o v e D e p t h (CGD) o f n o r m a l (N) b r o i l e r s and t h o s e a f f e c t e d w i t h t w i s t e d l e g ( T L ) . The  equations  of the l i n e s a r e :  N,  CGD= 1.29 + 0.56X - 0.02X (±0.26) (±0.15) (±0.01)  TL,  CGD= -0.17 + 1.32X -0.12X2 (±0.91) (±0.47) (±0.05)  2  Slopes are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). ± Standard E r r o r of Estimate. r= 0.99 (p<0.05).  75  the  patella  genital  disorders;  lateral  one  may  be  that  valgus-varus  shallow slight  a similar  on  of  the  the  modeling  and  groove  and  were a l s o  then  However, t h o s e  the  i n t h e growth  linear  appeared  birds  to  affected  increase.  increase  increase  of  the  in tissue  displace-  distal  re-  tibiae. tibial  In  normal  initially in-  at  5-6  weeks.  l e g showed a p r o -  was  distal  on  hence  structural  tibiae  with twisted  This  this  4.14).  off  to a  and  o f the d i s t a l  (Figure  the  tibia  tendon  of the  level  the  Perhaps  distal  cause  i n width  of  1982).  time,  of the d i s t a l  p r o g r e s s i v e bending  subsequent  to  observed  t h e growth i n w i d t h  gressive  strain  con-  i s responsible for  gastrocnemius With  many  flattening  poultry.  hence p r o g r e s s i v e bowing  Differences  creased  in  to  Heywood,  mechanism  condyles.  provide s u f f i c i e n t  birds  and  p r e d i s p o s e s the  ment may  condyle  involves  (Helfet  groove  displacement tension  been a t t r i b u t e d  deformations  condyle  uneven  also  o f which  femoral condyles  It the  i n humans has  associated tibiae  with  and of  a  the  convex  side  the  both  normal  and  abnormal  birds  showing  deviations. The chickens  diameter increased  of  with  consistantly  wider  the  in tibial  increase  cent  cortical  tibiae  results  age,  diameters  with  was  thickness (Figure  suggest  birds that  abnormal  (Figure  diameter  more g r a d u a l i n a b n o r m a l These  from  4.15). a  decrease  4.16).  compared  abnormal  Associated with  This with  tibiae  i n the decrease  normal may  perwas  birds.  have  been  AGE (Weeks) Figure  4.14  C o n d y l e G r o o v e W i d t h (CGW) o f n o r m a l and t h o s e a f f e c t e d w i t h t w i s t e d l e g The  equations  N,  CGW-  TL,  CGW-  of  the  lines  (N) broilers (TL).  are:  7.33 + 2.3X 0.23X ( ± 0 . 5 2 ) ( ± 0 . 3 0 )  2  ( ± 0 . 0 4 )  8 . 7 5 + 1.34X ( ± 0 . 5 6 ) ( ± 0 . 1 6 )  Slopes are ± Standard  significantly different (p<0.05). E r r o r of E s t i m a t e r= 0 . 9 9 (p<0.05).  77  7.0-  AGE (Weeks)  Figure  A.15  T i b i a l D i a m e t e r (TD) o f n o r m a l (N) b r o i l e r s and t h o s e a f f e c t e d w i t h t w i s t e d l e g ( T L ) . The  equations  N,  TD= 1.9 + 0.95X - 0 . 0 8 X (±0.39) (±0.22)  TL,  of  the  lines  are: 2  (±0.03)  TD= 2 . 9 + 0.55X (±0.37) (±0.11)  Slopes are ±Standard  significantly different (p<0.05). E r r o r of E s t i m a t e r= 0 . 9 9 ( p < 0 . 0 5 ) .  78  Figure  4.16  Percent C o r t i c a l broilers  T h i c k n e s s (PCT) of  and t h o s e  The e q u a t i o n s  of  N,  P C T - 34.84 -  TL,  PCT« 3 3 . 1 3  ( ± 0.B7) -  (±1.5)  affected  the  lines  normal ( N )  with twisted  leg  (TL).  are:  2.61X  (±0.52) 2.09X  (±0.45)  Slopes are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). ± S t a n d a r d E r r o r of E s t i m a t e . r « 0 . 9 9 (p<0.05).-  79  reacting  i n an  associated  to  adaptive  manner t o  reduce  with  the  Pellegrino  and  Blitz  (1983),  radial  bone  growth,  evaluate  formation  on  resorption  the on  the  thickened  cortex  using  f o r the  to  the  chick  no  no  surface  abnormal  relative  a  found  s u r f a c e and  periosteal  i n order  evidence  of  the  tibiae  normal  bone r e s o r p t i o n i n t h o s e  areas  dered  must have been r e d u c e d . .  Presumably  resulted stand  i n an  the  This  diameter  optimum  a  ash  decrease  the  Moreover,  the  may  been with  Results  in tibial  tibia  increase  sociated  in  size  due  ash  may  bone  deformed this  distal  the must  the  same engen-  to  with-  deformity.  abnormal  birds  ( F i g u r e 4.17).  explained  Blitz,  by  the  to t r a n s v e r s e  1983)  or  by  the  epiphyses.  abnormal  noncalcified  tibiae  tissue  as-  that  the  condyle.  experiment  development  of t w i s t e d l e g i n b r o i l e r s  structural  abnormality  i n the  the  cartilaginous  additional  tibia.  coordination  relative  and  the  be  bone  was  able  birds  between n o r m a l and  to the  from  of  with  normal  (Pellegrino  difference  the  age;  for  bone r e s o r p t i o n  a s s o c i a t e d with with  At  the  endosteal  bone  there  where s t r a i n  s t r u c t u r e more  in cortical  relative  have  strains  and  d e c l i n e than  decrease of  tibial  decreased  sharper  overall  relative  formation  functional  Tibial showing  bone  of  acquire  ones,  time,  model  chick  to  bone f o r m a t i o n .  periosteal  bone  evidence  have been i n c r e a s e d p e r i o s t e a l  of  strain  deformation.  endosteal  Therefore,  functional  distal  suggest c o u l d be  tibiae;  related  namely  to a  shallow  80  Figure  4.17  P e r c e n t Ash (PASH) o f n o r m a l (N) b r o i l e r s and those a f f e c t e d with twisted l e g ( T L ) . The  equations  of  N,  PASH= 42.24 -  the l i n e s  (±0.49) TL,  PASH= 43.03 -  (±0.88)  are:  1.59X  (±0.29) 1.88X  ,  (±0.25)  Slopes are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). ± S t a n d a r d E r r o r of E s t i m a t e . r«= 0.99 ( p < 0 . 0 5 ) .  81  distal  condyle  grooves.  may  predispose  the  the  gastrocnemius  distal  condyles.  tibiae  and  istic  distal  With  Other  changes  or  i n  distal  functional  adaptations of  Sequential broilers plasia is  i n the  therefore  more  common  the  bone  the  a  i t is  of  condyle  strain  strain  the  distal  character-  appeared  rather  than  at as the  themselves.  tibiae  realized.  the  (diameter  etc.)  deformation  tibial  on  of  deformations.  width,  at  on  the  morphology  metaphyses  groove  displacement  uneven  (medial)  incidence  that  slight  produces  deviations  high  concluded  a  uneven  groove  radiography  proximal  than  the  tibiae  to  distal  hence  varus  condyle  revealed  to  tarsometatarsus  (lateral)  cause  and  time,  midshaft,  primary  shallow  tibiae  tendon  proximal  valgus  The  from of 3,  clinically  tibial 4,  and  normal  dyschondro5  weeks.  dyschondroplasia  may  It be  CHAPTER  FIVE  SUMMARY AND  A  number  broiler loss  the  leg  leg  factor  1971).  most  present  and  that  ities  widespread  are  stress  factors  n u t r i t i o n abnormalities Twisted deviation leg  of  abnormality  twisted  conditions) A%  (at A  was  weeks)  on,  in  either  from  the  tibia,  both  for  at  the  c l i n i c a l  Cruickshank,  to  a  Few  single of  supported,  the  reared  by  a  reared  abnormal-  strains  and  that  environment signs  medial as  the  However, the in  cages  A weeks; c o n s i d e r a b l y  those  leg  of  or leg  1985).  emerged  trials.  broilers  21%  defined.  of  interaction  and  broiler  characterized  distal  l e g i n the  based  i n commercial  and  poorly  an  National  pathogenesis  attributed  involve  economic  1981;  p r e d i s p o s i t i o n s to  trigger  leg, the  was  derived  (Sim  be  to  hereditary  may  often  in  environment.  study  hypothesis  significant  (Riddell,  and  can  appear  been d e s c r i b e d  e t i o l o g y and  i s complex  nutrition,  The  The  have  cause  industry  abnormalities  and  genetics,  together  poultry  deformities  the  abnormalities  which  Federation.  these of  chickens  for  Turkey  of  CONCLUSIONS  or  lateral  predominant incidence  (under  control  higher  conventionally  of  than in  the  floor  pens. The  morphometric  comparison 82  of  tibiae  from  normal  83  c h i c k e n s and the a  those  development  structural  shallow groove ment  of  condyle  the  progression  of t h e  and  in  the  varus  morphometry o f a f f e c t e d Cage  rearing  of  the  reported  consistently  reduce  the  be  namely  distal  condyle  displace-  resultant  strain  deformations.  by  to r e s u l t  sequential  to  The  from  normal  radiography  tibiae.  i n c i d e n c e of  was  shown  twisted  that  more  leg.  in  this  It  exercise  study  has  was  also  Andrews e t a l . , 1974;  Haye  to  been  needed  i n c i d e n c e of t w i s t e d l e g i n c a g e - r e a r e d  ( R e e c e e t a l . , 1971;  that  related  tibiae,  the  appeared  broilers  increase  may  to a s l i g h t  with  valgus  as e v i d e n c e d  suggest  shallow  tibia  tendon; or  leg  distal The  distal  deformity  remodeling;  the  grooves.  gastrocnemius  conferring  adaptive  twisted  of t w i s t e d l e g i n b r o i l e r s  predispose  the  with  abnormality  distal may  affected  to  broilers  and  Simons,  1978). Results  from  this  study  this  hypothesis.  Difficulty  wire  floors  and  may  (Haye  c o n t r i b u t e an  thus with  aggravate shallow  gained  from  density  cages  and/or  condyle  grooves.  with  Andrews e t a l . ,  1974)  on  the  any  hock  strain  Any  joint  and  associated  benefit  initially  i n t e r m s of i n c r e a s e d e x e r c i s e ( R o d e n h o f f  and  and  1974)  may  hock  accentuate  associated  high  and  the  strain  with  the  1971)  on  1978:  the i n c r e a s e d a c t i v i t y  Damrarich, Sunde,  i n g e n e r a l agreement  i n walking  Simons,  additional  distal  are  joint.  a s s o c i a t e d with  increased t i b i a l have been l o s t This  was  due  evidenced  bone s t r e n g t h  (Meyer  to i n c r e a s e d  stress  by  the  sharp  initial  84  rise  i n incidence  Later,  the  exercise  to  The caused  the  have  reduce  incidence  mannner rise  an  exercise;  However,  more  in in  However,  (associated  produced  result.  the  sharper  decreased  this  l e g i n the  activity  unclear.  muscles  twisted  increased  precise  remains leg  of  effect  may  a  the  be  that  vitamin  similar  i s needed  E  to  that  legs  and  cages.  sufficient  leg.  excess  incidence  namely weaker  research  twisted  which  i t may  with  density  have p r o v i d e d  of  the  high  of  vitamin twisted  myopathy  Dg leg  of  the  deficiency)  may  associated more  with  disorders.  t o more p r e c i s e l y  explain  LITERATURE  CITED  A n d e r s o n , J.O., W a r n i c k , R.E., and N. 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S c i . 11:447-451.  in  Broiler  Wise,  D.R., and A.R. J e n n i n g s , 1973. The D e v e l o p m e n t Morphology of the Growth P l a t e s o f Two Long Bones t h e T u r k e y . Res. V e t . S c i . 14:161-166.  Wise,  D.R., and A.R. J e n n i n g s , D o m e s t i c P o u l t r y . V e t . Rec.  1972. Dyschondroplasia 91:285-286.  and of in  Wolbach, S.B., and D.M. Hegsted, 1952. E n d o c h o n d r a l bone growth i n the C h i c k . AMA, Arch Path., 54(1):1-12. W o l b a c h , S.B., and D.M. H e g s t e d , 1952. in the Duck. Skeletal Growth S y s t e m . A r c h . P a t h o l . 54:548-557.  Vitamin A Deficiency and C e n t r a l Nervous  Young, R.J., Edwards, H.M. J r . , and M.B. G i l l i s , 1958. Studies on Zinc in Poultry Nutrition. 2. Zinc R e q u i r e m e n t and D e f i c i e n c y Symptoms o f C h i c k s . P o u l t r y S c i . 37:1100-1107. Yuile, C.L., Chen, P.S., and A n t i r a c h i t i c Sterols in Chicks. 250.  H.B. Arch.  Bosmann, 1967. P a t h o l . 83:241-  94  APPENDIX  95  Table  Regression B i r d Age.  Analysis  of P r o d u c t i o n Parameters  Square  f o r Diet  over  P>F  df  Mean  1 2 2  1397430.679 0.002 30467.467 202542.110 2202.095  634.59 0.00 13.84 45.99  0.0001 0.9993 0.0001 0.0001  1 2  1138350.364 754.657 1707427.600 1211.020  939.99 0.62 1409.91  0.0001 0.4332 0.0001  1 2  1408.506 0.013 2008.412 70.974  19.85 0.00 28.30  0.0001 0.9890 0.0001  Source  Dependant Variable  I  1  Body Wei ght Model 5 Diet Day*Diet Day *Diet 54 Error 2  Feed Consumption Model Diet Day*Diet Error Incidence of Leg Abnormalities  56  2  Model Diet Day*Diet Error  56  Type I I I SS were used t h e model p a r a m e t e r s .  2  Data  was a r c s i n  to  transformed  calculate  prior  t h e Mean S q u a r e s f o r  to a n a l y s i s .  96  Table Regression An alysis over Bird Age.  of  Source  Dependant Variable  II  Production  df  Mean  Parameters  Square  for  Density  P>F  1  Body Wei ght Model 5 Density Day*Density Day *Density Error 54 2  1 2 2  1405995.28 17.26 30340.22 102037.15 1409.07  997.81 0.01 21.53 72.41  1 2  1143919.52 155.74 1710281.40 912.67  1253.37 0.17 1873.93  1 2 2  904.41 3.23 624.96 249.33 68.11  13.28 0.05 9.18 3.66  0.0001 0.9100 0.0001 0.0001  Feed Consumption Model  3  Density Day*Density Error 56  0.0001 0.6800 0.0001  Incidence of Leg Abnormalities' Model 5 Density Day*Density Day *Density Error 54 2  1  2  Type III the model  Data  was  SS w e r e u s e d components.  arcsin  to  calculate  transformed  prior  to  the  Mean  analysis.  0.0001 0.8200 0.0004 0.0300  Squares  for  97  Table Analysis  Age (Days)  21  28  of  Variance  on  Severity  Model Diet Density D i e t * D e n s i ty Error  3  Model Diet Density Diet*Density Error  3  8  8  1 1 1  1 1 1  Scores  Mean  df  Source  III  .  of  Leg  Square  Abnormalities.  F  P>F  0.52 0.89 0.18 0.58  0.3519 0.3519 0.9075 0.1A08 0.A367  0.81 0.02 2.08 0.32  0.596A 0.2A08 1.5A08 0.0075 0.3825  0.27 1.56 0.63 0.A5 A.03 0.08 0.002 0.89  98 T a b l e IV  Regression Analysis of Body Weight p a r a m e t e r s o v e r age w i t h body w e i g h t as a  Dependant Variable  Body Weight  Source  Model Leg Week*Leg Week *Leg Error  df  Tibial Length  Model Leg Week*Leg Week *Leg BWT Error  Model Leg Week*Leg Week *Leg BWT Error  Model Leg Week*Leg Week *Leg BWT Error Model Leg Week*Leg Week *Leg BWT Error  110015. 622. 333. 73. 301. 4.  2 2 2 1  184. 0. 0. 0. 0. 0.  2 2 2 1  3849. 32. 9. 5. 20. 0.  2 2 2 1  704. 2. 1. 0. 9. 0.  86  7  86  7  2  Tibial Diameter  2 2 2 1  7  2  Condyle Groove Width  22589885. 135130. 242720. 268897. 16655.  87  2  Condyle Groove Depth  2 2 2  6  2  86 7  2  86  Mean S q u a r e  742 984 649 877 443  and Morphometric covariate.  1  F  31 11 57 14  0. 0. 0. 0.  0001 0006 0001 0001  869 2 5 7 1 1 . 08 145. 58 929 374 7 7 . 91 17. 10 149 7 0 . 53 782 279  0. 0. 0. 0. 0.  0001 0001 0001 0001 0001  90 18 20 84 00  0. 0. 0. 0. 0.  0001 0001 0001 0254 0486  866 12554. 43 444 105. 80 667 3 1 . 53 366 17. 50 074 6 5 . 46 307  0. 0. 0. 0. 0.  0001 0001 0001 0001 0001  296 994 623 665 091 179  0. 0. 0. 0. 0.  0001 0001 0003 0282 0001  006 938 785 295 308 077  1356. 8. 14. 16.  P>F  2388. 12. 10. 3. 4.  3938. 16. 9. 3. 50.  15 74 07 72 83  99  Table  IV  ,  Regression parameters  Continued  Model Leg Week*Leg BWT Error  2  2  2  Type III the model Data  df  Source  Percent Ash  Percent Cortical Thickness  previous  page.  Analysis of Body Weight o v e r a g e w i t h body w e i g h t a s a  Dependant Variable  1  from  Model Leg Week*Leg BWT Error  Square  P>F  1  2 2 1  27274.743 4590.285 27.622 11.908 1.014  26910.03 4528.91 27.25 11.75  0.0001 0.0001 0.0001 0.0009  2 2 1  14691.637 3029.488 44.161 24.492 3.123  4704.19 970.03 14.14 7.84  0.0001 0.0001 0.0001 0.0063  88  88  SS were used parameters.  was Arcsin  Mean  and Morphometric covariate.  to calculate  transformed  prior  to  the  Mean  analysis.  Squares  f o r  100 Table  V.  Parameter  Body Weight  Main E f f e c t Means o f V i t a m i n on P r o d u c t i o n P a r a m e t e r s . Bird Age (weeks)  Diet Control  D3 and  Density  2  Excess  Cage  Density  SEM  3  Low  High  4  (g) 1  37.1  36.6  36.9  36.8  0.2  7  148.6  138.7  143.5  143.8  4.4  14  338.1  326.9  338.8  326.1  7.6  21  647.0  645.0  680.6  611.1  18.8  28  966.0  971.7  1018.5  919.2  13.6  7  129.6  117.4  126.3  120.7  4.0  14  292. 7  288.0  298. 5  282. 2  8.8  21  494.3  500.1  530.3  464.2  13.5  28  640.4  669. 5  679. 3  630.6  7.4  1  0  0  0  0  0  7  5:8  5.8  5.0  6.7  1.4  14  7.5  12.5  8.3  11.7  1.7  21  16.7  15.0  13.3  15.8  3.3  28  13.3  25.0  23.3  19.2  2.9  Feed Consumption (g/bird)  % Incidence Leg A b n o r m a l i t i e s  T h e r e were no s i g n i f i c a n t Control supplied  s u p p l i e d 400 ICU v i t a m i n D3 4000 ICU v i t a m i n D3 /kg f e e d .  High D e n s i t y , +/-  Diet*Density  Standard  340 c m / b i r d ; 2  i n t e r a c t i o n s (p>0.05) /kg  Low D e n s i t y ,  E r r o r o f t h e Mean.  feed;  680  Excess  cm /bird. 2  Table VI  Mean Values for Morphometric Parameters, Tibial Ash and % Cortical Thickness  (+ Standard Error of the Mean)  PARAMETERS MEASURED  Bird Age (weeks)  Body Weight (g) N*  Tibial Length (mm)  A*  N  A  Condyle Groove Depth (mm) N  A  Condyle Groove Width (mm)  Tibial Diameter (mm)  Cortical Thickness (%)  Tibial Ash (%)  N  2  337 273 (+/- 6)  61.07 59.30 (+/- 0.27)  2.45 2.10 (+/- 0.02)  12.36 11.00 4.34 4.60 (+/- 0.09) (+/- 0.05)  26.0 27.2 (+/- 0.3)  40.9 39.3 (+/- 0.3)  3  652 494 (+/- 15)  75.59 73.32 (+/- 0.48)  3.19 2.92 (+/- 0.17)  14.60 14.62 5.59 5.87 (+/- 0.11) (+/- 0.06)  26.3 23.5 (+/- 0.5)  41.3 40.0 (+/- 0.3)  4  1029 942 (+/- 14)  89.98 87.87 (+/- 0.25)  3.74 3.70 (+/- 0.05)  16.81 16.82 6.89 6.50 (+/- 0.13) (+/- 0.09)  20.9 20.3 (+/- 0.3)  37.5 37.2 (+/- 0.3)  5  1433 1387 ( + /- 26)  101.70 100.87 (+/- 0.60)  4.06 3.97 (+/- 0.04)  18.76 19.77 8.38 8.93 (+/- 0.11) (+/- 0.10)  20.5 21.2 (+/- 0.6)  37.1 35.5 (+/- 0.2)  6  1984 1176 (+/- 39)  116.27 101.80 (+/- 0.78)  4.86 4.00 (+/- 0.07)  20.49 20.10 9.61 8.62 (+/- 0.18) (+/- 0.13)  19.7 18.4 (+/- 0.5)  37.7 32.6 (+/- 0.4)  N,  normal b i r d s ;  A, abnormal  birds.  

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